Abstract: The spinal column is the load-bearing structure of the human being along with its components, which together build a strong, resistant, and stable structure, but there are a few different pathologies from which it can suffer, such as herniated discs. The intervertebral disc acts as a shock absorber and ensures the spine’s great capacity to support high loads and different states of stress, thanks to its viscoelastic properties. Some studies have attempted to describe the viscoelastic behaviour of the intervertebral disc using classical rheological models, such as the Kelvin-Voigt, or multi-parameter models. Even if these models partially describe the viscoelastic response of disc, all viscoelastic characteristics are not fully captured. This article aims to present the current studies on the biomechanics of intervertebral disc and to introduce a new approach using the powerful mathematical tool of fractional calculus. With fractional rheological models, it could be possible to formulate a fractional law that can fully describe the viscoelastic behaviour of the intervertebral disc. This new approach could lead to a breakthrough in the study of herniated pathologies by understanding how the intervertebral disc is damaged and identifying strategies to deal with these pathological problems.

Keywords: Biomechanics | Fractional calculus | Fractional rheological model | Intervertebral disc | Spinal column | Viscoelastic behaviour

Abstract: The growing attention of people to aesthetics has led to a greater demand for dental whitening treatments. Several solutions can be utilized to obtain the desired visual whiteness of teeth but, according to literature, at-home supervised treatments are the standard in dental bleaching. They require soft plastic trays to contain a whitening gel, with active chemical agents, and keep it in contact with the patient’s teeth. The fitting, comfort, and tightness of trays play a fundamental role in the treatment. Any gel leakage can compromise the effectiveness of the treatment and damage soft tissues. Commonly, the trays are ready-made or based on physical dental impressions and manually modified by the dental technician. These procedures have low repeatability and do not always ensure high accuracy. This work presents an automatic digital algorithm to design customized whitening trays. Starting from a digital scan acquisition of the patient’s dental arches, it generates the 3D models of the bespoke trays, in approximately two minutes per arch, ready to be produced by additive manufacturing and thermoforming technologies. The evaluation of the method involved 20 patients. The results emphasize that the custom trays were comfortable and ensured high levels of tightness and fitting.

Keywords: automatic product design | custom teeth trays | dental whitening | digital process

Abstract: This work aims at the development of a streamlined and robust CAD procedure to design load-bearing implants. The methodology used to reach this result is explained in the paper: 3D digital anatomy reconstruction of defective structures of the patient is performed with the help of a statistical shape model; subsequently, a CAD modelling tool based on implicit modelling (i.e., nTopology) is used to implement a repeatable semi-automatic procedure that can be performed by a competent user with little effort and limited manual operations. Once that the main shape of the implant is defined, lattice geometries are generated to improve mechanical properties of the implant. The procedure requires as inputs the reconstructed anatomy of the patient and a series of clinical indications on the type of implant that needs to be designed. The paper discusses the development of the whole procedure; achieved results, which include the application of the whole framework on multiple case studies, are presented. The procedure allows the design of a whole implant in 20 minutes circa.

Keywords: CAD Design Automation | Custom Implant; Additive Manufacturing | Implicit Modelling | nTopology

Abstract: Due to the increasing number of people with severe obesity, the demand for patient-specific modelling in bariatric surgery (BS) is increasing because its potentialities in the improvement of surgical planning, optimization of outcomes and prediction of the mechanical response of the stomach. However, the patient-specific anatomical reconstruction is a pivotal and often time-consuming step due to the lack of efficient and fully automatized tools. Ongoing studies on multi-organ segmentation methods based on neural networks for magnetic resonance images (MRI) are currently available, but they have still several limits, mainly due to both the highly flexible individuals anatomical properties, and convolutional neural networks (CNN) trained only in the detection of physiological stomachs. The aim of this work is to perform a convenient transfer learning from a general-purpose CNN, able to improve the performance in automatically detecting the stomach region of patients with severe obesity. The proposed approach represents the basis for the development of pre- and post-surgical computational models for rapid clinical analysis, especially to boost the mechanical stimulation of gastric receptors. The segmentation masks and the corresponding 3D models were compared with the corresponding manual MRI segmentation as ground truth. Intersection Over Union (IOU) and DICE coefficients (DICE) were used to evaluate 2D masks segmentation, while the Relative Volume Error (RVE), mean surface distance (MSD), standard deviation and the Normalised Hausdorff distance (NHD) were applied to assess the obtained 3D results.

Keywords: Bariatric surgery | Image segmentation | MRI | Stomach

Abstract: Additive manufacturing allows the creation of highly customized and complex objects that could not be achieved with traditional methods. These characteristics of the production method make the products perfectly suitable for the design of orthotics, where the customization of the device and the speed of production are essential. For example, it may be necessary to create locally more or less rigid orthose depending on the anatomic area or its local function. The 3D printing of objects can be performed with variable properties within their domain by means of the so called Functionally Graded Additive Manufacturing (FGAM). This article presents a new method for the production of reticular orthoses which begins with the acquisition of the area of interest using a 3d scanner, followed by the generation of the reticular structure locally densified according to ergonometric models, and the finalization of the model with truss thickening and application of a closure system. Some models were then reproduced with AM techniques such as SLA and MJF and tested in daily use.

Keywords: Additive manufacturing | Custom manufacturing | Functionally graded materials | Orthotics

Abstract: Tip steering by induced deformation constitutes one of the most prominent feature to effectively navigate constrained environments with soft growing robots. In this work, we analyze the effects of design parameters on the tip steering capabilities of pneumatically-actuated soft growing robots built from fabric. More specifically, we consider the variability of material, fabric Pneumatic Artificial Muscles (fPAM) diameter, and backbone internal pressure and statistically quantify the effect on the maximum curvature achieved by the robot when a constant fPAM input pressure is applied. In our considered settings, we found a statistically significant main effect (p<0.05 ) of the fPAM diameter and a relevant interaction effect between this and the material factor. These findings provide useful guidelines for the design of fabric-based PAM-actuated soft growing robots with enhanced tip steering capabilities.

Keywords: Design of bioinspired soft robots | Soft actuators | Soft robotics

Abstract: Over the past years, a wide range of dental implants has been proposed. In general, the dentists may find the best solutions according to the specific needs of the patients. A variety of factors influences the level of osseointegration and, consequently, the anchorage of the implant to the bone. The stress transfer mechanism along the bone-implant interface depends upon the surface area of the bone-implant contact. Great efforts have been devoted to the design of 3D porous lattice structures with tailored architectural features in order to reduce the implant stiffness as well as to favour bone ingrowth, thus stabilizing the device. Accordingly, the aim of the current study was to provide further insight into the design criteria for dental implants. In particular, starting from a screw implant (Implant A), different concepts of dental implants were developed: i) Implants B1–B5, with lattice shell surrounding a solid core, without thread; ii) Implant C, with lattice structure; iii) Implant D as topography optimized implant. Finite element analysis on the several models of bone-implant provided interesting information in terms of stress distributions in cortical and trabecular bone. Some differences among the implants may be ascribed to the different design criteria.

Keywords: Dental implants | Design criteria | Finite element analysis | Lattice structure | Topography optimization | Topology optimization

Abstract: Preface and Acknowledgements (Editorial)

Keywords: Editorial

Abstract: Objective and reliable assessment of motor functions, such as dexterity, is a key point for evaluating worker’s abilities. In this context, the proposed work presents a tool for objective automatic assessment of the Minnesota Dexterity Test using cameras with depth sensors. Typical performance measurements (i.e., total time and associated percentiles) were estimated using custom algorithms. In addition, the possibility to identify the qualifiers for the code d440 of the International Classification of Functioning, Disability and Health was implemented in the developed algorithms. The proposed tool can also identify the mistakes most frequently committed by the subjects. To prove the capabilities of the proposed method, a series of experimental trials was conducted with 10 healthy young volunteers. Results showed that the developed tool helps clinicians to obtain performance feedback and evaluate patients’ dexterity quickly without bias.

Keywords: Automatic assessment | Biomechanics | Depth cameras | Manual dexterity | Motion capture

Abstract: This paper proposes a systematic approach for involving the clinicians in the design of medical devices, here used for the development of a soft robotic glove for rehabilitation. The approach considers the integration of different methodologies that take into account the emotional information of the clinicians considered as end–users (i.e. Kano–Kansei) and a deep analysis of the needs of both the patients and the clinicians (i.e. house of quality). Based on this user–centered approach, the paper develops different rehabilitation concepts realized through the technique referred to as design of experiments. Finally the optimal one is chosen re–involving the clinicians and using the ANOVA analysis.

Keywords: Hand rehabilitation | Product development | Soft robotics | User-centred design

Abstract: The study of predictive models describing the biological processes relating extra-cellular mechanical stimuli to structural responses of living cells, or even a differentiation, as in the case of mesenchymal stem cells (MSCs), is a relevant aspect in mechanobiology. A preliminary phase for these studies is the assessment of the mechanical behavior of whole living cells or their subcellular components, often performed by means of Atomic Force Microscopy (AFM). In this study we developed a numerical optimization framework aiming at matching the computed results obtained from a sequence of FEM simulations to an experimental AFM report curve associated to a MSC under investigation, in order to extract the elastic parameters of subcellular components and to assess how the mechanical response changes if the stress fibers network present in the interior of the cell is activated or not. By means of the proposed study, we extracted a set of Young’s moduli for the main subcellular components, which resulted comparable to the values computed by means of the Hertzian contact theory, and was also in good agreement with the related literature. By neglecting the effect of the tensioning pre-stress field induced by the stress fibers network, an underestimation of the Young’s moduli of subcellular components, up to a 15% in magnitude, was obtained.

Keywords: Finite element method | Mechanical simulation | Mechanobiology | Stem cells | Stress fibers

Abstract: Tracheomalacia (TM) is a tracheal weakening that causes the cartilage structure to collapse during breathing. The term tracheobronchomalacia (TBM) is used when the bronchi are also implicated in the disease. This illness can be treated in a variety of methods, including the insertion of stents in the cartilage-restricted region. Stents are commercially available in numerous sizes (diameter and length), different shapes and materials. The shape of the stent is chosen based on where the disease is located, while the size is derived from measurements on CT images or by endoscopic investigations. This task is extremely critical for the patient's health since improper stent can have serious and even deadly repercussions for the patient. Therefore, it is necessary to choose a stent that fits the patient's anatomy as closely as possible. To this end, it is possible to employ a three-dimensional model of the investigated anatomy and choose the most suitable type of stent following measurements made on the model itself. In this work, a method to assist physicians in the choice of the stent to be used in TM or TBM patients, is proposed. By analyzing the tracheobronchial tree and measuring successive cross-sections along the centerline of the lumen, the automated procedure allows to localize the diseased area and to identify the optimal shape and size of the stent to be implanted. Four case studies of paediatric patients were performed and the results were validated by a team of physicians specialized in the treatment of upper and lower airways.

Keywords: 3D modelling | Airway obstruction | Reverse engineering | Stent

Abstract: When dealing with craniofacial impairments, restoring the morphological condition is as crucial as restoring the functional ones to avoid psychosocial disabilities for the patient. For this aim, the accurate location of the midsagittal plane is essential for performing reliable symmetry analyses and guiding effective surgery planning. To provide a fully automatic and landmark-independent approach, capable of providing a midsagittal plane for craniofacial skeleton even from anatomical models with high asymmetries, an innovative method, called MaWR-method, was developed by the authors in a previous work. This paper further investigates the MaWR-method by evaluating its capacity to produce a successful outcome even in the worst-case scenario that may be considered in maxillofacial surgery, namely panfacial fractures. In all the test cases considered in this work, the method proved robust and reliable in its original design. It provided a consistent result requiring no user involvement, even when dealing with extreme asymmetries because of extensive and complex fractures.

Keywords: Feature recognition | Mid-sagittal plane | Symmetry analysis | Symmetry plane detection

Abstract: In this paper, a semi-automatic procedure to perform point clouds registration is presented. The method was developed for upper limb 3D scanning. During the acquisition, several frames are acquired from different points of view, to obtain a full 360° acquisition of the arm. Each frame stores both the point clouds coordinates and the corresponding RGB image. During post-processing, the RGB image is elaborated through a neural network, to detect relevant key points of the hand, which are then projected to the point clouds. The corresponding key points detected from different acquisitions are then used to automatically obtain a rough 3D rotation that aligns the point clouds corresponding to different perspectives in a common reference frame. Finally, the registration is refined through an iterative closest point algorithm. The method was tested on actual arm acquisitions, and the registration results are compared with the conventional fully manual 3-2-1 registration procedure, showing promising results of the proposed method.

Keywords: Neural network | Semi-automatic registration | Upper limb 3D scan

Abstract: The orbital walls and floor are common sites of facial bone fracture and may cause severe functional impairment. The complex geometry of the bony orbit makes anatomical reconstruction extremely challenging, with main issues related to the implant’s correct shaping, positioning, and orientation inside the orbital cavity. This study proposes an innovative medical device to place patient-specific implants in fractured eye sockets properly. The device must be used with the developed improved version of a tailored implant shaping mould. The design of the orbital implant positioner followed specific clinical and technical requirements and specifications investigated through the Quality Function Deployment method. The device has been conceived to be simple, economical, capable of managing deantigenated bones or titanium meshes for orbital floor and wall, and reusable multiple times. The positioner consists of two handles hinged together and adequately coupled by a spring to allow the grasping and placing of the implant. Positioner and mould have been manufactured in polyamide using the Selective Laser Sintering technique. The system accuracy assessment resulted in promising outcomes. The mould can precisely shape the implant with a lower than 0.1 mm deviation. The implant positioner can place the implant with a rotation angle around the orbital rim of barely 7.1° and 1.2 mm deviation in the mediolateral direction (no deviations in the anteroposterior and superior-inferior directions occur)

Keywords: Computer-aided design | Craniomaxillofacial surgery | Implant design | Medical devices | Rapid prototyping

Abstract: These authors presented an automatic computer-based method for morphological feature segmentation and recognition for thoracic and lumbar human vertebrae in a previous paper. The method analyses high-density discretized models by segmentation and recognition rules codifying the vertebra morphology information, which does not change between different subjects. The methodology has been demonstrated to be valid and repeatable in segmenting and recognizing morphological features of vertebrae. The proposed one gives repeatable and reproducible results concerning the traditional manual methods. Nonetheless, the method has been tested only on human lumbar and thoracic vertebrae without distinctive pathologies. This paper aims to extend this methodology for much wider use by analyzing single vertebrae affected by common defectiveness in archaeological and medical fields. The results of the experimentations, analyzed by a skilled anthropologist and radiologist, show that the method correctly segments the analyzed morphological features, also for thoracic and lumbar vertebrae with defectiveness: in particular, defects that alter the shape of features or the symmetry of the vertebra, determine the absence of a feature, or heavily change the spatial distribution of the anterior part respect to the posterior one, have been analyzed.

Keywords: 3D medical image analysis | Feature recognition | Thoracic and lumbar vertebrae analysis | Vertebrae analysis computer-based methods

Abstract: In the field of medical image processing, the resolution capacity exhibited by the initial diagnostic investigations is becoming increasingly important. With respect to them, in fact, the row image set is subjected to three-dimensional reconstruction analysis, by partitioning the regions of interest, as well as to local investigations, aimed, for example, at the extrapolation of topological information, relating to the morphology of the object that needs to be investigated. The accuracy of these functions is, however, difficult to quantify, due to the lack of three-dimensional models that act as a reference Gold Standard. The reproduction of CT-type diagnostic acquisitions, starting from a virtual scanning procedure of a starting known three-dimensional geometry is used. To do this, triangular tessellated three-dimensional models of various geometries were examined. These were broken down into cubic elements, equal in size to those of a common voxel, thus resulting in a volume scan simulation of the original region considered. The structure thus obtained was then subjected to skeletonization and medial axis algorithms to evaluate the effectiveness of some of the most commonly used functions in medical processing. A virtual scanning model of this type can be an extremely effective evaluation analysis tool in discriminating the resolutive quality of the medical image processing functions. From a qualitative comparison of this type, it is possible to optimize automated anatomical investigation algorithms, making a significant contribution in the refinement of the techniques, now more and more demanding, of image processing in the biomedical field.

Keywords: Medical image acquisition | Thinning and Medial Axis | Voxelization

Abstract: The demand for orthodontic and aesthetic treatments, aimed at having healthier teeth and more beautiful smiles, is increasingly growing. The devices on which these treatments are based must be rigorously bespoke for each patient. This is amplifying the need to develop digitized workflows, ranging from scanning to Additive Manufacturing (AM). The present work proposes an alternative workflow for designing and manufacturing orthodontic aligners, also known as clear aligners, starting from the intraoral scanning of the patient’s dentition. Orthodontic aligners are an alternative to metal brackets to correct dental malocclusions and they are often preferred by the patients because of their lower impact on facial aesthetics and for their higher comfort. The orthodontic treatments based on the aligners utilize a series of aligners, each one with a geometry slightly different from the previous one. The use of the single aligners is aimed to apply a force to the teeth and gradually aligning them until the end of the treatment. The workflow we propose in the present study is based on the following three main stages: intraoral scanning of the patient’s dentition, design of the aligners through a semi-automatic algorithm, and the direct additive manufacturing of the aligners through VAT photopolymerization technique. The possibility to directly additive manufacturing the aligners allows us to rethink the current orthodontic treatments. The aligners geometry can be re-designed, with the possibility of locally manipulating the thickness. This approach would allow the regulation of the amount of force applied locally to the tooth, thus optimizing the treatment and its duration. A feasibility study of the proposed workflow is reported in the present paper, with a focus on the semi-automatic design algorithm and on the additive manufacturing process of the aligners.

Keywords: Additive Manufacturing | Bespoke Medical Devices | Dental Appliances | Design Algorithms for Medical Applications | DfAM

Abstract: The human hand is a versatile and complex body part. It permits difficult movements with various degrees of precision and force. Several causes can lead to upper limb damage, including musculoskeletal disorders and diseases like stroke. The impairment can affect daily living activities. Patients usually undergo rehabilitation therapy with medical personnel for a long time after the traumatic event. In most cases, they use off-the-shelf medical devices. However, the shape of the upper limbs can differ a lot among people. A bespoke rehabilitative device could provide better comfort and usability, but the design process can be challenging. This work aims to present a digital workflow to generate a 3D virtual reconstruction of the patient’s upper limb structure, to be used in the device design. Starting from a 3D scan acquisition of the patient’s upper limb, the algorithm allows the creation of a polygonal mesh of the arm and the hand by a semi-automatic procedure. The algorithm uses neural networks’ capability to automatically detect the upper limb’s landmarks to localize the joints’ coordinates. The joints’ positions can be used to build a virtual skeleton for a 3D model of a human arm. The mesh of the model is subsequently wrapped around the scan of the real arm. The output consists in the 3D rigged model of the patient’s upper limb with a manifold mesh that can be deformed using its virtual skeleton. The results have been assessed with patients who had sports injuries or strokes. The 3D deviations between the scan acquisition of the arm and the resulting model have been evaluated.

Keywords: 3D scan | 3D virtual reconstruction | automatic landmarks detection | neural network | upper limb rigged model

Abstract: In the field of optical 3D scanning for healthcare applications, low-cost depth cameras can be efficiently used to capture geometry at video frame rates. However, the complete reconstruction of anatomical geometries remains challenging since different scans, collected from multiple viewpoints, must be aligned into a common reference frame. This paper proposes a fully automatic procedure to align scans of the upper limb patient’s anatomy. A 3D optical scanner, obtained by assembling three depth cameras, is used to collect upper limb acquisitions. A relevant dataset of key points on the hand and the forearm geometry is then determined and used to automatically obtain a rough 3D alignment of the different scans. Hand key points are identified through a neural network, which works on RGB images captured by the depth cameras; forearm key points are recognized by directly processing the point clouds through a specifically designed algorithm that evaluates the skeleton line of the forearm. The approach was tested on forearm acquisitions, and the results were compared to alternative alignment methodologies.

Keywords: 3D optical scanning | automatic point clouds alignment | depth cameras | upper limb anatomy

Abstract: The treatment of burn scars is a much discussed and sensitive topic because an improper therapy can have a significant impact on the quality of people's lives. To accurately assess both the health of scars and the outcomes of treatment, the medical evaluation should be based on objective measurements of progression over time. To overcome the limitations of subjective assessment is to leverage, 3D scanning technologies can be used to acquire topological information about the lesions and extract a set of relevant statistical parameters describing them. Accordingly, the present work aims at addressing both efficiency and reliability of a preliminary method based on the objective investigation of the surface topography of burn scars by applying it on several patients of the Meyer Children's Hospital burns department. A commercial 3D scanner is used to acquire 3D data relative to the scars of five patients. By applying a method based on the computational analysis of scan data, a significant number of roughness-related parameters are retrieved. This information is used to create a coherent dataset that allows the severity of burn scars to be inferred objectively. The developed method facilitates the evaluation of treatment efficacy by assessing wound healing during follow-up visits.

Keywords: 3D scan | Burn scar | Surface roughness

Abstract: Analyzing pathological movements can substantially help neurologists in the diagnosis and treatment improvement for patients with Parkinson’s disease (PD). A linkage between the intensity and characteristics of moving and walking disorders and the stage and types of PD can be actually established. The main aim of this study is to develop an effective methodology that allows to evaluate, in real time and / or in deferred time, movements and posture of PD patients in their usual living environments. For this purpose, a wearable suit with Inertial Measurement Unit (IMU) sensors was designed; it has made it possible to acquire linear and angular signals of displacement, velocity and acceleration of the most relevant body points of the patients. The filtered and integrated signals were then used to animate a human parametric multibody model that virtually reproduces in real time and / or in deferred patient’s movements and posture. Serving as the patient's “avatar”, the multibody model enables the neurologist to carry out an accurate assessment of the patient’s movements and posture (freezing, festination, postural balance) as well as to measure disease progression and response to interventions. If compared to traditional 3D video-based motion analysis systems, the proposed method has the advantage of providing a more accurately measurable patients movements analysis and comparison performed in their usual living environments in real-world conditions.

Keywords: 3D posture analysis | Human parametric multibody model | Inertial Measurement Unit sensors | Motion recognition algorithms | Parkinson’s disease movements

Abstract: Nowadays the rehabilitation process involves the patient and the therapist, that must interact to recover the motion of limbs and the strength of related muscles to restore the initial functionalities. The therapy relies on the experience and sensitivity of the therapist that identifies the rehabilitation exercises which are necessary to recover the expected ability. To prevent inappropriate practices an interesting aid may come by mixing collaborative robots, namely Cobots, and additive manufacturing technologies. The proper integration of a Cobot assistant and custom-printed training objects enables a significant improvement in the effectiveness of the therapy action and the related user experience since the programmed trajectories can mimic the movements related to activities of daily living. To this aim, this work describes an integrated approach to support the design of Cobot assisted rehabilitative solutions. The object selected by the patient and therapist, the motion pattern, the clamping area, and loads on the limb represents the design requirements. The motion trajectories defining the specific training tasks are the starting point to the optimal placement within the Cobot workspace. Specifically, manipulability maps can provide an objective evaluation of the locations where the exercises are performed at the best of workspace and configuration of the Cobot. A simple upper limb rehabilitation exercise based on a demonstrative handle has been selected to prove the effectiveness of the proposed approach. The results confirm that the manipulability index can be adopted to drive the preliminary design of the Cobotic solution toward a feasible configuration.

Keywords: Assisted Rehabilitation | Cobot | Integrated Design | Manipulability Index | Occupational Therapy

Abstract: The 3D reconstruction of upper limb anatomy plays a significant role in many biomedical fields such as ergonomics, motion rehabilitation, and prosthesis design. In the last few years, the technical advancement of consumer-grade depth cameras has supported the development of portable and low-cost optical 3D body scanners for healthcare applications. The real-time scanning of human body parts, however, still represents a complex task due to the non-stationary nature of the scanning target. This issue imposes that the scanning time must be reduced as much as possible to minimize scanning artifacts. In this regard, depth cameras can capture geometrical information at video frame rates, thus guaranteeing fast acquisition times. Furthermore, the simultaneous use of multiple sensors would minimize undercut geometries, which impair the 3D reconstruction’s completeness. In this work, a portable 3D optical scanner has been developed by rigidly assembling three Intel® RealSense™ D415 depth cameras on a lightweight circular frame. The three sensors are mutually calibrated, by using a 3D printed calibration specimen, to simultaneously align acquisitions from the three different camera viewpoints for each scanner pose. The system’s effectiveness has been assessed by acquiring the geometry of both a plaster hand and a human hand and comparing the results with those obtained by a high-end stationary structured light scanner. The developed system represents a low-cost handheld alternative to existing body scanners for collecting and storing 3D anatomical data, which can be used in the design process of bespoke medical devices.

Keywords: 3D optical scanning | D415 Intel® RealSense™ | Depth-camera | Upper Limb Reconstruction

Abstract: In response to rapid population ageing, digital technology represents the greatest resource in supporting the implementation of active and healthy ageing principles at clinical and service levels. However, digital information platforms that deliver coordinated health and social care services for older people to cover their needs comprehensively and adequately are still not widespread. The present work is part of a project that focuses on creating a new personalised healthcare and social assistance model to enhance older people’s quality of life. This model aims to prevent acute events to favour the elderly staying healthy in their own home while reducing hospitalisations. In this context, the prompt identification of criticalities and vulnerabilities through ICT devices and services is crucial. According to the human-centred care vision, this paper proposes a decision-support algorithm for the automatic and patient-specific assignment of tailored sets of devices and local services based on adults’ health and social needs. This decision-support tool, which uses a tree-like model, contains conditional control statements. Using sequences of binary divisions drives the assignation of products and services to each user. Based on many predictive factors of frailty, the algorithm aims to be efficient and time-effective. This goal is achieved by adequately combining specific features, thresholds, and constraints related to the ICT devices and patients’ characteristics. The validation was carried out on 50 participants. To test the algorithm, its output was compared to clinicians’ decisions during the multidimensional evaluation. The algorithm reported a high sensitivity (96% for fall monitoring and 93% for cardiac tracking) and a lower specificity (60% for fall monitoring and 27% for cardiac monitoring). Results highlight the preventive and protective behaviour of the algorithm.

Keywords: decision-support algorithm | digital health | elderly | healthy ageing | personalised care | wearable sensors

Abstract: Artificial limbs can help people missing body parts to restore some of their daily-life activities. However, the user should spend up to a few months to intuitively control the new device. During this period, she/he may suffer pain due to wearing or using the prosthesis inappropriately. This research presents a virtual simulator that allows the user to carry out training sessions for controlling the prosthesis. A set of Surface Electromyographic (sEMG) sensors are used to acquire the signals from user's muscles and send them to a recognition algorithm that interprets the patient's intentions. Simultaneously, the patient observes the response of her/his device on the simulator. Two studies are presented: the first study evaluate the performance of three different recognition algorithms i.e., Linear Discriminant Analysis (LDA), Support Vector Machine (SVM), and Multi-Layer Perceptron (MLP), based on the successful recognition of the patient's intentions. The second study investigates the least number of sEMG sensors to be used, as having less components improves the patient's wearability and decreases the processing time. The developed simulator represents a real prosthetic device, PRISMA hand II. The results showed the superiority of the MLP with 80% of successful recognition when 6-sEMG sensors are used. If a reduced set of gestures is considered (frequently needed by the patient), 90% of successful recognition could be achieved. Less sEMG sensors significantly degraded the performance of the recognition algorithm as only 53.8% of successful recognition could be achieved. All experiments were conducted with the help of a patient with below-elbow amputation.

Keywords: Active prosthetic hand | Biomechatronic application | Multi-Layer Perceptron (MLP) | Pattern recognition | Rehabilitation robotics | sEMG signal processing

Abstract: PURPOSE. Digital technology has enabled improvements in the fitting accuracy of denture bases via milling techniques. The aim of this study was to evaluate the trueness and precision of digital and analog techniques for manufacturing complete dentures (CDs). MATERIALS AND METHODS. Sixty identical CDs were manufactured using different production protocols. Digital and analog technologies were compared using the reference geometric approach, and the Δ-error values of eight areas of interest (AOI) were calculated. For each AOI, a precise number of measurement points was selected according to sensitivity analyses to compare the Δ-error of trueness and precision between the original model and manufactured prosthesis. Three types of statistical analysis were performed: to calculate the intergroup cumulative difference among the three protocols, the intergroup among the AOIs, and the intragroup difference among AOIs. RESULTS. There was a statistically significant difference between the dentures made using the oversize process and injection molding process (P <.001), but no significant difference between the other two manufacturing methods (P =.1227). There was also a statistically significant difference between the dentures made using the monolithic process and the other two processes for all AOIs (P =.0061), but there was no significant difference between the other two processes (P = 1). Within each group, significant differences among the AOIs were observed. CONCLUSION. The monolithic process yielded better results, in terms of accuracy (trueness and precision), than the other groups, although all three processes led to dentures with Δ-error values well within the clinical tolerance limit.

Keywords: CAD-CAM | Complete denture | Digital denture | Digital workflow | Reference geometry measurement

Abstract: The Heavy Ion Therapy Research Integration plus (HITRIplus) is an European project that aims to integrate and propel research and technologies related to cancer treatment with heavy ion beams. Among the ambitious goals of the project, a specific work package includes the design of a gantry for carbon ions, based on superconducting magnets. The first milestone to achieve is the choice of the fundamental gantry parameters, namely the beam optics layout, the superconducting magnet technology, and the main user requirements. Starting from a reference 3 T design, the collaboration widely explored dozens of possible gantry configurations at 4 T, aiming to find the best compromise in terms of footprint, capital cost, and required R&D. We present here a summary of these configurations, underlying the initial correlation between the beam optics, the mechanics and the main superconducting dipoles design: the bending field (up to 4 T), combined function features (integrated quadrupoles), magnet aperture (up to 90 mm), and angular length (30° – 45°). The resulting main parameters are then listed, compared, and used to drive the choice of the best gantry layout to be developed in HITRIplus.

Keywords: Heavy ions | Ion beams

Abstract: This paper presents a collaborative platform developed to allow the communication between surgeons and engineers in the process of designing patient-specific surgical instruments. To date, only a few applications are available to collaboratively create surgical instruments from medical 3D models, mostly dedicated to expert CAD modelers. This makes the preoperative planning process time-consuming and inefficient limiting the usability of applications and making planning difficult and inaccurate. Accordingly, we propose a solution in the form of a web-based, interactive, extendable, 3D navigation and manipulation application, called Precise, which does not require client installation. Precise is a lightweight, high-performance application built to provide easy-to-use, powerful, on-demand visualization and manipulation of 3D images, implemented using open-source libraries.

Keywords: 3D manipulation | Medical application | Rapid prototyping | Surgical planning

Abstract: Background and objective: The ability to accomplish a consistent restoration of a missing or deformed anatomical area is a fundamental step for defining a custom implant, especially in the maxillofacial and cranial reconstruction where the aesthetical aspect is crucial for a successful surgical outcome. At the same time, this task is also the most difficult, time-consuming, and complicated across the whole reconstruction process. This is mostly due to the high geometric complexity of the anatomical structures, insufficient references, and significant interindividual anatomical heterogeneity. Numerous solutions, specifically for the neurocranium, have been put forward in the scientific literature to address the reconstruction issue, but none of them has yet been persuasive enough to guarantee an easily automatable approach with a consistent shape reconstruction. Methods: This work aims to present a novel reconstruction method (named HyM3D) for the automatic restoration of the exocranial surface by ensuring both the symmetry of the resulting skull and the continuity between the reconstructive patch and the surrounding bone. To achieve this goal, the strengths of the Template-based methods are exploited to provide knowledge of the missing or deformed region and to guide a subsequent Surface Interpolation-based algorithm. HyM3D is an improved version of a methodology presented by the authors in a previous publication for the restoration of unilateral defects. Differently from the first version, the novel procedure applies to all kinds of cranial defects, whether they are unilateral or not. Results: The presented method has been tested on several test cases, both synthetic and real, and the results show that it is reliable and trustworthy, providing a consistent outcome with no user intervention even when dealing with complex defects. Conclusions: HyM3D method proved to be a valid alternative to the existing approaches for the digital reconstruction of a defective cranial vault; furthermore, with respect to the current alternatives, it demands less user interaction since the method is landmarks-independent and does not require any patch adaptation.

Keywords: Bioinformatics | Computed aided design | Cranioplasty | Statistical shape model | Surface Interpolation

Abstract: Background: The functional results of total elbow arthroplasty (TEA) are controversial and the medium- to long-term revision rates are relatively high. The aim of the present study was to analyze the stresses of TEA in its classic configuration, identify the areas of greatest stress in the prosthesis–bone–cement interface, and evaluate the most wearing working conditions. Materials and methods: By means of a reverse engineering process and using a 3D laser scanner, CAD (computer-aided drafting) models of a constrained elbow prosthesis were acquired. These CAD models were developed and their elastic properties, resistance, and stresses were studied through finite element analysis (finite element method—FEM). The obtained 3D elbow-prosthesis model was then evaluated in cyclic flexion–extension movements (> 10 million cycles). We highlighted the configuration of the angle at which the highest stresses and the areas most at risk of implant mobilization develop. Finally, we performed a quantitative study of the stress state after varying the positioning of the stem of the ulnar component in the sagittal plane by ± 3°. Results: The greatest von Mises stress state in the bone component for the 90° working configuration was 3.1635 MPa, which occurred in the most proximal portion of the humeral blade and in the proximal middle third of the shaft. At the ulnar level, peaks of 4.1763 MPa were recorded at the proximal coronoid/metaepiphysis level. The minimum elastic resistance and therefore the greatest stress states were recorded in the bone region at the apex of the ulnar stem (0.001967 MPa). The results of the analysis for the working configurations at 0° and 145° showed significant reductions in the stress states for both prosthetic components; similarly, varying the positioning of the ulnar component at 90° (− 3° in the sagittal plane, 0° in the frontal plane) resulted in better working conditions with a greater resulting developed force and a lower stress peak in the ulnar cement. Conclusion: The areas of greatest stress occur in specific regions of the ulnar and humeral components at the bone–cement–prosthesis interface. The heaviest configuration in terms of stresses was when the elbow was flexed at 90°. Variations in the positioning in the sagittal plane can mechanically affect the movement, possibly resulting in longer survival of the implant. Level of evidence: 5

Keywords: Biomechanics | Elbow finite element | Elbow replacement | Prosthetic posizioning | Totel elbow arthroplasty

Abstract: PURPOSE. The aim of this study is to evaluate the accuracy of removable partial denture (RPD) frameworks produced using different digital protocols. MATERIALS AND METHODS. 80 frameworks for RPDs were produced using CAD-CAM technology and divided into four groups of twenty (n = 20): Group 1, Titanium frameworks manufactured by digital metal laser sintering (DMLS); Group 2, Co-Cr frameworks manufactured by DMLS; Group 3, Polyamide PA12 castable resin manufactured by multi-jet fusion (MJF); and Group 4, Metal (Co-Cr) casting by using lost-wax technique. After the digital acquisition, eight specific areas were selected in order to measure the Δ-error value at the intaglio surface of RPD. The minimum value required for point sampling density (0.4 mm) was derived from the sensitivity analysis. The obtained Δ-error mean value was used for comparisons: 1. between different manufacturing processes; 2. between different manufacturing techniques in the same area of interest (AOI); and 3. between different AOI of the same group. RESULTS. The Δ-error mean value of each group ranged between -0.002 (Ti) and 0.041 (Co-Cr) mm. The Pearson’s Chi-squared test revealed significant differences considering all groups paired two by two, except for group 3 and 4. The multiple comparison test documented a significant difference for each AOI among group 1, 3, and 4. The multiple comparison test showed significant differences among almost all different AOIs of each group. CONCLUSION. All Δ-mean error values of all digital protocols for manufacturing RPD frameworks optimally fit within the clinical tolerance limit of trueness and precision.

Keywords: Accuracy | CAD-CAM | Digital framework | Metrological measurements | Removable partial denture

Abstract: According to previous research, shore 40 A casting silicone is currently one of the more suitable materials for simulating the physical behavior of the airways in medicine simulation. This is essential to attain high-fidelity manikins that can perfectly mimic the simulated anatomic region, not just geometrically, but also in terms of haptic feedback. Due to the geometrical complexity of the tracheo-bronchial tree, mold design is a difficult and time-consuming process. An interactive modeling procedure for modeling mold parts for tracheo-bronchial tree casting is proposed in this paper, with the purpose of reducing modeling time without compromising quality. Following the definition of a standard modeling procedure, this was implemented in the Matlab language by using an IGES and STL editing toolbox. By using the interactive procedure it is possible to reduce the time required for virtual modeling from several hours to less than 1 min. Given this preliminary result, the proposed procedure will be further tested and developed in the near future, with the possibility of automating other lower airway modeling steps, such as vent generation and mounting holes/pins.

Keywords: 3D modelling | Airway simulation | Interactive design | Mold casting

Abstract: An area of interest in orthopaedics is the development of efficient customized neck orthoses, considered that pathologies which affect the neck area are widespread. Advanced acquisition and modelling approaches combined with Additive Manufacturing (AM) can potentially provide customized orthoses with improved performance and complexity. However, in the design of these devices, besides functional and structural requirements, benefit and comfort of the patient should be a main concern, in particular, at the early stage of design during the acquisition of the body’s part, and while using the printed orthosis. In this paper, a scanning system with three sensors was developed which allows a fast, about 5 s, and accurate acquisition of the neck area with minimum discomfort for the patient. A neck orthosis with a ventilation pattern obtained by Topology Optimization (TO), lightened by about 35%, was also established. In fact, a main role for comfort is played by the ventilation pattern which contributes both to lightness and breathability. Its structural and comfort performance was evaluated in comparison with an orthosis with a ventilation pattern configured by Voronoi cells. Structural assessment was carried out by means of finite element analysis under main loading conditions. An evaluation of neck temperatures in relation to wearing 3D printed prototypes, manufactured with Hemp Bio-Plastic® filament, was finally conducted by means of a thermal imaging camera. TO orthosis prototype showed a better performance regarding thermal comfort, with a maximum increase of neck temperature less than 1 °C, which makes the proposed configuration very promising for user's comfort.

Keywords: Additive manufacturing | CAD | Orthosis modelling | Reverse engineering | Thermal comfort | Topology optimization

Abstract: [No abstract available]

Abstract: When humans and robots work together, ensuring safe cooperation must be a priority. This research aims to develop a novel real-time planning algorithm that can handle unpredictable human movements by both slowing down task execution and modifying the robot’s path based on the proximity of the human operator. To achieve this, an efficient method for updating the robot’s motion is developed using a two-fold control approach that combines B-splines and hidden Markov models. This allows the algorithm to adapt to a changing environment and avoid collisions. The proposed framework is thus validated using the Franka Emika Panda robot in a simple start–goal task. Our algorithm successfully avoids collision with the moving hand of an operator monitored by a fixed camera.

Keywords: hidden Markov models | human–robot interaction | obstacle avoidance | splines

Abstract: This study evaluated the influence of distal implants angulation and framework material in the stress concentration of an All-on-4 full-arch prosthesis. A full-arch implant-supported prosthesis 3D model was created with different distal implant angulations and cantilever arms (30° with 10-mm cantilever; 45° with 10-mm cantilever and 45° with 6-mm cantilever) and framework materials (Cobalt–chrome [CoCr alloy], Yttria-stabilized tetragonal zirconia polycrystal [Y-TZP] and polyetheretherketone [PEEK]). Each solid was imported to computer-aided engineering software, and tetrahedral elements formed the mesh. Material properties were assigned to each solid with isotropic and homogeneous behavior. The contacts were considered bonded. A vertical load of 200 N was applied in the distal region of the cantilever arm, and stress was evaluated in Von Misses (σVM) for prosthesis components and the Maximum (σMAX) and Minimum (σMIN) Principal Stresses for the bone. Distal implants angled in 45° with a 10-mm cantilever arm showed the highest stress concentration for all structures with higher stress magnitudes when the PEEK framework was considered. However, distal implants angled in 45° with a 6-mm cantilever arm showed promising mechanical responses with the lowest stress peaks. For the All-on-4 concept, a 45° distal implants angulation is only beneficial if it is possible to reduce the cantilever’s length; otherwise, the use of 30° should be considered. Comparing with PEEK, the YTZP and CoCr concentrated stress in the framework structure, reducing the stress in the prosthetic screw.

Keywords: Dental implants | Finite element analysis | Polymers | Prosthodontics

Abstract: In this paper, we present a biomechanical analysis of the upper body, which includes upper-limb, neck and trunk, during the execution of overhead industrial tasks. The analysis is based on multiple performance metrics obtained from a biomechanical analysis of the worker during the execution of a specific task, i.e. an overhead drilling task, performed at different working heights. The analysis enables a full description of human movement and internal load state during the execution of the task, thought the evaluation of joint angles, joint torques and muscle activations. A digital human model is used to simulate and replicate the worker’s task in a virtual environment. The experiments were conduced in laboratory setting, where four subjects, with different anthropometric characteristics, have performed 48 drilling tasks in two different working heights defined as low configuration and middle configuration. The results of analysis have impact on providing the best configuration of the worker within the industrial workplace and/or providing guidelines for developing assistance devices which can reduce the physical overloading acting on the worker’s body.

Keywords: Biomechanics | Digital human models | Electromyography | Ergonomics | Industry | Overhead tasks

Abstract: The presented work shows how a user centered approach might be used to generate and select the optimal design of smart garments for biosignal acquisition. Design is driven by human biosignal analysis, allowing the translation of subjective user’s feelings into technical specification and the definition of customized criteria for concepts evaluation. So, different concepts are generated and, involving users again, the optimal one is chosen using multi criteria decision making based on Fuzzy AHP theory. A case study on a wearable system (i.e., electromyographic shorts) for football performance and risk injury analysis is shown.

Keywords: Biological knowledge in engineering science | User centered design | Wearable technologies

Abstract: In this study we propose a brief analysis of recent soft wearable robots for upper–limb which could have a major impact on future developments and applications. The systems are analysed with respect to: design concepts, actuation systems, sensing systems, control strategies and applications. Finally, a discussion and open issues are presented.

Keywords: Exoskeletons | Soft robotics | Wearable robotics

Abstract: In this work we derive the requirements of a soft upper-limb exoskeletons starting from the biomechanical analysis of human workers while performing three different industrial overhead tasks in laboratory settings. The results of the work allow to define the degrees of freedom which need to be supported to reduce the biomechanical overloads, as well the dimensional characteristics, in terms of required lengths and forces, of the soft actuators of the wearable robot.

Keywords: Biomechanics | Design | Industrial tasks | Soft exoskeleton | Soft robotics | Wearable robotics

Abstract: This study presents an alternative process for designing and manufacturing customized trays for dental-whitening treatments. The process is based on a digitized approach consisting of three main stages: design of a reference model, its manufacturing by AM, and thermoforming of the tray. The aim of the study was to develop a high-performance tray, able to guarantee comfort, safety, and efficacy for whitening treatments. To evaluate the patient’s experience, some tests under real operating conditions were performed. Twenty people carried out a nighttime treatment of 14 days. Each patient was asked to assess the overall level of satisfaction and the comfort of the tray and its ability to retain the gel. Tooth whitening was also determined according to the VITAPAN scale. All patients involved in the study were satisfied and provided positive feedback about comfort and tightness of the tray. At the end of the treatment, 15 out of 20 patients achieved shade A1 on the VITAPAN scale. The mean improvement in color shades was about 7. These results confirmed the great potential of the proposed dental tray. Its use was proven to guarantee a high level of quality, flexibility, and customization of dental-whitening treatments, improving comfort, safety, and efficacy.

Keywords: additive technologies | bespoke dental trays | custom design | dental engineering | digital manufacturing | esthetic dentistry | tooth whitening

Abstract: Home-based rehabilitation is becoming a gold standard for patient who have undergone knee arthroplasty or full knee replacement, as it helps healthcare costs to be minimized. Nevertheless, there is a chance of increasing adverse health effects in case of home care, primarily due to the patients’ lack of motivation and the doctors’ difficulty in carrying out rigorous supervision. The development of devices to assess the efficient recovery of the operated joint is highly valued both for the patient, who feels encouraged to perform the proper number of activities, and for the doctor, who can track him/her remotely. Accordingly, this paper introduces an interactive approach to angular range calculation of hip and knee joints based on the use of low-cost devices which can be operated at home. First, the patient’s body posture is estimated using a 2D acquisition method. Subsequently, the 3D posture is evaluated by using the depth information coming from an RGB-D sensor. Preliminary results show that the proposed method effectively overcomes many limitations by fusing the results obtained by the state-of-the-art robust 2D pose estimation algorithms with the 3D data of depth cameras by allowing the patient to be correctly tracked during rehabilitation exercises.

Keywords: 3D model | Body tracking | Data fusion | Joints estimation | RGB-D camera

Abstract: Numerical simulations and Finite Element Analysis (FEA) have currently increased their applications in medical field for making preoperative plans to simulate the response of tissues and organs. Soft tissue simulations, such as colorectal simulations, can be adopted to understand the interaction between colon tissues and surrounding tissues, as well as the effects of instruments used in this kind of surgical procedures. This paper analyses through FEA the interaction between a surgical device and a colon tissue when it is fully clamped. Sensitivity analysis in the respect of the material mechanical behaviour, geometric approximation and the effect of thickness variation are investigated with the aim of setting up a virtual prototype of the surgical operation to aid mentoring and preliminary evaluation via haptic solutions. Through this investigation, the force feedback estimation that is necessary in many virtual-reality applications, may be estimated without discharging nonlinear effects that occur during clamping and that usually cannot be simulated efficiently to guarantee real-time solutions. Results are aligned with experimental data, confirming the reliability and right the set-up of FEA. Through them, the preliminary set-up of a haptic force feedback has been described and simulated through Simulink 3D animation, confirming the feasibility of the concept.

Keywords: FEA | Force feedback | Haptic device | Metamodeling | Surgical simulation | Virtual prototyping

Abstract: Hepatic diseases are serious condition worldwide, and several times doctors analyse the situation and elaborates a preoperative planning based exclusively on the medical images, which are a drawback since they only provide a 2D vision and the location of the damaged tissues in the three-dimensional space cannot be easily determined by surgeons. Nowadays, with the advancement of Computer Aided Design (CAD) technologies and image segmentation, a digital liver model can be obtained to help understand the particular medical case; even with the geometric model, a virtual simulation can be elaborated. This work is divided into two phases; the first phase involves a workflow to create a liver geometrical model from medical images. Whereas the second phase provides a methodology to achieve liver prototype, using the technique of fused deposition modelling (FDM). The two stages determine and evaluate the most influencing parameters to make this design repeatable in different hepatic diseases. The reported case study provides a valuable method for optimizing preoperative plans for liver disease. In addition, the prototype built with additive manufacturing will allow the new doctors to speed up their learning curve, since they can manipulate the real geometry of the patient's liver with their hands.

Keywords: 3D printing | Convolutional neural network | FDM | Image segmentation | Liver disease

Abstract: In hip arthroplasty, preoperative planning is fundamental to reaching a successful surgery. Nowadays, several software tools for computed tomography (CT) image processing are available. However, research studies comparing segmentation tools for hip surgery planning for patients affected by osteoarthritic diseases or osteoporotic fractures are still lacking. The present work compares three different software from the geometric, dimensional, and usability perspectives to identify the best three-dimensional (3D) modelling tool for the reconstruction of pathological femoral heads. Syngo.via Frontier (by Siemens Healthcare) is a medical image reading and post-processing software that allows low-skilled operators to produce prototypes. Materialise (by Mimics) is a commercial medical modelling software. 3D Slicer (by slicer.org) is an open-source development platform used in medical and biomedical fields. The 3D models reconstructed starting from the in vivo CT images of the pathological femoral head are compared with the geometries obtained from the laser scan of the in vitro bony specimens. The results show that Mimics and 3D Slicer are better for dimensional and geometric accuracy in the 3D reconstruction, while syngo.via Frontier is the easiest to use in the hospital setting.

Keywords: bio-imaging | CT image segmentation | hip surgery | orthopaedics | reverse engineering | software comparison | surgical planning

Abstract: Purpose To evaluate the accuracy of 3-D printed models of the femoral head based on preoperative computed tomography (CT) images. Other goals were to compare the cartilage thickness of bony specimen to the printed models and calculate the standard deviation between 3-D printed models based on CT images and laser scan models. Methods This retrospective study analyzed 10 patients who underwent preoperative CT imaging and hip replacement. Preoperative femoral head 3-D printed models were produced from CT images. Bony specimens were collected from surgical operations and scanned using CT and 3-D laser scanning, and cartilage thickness subsequently was measured by histological analysis. Comparisons of printed models based on CT images and printed models based on 3-D laser scanning were performed by overlapping their external surfaces using dedicated software and the standard deviation was calculated. Results The average standard deviation between the bony specimen 3-D models and preoperative 3-D printed CT femoral head models was 0.651 mm. The cartilage was approximately 1.487 mm thick. Discussion The comparison between preoperative CT image-based 3-D models and the postoperative bony specimenbased models permitted evaluation of the accuracy of preoperative CT image-based 3-D printed models. Cartilage thickness was estimated indirectly by comparing models obtained by CT and laser scanning, and it was related to the calculated standard deviation to overcome the cartilage detection limit of CT. This study shows how each step can generate accuracy errors on the final 3-D printed model. A repeatable and sustainable workflow for creating accurate and reproducible 3-D printed models could overcome this issue. Moreover, orthopedic surgeons should be aware of 3-D printed model precision in clinical practice. Conclusions This study provides encouraging results on the accuracy of 3-D printed models for surgical planning.

Keywords: 3-D printing | accuracy assessment | bone segmentation | femoral head model | hip replacement surgical procedure

Abstract: Since custom-made 3D printed surgical guides for maxillofacial surgery are usually expensive, Augmented Reality (AR) can be efficiently employed to overcome the high costs. The proposed work aims to develop and test an AR application for different maxillofacial surgeries. The application consists in overlaying the cutting lines on the patient’s mandible to guide the clinician during the procedure. It has been realized in Unity and preliminary tested with HoloLens 2 and a 3D printed mandible. Seven participants performed two consecutive trials. The mandible with the obtained surgical lines has been scanned after each test to digitally reconstruct the traced lines and compare them with the surgical lines previously designed. The results allowed the preliminary analysis of the developed AR system’s accuracy and precision. Mean distances from the designed surgical guides showed good accuracy for the genioplasty (deviation error around 1.03 mm) and orthognathic surgery (deviation error around 1.27 mm), suggesting the applicability of HoloLens 2 for these kinds of surgery. On the contrary, the application was not suitable for the mandibular angle osteotomy (deviation error over 2.50 mm).

Keywords: Augmented reality | HoloLens 2 | Maxillofacial surgery | Surgical guides

Abstract: The Obstructive Sleep Apnea Syndrome (OSA) concerns episodes of complete or partial obstruction of the upper airway. Mandibular Advancement Device (MAD) is one of the most used systems for treating this syndrome. Clinicians frequently observe a combination of OSA and periodontitis. There is no research aiming to evaluate how periodontitis staging affects the overall mandibular and maxillary dental arches in the literature. Furthermore, no one has studied the combination between OSA and periodontitis and the effects of MADs on the patients in this condition. This paper aims to develop a numerical simulation approach based on FEM and evaluate the consequences (displacement and stress fields) of the periodontitis staging on PDL and teeth of patients suffering from OSA and treated with MADs. Simulations have been performed for evaluating Stage I of periodontitis. Results highlight a correlation between bone resorption and teeth displacement and periodontal ligaments stress (the higher the bone resorption, the higher the stress and displacement).

Keywords: Finite Element Analysis | Mandibular Advancement Device | Numerical simulation | Obstructive Sleep Apnea | Periodontitis

Abstract: Disability conditions characterized by hand dysfunction are particularly relevant for the use of touchscreen technology. This work investigates the effects of hand impairment produced by systemic sclerosis (SSc) on touchscreen interaction. It aims to fulfil a dual objective: to provide guidelines to design inclusive interfaces and interaction modalities for SSc patients and to design a hand physio-rehabilitation based on a touchscreen application. Eighty patients participated in the observational study and, accordingly, eighty subjects without impairments were recruited as a control cohort. A specific touchscreen application has been designed and developed including three gestures: tap, drag and drop, and pinch-to-zoom. The work allowed identifying the interface features that significantly influence the performance and, consequently, the design rules for the physio-rehabilitation application.

Keywords: Hand impairment | Human-computer interaction | Inclusive design | Interface design | Systemic sclerosis | User-centred design

Abstract: Several implant materials are used in cranial surgery. Still, each one has its drawbacks, such as the risk of infections, low mechanical strength, or low osseointegration. Implants with a porous surface are considered more effective than a smooth and rough coating. The porosity density and structure also influence the mechanical properties of the final implant. Moreover, the implant properties depend on the manufacturing method. This study aims to present a custom-made cranial scaffold composed of two distinct layers. A compact inner one guarantees adequate structural properties to the scaffold. In contrast, a porous outer one lightens the scaffold structure and assures the correct osseointegration. The customized scaffold has been designed through a 3D free-form modeling system. It can be manufactured by 3D printing techniques such as direct metal laser sintering in titanium or via selective laser sintering using PEEK. The advantages and limitations of the multi-layered custom-made scaffold and the related design process are qualitatively described.

Keywords: Additive manufacturing | Craniofacial reconstruction | Customized scaffolds | Multi-layered scaffolds | Porous scaffolds

Abstract: Dealing with the design of personalized medical devices, mass production is not an option that can be hypothesized. Indeed, a cumbersome production process must be considered in such cases, mainly to account for a delicate design phase that needs to take into consideration, as input, an anatomy that vary each time. This article discusses the development of a statistical tool able to support the design of patient-specific devices. By expanding the classical formulation of the Statistical Shape Model (SSM) with the introduction of multiple levels of information within the same model, the authors have experimented with the concept of an “enhanced SSM”. While the traditional SSM only provides information on the variations that a class of shapes can manifest, the eSSM may include more levels of information. The article discusses two possible mathematical formulations of such statistical tool. Its application to the design of custom-made pelvic implants is discussed. Such application scenario is described starting from the generation of the eSSM for the pelvis. The features of interest considered in this paper are the centers of the acetabular regions of the pelvis, the segmentation of the anatomy in a series of semantical regions that must be considered when developing a load-bearing implant. Finally, the conclusions of this research are drawn and discussed together with possible future development of eSSMs.

Keywords: Biomedical engineering | Custom implant design | Human modelling | Pelvis | SSM | Statistical shape analysis

Abstract: The realization of medical devices to assist the surgeon in autologous auricular reconstruction (personalized surgical guides) requires the use of depth maps images obtained from 3D scans of the patient's profile. In order to make the process of ear geometry acquisition and depth map realization faster, more comfortable for the patient and easily accessible by hospital staff, this work proposes a system able to create depth maps from a single RGB image. The proposed approach involves the integration of tools based on convolutional neural networks to build a modular system capable of isolating the ear from the profile, creating the corresponding depth map, and refining it to correct inaccuracies. The system was trained and tested using a database of human profile images and corresponding depth maps made available by the University of Notre Dame. To evaluate the result in this preliminary study, standard metrics such as mean square error and structural similarity were used, yielding results suitable for the targeted application.

Keywords: 3D vision | CNN | Depth map estimation | Ear reconstruction

Abstract: Orthognathic surgery allows broad-spectrum deformity correction involving both aesthetic and functional aspects on the TMJ (temporo-mandibular joint) and on the facial skull district. The combination of Reverse Engineering (RE), Virtual Surgery Planning (VSP), Computer Aided Design (CAD), Additive Manufacturing (AM), and 3D visualization allows surgeons to plan, virtually, manipulations and the translation of the human parts in the operating room. This work’s aim was to define a methodology, in the form of a workflow, for surgery planning and for designing and manufacturing templates for orthognathic surgery. Along the workflow, the error chain was checked and the maximum error in virtual planning was evaluated. The three-dimensional reconstruction of the mandibular shape and bone fragment movements after segmentation allow complete planning of the surgery and, following the proposed method, the introduction of both the innovative evaluation of the transversal intercondylar distance variation after mandibular arch advancement/set and the possibility of use of standard plates to plan and realize a customized surgery. The procedure was adopted in one clinical case on a patient affected by a class III malocclusion with an associated open bite and right deviation of the mandible with expected good results. Compared with the methods from most recent literature, the presented method introduces two elements of novelty and improves surgery results by optimizing costs and operating time. A new era of collaboration among surgeons and engineer has begun and is now bringing several benefits in personalized surgery.

Keywords: 3D-modelling | computer-aided surgery | methodology | orthognathic surgery | rapid manufacturing | surgical template

Abstract: Worldwide, stroke is the third cause of disability. The majority of people affected by this disease cannot perform activities of daily living. Bringing the therapy to the patients' home is complex, and in literature, there are still open challenges to face. Starting from therapists' and patients' needs, this paper describes a possible solution: HANDY, a rehabilitative active hand exoskeleton for post-stroke patients. With a desktop application, they perform three different types of exercises: passive, active and based on activities of daily living. They can also control the exoskeleton themselves in a serious-game approach with a leap motion controller. We evaluated our method with patients at the Villa Beretta rehabilitative center. Preliminary results from the session about comfort, usability and willingness to utilize the system are promising.

Keywords: Additive manufacturing | CAD modeling | Hand exoskeleton | Interactive applications | Stroke

Abstract: Currently, the growing need for highly customized implants has become one of the key aspects to increase the life expectancy and reduce time and costs for prolonged hospitalizations due to premature failures of implanted prostheses. According to the literature, several technological solutions are considered suitable to achieve the necessary geometrical complexity, from the conventional subtractive approaches to the more innovative additive solutions. In the case of cranial prostheses, which must guarantee a very good fitting of the region surrounding the implant in order to minimize micromotions and reduce infections, the need of a product characterized by high geometrical complexity combined with both strength and limited weight, has pushed the research towards the adoption of manufacturing processes able to improve the product’s quality but being fast and flexible enough. The attention has been thus focused in this paper on sheet metal forming processes and, namely on the Single Point Incremental Forming (SPIF) and the Superplastic Forming (SPF). In particular, the complete procedure to design and produce titanium cranial prostheses for in vivo tests is described: starting from Digital Imaging and COmmunications in Medicine (DICOM) images of the ovine animal, the design was conducted and the production process simulated to evaluate the process parameters and the production set up. The forming characteristics of the prostheses were finally evaluated in terms of thickness distributions and part’s geometry. The effectiveness of the proposed methodology has been finally assessed through the implantation of the manufactured prostheses in sheep.

Keywords: Custom prosthesis | In vivo tests | Single point incremental forming | Superplastic forming | Ti‐6Al‐4V ELI

Abstract: Burn injuries requires post-accident medical treatment. However, the treatment of burns does not end with first aid because scarred skin must be managed for many years, and in some circumstances, for life. The methods used to evaluate the state of a burn scar based, for instance, on Patient and Observer Scar Assessment Scale or similar ones, often lacks in univocally assessing the scarred skin’s state of health. As a result, the primary aim of this research is to design and build a prototype that can support the doctor during scar assessment, and eventually therapy, by providing objective information on the state of the lesion, particularly the value of skin pliability. The developed tool is based on the depressomassage treatment probe named LPG, currently used to treat burn scars in a number of hospitals. It consists of a non-invasive massage technique using a mechanical device to suction and mobilize scar tissue and is used as a post-operative treatment to speed up the healing process to make the mark of the scar less visible. The prototype is specifically designed to be manufactured using Additive Manufacturing and was validated comparing its performances against the ones of a certified instrument (i.e., the Romer Absolute ARM with RS1 probe). Validation was carried out by designing and developing a tool to put the RS1 probe in the same measurement conditions of the new prototype probe. Tests performed to assess the performance of the devised prototype show that the probe developed in this work is able to provide measurements with a sufficient degree of accuracy (maximum error ±0.1 mm) to be adopted for a reliable estimation of the pliability value in a hospital environment.

Keywords: 3D measurement | additive manufacturing (3D printing) | burn scars | pliability | reverse engineering

Abstract: Ear reconstruction surgery is a very demanding intervention for plastic surgeons. The results rely heavily on the “artistic skills” of the surgeon who has the task of creating a three-dimensional sculpture using harvested costal cartilage capable of replicating the shape of a physiological ear. By exploiting a combination of Reverse Engineering, CAD modelling, and Additive Manufacturing tools, it is possible to create efficient and highly personalized simulators to train and support the surgeon before and during surgery. In fact, the flexibility of these techniques allows the development of custom-made medical devices, designed directly on the patient's anatomy. In order to make the simulation as realistic as possible, this work focuses specifically on the creation of accurate costal cartilage replicas, both in terms of geometry and mechanical properties of the material, addressing two aspects: the systematization and automation of the CAD mould modelling procedure and the study of the most efficient mould casting materials.

Keywords: Costal cartilage mould | Ear reconstruction | Medical simulation

Abstract: Tissue engineering or tissue reconstruction/repair/regeneration may be considered as a guiding strategy in oral and maxillofacial surgery, as well as in endodontics, orthodontics, peri-odontics, and daily clinical practice. A wide range of techniques has been developed over the past years, from tissue grafts to the more recent and innovative regenerative procedures. Continuous research in the field of natural and artificial materials and biomaterials, as well as in advanced scaffold design strategies has been carried out. The focus has also been on various growth factors involved in dental tissue repair or reconstruction. Benefiting from the recent literature, this review paper illustrates current innovative strategies and technological approaches in oral and maxillofacial tissue engineering, trying to offer some information regarding the available scientific data and practical applications. After introducing tissue engineering aspects, an overview on additive manufacturing technologies will be provided, with a focus on the applications of superparamagnetic iron oxide nanoparticles in the biomedical field. The potential applications of magnetic fields and magnetic devices on the acceleration of orthodontic tooth movement will be analysed.

Keywords: 3D/4D printing | Dentistry | Design for additive manufacturing | Magnetism | SPIONs | Tissue engineering

Abstract: The aim of this study was to evaluate the effect of a time‐dependent magnetic field on the biological performance of periodontal ligament stem cells (PDLSCs). A Western blot analysis and Alamar Blue assay were performed to investigate the proliferative capacity of magnetically stimulated PDLSCs (PDLSCs MAG) through the study of the MAPK cascade (p‐ERK1/2). The observation of ALP levels allowed the evaluation of the effect of the magnetic field on osteogenic differentiation. Metabolomics data, such as oxygen consumption rate (OCR), extracellular acidification rate (ECAR) and ATP production provided an overview of the PDLSCs MAG metabolic state. Moreover, the mitochondrial state was investigated through confocal laser scanning microscopy. Results showed a good viability for PDLSCs MAG. Magnetic stimulation can activate the ERK phosphorylation more than the FGF factor alone by promoting a better cell proliferation. Osteogenic differentiation was more effectively induced by magnetic stimulation. The metabolic panel indicated significant changes in the mitochondrial cellular respiration of PDLSCs MAG. The results suggested that periodontal ligament stem cells (PDLSCs) can respond to biophysical stimuli such as a time‐dependent magnetic field, which is able to induce changes in cell proliferation and differentiation. Moreover, the magnetic stimulation also produced an effect on the cell metabolic profile. Therefore, the current study demonstrated that a time‐dependent magnetic stimulation may improve the regenerative properties of PDLSCs.

Keywords: Cellular respiration | Magnetic stimulation design | Metabolomics | Osteogenesis | Stem cells | Tissue engineering

Abstract: A computer-aided design/computer-aided manufacturing (CAD/CAM) resin block material for restoration of single-implant abutments can be milled and cemented on an optimized standard titanium abutment as a cheaper solution or, alternatively, individualization of the crown–abutment connection is required to fulfill the same mechanical requirements. The aim of this study was to evaluate how different structural and geometric configurations of the abutment influence the resistance of a nano ceramic resin crown (NCRC). During the test, 30 implants with an internal conical tapered configuration were considered. Each implant received a standard titanium abutment: in group 1, NCRCs were directly bonded to the titanium abutments; in group 2, NCRCs were cemented on a customized zirconia framework and then cemented on a standardized titanium abutment. Three crowns of each group were submitted to a static load test until failure. The remaining crowns were submitted to a fatigue test protocol with a dynamic load. The static and dynamic test showed earlier failure for group 1. In group 1, complete breaking of NCRCs was observed for all samples, with an almost total titanium abutment exposition. In the static tests, group 2 showed a mode of failure that involved only the crown, which partially debonded from the zirconia abutment. Within the limitations of the present preliminary study, it was possible to conclude that the shape of the abutment mainly influences the fatigue strength compared to the static tensile strength. The results of the performed test show that NCRC bonded to the customized zirconia abutments, and presented a 75% survival rate when compared to the same material bonded directly to a standard titanium abutment.

Keywords: CAD-CAM | Fatigue test | NCRC | Patient specific design

Abstract: Objective: To validate the use of a polyblend tape suture in equine laryngoplasty (PL). Study design: Experimental study. Animals: Thirty-two cadaveric larynges. Methods: Each larynx was randomly assigned to 1 of 4 groups: PL with polyblend tape suture (TigerTape), without (TT) or with a cannula (TTC) in the muscular process of the arytenoid cartilage, and PL with polyester suture (Ethibond), without (EB) or with a cannula (EBC). Construct stiffness, total migration, creep, and drift values were measured after 3000 cycles. The specimens were then loaded to failure to assess their residual properties: load at failure, total energy, displacement, and 2 stiffness coefficients. Results: After cyclic testing, the total migration and creep were lower in TTC (6.36 ± 1.20 mm; 1.35 ± 0.38 mm/s) than in EB (11.12 ± 4.20 mm; 3.39 ± 2.68 mm/s) and in the TT constructs (11.26 ± 1.49 mm; 3.20 ± 0.54 mm/s); however, no difference was found with EBC (9.19 ± 3.18 mm; 2.14 ± 0.99). A correlation was found between total migration and creep (R =.85). The TTC constructs failed at higher loads (129.51 ± 33.84 N) than EB (93.16 ± 18.21 N) and EBC (81.72 ± 13.26 N) whereas the EB and EBC constructs were less stiff than TT and TTC (P <.001). Conclusion: Biomechanical properties were generally superior for the TTC constructs tested under cyclical loading. The TT and TTC constructs failed at a higher load than EB and EBC constructs. The cannula in TTC and EBC reduced the failure at the muscular process. Clinical significance: These results provide evidence to support the in vivo evaluation of the polyblend tape suture with or without a cannula in the muscular process for laryngoplasty in horses.

Abstract: One of the main limitations in subject-centred design approach is represented by getting 3D models of the region of interest. Indeed, 3D reconstruction from imaging data (i.e., computed tomography scans) is expensive and exposes the subject to high radiation doses. Statistical Shape Models (SSMs) are mathematical models able to describe the variability associated to a population and allow predicting new shapes tuning model parameters. These parameters almost never have a physical meaning and so they cannot be directly related to morphometric features. In this study a gender-combined SSM model of the human mandible was setup, using Generalised Procrustes Analysis and Principal Component Analysis on a dataset of fifty mandibles. Twelve morphometric features, able to characterise the mandibular bone and readily collectable during external examinations, were recorded and correlated to SSM parameters by a multiple linear regression approach. Then a cross-validation procedure was performed on a control set to determine the combination of features able to minimise the average deviation between real and predicted shapes. Compactness of the SSM and main modes of deformations have been investigated and results consistent with previous works involving a higher number of shapes were found. A combination of five features was proved to characterise predicted shapes minimising the average error. As completion of the work, a male SSM was developed and performances compared with those of the combined SSM. The features-based model here proposed could represent a useful and easy-to-use tool for the generation of 3D customised models within a virtual interactive design environment.

Keywords: Features selection | Mandible | Morphometric measurements | PCA | Predicted shapes | Statistical shape model | Subject-specific model

Abstract: Purpose: The scope of the work is to present the state of the art of robotically assisted surgical systems and to give a general idea about how technology can help today and tomorrow robotic surgery. The road to innovation passes through research and on field trials; for this reason, not only commercial surgery robots, but also innovative prototype robots, proposed by the Academic world, are presented. Design/methodology/approach: Following a short introduction, robotically assisted surgery systems are introduced discussing their architectures and main peculiarities. A further section is dedicated to the key enabling technologies that will make possible to improve current systems and that will lead to a new generation of surgical robotic systems able to meet the patient's needs and facilitate the surgeon's task. Finally, brief concluding comments are given. Findings: The idea of using robots for surgery was born many years ago and in a short time a market demand was created. Today the market is very dynamic, and several new products are updated and created for the execution of both traditional and new procedures. The article provides a guide for the reader who has an interest in this area. Originality/value: This paper provides an insight into the commercial robotic surgical systems and a look on research prototypes from academic and industrial worlds.

Keywords: haptic feedback | laparoscopy | miniature instruments | minimally invasive surgery | remote surgery | robot surgery

Abstract: Emotion recognition through machine learning techniques is a widely investigated research field, however the recent obligation to wear a face mask, following the COVID19 health emergency, precludes the application of systems developed so far. Humans naturally communicate their emotions through the mouth; therefore, the intelligent systems developed to date for identifying emotions of a subject primarily rely on this area in addition to other anatomical features (eyes, forehead, etc.). However, if the subject is wearing a face mask this region is no longer visible. For this reason, the goal of this work is to develop a tool able to compensate for this shortfall. The proposed tool uses the AffectNet dataset which is composed of eight class of emotions. The iterative training strategy relies on well-known convolutional neural network architectures to identify five sub-classes of emotions: following a pre-processing phase the architecture is trained to perform the task on the eight-class dataset, which is then recategorized into five classes allowing to obtain 96.92% of accuracy on the testing set. This strategy is compared to the most frequently used learning strategies and finally integrated within a real time application that allows to detect faces within a frame, determine if the subjects are wearing a face mask and recognize for each one the current emotion.

Keywords: Artificial intelligence | COVID19 | Emotion recognition | Facial Expression Recognition | Grad-CAM | Non-verbal communication

Abstract: Torsional deformities of the lower limb are common in children with cerebral palsy (CP)-determining gait problems. The mechanisms underlying transverse plane gait deviations arise from a combination of dynamic and static factors. The dynamic elements may be due to spasticity, contractures and muscle imbalances, while the static ones may result from excessive femoral anteversion, which decreases the efficiency of the hip abductors by reducing the muscular lever arms. A therapeutic approach has been identified in multi-level functional surgery for the lower limb. Treating the malalignments of the lower limb with femoral or tibial derotation provides optimal results, especially when supported by adequate biomechanical planning. This planning requires an integrated static-dynamic approach of morphological and functional evaluation, based on radiological measurements, physical examination and gait analysis. Instrumented gait analysis has been confirmed as essential in the evaluation and surgical decision making process for children affected by CP with transverse plane deformities. Computational simulations based on musculoskeletal models that integrate patient-specific CT morphological data into gait analysis can be used for the implementation of a surgical simulation system in pre-operative planning to test the possible effects of the different surgical treatment options on the torsional defects of the lower limbs. Recently, a computer-aided simulation process has been implemented in the preoperative planning of complex osteotomies for limb deformities in children. Three-dimensional (3D) digital models were generated from Computed Tomography (CT) scans, using free open-source software. The aim of this study is to integrate the patient-specific CT musculoskeletal model with morphological data and gait analysis data, with the personalized calculation of kinematic and kinetic parameters, which allow us to generate an “avatar” of the patient for a more in-depth evaluation of the gait abnormalities. The computational simulation platform proposed provides a realistic movable musculoskeletal model in a virtual environment, with the possibility of planning and monitoring the effects of virtual three-dimensional surgical corrections.

Keywords: avatar | cerebral palsy | computed tomography | derotation | gait analysis | musculoskeletal modeling | torsional deformities | virtual surgical planning

Abstract: The present paper describes a procedure for the development and production of a physical model for surgical planning of a Left Ventricular Aneurysm. The method is based on the general approach provided in Otton et al. (2017) and was customized to seek a reliable and fast procedure for the production of a specific type of cardiac model – i.e. chambers of the left side of the heart. The paper covers all the steps: processing of the data, segmentation, modelling and 3D printing; details are provided for all the phases, in order to allow the reproduction of the achieved results. The procedure relies on Computed Tomography - CT imaging as data source for the identification and modelling of the anatomy. Materialise Mimics was used as segmentation software to process the CT data. While its usefulness for the surgical needs was verified on a single clinical case (provided by the Careggi Hospital of Florence, Italy), the modelling procedure was tested twice, to produce a physical replica both ex-ante and ex-post surgical intervention. • The tools used for segmentation and generation of the printable model were customized to reduce modelling time for the specific type of desired model. • Detailed information on the use of modeling tools, not available in the literature, will be provided. • The procedure allows fabrication of a physical model representing the heart chambers in a short time.

Keywords: 3D printing | Left Ventricular Aneurysm | Method for the production of an anatomical replica of a human heart for surgical planning | Surgical planning

Abstract: Additive Manufacturing technologies have opened new perspectives for the realization of tissue and organs substitutes. The main advantages come from the possibility of using the same technology to produce artificial or biological substitutes in a wide range of outer shapes and inner reticular architectures, which may pave the way to their use to produce personalized substitutes. Additive manufacturing technologies are based on layer-by-layer material fusion and deposition. As such, they have intrinsic limitations which may hinder the possibility to produce substitutes that meet the requirements for safe clinical use. As an example, discontinuities between layers may make the outer surface of a substitute significantly uneven, rough, and may even weaken the substitute mechanical properties in such an aggressive environment as the human body. Moreover, repeated thermal cycles (fusion and solidification) drastically limit the choice of materials which can be used. Finally, the outcome of the production technology is affected by many variables that it is not trivial to control to deliver the necessary quality and repeatability of the production process for medical applications. Indeed, the surface roughness of an implantable prosthesis or organ substitute is key to modulate cell adhesion and the susceptibility to chemical attack by body fluids. Structural strength is a mandatory requirement for load-bearing prostheses (e.g., orthopedic and dental prostheses). Materials for biomedical applications must not only be 3D printable, but also biocompatible and/or possibly have to promote cells growth and to prevent inflammatory reactions. The performance of artificial, bio artificial and tissue-engineered organs needs also to be certified and guaranteed, a rather difficult task to define for devices which may be unique, being tailored on the specific needs of the patient. In this paper, it will be discussed whether this technology is sufficiently mature to replace more traditional techniques or, alternatively, whether it should be limited to a restricted range of emergency applications until the existing relevant technological gaps are filled.

Keywords: 3D printing | additive manufaturing | artificial organs | clinical | corrosion | fatigue | prostheses | strength | surface | surgical guides | wear

Abstract: In the last years, the precision and personalized medicine is pushing the biomedical research efforts towards the direction of implant surgery requiring only 1-step approach: this goal has been achieved after the introduction of resorbable implants. The resorbable prosthetic support is indicated for temporary prosthetic applications, such as bone fractures fixation, or all those conditions usually treated with metal implants then removed with a second surgery, just after the healing of the bone defect. Biodegradable, bioactive and customizable implants for the treatment of bone fractures, both efficient in bearing the functional loads, and showing good biocompatibility and degradation properties matching the bone tissue healing, are still lacking. These premises have led to consider Magnesium (Mg) and its alloys as very promising candidates for the development of temporary, resorbable implants. However, the very high corrosion rate of Mg is the main problem, not yet solved. The material needs to be properly treated/coated, as well as manufactured, in order to design the most suitable duration of the temporary prosthesis permanence in situ. An innovative and interdisciplinary approach has been developed within the M.Era-Net ISIDE project and it is here briefly detailed with a special focus on the highlighted application fields.

Keywords: customade prostesis | Mg alloys | Reabsorbable implants

Abstract: The spine is the load-bearing structure of human beings and may present several disorders, with low back pain the most frequent problem during human life. Signs of a spine disorder or disease vary depending on the location and type of the spine condition. Therefore, we aim to develop a probabilistic atlas of the lumbar spine segment using statistical shape modeling (SSM) and then explore the variability of spine geometry using principal component analysis (PCA). Using computed tomography (CT), the human spine was reconstructed for 24 patients with spine disorders and then the mean shape was deformed upon specific boundaries (e.g., by (Formula presented.) or (Formula presented.) standard deviation). Results demonstrated that principal shape modes are associated with specific morphological features of the spine segment such as Cobb’s angle, lordosis degree, spine width and height. The lumbar spine atlas here developed has evinced the potential of SSM to investigate the association between shape and morphological parameters, with the goal of developing new treatments for the management of patients with spine disorders.

Keywords: biomechanics | pathological lumbar spine segment | PCA | spinal column | SSM

Abstract: The study of the spine range of motion under given external load has been the object of many studies in literature, finalised to a better understanding of the spine biomechanics, its physiology, eventual pathologic conditions and possible rehabilitation strategies. However, the huge amount of experimental work performed so far cannot be straightforwardly analysed due to significant differences among loading set-ups. This work performs a meta-analysis of various boundary conditions in literature, focusing on the flexion/extension behaviour of the lumbar spine. The comparison among range of motions is performed virtually through a validated multibody model. Results clearly illustrated the effect of various boundary conditions which can be met in literature, so justifying differences of biomechanical behaviours reported by authors implementing different set-up: for example, a higher value of the follower load can indeed result in a stiffer behaviour; the application of force producing spurious moments results in an apparently more deformable behaviour, however the respective effects change at various segments along the spine due to its natural curvature. These outcomes are reported not only in qualitative, but also in quantitative terms. The numerical approach here followed to perform the meta-analysis is original and it proved to be effective thanks to the bypass of the natural variability among specimens which might completely or partially hinder the effect of some boundary conditions. In addition, it can provide very complete information since the behaviour of each functional spinal unit can be recorded. On the whole, the work provided an extensive review of lumbar spine loading in flexion/extension.

Keywords: Biomechanics | Follower load | Lumbar spine | Mechanical tests | Multibody | ROM

Abstract: Titanium and its alloys are widely employed in commercial dental devices. Because the surface morphology and chemical composition of Ti-based dental implants play a relevant role in osseointegration, three different commercial threaded implants have been investigated by scanning electron microscopy and X-ray photoelectron spectroscopy (XPS). The Implants A and C were made of pure Ti whereas the Implant B was made of Ti6Al4V alloy. Obtained results evidenced the common features and differences due to specific process parameters used in the treatments of mordanting and sandblasting for surface roughening. Implant A exhibits a uniform surface covered by very small dimples of about 1–2 μm. The surface of Implant B is not homogeneous: The thread tops present an irregular morphology (dimples size >10 μm) while finer dimples (about 1 μm) are observed along the thread flanks and valleys. Implant C shows an irregular morphology with dimples of different sizes and shapes distributed on thread tops, flanks, and valleys. XPS analyses revealed the presence of metal oxides: TiO2 in all the implants; Al2O3 and V2O5 only in the implant B. Moreover, these results demonstrated that Mg2SiO4 is present on the surface of Implant A, probably due to a specific preparation process. Obtained results have been discussed on the basis of the factors promoting the osseointegration.

Keywords: dental implants | SEM | surface morphology | Ti6Al4V | titanium | XPS

Abstract: Fractures to the orbital walls and floor must be appropriately managed to avoid severe conditions. This results in particularly challenging anatomical reconstructions. The main issues are the implant’s proper shaping, placement, and orientation onto the eye socket. A new, customized implant-shaping mould has already been developed to shape patient-specific implants. However, it still does not address the implant positioning in the fractured orbital cavity. This present research aims to design, develop, and assess an innovative implant positioner to be used with the optimized version of the aforementioned implant-shaping mould. The new medical device was designed to be used with titanium meshes and deantigenated bone implants. It is easy to use, has a low cost, and is reusable several times. It is composed of (1) two coupled and hinged handles that allow the grasping of the implant, and (2) the positioner itself that permits proper implant placement and orientation. Selective laser sintering was used to print the mould and the new device in polyamide. Promising results for implant shaping, positioning, and orientation accuracy were obtained. An accuracy of 0.1 mm and 1.3 mm was, respectively, achieved for the implant shape and its placement in the mediolateral direction. The mean malrotation angle around the orbital rim was about 6°.

Abstract: Objectives: This study aims to evaluate the acceptability of Cinematic VR technology as a novel therapeutic approach supporting Social Skills Training (SST) rehabilitation interventions among patients with schizophrenia. Materials and Methods: We developed an innovative cinematic VR-based platform as a support system for SST rehabilitation of independent living skills and evaluated its acceptance among psychiatric patients in terms of usability, user experience, and use performance. Ten voluntary participants were enrolled in the study. The study inclusion criteria consisted of age 18-65 years, lack of moderate and severe intellectual disability, no substance use disorder, and schizophrenia spectrum disorder pathology according to DSM V. We administered post treatment questionnaires and developed the platform to capture relevant data automatically. Results: Patients rated usability and user experience from good to excellent. We also observed an improvement in the use performance. Conclusions: Cinematic Virtual Reality based applications showed good acceptability among patients with schizophrenia. This result supports further efforts in evaluating its effectiveness as a novel therapeutic approach supporting SST rehabilitation interventions.

Keywords: Cinematic virtual reality | Schizophrenia rehabilitation | Social skills training | Task performance | Usability | User experience

Abstract: In this paper, the problem of robotic rehabilitation of upper limbs is addressed by focusing attention on the control of a standard collaborative robot for those training activities that can be performed with the aid of an end-effector type system. In particular, a novel admittance control, that constrains the motion of the robot along a prescribed path without imposing a specific time law along it, has been devised. The proposed approach exploits the features of the arc-length parameterization of a generic curve to obtain a simple control formulation able to guide the patient in both a passive or an active way, with the possibility of supporting the execution of the task with an additional force or opposing the motion with a braking force. Being the method independent from the particular curve considered for the constraint specification, it allows an intuitive definition of the task to be performed via Programming by Demonstration. Experimental results show the effectiveness of the proposed approach.

Keywords: Admittance control | Guidance virtual fixtures | Human-robot interaction | Rehabilitation

Abstract: Objective: The aim of this study was to evaluate the influence of three different dental implant neck geometries, under a combined compressive/shear load using finite element analysis (FEA). The implant neck was positioned in D2 quality bone at the crestal level or 2 mm below. Methods: One dental implant (4.2 × 9 mm) was digitized by reverse engineering techniques using micro CT and imported into Computer Aided Design (CAD) software. Non-uniform rational B-spline surfaces were reconstructed, generating a 3D volumetric model similar to the digitized implant. Three different models were generated with different implant neck configurations, namely 0°, 10° and 20°. D2 quality bone, composed of cortical and trabecular structure, was modeled using data from CT scans. The implants were included in the bone model using a Boolean operation. Two different fixture insertion depths were simulated for each implant: 2 mm below the crestal bone and exactly at the level of the crestal bone. The obtained models were imported to FEA software in STEP format. Von Mises equivalent strains were analyzed for the peri-implant D2 bone type, considering the magnitude and volume of the affected surrounding cortical and trabecular bone. The highest strain values in both cortical and trabecular tissue at the peri-implant bone interface were extracted and compared. Results: All implant models were able to distribute the load at the bone-implant contact (BIC) with a similar strain pattern between the models. At the cervical region, however, differences were observed: the models with 10° and 20° implant neck configurations (Model B and C), showed a lower strain magnitude when compared to the straight neck (Model A). These values were significantly lower when the implants were situated at crestal bone levels. In the apical area, no differences in strain values were observed. Significance: The implant neck configuration influenced the strain distribution and magnitude in the cortical bone and cancellous bone tissues. To reduce the strain values and improve the load dissipation in the bone tissue, implants with 10° and 20 neck configuration should be preferred instead of straight implant platforms.

Keywords: Dental implants | Finite element analysis | Implant design | Strain distribution

Abstract: Background and objective: Because of the three-dimensional distribution of morphological features of human vertebrae and the whole spine, in recent years, to make more precise diagnoses and to design optimized surgical procedures, new protocols have been proposed based on analysing their three-dimensional (3D) models. In the related literature, processes of segmentation and morphological features recognition are essentially performed by a skilled operator that selects the interesting areas. So, being affected by the preparation and experience of the operator, this produces an evaluation that is poorly reproducible and repeatable for the uncertainties of a typical manual measurement process. Methods: To overcome this limitation, in this paper a new automatic method is proposed for feature segmentation and recognition of human vertebrae. The proposed computer-based method, starting from 3D high density discretized models of thoracic and lumbar vertebrae, automatically performs both the semantic and geometric segmentation of their morphological features. The segmentation and recognition rules codify some important definitions used in the traditional manual method, considering all the vertebra morphology information that is invariant inter-subject. Results: The automatic method proposed here is verified by analysing many real vertebrae, both acquired using a 3D scanner and coming from Computerized Tomography (CT) scans. The obtained results are critically discussed and compared with the traditional manual methods for vertebra analysis. The method has proven to be robust and reliable in the segmentation and recognition of morphological features of vertebrae. Furthermore, the proposed automatic method avoids the blurring of quantitative parameters get from vertebrae, resulting from poor repeatability and reproducibility of manual methods used in the state-of-the-art. Conclusions: Starting from the automatic segmentation and recognition here proposed, it is possible to automatically calculate the parameters of thoracic or lumbar vertebrae used in archaeology, medicine, or biomechanics or define their new ones.

Keywords: 3D medical image analysis | Computer methods for vertebra analysis | Shape segmentation | Thoracic and lumbar vertebrae | Three-dimensional measurement

Abstract: Evidence regarding the effect of the onlay preparation design for different CAD/CAM restorative materials considering the preservation of cusps is lacking. Molars were 3D-modeled in four preparation designs for onlay restoration: Traditional design with functional cusp coverage (TFC), non-retentive design with functional cusp coverage (NFC), traditional design with non-functional cusp coverage (TNFC) and non-retentive design with non-functional cusp coverage (NNFC). The restorations were simulated with two CAD/CAM restorative materials: LD—lithium disilicate (IPS e.max CAD) and RC—resin composite (GrandioBloc). A 100 N axial load was applied to the occlusal surface, simulating the centric contact point. Von Mises (VM) and maximum principal (Pmax) stress were evaluated for restorations, cement layer and dental substrate. The non-retentive preparation design reduced the stress concentration in the tooth structure in comparison to the conventional retentive design. For LD onlays, the stress distribution on the restoration intaglio surface showed that the preparation design, as well as the prepared cusp, influenced the stress magnitude. The non-retentive preparation design provided better load distribution in both restorative materials and more advantageous for molar structure. The resin composite restoration on thenon-functional cusp is recommended when the functional cusp is preserved in order to associate conservative dentistry and low-stress magnitude.

Keywords: Biomechanics | Dental materials | Finite element analysis | Prosthodontics

Abstract: The aim of the present study was to investigate the effect of shrinking and no shrinking dental filling materials combination in posterior restorations under the combined effects of polymerization shrinkage and occlusal load by means of 3D Finite Elements Analysis. Six computer-generated and restored class I or class II cavities models of a lower molar were designed in the CAD software and evaluated according to the cavity and restorative procedure. Different shrinking and no shrinking adhesive materials combination with diverse Young’s modulus were considered. A food bolus was modeled on the occlusal surface replicating the chewing load using static linear analyses Polymerization shrinkage was simulated for the shrinking different restorative materials. The maximum principal stress was selected as analysis criteria. All models exhibited higher stresses along the dentine restoration interfaces with different magnitude and a similar stress trend along enamel restoration interface. Stress values up to 22 MPa and 19 MPa were recorded in the enamel and restoration, respectively. The use of elastic not shrinking material layer in combination with bulk fill composite reduced the stress magnitude in dentine and enamel to replace dental tissues. Class I and class II posterior cavities adhesively restored with shrinking filling material’s combination showed the most unfavorable stress concentrations and the multilayer technique is a promising restorative alternative in posterior adhesive restorations when deep dentin and enamel volumes are missing.

Keywords: Dental materials | Dental restoration failure | Finite element analysis | Shrinkage polymerization

Abstract: Home-based recovery is gradually being used to reduce health-care costs; however, with a shorter stay in the hospital, the risk of growing adverse clinical outcomes exists, mainly due to the lack of motivation in the patient and on the difficulties in performing a strict control by the doctors. This is particularly true for patients who went under knee arthroplasty or total knee replacement who should strictly follow the effective recovery protocols delivered by the doctors. The development of tools for measuring the functional recovery of the operated joint is therefore deemed crucial both for the patient to feel motivated in performing the right number of exercises, and for the doctor that can follow him/her up remotely. One of the most recognized methods for assessing the correctness of a series of recovery exercises, is to monitor the pose of the patient in real-time so as to evaluate its posture in his range of motion. Accordingly, in this paper a novel hybrid approach to 3D human pose estimation is proposed. A first estimation of 2D body pose of the patient in the scene is given, then the depth information coming from the RGB-D sensor is exploited to estimate the joints 3D coordinates. The proposed algorithm proved to overcome the main limitation of using a pure 3D skeleton tracking algorithm during physiotherapy rehabilitation.

Keywords: 3D | Body tracking | Data fusion | Joints estimation | RGB-D camera

Abstract: Autologous ear reconstruction is the preferred treatment in case of partial or total absence of the external ear. The surgery can be very challenging to perform and the aesthetic result highly dependent on the surgeon’s “artistic skills”. In this context a preoperative planning and simulation phase based on the patient’s specific anatomy may result crucial for the surgical outcome. In this work, starting from a case study, the elements necessary for an effective simulation are identified and a strategy for their interactive design and customization is devised with a perspective of a semi-automatization of the procedure.

Keywords: Additive manufacturing | Autologous ear reconstruction | Microtia | Preoperative planning | Reverse engineering

Abstract: Convolutional neural networks are increasingly used in the medical field for the automatic segmentation of several anatomical regions on diagnostic and non-diagnostic images. Such automatic algorithms allow to speed up time-consuming processes and to avoid the presence of expert personnel, reducing time and costs. The present work proposes the use of a convolutional neural network, the U-net architecture, for the segmentation of ear elements. The auricular elements segmentation process is a crucial step of a wider procedure, already automated by the authors, that has as final goal the realization of surgical guides designed to assist surgeons in the reconstruction of the external ear. The segmentation, performed on depth map images of 3D ear models, aims to define of the contour of the helix, antihelix, tragus-antitragus and concha. A dataset of 131 ear depth map was created;70% of the data are used as the training set, 15% composes the validation set, and the remaining 15% is used as testing set. The network showed excellent performance, achieving 97% accuracy on the validation test.

Abstract: The strong impulse recently experienced by the manufacturing technologies as well as the development of innovative biocompatible materials has allowed the fabrication of high-performing scaffolds for bone tissue engineering. The design process of materials for bone tissue scaffolds represents, nowadays, an issue of crucial importance and the object of study of many researchers throughout the world. A number of studies have been conducted, aimed at identifying the optimal material, geometry, and surface that the scaffold must possess to stimulate the formation of the largest amounts of bone in the shortest time possible. This book presents a collection of 10 research articles and 2 review papers describing numerical and experimental design techniques definitively aimed at improving the scaffold performance, shortening the healing time, and increasing the success rate of the scaffold implantation process.

Keywords: Bone regeneration | Bone tissue engineering | Porous materials

Abstract: Laryngoscopes are used as diagnostic devices for throat inspection or as an aid to intubation. Their blade must be geometrically compatible with patients’ anatomy to provide a good view to doctors with minimal discomfort to patients. For this reason, this paper was aimed to investigate the feasibility of producing customized blades. The customizable blade model was developed following a feature-based approach with eight morphological parameters. The thickness of such a blade was determined through numerical simulations of ISO certification tests, where the finite element mesh was obtained by morphing a ‘standard’ mesh. The following procedure was applied: the model was built from the selected parameters; the blade was tested in silico; finally, the blade was produced by additive manufacturing with an innovative biodegradable material (Hemp Bio-Plastic® -HBP-) claimed to feature superior mechanical properties. The procedure evidenced that the mechanical properties of current biodegradable materials are unsuitable for the application unless the certification norm is revised, as it is expected.

Keywords: Additive manufacturing | Biodegradable materials | Feature-based modeling | Laryngoscope blades | Mesh-morphing | Parametric drawing | Patient-specific design

Abstract: Robotic devices are being employed in more and more sectors to enhance, streamline, and augment the outcomes of a wide variety of human activities. Wearable robots arise indeed as of-vital-importance tools for telerehabilitation or home assistance targeting people affected by motor disabilities. In particular, the field of “Robotics for Medicine and Healthcare” is attracting growing interest. The development of such devices is a primarily addressed topic since the increasing number of people in need of rehabilitation or assistive therapies (due to population aging) growingly weighs on the healthcare systems of the nation. Besides, the necessity to move to clinics represents an additional logistic burden for patients and their families. Among the various body parts, the hand is specially investigated since it most ensures the independence of an individual, and thus, the restoration of its dexterity is considered a high priority. In this study, the authors present the development of a fully wearable, portable, and tailor-made hand exoskeleton designed for both home assistance and telerehabilitation. Its purpose is either to assist patients during activities of daily living by running a real-time intention detection algorithm or to be used for remotely supervised or unsupervised rehabilitation sessions by performing exercises preset by therapists. Throughout the mechatronic design process, special attention has been paid to the complete wearability and comfort of the system to produce a user-friendly device capable of assisting people in their daily life or enabling recorded home rehabilitation sessions allowing the therapist to monitor the state evolution of the patient. Such a hand exoskeleton system has been designed, manufactured, and preliminarily tested on a subject affected by spinal muscular atrophy, and some results are reported at the end of the article.

Keywords: hand exoskeleton | home assistance | mechatronics design | robotics | telerehabilitation | wearable robot

Abstract: Cranioplasty is a procedure performed to repair defects in the human skull bone by surgically reconstructing the shape and function of the cranium. Several complications, both intraoperative and postoperative, can affect the procedure’s outcome (e.g., inaccuracies of the reconstructed shape, infections, ulcer, necrosis). Although the design of additive manufactured implants in a preoperative stage has improved the general quality of cranioplasties, potential complications remain significant, especially in the presence of critical skin tissue conditions. In this paper, an innovative procedure to improve the chances of a positive outcome when facing critical conditions in a cranioplasty is described. The proposed approach relies on a structured planning phase articulated in a series of digital analyses and physical simulations performed on personalized medical devices that guide the surgeon in defining surgical cuts and designing the implant. The ultimate goal is to improve the chances of a positive outcome and a fast recovery for the patient. The procedure, described in extenso in the paper, was positively tested on a cranioplasty case study, which presented high risk factors.

Keywords: Additive manufacturing | Cranioplasty | Patient-specific implant | Skull reconstruction

Abstract: Robotics for Medicine and Healthcare is undoubtedly an important emerging sector of the newborn third millennium. There are many aspects in which this branch of robotics already operates; in this article, the focus will be on the so-called “Robotic assistive technology”. In particular, a novel electromechanical design for an assistive Hand Exoskeleton System is presented here. Since freedom of movement plays a crucial role in making actually usable an assistive device, the main point of innovation of the proposed solution lies in the complete wearability of the resulting system: including mechanics, control electronics, and power supply. From the combination of the authors’ previous experience with the improvements presented in this article comes a fully standalone tailor-made assistive device.

Abstract: Spine surgery is based, nowadays, on the use of cutting-edge instruments that optimize the intervention processes in the operating room, with advantages that affect the patient himself. Among these, rapid prototyping is configured as a first-rate tool, thanks to its ability to detail the diagnostic treatment according to the specific pathological case under examination. An example of this technology is represented by the generation of a drilling template, to assist the surgeon in identifying the optimal direction of insertion of the pedicle screws, capable of significantly reduce intervention times, in addition to the inevitable exposure of the patient to ionizing radiation, to which he is subjected during a normal arthrodesis intervention procedure. The design of a drilling guide requires, however, a particular attention in identifying the undercuts present on the vertebral surface, those areas of the spinous process which, reported inside the cavity of the template, involve complications at the time of extraction. In parallel, it is vitally important to carry out an evaluation of its stability during its use. In this article, starting from the analysis of the interferences present during the insertion of the template, a semi-automatic correction model is proposed for the generation of a new profile of the same, which facilitates its extraction without causing injury to the vertebral regions involved from the contact with the mask.

Keywords: Computer‐assisted surgery | Pedicle screw fixation | Spine | Surgical template insertion optimization | Undercuts

Abstract: Improvements in software for image analysis have enabled advances in both medical and engineering industries, including the use of medical analysis tools to recreate internal parts of the human body accurately. A research analysis found that FDM-sourced elements have shown viability for a customized and reliable approach in the orthopedics field. Three-dimensional printing has allowed enhanced accuracy of preoperative planning, leading to reduced surgery times, fewer unnecessary tissue perforations, and fewer healing complications. Furthermore, using custom tools chosen for each procedure has shown the best results. Bone correction-related surgeries require customized cutting guides for a greater outcome. This study aims to assess the biopolymer-based tools for surgical operations and their ability to sustain a regular heat-sterilization cycle without compromising the geometry and fit characteristics for a proper procedure. To achieve this, a DICOM and FDM methodology is proposed for fast prototyping of the cutting guide by means of 3D engineering. A sterilization test was performed on HTPLA, PLA, and nylon polymers. As a result, the unique characteristics within the regular autoclave sterilization process allowed regular supplied PLA to show there were no significant deformations, whilst annealed HTPLA proved this material’s capability of sustaining repeated heat cycles due to its crystallization properties. Both of these proved that the sterilization procedures do not compromise the reliability of the part, nor the safety of the procedure. Therefore, prototypes made with a similar process as this proposal could be safely used in actual surgery practices, while nylon performed poorly because of its hygroscopic properties.

Keywords: 3D engineering | Cutting guide | FDM | HTPLA | Nylon FDM | Preoperative planning | Sterilization

Abstract: This experimental study defines the usage of a computer-aided surgical simulation process that is effective, safe, user-friendly, and low-cost, that achieves a detailed and realistic representation of the anatomical region of interest. The chosen tools for this purpose are state-of-the-art Computer Aided Design (CAD) software for mechanical design, and are the fundamental application dedicated to parametric modeling. These tools support different work environments, each one is for a specific type of modeling, and they allow the simulation of surgery. The result will be a faithful representation of the anatomical part both before and after the surgical procedure, screening all the intermediate phases. The doctor will assess different lines of action according to the results, then he will communicate them to the engineer who, consequently, will correct the antisymmetric issue and regenerate the model. Exact measurements of the mutual positions of the various components, skeletal and synthetic, can be achieved; all the osteosynthesis tools, necessary for the surgeon, can be included in the project according to different types of fracture to perfectly match the morphology of the bone to be treated. The method has been tested on seven clinical cases of different complexity and nature and the results of the simulations have been found to be of great effectiveness in the phase of diagnosis and of preoperative planning for the doctors and surgeons; therefore, allowing a lower risk medical operation with a better outcome. This work delivers experimental results in line with theoretical research findings in detail; moreover, full experimental and/or methodical details are provided, so that outcomes could be obtained.

Keywords: 3D processing | CAD-aided | Customized surgery | Pediatric orthopedics | Preoperative planning | Surgical simulation

Abstract: This work aims to present the application of mechanical modeling software in three dimensions in the medical field, analyzing the procedures used by the engineer to support the orthopedic surgeon in preoperative planning. The first step of the procedure involves CT examinations in patients selected for surgery: DICOM images are managed in post-processing to obtain multiplanar reconstructions of the bone lesion to be treated. The files are then optimized, made shareable and imported into CREO's work platform; this is part of a family of CAD software products for mechanical design, developed by PTC, and is the fundamental application dedicated to parametric modeling. The result will be a faithful representation of the anatomical part both before and after surgical procedure, screening all the intermediate phases. The doctor will assess different lines of action according to the results, than he will communicate them to the engineer who, consequently, will correct and regenerate the model. The method finds its power in the dialogue between engineer and doctor: In complex cases closer collaboration is needed while, for the evaluation of less demanding injuries, the exam could be assigned as a remote project which, once completed, is returned to the medical facility of competence.

Keywords: 3D modeling | Computer aided | Parametric software | Preoperative planning | Surgical simulation

Abstract: Artificial Intelligence (AI) algorithms, together with a general increased computational performance, allow nowadays exploring the use of Facial Expression Recognition (FER) as a method of recognizing human emotion through the use of neural networks. The interest in facial emotion and expression recognition in real-life situations is one of the current cutting-edge research challenges. In this context, the creation of an ecologically valid facial expression database is crucial. To this aim, a controlled experiment has been designed, in which thirty-five subjects aged 18–35 were asked to react spontaneously to a set of 48 validated images from two affective databases, IAPS and GAPED. According to the Self-Assessment Manikin, participants were asked to rate images on a 9-points visual scale on valence and arousal. Furthermore, they were asked to select one of the six Ekman’s basic emotions. During the experiment, an RGB-D camera was also used to record spontaneous facial expressions aroused in participants storing both the color and the depth frames to feed a Convolutional Neural Network (CNN) to perform FER. In every case, the prevalent emotion pointed out in the questionnaires matched with the expected emotion. CNN obtained a recognition rate of 75.02%, computed comparing the neural network results with the evaluations given by a human observer. These preliminary results have confirmed that this experimental setting is an effective starting point for building an ecologically valid database.

Keywords: 3D facial database | Affective database | Basic emotions | Ecologically-valid data | Facial expression recognition | Human-robot interaction

Abstract: This work shows a preoperative simulation procedure with Computer Aided Design (CAD) 3D software for a patient suffering from Ollier's disease. This pathology is very rare and occurs in extremely different ways depending on the case. Consequently, it is difficult to establish a correct surgical strategy that can be applied in a similar way to all patients. Computer Aided Surgical Simulation (CASS) process uses advanced modeling technologies to reproduce bony anatomy and simulate the surgery. The starting point is represented by the 3D digital model of the bone obtained from tomographic images. Through CAD modeling software such as Creo Parametric and following surgeons directives, engineers can provide doctors with orthopedic simulation and expectation of achievable surgical outcome. If virtual surgical prediction doesn’t meet doctors requirements, model is regenerated and it is possible to seek for a better solution. CASS process allow for extensive surgical planning, enhancing accuracy in theatre and enriching the amount of medical information that is needed to perform complex orthopedic procedures. In conclusion, the possibility to recognize in advance the overall orthopedic situation and outcoming expectancy represent an extraordinary upgrade of current surgical state of the art, leading to minimally invasive surgeries and patient-specific solutions.

Keywords: 3D modeling | CAD | CASS | Parametric software | Preoperative planning

Abstract: Autologous ear reconstruction is the preferred treatment in case of partial or total absence of the patient external ear. This kind of surgery can be really challenging since precise replication of complex three-dimensional structure of the ear is crucial to provide the patients with aesthetically consistent reconstructed anatomy. Therefore, the results strongly depends on the “artistic skills” of the surgeon who is in charge to carry out a three-dimensional sculpture, which resembles the shape of a normal ear. In this context, the definition of a preoperative planning and simulation process based on the patient's specific anatomy may help the surgeon in speeding up the ear reconstruction process and, at the same time, to obtain better results, thus allowing a superior surgical outcome. In the present work the main required features for performing an effective simulation of the ear reconstruction are identified and a strategy for their interactive design and customization is devised with the perspective of a semi-automatization of the procedure. In detail, the paper provides a framework which start from the acquisition of 3D data from both a healthy ear of the patient (or, if not available e.g. due to bilateral microtia of the ear of one of his parents or from a template) and of costal cartilage. Acquired 3D data are properly processed to define the anatomical elements of the ear and to find, using nesting-based algorithms, the costal cartilage portions to be used for carving the ear itself. Finally, 3D printing is used to create a mockup of the ear elements and a prototype of the ear to be reconstructed is created. Validated on a test case, the devised procedure demonstrate its effectiveness.

Keywords: Additive manufacturing | Autologous ear reconstruction | Microtia | Preoperative planning | Reverse engineering

Abstract: The increasing availability of 3D anatomical models obtained from diagnostic images exploiting Reverse Engineering techniques allows the application of statistical analysis in the quantitative investigation of anatomical shapes variability. Statistical Shape Models are a well-established method for representing such variability, especially for complex forms like the anatomical ones. Not by chance, these models are widely used for medical applications, such as guiding segmentation of the diagnostic image and virtual reconstruction of incomplete anatomic region. The application of a statistical analysis on a set of shapes representing the same anatomical region essentially requires that shapes must be in correspondence, i.e. constituted by the same number of points in corresponding position. This work aims to compare two established algorithms, namely a modified version of the Iterative Closest Point and the non-rigid version of the Coherent Point Drift, to solve the correspondences’ problem in the construction of a Statistical Shape Model of the human cranium. The comparison is carried out on the models using the standard evaluation criteria: Generalization, Specificity and Compactness. The modified version of the Iterative Closest Point delivers a better Statistical Shape Model in terms of Generalization and Specificity, but not for Compactness, than the Coherent Point Drift-based model.

Keywords: Computer-Aided Technologies | Correspondences’ problem | Reverse Engineering | Statistical Shape Analysis | Statistical Shape Model

Abstract: Disruptive 3D technologies, such as reverse engineering (RE) and additive manufacturing (AM), when applied in the medical field enable the development of new methods for personalized and non-invasive treatments. When referring to the monitoring of pectus excavatum, one of the most common thoracic malformations, 3D acquisition of the patient chest proved to be a straightforward method for assessing and measuring chest deformation. Unfortunately, such systems are usually available in a dedicated facility, can be operated only by specialized doctors with the support of engineers and can be used only with patients on site. It is therefore impossible to perform any routine check-up when the patient is unable to reach the outpatient clinic. The COVID19 pandemic situation has placed even greater restrictions on patient mobility, worsening this problem. To deal with this issue, a new low-cost portable optical scanner for monitoring pectus excavatum is proposed in this work. The scanner, named Thor 2.0, allows a remote diagnostic approach, offering the possibility to perform routine check-ups telematically. Usability tests confirmed the user-friendly nature of the devised system. The instrument was used at the Meyer Children’s Hospital (Florence, Italy) chest-malformations center to treat PE patients. The performed measurements proved to be in line with the current state of the art.

Keywords: Handheld scanner | Intel RealSense | Optical chest index | Pectus excavatum | Telemedicine | Usability test | Vacuum bell

Abstract: The growing interest in the auricular anatomy is due to two different strands of research: 1) in the medical field it is associated with autologous ear reconstruction, a surgery adopted following trauma or congenital malformations; 2) in surveillance and law enforcement the ear is used for human detection and recognition. Alternative systems of ear analysis can be differentiated for the type of input data (two-dimensional, three-dimensional or both), for the type of acquisition tools (3D scanner, photographs, video surveillance, etc.) and finally for the adopted algorithms. Although the segmentation and recognition of the ear from the face is a widely discussed topic in literature, the detection and recognition of individual anatomical elements has not yet been studied in depth. To this end, this work lays the foundation for the identification of the auricular elements through image processing algorithms. The proposed algorithm automatically identifies the contours of the main anatomical elements by processing depth map images. The algorithm was tested qualitatively and quantitatively on a dataset composed of 150 ears. The qualitative evaluation was performed with the collaboration of medical staff and the quantitative tests were performed using manually annotated ground truth data.

Keywords: Depth map | Ear biometrics | Ear dataset | Ear reconstruction | Ear segmentation | Microtia

Abstract: The major breakthroughs in the fields of reverse engineering and additive manufacturing have dramatically changed medical practice in recent years, pushing for a modern clinical model in which each patient is considered unique. Among the wide spectrum of medical applications, reconstructive surgery is experiencing the most benefits from this new paradigm. In this scenario, the present paper focuses on the design and development of a tool able to support the surgeon in the reconstruction of the external ear in case of malformation or total absence of the anatomy. In particular, the paper describes an appositely devised software tool, named G-ear, which enables the semi-automatic modeling of intraoperative devices to guide the physician through ear reconstruction surgery. The devised system includes 3D image segmentation, semi-automated CAD modelling and 3D printing to manufacture a set of patient-specific surgical guides for ear reconstruction. Usability tests were carried out among the surgeons of the Meyer Children's Hospital to obtain an assessment of the software by the end user. The devised system proved to be fast and efficient in retrieving the optimal 3D geometry of the surgical guides and, at the same time, to be easy to use and intuitive, thus achieving high degrees of likability.

Abstract: Driver behaviour recognition is of paramount importance for in-car automation assistance. It is widely recognized that not only attentional states, but also emotional ones have an impact on the safety of the driving behaviour. This research work proposes an emotion-aware in-car architecture where it is possible to adapt driver’s emotions to the vehicle dynamics, investigating the correlations between negative emotional states and driving performances, and suggesting a system to regulate the driver’s engagement through a unique user experience (e.g. using music, LED lighting) in the car cabin. The relationship between altered emotional states induced through auditory stimuli and vehicle dynamics is investigated in a driving simulator. The results confirm the need for both types of information to improve the robustness of the driver state recognition function and open up the possibility that auditory stimuli can modify driving performance somehow.

Keywords: Driver monitoring system | Emotion recognition | Facial expression recognition

Abstract: The advantages of additive manufactured scaffolds, as custom-shaped structures with a completely interconnected and accessible pore network from the micro- to the macroscale, are nowadays well established in tissue engineering. Pore volume and architecture can be designed in a controlled fashion, resulting in a modulation of scaffold’s mechanical properties and in an optimal nutrient perfusion determinant for cell survival. However, the success of an engineered tissue architecture is often linked to its surface properties as well. The aim of this study was to create a family of polymeric pastes comprised of poly(ethylene oxide therephthalate)/poly(butylene terephthalate) (PEOT/PBT) microspheres and of a second biocompatible polymeric phase acting as a binder. By combining microspheres with additive manufacturing technologies, we produced 3D scaffolds possessing a tailorable surface roughness, which resulted in improved cell adhesion and increased metabolic activity. Furthermore, these scaffolds may offer the potential to act as drug delivery systems to steer tissue regeneration.

Keywords: additive manufacturing | mechanical analysis | mesenchymal stem cells | microparticles | polymers | tissue engineering

Abstract: The concept of magnetic guidance has opened a wide range of perspectives in the field of tissue regeneration. Accordingly, the aim of the current research is to design magnetic responsive scaffolds for enhanced bone tissue regeneration. Specifically, magnetic nanocomposite scaffolds are additively manufactured using 3D fibre deposition technique. The mechanical and magnetic properties of the fabricated scaffolds are first assessed. The role of magnetic features on the biological performances is properly analyzed.

Keywords: bone tissue engineering | design for additive manufacturing | magnetic nanocomposite scaffolds | mechanical and functional properties

Abstract: This paper introduces a new recommendation system for museums able to profile the visitors and propose them the most suitable exhibition path accordingly, to improve visitors’ satisfaction. It consists of an interactive touch screen totem, which implements a USB camera and exploits Convolutional Neural Network to perform facial coding to measure visitors’ emotions and estimate their age and gender. Based on the detected level of emotional valence, the system associates visitors with a profile and suggests them to visit a selection of five works of art, following a specific itinerary. An extensive experimentation lasting 2 months has been carried out at the Modern Art Museum “Palazzo Buonaccorsi” of Macerata. Results evidence that the proposed system can create an interactive and emotional link with the visitors, influencing their mood in the Pre-Experience phase and in the subsequent Post-Experience phase. In particular, they highlight that the proposed system, which aims at acting as emotional leverage, has been able to improve the positiveness of the emotions experienced by the visitors.

Keywords: Affective computing | Cultural heritage | Emotion recognition | Facial expression recognition

Abstract: The conventional camera-based systems and electronic gloves for gesture recognition are limited by the influence of lighting conditions, occlusions, and movement restrictions. A wearable smart band with integrated nanocomposite pressure sensors has been developed to overcome these shortcomings. The sensors consist of homogeneously dispersed carbon nanotubes in a polydimethylsiloxane polymer matrix prepared by an optimized synthesis process. The sensor band can actively monitor contractions/relaxations of muscles in the arm due to the sensor's high sensitivity in the low forces and stability. The band has eight sensors placed on a stretchable adhesive textile material and connected to a data logger with a multiplexed sensor interface and wireless communication capabilities. The novel smart band was validated by measurements on ten subjects to perform numerical gestures in American sign language from 0 to 9 with ten trials each. The data were recorded at 100 Hz, and a total of 100 datasets were generated for each subject. By feeding the datasets to an extreme machine learning algorithm that selects features, weights, and biases to classify the gestures, an overall gesture recognition accuracy of 93% could be achieved.

Keywords: American sign language | gesture recognition | polymer carbon nanocomposite (PCN) pressure sensors | Sensor applications | wearable smart band

Abstract: The cooling of a melt corresponding to the eutectic between wollastonite (CaSiO3) and diopside (CaMgSi2O6) determines the synthesis of an interesting example of alkali-free bioactive glass, easily converted into glass-ceramics featuring two silicate phases, coupled also with åkermanite (Ca2MgSi2O7), by sinter-crystallization of fine glass powders at 1000°C. The fabrication of scaffolds by digital light processing of glass powders suspended in a photo-curable, sacrificial binder, is a well-established technique; the present paper aims at disclosing novel approaches, concerning the topology of scaffolds, offering components with remarkable strength, especially in bending conditions. As an alternative, glass-ceramic foams were fabricated by the firing of porous precursors derived from the gelation of suspensions of glass powders in alkali-free basic aqueous solution.

Keywords: additive manufacturing | alkali-free bioactive glasses | bioactive glass-ceramics | gel casting | scaffolds | sinter-crystallization

Abstract: Additive manufacturing technologies, compared to conventional shaping methods, offer great opportunities in design versatility, for the manufacturing of highly porous ceramic components. However, the application to glass powders, later subjected to viscous flow sintering, involves significant challenges, especially in shape retention and in the achievement of a substantial degree of translucency in the final products. The present paper disclosed the potential of glass recovered from liquid crystal displays (LCD) for the manufacturing of highly porous scaffolds by direct ink writing and masked stereolithography of fine powders mixed with suitable organic additives, and sintered at 950◦C, for 1–1.5 h, in air. The specific glass, featuring a relatively high transition temperature (Tg~700◦C), allowed for the complete burn-out of organics before viscous flow sintering could take place; in addition, translucency was favored by the successful removal of porosity in the struts and by the resistance of the used glass to crystallization.

Keywords: Additive manufacturing | Direct ink writing | Glass recycling | LCD glass | Scaffolds

Abstract: The development of new bent superconducting magnets together with the optimization of the support structure open the way to a considerable reduction in the weight and complexity of rotating gantries for medical applications. The magnets, which define the transfer line to deliver carbon ions to the patients from different angles, are supported by a rotating structure that should be as rigid and as lightweight as possible. Relative displacements of the magnets due to deformations cause incorrect beam position and consequent errors in hitting the target tissues. This paper describes a possible rotating structure which is considerably lighter than the previous designs. A method to compensate part of the deformation by complementary rotations of the driving motor is proposed. The influence of the construction tolerances and deformations of the supports is also analyzed and alignment and adjustment possibilities are discussed.

Keywords: Curved magnets | Gantry for medical applications | Ion therapy

Abstract: Short bowel syndrome is a pathological condition resulting from extensive resection of the intestine, generally performed due to congenital abnormalities, Crohn’s disease, mesenteric ischemia, or neoplasms. The main consequence of this syndrome is a reduction of intestinal absorp-tion, which causes malnutrition and dehydration. In the most severe cases, specific and complex surgical procedures are requested to manage the syndrome. Such procedures consist of the intestinal lengthening, with lead to an increase of absorptive mucosal surface and intestinal transit time and an overall enhancement of intestinal absorption. One of the most promising surgical procedures is spiral intestinal lengthening and tailoring, which consists of a spiral incision of the intestinal wall and in the elongation longitudinally of the intestine by sliding one flap over the other. The final intestinal lengthening is strictly dependent on a series of parameters, some of which are defined by the surgeon. The present paper proposes a mathematical model, based on patient specific anatomical data, which aims to help the surgeon in defining the optimal parameters for the intervention and in foreseeing its outcomes from the preoperative planning phase. Such a tool can assist the physician in the surgery room by improving the procedure and reducing surgical times.

Keywords: Intestinal failure | Intestinal lengthening | Pediatric | Preoperative planning | Short bowel syndrome | Surgical simulation

Abstract: Liver cells cultured in 3D bioreactors is an interesting option for temporary extracorporeal liver support in the treatment of acute liver failure and for animal models for preclinical drug screening. Bioreactor capacity to eliminate drugs is generally used for assessing cell metabolic competence in different bioreactors or to scale-up bioreactor design and performance for clinical or preclinical applications. However, drug adsorption and physical transport often disguise the intrinsic drug biotransformation kinetics and cell metabolic state. In this study, we characterized the intrinsic kinetics of lidocaine elimination and adsorption by porcine liver cells cultured in 3D four-compartment hollow fiber membrane network perfusion bioreactors. Models of lidocaine transport and biotransformation were used to extract intrinsic kinetic information from response to lidocaine bolus of bioreactor versus adhesion cultures. Different from 2D adhesion cultures, cells in the bioreactors are organized in liver-like aggregates. Adsorption on bioreactor constituents significantly affected lidocaine elimination and was effectively accounted for in kinetic analysis. Lidocaine elimination and cellular monoethylglicinexylidide biotransformation featured first-order kinetics with near-to-in vivo cell-specific capacity that was retained for times suitable for clinical assist and drug screening. Different from 2D cultures, cells in the 3D bioreactors challenged with lidocaine were exposed to close-to-physiological lidocaine and monoethylglicinexylidide concentration profiles. Kinetic analysis suggests bioreactor technology feasibility for preclinical drug screening and patient assist and that drug adsorption should be accounted for to assess cell state in different cultures and when laboratory bioreactor design and performance is scaled-up to clinical use or toxicological drug screening.

Keywords: Adsorption | Bioreactor | Elimination | Kinetics | Lidocaine | Liver cells | Tissue engineering

Abstract: In the current research, an optimization design strategy for additive manufacturing processes based on extrusion/injection methods was extended to the fabrication of poly(ε-caprolactone) (PCL)/iron oxide (Fe3O4) scaffolds for tissue engineering. The attention was focused on four parameters: process temperature (PT), deposition velocity (DV), screw rotation velocity (SRV), slice thickness (ST). Specifically, PCL/Fe3O4 scaffolds were manufactured varying iteratively one parameter, while maintaining constant the other three parameters. A further insight into the influence of process parameters on the morphological features and mechanical properties of PCL/Fe3O4 scaffolds was provided.

Keywords: Design for additive manufacturing | Magnetic nanocomposite scaffolds | Mechanical and morphological properties | Tissue engineering

Abstract: Nowadays, technology in sport plays an important role to help training and judgement processes. This study proposes the use of a wearable inertial system to derive novel biomechanical indices for the assessment of performance and infringements in race-walking. These indices are built from five inertial-based parameters: loss of ground contact time, loss of ground contact step classification, step length ratio, step cadence and smoothness. The biomechanical indices are customized for elite race-walkers, and represented on a radar chart for an intuitive analysis of performance and infringements. From the radar chart, a synthetic index regarding the athlete’s overall gesture is derived. The validation of the biomechanical indices is carried out in field tests, involving nine elite race-walkers wearing an inertial sensor located at the end of the column vertebra (L5–S1). A statistical analysis is used to determinate the quality and reliability of the proposed indices and of their representation. The results show that these biomechanical indices can be implemented on a wearable inertial system for assistance in training and judgement in race-walking.

Keywords: Biomechanics | Field tests | Graphical data analysis | Infringements | Performance | Race-walking | Wearable sensors

Abstract: In this paper we present novel biomechanical indices for site-specific assessment of injury risk in cycling. The indices are built from a multifactorial analysis based on the kinematics and kinetics of the cyclist from the biomechanical side, and muscle excitations and muscle synergies from the neurophysiological side. The indices are specifics for three body regions (back, knee, ankle) which are strongly affected by overuse injuries in cycling. We use these indices for injury risks analysis of a recreational cyclist, who offered to participate in the experiments. The preliminary results are promising towards the use of such indices for planning and/or evaluating training schedule with the final goal of reducing non-traumatic injuries in cycling.

Keywords: biomechanics | cycling | electromyography | injury risk | laboratory test

Abstract: This paper shows how studies on the biomechanics and neuroscience of human movements might be used for the design of wearable systems customized for humans. Such design is driven by key biomechanical and neuromuscular parameters extracted from accurate measurements made on the human body motion, as well as by subjective data collected from the end-users of the products through questionnaires. We present three case studies developed at ERGOS Lab: a wearable system for sports performance analysis; a synergy-based approach for industrial wearable robots; a soft wearable robotic glove for hand rehabilitation.

Keywords: Biomechanics | Design methods | Neuromuscular activity | Wearable technology

Abstract: 3D digital models of the upper limb anatomy represent the starting point for the design process of bespoke devices, such as orthoses and prostheses, which can be modeled on the actual patient’s anatomy by using CAD (Computer Aided Design) tools. The ongoing research on optical scanning methodologies has allowed the development of technologies that allow the surface reconstruction of the upper limb anatomy through procedures characterized by minimum discomfort for the patient. However, the 3D optical scanning of upper limbs is a complex task that requires solving problematic aspects, such as the difficulty of keeping the hand in a stable position and the presence of artefacts due to involuntary movements. Scientific literature, indeed, investigated different approaches in this regard by either integrating commercial devices, to create customized sensor architectures, or by developing innovative 3D acquisition techniques. The present work is aimed at presenting an overview of the state of the art of optical technologies and sensor architectures for the surface acquisition of upper limb anatomies. The review analyzes the working principles at the basis of existing devices and proposes a categorization of the approaches based on handling, pre/post-processing effort, and potentialities in real-time scanning. An in-depth analysis of strengths and weaknesses of the approaches proposed by the research community is also provided to give valuable support in selecting the most appropriate solution for the specific application to be addressed.

Keywords: Body scanner | Depth cameras | Handheld scanner | Stationary scanner | Structured light scanning | Upper limb 3D scanning

Abstract: Pectus Arcuatum (PA) is a congenital chest wall deformity which produces a superior manubrial and sternal protrusion, particularly at the sternal angle. PA surgical correction to reduce the angle of the sternum always includes the removal of bone portion by means of horizontal sternal osteotomies, resection of deformed rib cartilage and finally stabilization of the anterior thoracic wall. Within this process an incorrect assessment of the sternotomy angle during the procedure may lead to the need for bone or cartilage grafts to fill the left voids. This problem has been addressed with a patient-specific cutting template, realized with Reverse Engineering and Additive Manufacturing techniques, which proved to be a key element to simplify the procedure and avoid the occurrence of this type of complications. In this work is presented and validated a procedure that, through common CAD operations, realizes in a completely automatic way the CAD model of the custom cutting template, so as to make non-expert users independent in the realization of the medical device.

Abstract: Total hip arthroplasty (THA) and total knee arthroplasty (TKA) have been recently heralded as the operations of the Century. Large improvements in mobility and patient-reported outcomes are typically observed compared with the small-to-moderate effects experienced with non-surgical interventions. Following surgery, physiotherapy-led exercise-based rehabilitation is often prescribed to yield better gait-related outcomes. Nevertheless, outpatient rehabilitation is expensive and heavily burden the national health service. When specific machines are not needed during the physiotherapy, patients, if assisted, can perform a home program. The purpose of this paper is to qualitatively investigate the applicability of a self-managed, home-based system for the automated evaluation of a home physiotherapy rehabilitation after TKA and THA. The system leverages the cost effectiveness and the versatility of a RGB-Depth camera system together with a commercial skeleton tracking system to analyse specific exercises. A novel computation of lower limb movements and related angles is proposed to evaluate the quality of the daily exercises. The laboratory experimental campaign, envisaged the analysis of the rotation angles of hips and knees; a lower limb schematic model is considered to estimate both knee and hip angles during ab/adductor and flex/extension movements. A novel real time calculation of the hip bone plane is proposed to assess the joint angles during specific exercises performance. A qualitative data analysis of each exercise has been performed. Results on the system usability in a domestic environment are reported as well as a visual comparison of the analysed output.

Keywords: 3D | Body tracking | RGB-D camera

Abstract: In patients affected by craniosynostosis, i.e. a congenital cranial defect, diagnostic evaluation for a prompt surgical treatment is performed using low-dose three-dimensional computer tomography (CT), characterized by a poor spatial resolution (in terms of slice thickness). The limited number of CT images reduces the accuracy of the 3D reconstruction of the skull and leads to a coarser segmentation and modelling. In this paper, Motion Compensated Frame Interpolation (MCFI) techniques are applied for an effective axial interpolation of tomographic images sequences, with the main objective of obtaining a refined 3D reconstruction. The performance of the proposed method was assessed by using high-resolution CT sequences. After downsampling along the axial direction, the missing slices were recovered by using the proposed algorithm, to obtain an estimate of the original sequence. The experimental results show that the 3D models obtained from the downsampled/interpolated sequence are very close to those obtained from the original one thus providing a high-quality 3D skull reconstruction.

Keywords: 3D modeling | CT slices | Interpolation | Motion compensation

Abstract: The use of continuum mechanics, especially Finite Element Analysis (FEA) has gained an extensive application in the medical field, in order to simulate soft tissues. In particular, colorectal simulations can be used to understand the interaction between colon and the surrounding tissues, and also, between colon and surgical instruments. Although several works have been introduced considering small displacements, FEA applied to colorectal surgical scenarios with large displacements is still a challenge. This work aims to investigate how FEA can describe non-linear effects induced by material properties and different approximating geometries for colon. More in detail, it shows a comparison between simulations that are performed using well-known hyperelastic models (principally Mooney-Rivlin and, in one case, Yeoh) and the linear one. These different mechanical behaviours are applied on different geometrical models (planar, cylindrical and a 3D-shape from digital acquisitions) with the aim of evaluating also the effects of geometric non-linearity. Increasing the displacements imposed by the surgical instruments, the adoption of a hyperelastic model shows lower stresses than the linear elastic one that seems to overestimate the averaged stress. Moreover, the details of the geometrical models affect the results in terms of stress-strain distribution, since it provides a better localisation of the effects related to the hypothesis of large strains.

Keywords: computer assisted surgical planning | Finite element analysis | segmentation of medical images | soft tissues simulation | surface modelling

Abstract: Despite the wide use of scaffolds with spherical pores in the clinical context, no studies are reported in the literature that optimize the micro-architecture dimensions of such scaffolds to maximize the amounts of neo-formed bone. In this study, a mechanobiology-based optimization algorithm was implemented to determine the optimal geometry of scaffolds with spherical pores subjected to both compression and shear loading. We found that these scaffolds are particularly suited to bear shear loads; the amounts of bone predicted to form for this load type are, in fact, larger than those predicted in other scaffold geometries. Knowing the anthropometric characteristics of the patient, one can hypothesize the possible value of load acting on the scaffold that will be implanted and, through the proposed algorithm, determine the optimal dimensions of the scaffold that favor the formation of the largest amounts of bone. The proposed algorithm can guide and support the surgeon in the choice of a "personalized" scaffold that better suits the anthropometric characteristics of the patient, thus allowing to achieve a successful follow-up in the shortest possible time.

Keywords: Bone tissue engineering | Computational mechanobiology | Geometry optimization | Parametric CAD (Computer aided design) model | Python code

Abstract: In spite of the rather large use of the fused deposition modeling (FDM) technique for the fabrication of scaffolds, no studies are reported in the literature that optimize the geometry of such scaffold types based on mechanobiological criteria. We implemented a mechanobiology-based optimization algorithm to determine the optimal distance between the strands in cylindrical scaffolds subjected to compression. The optimized scaffolds were then 3D printed with the FDM technique and successively measured. We found that the difference between the optimized distances and the average measured ones never exceeded 8.27% of the optimized distance. However, we found that large fabrication errors are made on the filament diameter when the filament diameter to be realized differs significantly with respect to the diameter of the nozzle utilized for the extrusion. This feasibility study demonstrated that the FDM technique is suitable to build accurate scaffold samples only in the cases where the strand diameter is close to the nozzle diameter. Conversely, when a large difference exists, large fabrication errors can be committed on the diameter of the filaments. In general, the scaffolds realized with the FDM technique were predicted to stimulate the formation of amounts of bone smaller than those that can be obtained with other regular beam-based scaffolds.

Keywords: Biomaterials | Geometry optimization | Mechanobiology | Scaffold design | Tissue engineering

Abstract: The aim of this research is to develop patient-specific 3D mandible models, based on a limited number of measurements taken on the patient. Twenty Computed Tomography scans were used to build the respective 3D cad models of the mandible. Fifteen of these models were given as an input to a Principal Component Analysis software, and eight ‘principal’ mandible morphologies were produced. The following step was to identify the most efficient landmarks to ‘weight’ these morphologies when building a patient-specific model. Two further mandible computed tomography scans (a ‘normal’ mandible and a ‘severely resorbed’ one) were used to test the full procedure and to assess its accuracy. The accuracy of the 3D morphed surface resulted to range between 0.025 and 3.235 mm for the ‘normal’ mandible and between 0.012 and 1.149 mm for the ‘severely resorbed’ one having used eight landmarks to morph a ‘standard’ mandible. This work demonstrates how patient-specific models can be obtained registering the position of a limited number of points (on panoramic x-ray or on the physical model), reaching a good accuracy. This allows performing patient-specific planning and numerical simulations even for those cases where a computed tomography scan would not be available. In fact, this procedure can be interfaced with mesh morphing algorithms to automatically build finite element models. The accuracy of the procedure can be further improved, widening the mandibles computed tomography scans database and optimizing landmarks position.

Keywords: Morphing | Patient-specific models | Principal Component Analysis

Abstract: This paper presents a methodological procedure, based on the anatomical reconstruction and constrained deformation, to design custom-made implants for forehead augmentation in people affected by Apert syndrome, experiencing a frontal bone deficiency. According to the anthropometric theory, a cranial landmarks identification procedure was applied to retrieve, from a repository, a healthy skull, used as reference geometry for implant modelling. Then, using constrained deformation and free-form modelling techniques, it was possible to design a patient-specific implant. At last, the implant was realised using a custom mould, specially designed according to the patient’s needs to provide an accurate fit of the defect site. The design procedure was tested on a patient suffering from Apert syndrome. Three implants were virtually modelled and 3D-printed for pre-surgical evaluation. Their shapes were 3D compared with a reference one (handcrafted by a surgeon) to test the accuracy. Deviations are negligible, and the customised implant fulfilled the surgeon’s requirements.

Keywords: Computer-aided design | Craniomaxillofacial surgery | Implant design | Medical devices | Rapid prototyping

Abstract: Impaired hand function is a major contributor to overall disability and reduced health-related quality of life in scleroderma patients. A relevant issue concerns interaction of scleroderma subjects with touchscreen interfaces. This study aims at investigating this problem assessing scleroderma patients’ performance with a novel, aptly designed, touchscreen application in order to identify critical items of touchscreen technology which may impair or facilitate the use by scleroderma subjects. Eighty scleroderma patients performed this novel application including three games, each of which tested a different gesture: tapping, dragging/dropping, and pinching-to-zoom. Eighty healthy subjects without hand impairments were recruited as controls. Scleroderma patients performed worse than healthy users in each game, and statistically significant negatively impacting items were identified. In the second phase of the study, the 10 worst touchscreen performers within the scleroderma cohort were recruited for a physio-rehabilitation trial based on the daily use at home of a modified version of the software application downloaded into the personal devices of patients. The results of this study allow introduction of guidelines to design accessible touchscreen interfaces for subjects with scleroderma and suggest that touchscreen technology may be included in self-administered physio-rehabilitation programs for scleroderma hand.

Keywords: hand | hand disability | hand rehabilitation | Scleroderma | SSc | systemic sclerosis | touchscreen | touchscreen application | touchscreen device | touchscreen interface

Abstract: In recent years, breakthroughs in the fields of reverse engineering and additive manufacturing techniques have led to the development of innovative solutions for personalized medicine. 3D technologies are quickly becoming a new treatment concept that hinges on the ability to shape patient-specific devices.Among the wide spectrum of medical applications, the orthopaedic sector is experiencing the most benefits. Several studies proposed modelling procedures for patient-specific 3D-printed casts for wrist orthoses, for example. Unfortunately, the proposed approaches are not ready to be used directly in clinical practice since the design of these devices requires significant interaction among medical staff, reverse engineering experts, additive manufacturing specialists and CAD designers. This paper proposes a new practical methodology to produce 3D printable casts for wrist immobilization with the aim of overcoming these drawbacks. In particular, the idea is to realize an exhaustive system that can be used within a paediatric environment. It should provide both a fast and accurate dedicated scanning of the hand-wrist-arm district, along with a series of easy-to-use semi-automatic tools for the modelling of the medical device. The system was designed to be used directly by the clinical staff after a brief training. It was tested on a set of five case studies with the aim of proving its general reliability and identifying possible major flaws. Casts obtained using the proposed system were manufactured using a commercial 3D printer, and the device’s compliance with medical requirements was tested. Results showed that the designed casts were correctly generated by the medical staff without the need of involving engineers. Moreover, positive feedback was provided by the users involved in the experiment.

Keywords: CAD | Cast modelling | Orthosis modelling | Personalized medicine | Reverse engineering

Abstract: Bone tumor resections have to be carefully planned in order to avoid intralesional cuts and thus lower the recurrence rate. Until the present-day bone resections have been performed freehand, using anatomical landmarks as reference points to retrieve planned resection planes over the very patient. Such method is highly prone to failure to the detriment of the patient’s health, in fact survival rate for osteosarcomas is very low, ranging between 20% and 47%. The clinical outcome is highly dependent on the resections’ accuracy; several emerging techniques proved to dramatically increase cutting accuracy, as well as survival rate, in particular Patient Specific Instruments (PSIs) and custom 3D printed metal prosthesis. The main limitation to a massive spread of this method is the large manufacturing time due to a lack of communication between surgeons and engineers about the surgical approach and the design constraints. This paper aims to compare several general-purpose low-cost software and to provide surgeons with an effective and easy to use platform to visually share information in a natural manner with engineers thus providing as many design constraints as possible, speed up the design process and avoid unfeasible results. Two surgeons from Azienda Ospedaliera Universitaria Careggi tested and evaluated a series of software. From this preliminary investigation Forger, a digital sculpting and texture painting application for iOS, resulted as the most user friendly and intuitive application among the test group.

Keywords: Computer aided surgery | Concurrent design | Digital surgical planning | Human computer interaction

Abstract: This paper presents IART, a novel inertial wearable system for automatic detection of infringements and analysis of sports performance in race walking. IART algorithms are developed from raw inertial measurements collected by a single sensor located at the bottom of the vertebral column (L5–S1). Two novel parameters are developed to estimate infringements: loss of ground contact time and loss of ground contact step classification; three classic parameters are indeed used to estimate performance: step length ratio, step cadence, and smoothness. From these parameters, five biomechanical indices customized for elite athletes are derived. The experimental protocol consists of four repetitions of a straight path of 300 m on a long-paved road, performed by nine elite athletes. Over a total of 1620 steps (54 sequences of 30 steps each), the average accuracy of correct detection of loss of ground contact events is equal to 99%, whereas the correct classification of the infringement is equal to 87% for each step sequence, with a 92% of acceptable classifications. A great emphasis is dedicated on the user-centered development of IART: an intuitive radar chart representation is indeed developed to provide practical usability and interpretation of IART indices from the athletes, coaches, and referees perspectives. The results of IART, in terms of accuracy of its indices and usability from end-users, are encouraging for its usage as tool to support athletes and coaches in training and referees in real competitions.

Keywords: Biomechanics | Inertial sensor | Judgment | Race walking | Step classification | Training improvement | User-centered design

Abstract: The most common type of spine instrumentation is the pedicle screw fixation. The recent literature shows how customized drilling templates help surgeons to perform the surgery better. This work aims to validate the design of a customized template for inserting lumbar pedicle screw via a procedure based on rapid prototyping and reverse engineering techniques and to show the benefits. The novelties of this template are its low-invasive sizes, its design based on a patented algorithm, which calculates the sizes of the screws and the optimal insertion direction, the engage/disengage system, and the adaptability to every kind of surgeon's kit. Accuracy of pedicle screw location, surgery duration, and X-ray exposition have been used to evaluate the performances of the template. Mono-centric in vivo trial was performed. Twenty patients (8 women and 12 men) were enrolled randomly corresponding to sixty vertebrae treated with spinal arthrodesis (30 with and 30 without templates). Accuracy of the screw positioning and reduction in both surgery duration and patients' exposure to X-rays achieved excellent results because the time spent on the insertion of pedicle screws via the surgical template was cut down by about 63%, while the number of X-ray shots was reduced by about 92%. The proposed template performed better than the standard approach and could be helpful both for skilled and novice surgeons.

Keywords: Lumbar spinal arthrodesis | Screw location optimisation | Spine surgery | Surgical template | X-ray minimisation

Abstract: Virtual and Augmented Reality systems have been increasingly studied, becoming an important complement to traditional therapy as they can provide high-intensity, repetitive and interactive treatments. Several systems have been developed in research projects and some of these have become products mainly for being used at hospitals and care centers. After the initial cognitive rehabilitation performed at rehabilitation centers, patients are obliged to go to the centers, with many consequences, as costs, loss of time, discomfort and demotivation. However, it has been demonstrated that patients recovering at home heal faster because surrounded by the love of their relatives and with the community support.

Keywords: Cognitive rehabilitation | Gaming | LeapMotion | Oculus rift | VR/AR

Abstract: XR is an acronym used to refer to the spectrum of hardware, software applications, and techniques used for virtual reality or immersive environments, augmented or mixed reality and other related technologies. The special thematic session on ‘XR Accessibility’ explores current research and development as well as presenting diverse approaches to meeting real user needs in immersive environments. The contributed research papers range from using spatial sound for object location and interaction for blind users, to alternative symbolic representation of information, Augmented Reality (AR) used in rehabilitation for stroke patients and vocational skills training for students with intellectual disabilities. The session also explores what we can learn from previous research into immersive environments – looks at opportunities for future research and collectively explores how we can together iterate accessibility standards.

Keywords: Accessibility | Augmented Reality | Immersive web | Inclusive design | Rehabilitation | Serious games | Usability | Virtual reality

Abstract: Background: Lumbrical muscles originate in the palm from the 4 tendons of the flexor digitorum profundus and course distally along the radial side of the corresponding metacarpophalangeal joints, in front of the deep transverse metacarpal ligament. The first and second lumbrical muscles are typically innervated by the median nerve, and third and fourth by the ulnar nerve. A plethora of lumbrical muscle variants has been described, ranging from muscles’ absence to reduction in their number or presence of accessory slips. The current cadaveric study highlights typical and variable neural supply of lumbrical muscles. Materials: Eight (3 right and 5 left) fresh frozen cadaveric hands of 3 males and 5 females of unknown age were dissected. From the palmar wrist crease, the median and ulnar nerve followed distally to their terminal branches. The ulnar nerve deep branch was dissected and lumbrical muscle innervation patterns were noted. Results: The frequency of typical innervations of lumbrical muscles is confirmed. The second lumbrical nerve had a double composition from both the median and ulnar nerves, in 12.5% of the hands. The thickest branch (1.38 mm) originated from the ulnar nerve and supplied the third lumbrical muscle, and the thinnest one (0.67 mm) from the ulnar nerve and supplied the fourth lumbrical muscle. In 54.5%, lumbrical nerve bifurcation was identified. Conclusion: The complex innervation pattern and the peculiar anatomy of branching to different thirds of the muscle bellies are pointed out. These findings are important in dealing with complex and deep injuries in the palmar region, including transmetacarpal amputations.

Keywords: anomaly | clinical implication | lumbrical muscle | lumbrical nerve | variation

Abstract: Additive Manufacturing is a widespread technology that may enhance product customization based on specific users’ needs, as in the case of assistive devices. Many chronic physical progressively disabling diseases, but also ageing, may cause severe limitations in daily life, which can be overcome by highly customized aids. Literature shows that the active involvement of the patient in the development of assistive devices through co-design allows for their greater therapeutic effectiveness and acceptance. Therefore, this paper proposes a methodological approach for the development of inclusive assistive devices to support daily activities in persons with disabling diseases of the upper-limb. The approach integrates co-design, standardized tools, and low- and high-tech prototyping techniques and tools, which lead to significant feedbacks from patients. The patients are encouraged to interact with conceptual prototypes through direct 3D CAD modelling and touch screen devices. Assessment tests highlight the suitability of the method to achieve the expected goals.

Keywords: Additive Manufacturing | Assistive device | Co-design | Hand pathologies | Inclusive method | Occupational therapy | Parametric modelling

Abstract: This work aims to present an in-house low-cost computer-aided simulation (CASS) process that was recently implemented in the preoperative planning of complex osteotomies for limb deformities in children. Five patients admitted to the Unit of Paediatric Orthopaedics and Traumatology from April 2018 to December 2019, for correcting congenital or post-traumatic limb deformities were included in the study. Three-dimensional (3D) digital models were generated from Computed Tomography (CT) scans, using free open-source software, and the surgery was planned and simulated starting from the 3D digital model. 3D printed sterilizable models were fabricated using a low-cost 3D printer, and animations of the operation were generated with the aim to accurately explain the operation to parents. All procedures were successfully planned using our CASS method and the 3D printed models were used during the operation, improving the understanding of the severely abnormal bony anatomy. The surgery was precisely reproduced according to CASS and the deformities were successfully corrected in four cases, while in one case, the intraoperative intentional undersizing of the bone osteotomy produced an incomplete correction of a congenital forearm deformity. Our study describes the application of a safe, effective, user-friendly, and low-cost CASS process in paediatric orthopaedics (PO) surgery. We are convinced that our study will stimulate the widespread adoption of this technological innovation in routine clinical practice for the treatment of rare congenital and post-traumatic limb deformities during childhood.

Keywords: 3D modeling | Computer aided | Osteotomy | Paediatric orthopaedics | Preoperative planning | Surgery | Surgical simulation

Abstract: Pectus Excavatum (PE) is a congenital anomaly of the ribcage, at the level of the sterno-costal plane, which consists of an inward angle of the sternum, in the direction of the spine. PE is the most common of all thoracic malformations, with an incidence of 1 in 300-400 people. To monitor the progress of the pathology, severity indices, or thoracic indices, have been used over the years. Among these indices, recent studies focus on the calculation of optical measures, calculated on the optical scan of the patient's chest, which can be very accurate without exposing the patient to invasive treatments such as CT scans. In this work, data from a sample of PE patients and corresponding doctors' severity assessments have been collected and used to create a decision tool to automatically assign a severity value to the patient. The idea is to provide the physician with an objective and easy to use measuring instrument that can be exploited in an outpatient clinic context. Among several classification tools, a Probabilistic Neural Network was chosen for this task for its simple structure and learning mode.

Abstract: In brain tumor surgery, an appropriate and careful surgical planning process is crucial for surgeons and can determine the success or failure of the surgery. A deep comprehension of spatial relationships between tumor borders and surrounding healthy tissues enables accurate surgical planning that leads to the identification of the optimal and patient-specific surgical strategy. A physical replica of the region of interest is a valuable aid for preoperative planning and simulation, allowing the physician to directly handle the patient’s anatomy and easily study the volumes involved in the surgery. In the literature, different anatomical models, produced with 3D technologies, are reported and several methodologies were proposed. Many of them share the idea that the employment of 3D printing technologies to produce anatomical models can be introduced into standard clinical practice since 3D printing is now considered to be a mature technology. Therefore, the main aim of the paper is to take into account the literature best practices and to describe the current workflow and methodology used to standardize the pre-operative virtual and physical simulation in neurosurgery. The main aim is also to introduce these practices and standards to neurosurgeons and clinical engineers interested in learning and implementing cost-effective in-house preoperative surgical planning processes. To assess the validity of the proposed scheme, four clinical cases of preoperative planning of brain cancer surgery are reported and discussed. Our preliminary results showed that the proposed methodology can be applied effectively in the neurosurgical clinical practice both in terms of affordability and in terms of simulation realism and efficacy.

Keywords: 3D casting | 3D printing | Additive manufacturing | Brain | Cancer | Computer aided design | Neurosurgery | Physical simulation | Preoperative planning | Virtual planning

Abstract: Pectus Excavatum (PE) is a congenital anomaly of the thoracic cage, at the level of the sternal-costal plane, which consists of an inward angle of the sternum, in the direction of the spine. Its incidence, equal to 1 in 300–400 people, makes it the most frequent among thoracic malformations. For a proper care of patients suffering from PE, it is essential to monitor the progression of the disease and estimate its severity, in order to follow the course of the pathology over time and define the correct treatment. To this end, over the years, severity indexes, or chest indexes, have been introduced. Among them, in recent years, the so-called optical indices, calculated on optical scans of the patient’s chest, are gaining ground. In fact, the optical scan is faster to apply and prevents the patient from being exposed to radiation. In this work the peculiar morphological features of PE have been examined by extracting various geometric parameters, in order to develop an outpatient support tool for the evaluation of the severity of the pathology and the monitoring of its progression over time. The extracted values have been compared against a ground truth obtained through five independent surveys collected from paediatric specialists. A Linear Discriminant Analysis was performed to determine the accuracy of the classification using the proposed geometric parameters, obtaining positive results.

Keywords: Clinical support | Depth camera | Pectus Excavatum | Severity index

Abstract: In cranioplasty surgery, achieving an effective aesthetic shape restoration of the cranial vault is the most important issue to ensure a proper outcome in terms of social and psychological benefits for the patient. To date, the most advanced approach uses CT/MRI data to reconstruct, in a pre-operative stage, the 3D anatomy of the defective skull in order to design a patient-specific prosthesis. In the last years, several techniques have been proposed to improve the applicability of such approach in the clinical practice, but the analysis of the related literature shows still open issues, due to the wide anatomical variability and complexity of the craniofacial anatomy that needs to be retrieved. With the aim to overcome the State-of-the-Art drawbacks, a new semi-automatic hybrid procedure for repairing unilateral or quasi-unilateral (i.e. a single defect slightly passing the sagittal plane) cranial defects is presented. The novel approach is hybrid because a surface interpolation for filling the hole is used together with a template-based reconstruction guided by the healthy counterpart. The procedure, being landmark-independent and avoiding any patch adaptation, represents a valid alternative for the existing approaches also in terms of user's burden, requiring less time consuming and less cumbersome operations. In addition, a new evaluating technique able to measure the symmetry of the reconstruction as well as the continuity between patch and healthy bone is proposed to test the procedure performance. Several test cases have been then addressed to prove the effectiveness and repeatability of the proposed procedure in reconstructing large-size defects of the skull.

Keywords: CAD | Cranioplasty | Reverse Engineering | Skull Reconstruction

Abstract: The paper describes the conceptual model of an emotion-aware car interface able to: map both the driver’s cognitive and emotional states with the vehicle dynamics; adapt the level of automation or support the decision-making process if emotions negatively affecting the driving performance are detected; ensure emotion regulation and provide a unique user experience creating a more engaging atmosphere (e.g. music, LED lighting) in the car cabin. To enable emotion detection, it implements a low-cost emotion recognition able to recognize Ekman’s universal emotions by analyzing the driver’s facial expression from stream video. A preliminary test was conducted in order to determine the effectiveness of the proposed emotion recognition system in a driving context. Results evidenced that the proposed system is capable to correctly qualify the drivers’ emotion in a driving simulation context.

Keywords: Driver Monitoring System | Emotion recognition | Facial expression recognition

Abstract: Degeneration of articular cartilage (AC) is a common healthcare issue that can result in significantly impaired function and mobility for affected patients. The avascular nature of the tissue strongly burdens its regenerative capacity contributing to the development of more serious conditions such as osteoarthritis. Recent advances in bioprinting have prompted the development of alternative tissue engineering therapies for the generation of AC. Particular interest has been dedicated to scaffold-based strategies where 3D substrates are used to guide cellular function and tissue ingrowth. Despite its extensive use in bioprinting, the application of polycaprolactone (PCL) in AC is, however, restricted by properties that inhibit pro-chondrogenic cell phenotypes. This study proposes the use of a new bioprintable poly(ester urea) (PEU) material as an alternative to PCL for the generation of an in vitro model of early chondrogenesis. The polymer was successfully printed into 3D constructs displaying adequate substrate stiffness and increased hydrophilicity compared to PCL. Human chondrocytes cultured on the scaffolds exhibited higher cell viability and improved chondrogenic phenotype with upregulation of genes associated with type II collagen and aggrecan synthesis. Bioprinted PEU scaffolds could, therefore, provide a potential platform for the fabrication of bespoke, pro-chondrogenic tissue engineering constructs.

Keywords: 3D bioprinting | Cartilage repair | Poly(ester urea) | Scaffold design | Tissue engineering

Abstract: Background: In the case of a degenerated intervertebral disc (IVD), even though spinal fusion has provided good short-term clinical results, an alteration of the spine stability has been demonstrated by long-term studies. In this context, different designs of IVD prostheses have been proposed as alternative to spinal fusion. However, over the past few years, much of the recent research has been devoted to IVD tissue engineering, even if several limitations related to the complex structure of IVD are still presented.Purpose/Aim: Accordingly, the aim of the current paper was to develop a strategy in designing customised multiphasic nucleus/annulus scaffolds for IVD tissue engineering, benefiting from the great potential of reverse engineering, additive manufacturing and gels technology.Materials and Methods: The device consisted of a customised additive-manufactured poly(ε-caprolactone) scaffold with tailored architectural features as annulus and a cell-laden collagen-low molecular weight hyaluronic acid-based material as nucleus with specific rheological and functional properties. To this aim, injectability and viscoelastic properties of the hydrogel were analyzed. Furthermore, a mechanical and biological characterization of cell-laden multiphasic nucleus/annulus scaffold was performed.Results and Conclusions: Analyses on the developed devices demonstrated appropriate viscoelastic and mechanical properties. As evidenced by rheological tests, the hydrogel showed a shear-thinning behaviour, supporting the possibility to inject the material. The mechanical characterization highlighted a compressive modulus which falls in the range of lumbar discs, with the typical initial J-shaped stress–strain curve of natural IVDs. Furthermore, preliminary biological tests showed that human mesenchymal stem cells were viable over the culture period.

Keywords: additive manufacturing | gels | intervertebral disc | Polymers | reverse engineering | tissue engineering

Abstract: The concept of magnetic guidance is still challenging and has opened a wide range of perspectives in the field of tissue engineering. In this context, magnetic nanocomposites consisting of a poly(ε-caprolactone) (PCL) matrix and iron oxide (Fe3 O4) nanoparticles were designed and manufactured for bone tissue engineering. The mechanical properties of PCL/Fe3 O4 (80/20 w/w) nanocomposites were first assessed through small punch tests. The inclusion of Fe3 O4 nanoparticles improved the punching properties as the values of peak load were higher than those obtained for the neat PCL without significantly affecting the work to failure. The effect of a time-dependent magnetic field on the adhesion, proliferation, and differentiation of human mesenchymal stem cells (hMSCs) was analyzed. The Alamar Blue assay, confocal laser scanning microscopy, and image analysis (i.e., shape factor) provided information on cell adhesion and viability over time, whereas the normalized alkaline phosphatase activity (ALP/DNA) demonstrated that the combination of a time-dependent field with magnetic nanocomposites (PCL/Fe3 O4 Mag) influenced cell differentiation. Furthermore, in terms of extracellular signal-regulated kinase (ERK)1/2 phosphorylation, an insight into the role of the magnetic stimulation was reported, also demonstrating a strong effect due the combination of the magnetic field with PCL/Fe3 O4 nanocomposites (PCL/Fe3 O4 Mag).

Keywords: Bone tissue engineering | Design of magnetic nanocomposite substrates | Magnetic stimulation | Material interaction | Mechanical properties and cell | Reverse engineering/image analysis

Abstract: AIM: The purpose of this study is to compare the stress effects developed on the periodontal ligaments and teeth by three different types of mandibular advancement devices (MADs) using a finite element method (FEM) analysis. Introduction: Obstructive sleep apnea (OSA) is a disease with a high prevalence and, in recent years, the use of MADs as an alternative or support treatment to the continuous positive airway pressure (CPAP) has spread. Their use finds relative contraindications in the case of partial edentulism and severe periodontal disease. Given the widespread of periodontal problems, it is essential to know the effects that these devices cause on the periodontal ligament of the teeth. Materials and methods: Starting from the computed tomography (CT) scan of a patient’s skull, 3D reconstructions of the maxilla and mandible were implemented. Three different MADs were prepared for the patient, then 3D scanned, and lastly, coupled with the 3D models of the jaws. The devices have two different mechanics: One has a front reverse connecting rod (Orthoapnea™), and two have lateral propulsion (Somnodent™ and Herbst™). A FEM analysis was performed to calculate the stress applied on periodontal ligaments, on every single tooth and the displacement vectors that are generated by applying an advancement force on the mandible. Results: Herbst™ and Somnodent™ devices present very similar stress values, mainly concentrated on lateral teeth, but in general, the forces are very mild and distributed. The maximum stresses values are 3.27 kPa on periodontal ligaments and 287 kPa on teeth for Somnodent™ and 3.56 kPa on periodontal ligaments and 302 kPa on teeth for Herbst™. Orthoapnea™ has, instead, higher and concentrated stress values, especially in the anterior maxillary and mandibular area with 4.26 kPa and 600 kPa as maximum stress values, respectively, on periodontal ligaments and teeth. Conclusions: From the results, it is concluded that devices with a bilateral mechanism generate less and more distributed stress than an anterior connecting rod mechanism. Therefore, they may be advisable to patients with compromised periodontal conditions in the anterior area.

Keywords: Dental materials | Finite element method | Mandibular advancement device | Obstructive sleep apnea | Orthodontics

Abstract: This work proposes an innovative method for evaluating usersâ™ engagement, combining the User Engagement Scale (UES) questionnaire and a facial expression recognition (FER) system, active research topics of increasing interest in the humanâ"computer interaction domain (HCI). The subject of the study is a 3D simulator that reproduces a virtual FabLab in which users can approach and learn 3D modeling software and 3D printing. During the interaction with the virtual environment, a structured-light camera acquires the face of the participant in real-time, to catch its spontaneous reactions and compare them with the answers to the UES closed-ended questions. FER methods allow overcoming some intrinsic limits in the adoption of questioning methods, such as the non-sincerity of the interviewees and the lack of correspondence with facial expressions and body language. A convolutional neural network (CNN) has been trained on the Bosphorus database (DB) to perform expression recognition and the classification of the video frames in three classes of engagement (deactivation, average activation, and activation) according to the model of emotion developed by Russell. The results show that the two methodologies can be integrated to evaluate user engagement, to combine weighted answers and spontaneous reactions and to increase knowledge for the design of the new product or service.

Keywords: 3D simulator | CNN | Deep learning | Facial expression recognition | Human-computer interaction | User engagement scale | User-centered design

Abstract: The ovary is a dynamic mechanoresponsive organ. In vitro, tissue biomechanics was reported to affect follicle activation mainly through the Hippo pathway. Only recently, ovary responsiveness to mechanical signals was exploited for reproductive purposes. Unfortunately, poor characterization of ovarian cortex biomechanics and of the mechanical challenge hampers reproducible and effective treatments, and prevention of tissue damages. In this study the biomechanical response of ovarian cortical tissue from abattoir bovines was characterized for the first time. Ovarian cortical tissue fragments were subjected to uniaxial dynamic testing at frequencies up to 30 Hz, and at increasing average stresses. Tissue structure prior to and after testing was characterized by histology, with established fixation and staining protocols, to assess follicle quality and stage. Tissue properties largely varied with the donor. Bovine ovarian cortical tissue consistently exhibited a nonlinear viscoelastic behavior, with dominant elastic characteristics, in the low range of other reproductive tissues, and significant creep. Strain rate was independent of the applied stress. Histological analysis prior to and after mechanical tests showed that the short-term dynamic mechanical test used for the study did not cause significant tissue tear, nor follicle expulsion or cell damage.

Keywords: Biomechanics | Creep | Elastic modulus | Ovarian tissue | Tensile test | Viscous behavior

Abstract: A number of surgical practices are aimed to compensate for tissue relaxation or weakened/atrophied muscles by means of suture prostheses/thread lifts. The success rate of these procedures is often very good in the short term, while it is quite variable among subjects and techniques in the middle-long term. Middle-long term failures are mostly related to suture distraction, loosening or wear, coming from repeated loading cycles. In this work, an experimental device to perform ex vivo tests on prosthetic sutures has been set up. An equine laryngoplasty has been used as a benchmark, being representative of sutures aimed to compensate for atrophied muscles. The peculiarity of this experimental set up is that the suture is on-site and it has been tightened with known, repeated loads, which do not depend on thread deformation at different load levels. Preliminary tests have been performed applying over 3000 load cycles and finally a tensile test up to rupture. Force/displacement curves obtained with this experimental set up have been reported and parameters useful to classify the biomechanical performance of sutures versus time (mainly its creep behaviour), have been outlined. Results have outlined that the organ-suture system undergoes significant creep over 3000 cycles, and this should be taken into account in order to foresee its long-term behaviour; in addition, the suture anchorage to cartilage should be improved. The experimental set up can be used to perform on-site testing of sutures, taking into account the compliance and creep response at both suture anchorage ends, in order to compare different surgeries and different kinds of thread.

Keywords: Creep | Distraction | Failure | Neuropathy | Suture testing | Tissue relaxation

Abstract: Intramedullary nails constitute a viable alternative to extramedullary fixation devices; their use is growing in recent years, especially with reference to self-locking nails. Different designs are available, and it is not trivial to foresee the respective in vivo performances and to provide clinical indications in relation to the type of bone and fracture. In this work a numerical methodology was set up and validated in order to compare the mechanical behavior of two new nailing device concepts with one already used in clinic. In detail, three different nails were studied: (1) the Marchetti-Vicenzi's nail (MV1), (2) a revised concept of this device (MV2), and (3) a new Terzini-Putame's nail (TP) concept. Firstly, the mechanical behavior of the MV1 device was assessed through experimental loading tests employing a 3D-printed component aimed at reproducing the bone geometry inside which the device is implanted. In the next step, the respective numerical model was created, based on a multibody approach including flexible parts, and this model was validated against the previously obtained experimental results. Finally, numerical models of the MV2 and TP concepts were implemented and compared with the MV1 nail, focusing the attention on the response of all devices to compression, tension, bending, and torsion. A stability index (SI) was defined to quantify the mechanical stability provided to the nail-bone assembly by the elastic self-locking mechanism for the various loading conditions. In addition, results in terms of nail-bone assembly stiffness, computed from force/moment vs. displacement/rotation curves, were presented and discussed. Findings revealed that numerical models were able to provide good estimates of load vs. displacement curves. The TP nail concept proved to be able to generate a significantly higher SI (27 N for MV1 vs. 380 N for TP) and a greater stiffening action (up to a stiffness difference for bending load that ranges from 370 Nmm/° for MV1 to 1,532 Nmm/° for TP) than the other two devices which showed similar performances. On the whole, a demonstration was given of information which can be obtained from numerical simulations of expandable fixation devices.

Keywords: biomechanical stability | experimental tests | flexible bodies | intramedullary nails | Marchetti-Vicenzi nail | multibody analysis | stiffness

Abstract: A number of applications in the surgical practice are based on tensile sutures aimed to keep soft tissues in place and compensate the exit of neuropathies, prolapses or general tissue relaxation. Long-term behaviour of these constructs need to be carefully examined in order to define tensile forces to be applied and to compare different suture anchors. Data here reported refer to equine laryngoplasties, where a suitable loading system has been designed in order to be able to test sutures in-sito, applying known forces (“On-site testing of sutured organs: an experimental set up to cyclically tighten sutures” (Pascoletti et al., 2020 [1])). The loading protocol was made of two steps: in the first step, 3000 loading cycles have been performed; in the following step, a tensile test up to rupture was performed. Cyclic load/displacement curves allow evaluating suture distraction, as a consequence of suture migration and/or soft tissues creep. Tensile curves allow evaluating the residual thread strength and its ultimate displacement. These data can provide a detailed insight of long-term suture behaviour and can be a reference to compare different threads and/or suture anchors.

Keywords: Creep | Distraction | Failure | Neuropathy | Suture testing | Tissue relaxation

Abstract: The design of loading systems to test biologic samples is often challenging, due to shape variability and non-conventional loading set-ups. In addition to this, large economic investments would not be justified since the loading set up is usually designed for one single or for a limited range of applications. The object of this work is the development of a loading set-up finalised to on-site testing of sutures whose main function is applying a localised tensile load. The main challenges of this design process can be so summarized: • Applying cyclic tensile loads on the suture wire, mimicking the physiologic condition where both suture anchorage points have a certain compliance; • Designing a loading system as versatile as possible, in order to be able to accommodate organs with different geometries and sizes; • Keeping low both the complexity and costs of realization.All these considerations and the design calculi are here reported in detail, discussing the novelty of the system, and its main advantages.

Keywords: Anchorage points migration | Cyclic loads | On-site testing of prosthetic sutures | Suture distraction | Suture test

Abstract: Cement-retained implant-supported prosthetics are gaining popularity compared to the alternative screw-retained type, a rise that serves to highlight the importance of retrievability. The aim of the present investigation is to determine the influence of luting agent, abutment height and taper angle on the retrievability of abutment-coping cementations. Abutments with different heights and tapers were screwed onto an implant and their cobalt-chrome copings were cemented on the abutments using three different luting agents. The removals were performed by means of Coronaflex®. The number of impulses and the forces were recorded and analyzed with a Kruskal-Wallis test. Harvard cement needed the highest number of impulses for retrieval, followed by Telio CS and Temp Bond. However, abutment height and taper showed a greater influence on the cap's retrievability (p < 0.05). Long and tapered abutments provided the highest percentage of good retrievability. The influence of the luting agent and the abutment geometry on the cap's retrieval performed by Coronaflex® reflects data from literature about the influence of the same factor on the maximum force reached during uniaxial tensile tests. The impulse force was slightly affected by the same factors.

Keywords: Abutments geometry | Coronaflex | Dental cements | Dental implants | Retrievability

Abstract: A number of studies have recently demonstrated that the geometry of scaffolds for bone tissue engineering significantly affects the tissue differentiation process and the rate of bone tissue regeneration. These findings and the possibility of fabricating any kind of sophisticated geometries by additive manufacturing techniques led many researchers throughout the world to investigate strategies for the design of scaffolds and for the optimization of their geometry. In this chapter, after revising the numerical optimization algorithms recently implemented to determine the best scaffold geometry we will investigate, in particular, those that are mechanobiology-driven. These algorithms perturb the scaffold microarchitecture until the optimal scaffold geometry, i.e., the geometry that allows maximizing the amounts of bone forming within the scaffold pores, is computed. Different applications of these algorithms to different regular and irregular scaffold geometries will be shown.

Keywords: Beam-based scaffold | Irregular scaffold | Mechanobiology | Mechanoregulation algorithm | Regular scaffold

Abstract: Light activated composites are the most popular choice in the field of dental restoration. They generally show internal stress even after a prolonged time period. The knowledge of mechanical properties and residual stress should provide interesting information on the clinical performance of such materials. Accordingly, in the current research experimental analyses were carried out to assess the effect of the curing process on the properties of one of the most commonly employed light activated dental composites (Gradia Direct—GC Corporation, Japan). At 10 min, 1 h and 24 h after light curing, the bending modulus (4.7–6.2 GPa) as well as the punching performance (peak load of 12.1–17.5 N) were evaluated for the micro-hybrid composite. Scanning electron microscopy also allowed to analyze the fracture surface. Residual stresses ranging from 0.67 ± 0.15 MPa to 1.12 ± 0.17 MPa were measured by means of the thin-ring-slitting approach reported in the literature, according to measurement time and cutting time.

Keywords: CAD/CAM system | Dental materials | Mechanical and morphological properties | Residual stress

Abstract: The control of the process–structure–property relationship of a material plays an important role in the design of biomedical metal devices featuring desired properties. In the field of endodontics, several post-core systems have been considered, which include a wide range of industrially developed posts. Endodontists generally use posts characterized by different materials, sizes, and shapes. Computer-aided design (CAD) and finite element (FE) analysis were taken into account to provide further insight into the effect of the material–shape combination of metal posts on the mechanical behavior of endodontically treated anterior teeth. In particular, theoretical designs of metal posts with two different shapes (conical-tapered and conical-cylindrical) and consisting of materials with Young’s moduli of 110 GPa and 200 GPa were proposed. A load of 100 N was applied on the palatal surface of the crown at 45◦ to the longitudinal axis of the tooth. Linear static analyses were performed with a non-failure condition. The results suggested the possibility to tailor the stress distribution along the metal posts and at the interface between the post and the surrounding structures, benefiting from an appropriate combination of a CAD-based approach and material selection. The obtained results could help to design metal posts that minimize stress concentrations.

Keywords: Computer-aided design (CAD) | Dental materials | Finite element analysis | Image analysis | Mechanical properties | Metal posts

Abstract: The accurate location of the mid-sagittal plane is fundamental for the assessment of craniofacial dysmorphisms and for a proper corrective surgery planning. To date, these elaborations are carried out by skilled operators within specific software environments. Since the whole procedure is based on the manual selection of specific landmarks, it is time-consuming, and the results depend on the operators' professional experience. This work aims to propose a new automatic and landmark-independent technique which is able to extract a reliable mid-sagittal plane from 3D CT images. The algorithm has been designed to perform a robust evaluation, also in the case of large defect areas. The presented method is an upgraded version of a mirroring-and registration technique for the automatic symmetry plane detection of 3D asymmetrically scanned human faces, previously published by the authors. With respect to the published algorithm, the improvements here introduced concern both the objective function formulation and the method used to minimize it. The automatic method here proposed has been verified in the analysis of real craniofacial skeletons also with large defects, and the results have been compared with other recent technologies.

Keywords: Cranio-maxillofacial | Feature recognition | Medical imaging | Mid-sagittal plane | Symmetry analysis

Abstract: The musculoskeletal disorders represent one of the most common problems in industrial environment; they impact the health of workers and employees. In this work we present a preliminary study towards the use of biomechanical models for improving classic methods for ergonomic assessment in industry. To this end, we use OpenSim, a software for biomechanical simulation and analysis. With OpenSim, we reconstruct the human motion corresponding to the execution of industrial tasks, performed in laboratory settings. In particular, we compute the evolution over time of the joint angles that, according to a classic observation method for ergonomic assessment, are needed to evaluate the risks associated to the musculoskeletal disorders for the upper limb.

Keywords: biomechanics | digital human model | ergonomics | industry

Abstract: In this work we present a study for the experimental reconstruction of the human shoulder torque in the sagittal plane, since this is usually overloaded in industrial overhead tasks. To this end, we measure the three-dimensional motion of the human upper limb while performing selected movements using an optical motion capture system. Then, using a skeleton model implemented in one of the most common software for industrial ergonomic assessment, we reconstruct the shoulder angle and torque in the sagittal plane. A possible exploitation of this reconstruction strategy is presented for active compensation of this torque. The implementation of this simple strategy in a custom developed assistive device could augment human workers in performing repetitive jobs.

Keywords: biomechanics | digital human models | human motion analysis | industrial assistive devices

Abstract: In this work we will show some preliminary results on the use of a wearable inertial system for assessment of performances and infringements in race-walking. The proposed system is composed by two parts, one for measurement and one for management purposes. The management unit is based on biomechanical-based parameters for evaluating performances and infringements. The preliminary experimental results are promising towards the use of this system in real field training and competition scenarios, to respectively assist coaches and judges.

Keywords: race-walking | sports biomechanics | wearable inertial sensors

Abstract: Purpose: Shoulder instability and reduced range of motion are two common complications of a total reverse shoulder arthroplasty. In this work, a new approach is proposed to estimate how the glenoid component positioning can influence the stability and the range of motion of a reverse shoulder prosthesis. Materials and methods: A standard reverse shoulder prosthesis has been analysed. To perform virtual simulation of the shoulder-prosthesis assembly, all the components of the prosthesis have been acquired via a 3D laser scanner and the solid models of the shoulder bones have been reconstructed through CT images. Loads on the shoulder joint have been estimated using anatomical models database. A new virtual/numerical procedure has been implemented using a 3D parametric modelling software to find the optimal position of the glenosphere. Results: Several analyses have been performed using different configurations obtained by changing the glenoid component tilt and the lateral position of the glenosphere, modified through the insertion of a cylindrical spacer. For the analysed case study, it was found that the interposition of a spacer (between the baseplate and the glenoid) and 15° inferior tilt of the glenosphere allow improving the range of motion and the stability of the shoulder. Conclusions: Some common complications of the reverse shoulder arthroplasty could be effectively reduced by a suitable positioning of the prosthesis components. In this work, using a new method based on virtual simulations, the influence of the glenosphere positioning has been investigated. An optimal configuration for the analysed case study has been found. The proposed approach could be used to find, with no in vivo experiments, the optimal position of a reverse shoulder prosthesis depending on the different dimensions and shape of the bones of each patient.

Keywords: CAD modelling &amp; simulation | Digital shape acquisition | Instability ratio | Reverse shoulders prosthesis | ROM

Abstract: This scientific work aims at developing an innovative virtual platform to design lower limb prosthesis centered on the virtual model of the patient and based on a computer-aided and knowledge-guided approach. The main idea is to develop a digital human model of the amputee to be used by the prosthetist in a full virtual environment in which a platform provides a set of interactive tools to design, configure, and test the prosthesis. This virtual platform permits to design and configure the whole prosthesis, in particular, the 3D model of the assembled prosthesis, crucial to define the prosthesis setup and patient’s walking performance. An ad-hoc computer-aided design system has been developed in house to design the 3D model of the socket according to traditional operations made by technicians during traditional manufacturing process. Moreover, a finite element model has been defined to study the contact between residual limb and socket. The resulting 3D model of the socket can be realized by exploiting multimaterial additive manufacturing technology. Finally, the developed platform also permits to handle contact pressures and patient’s gait data in a unique application through the use of a low-cost motion capture (MOCAP) system. The whole platform has been tested with the help of an Italian orthopedic laboratory. The developed platform is a promising solution to develop the check socket, and the application may be used also for training purpose for junior orthopedic technicians.

Keywords: Low-cost MOCAP system | Lower limb prosthesis | Pressure analysis | Socket design and 3D modeling

Abstract: The use of fast and accurate scanning systems for human body digitization might pave the way towards the development of less invasive processes for medical manufacturing. In this work, an advanced measurement system for human body 3D reconstruction is used to design tailored assistive devices. The system is a photogrammetric 3D body scanner developed by the authors.

Keywords: 3D body measurements | assistive devices | medical manufacturing

Abstract: Purpose: Pectus arcuatum is an anterior chest wall deformity that requires transverse wedge sternotomy. Determining and delivering the correct cutting angle are crucial for successful correction. This report describes the early clinical experience with a novel cutting template technology able to deliver the optimal cutting angle. Description: From patients’ computed tomographic scans, the optimal cutting angle is obtained using computer-aided design. A template comprising slots tilted at the right cutting angle and a safety block to avoid damaging the posterior periosteum is printed through additive manufacturing. Evaluation: The template allows surgeons to perform a precise wedge sternotomy, safely sparing the posterior periosteum in all patients, without complications. Postoperative chest roentgenograms and clinical photographs demonstrate optimal sternal realignment and cosmetic outcome. In this report, the mean operative time was 110 minutes. All patients were successfully discharged, with a mean length of stay of 4 days. Conclusions: Transverse wedge sternotomy aided by a computer-aided design–devised cutting template may reduce the technical challenge of this procedure, thereby increasing its safety and reducing operative times and hospital stay. Further research on long-term patient outcomes is necessary.

Abstract: Pectus Arcuatum, a rare congenital chest wall deformity, is characterized by the protrusion and early ossification of sternal angle thus configuring as a mixed form of excavatum and carinatum features. Surgical correction of pectus arcuatum always includes one or more horizontal sternal osteotomies, consisting in performing a V-shaped horizontal cutting of the sternum (resection prism) by means of an oscillating power saw. The angle between the saw and the sternal body in the V-shaped cut is determined according to the peculiarity of the specific sternal arch. The choice of the right angle, decided by the surgeon on the basis of her/his experience, is crucial for a successful intervention. The availability of a patient-specific surgical guide conveying the correct cutting angles can considerably improve the chances of success and, at the same time, reduce the intervention time. The present paper aims to propose a new CAD-based approach to design and produce custom-made surgical guides, manufactured by using additive manufacturing techniques, to assist the sternal osteotomy. Starting from CT images, the procedure allows to determine correct resection prism and to shape the surgical guide accordingly taking into account additive manufacturing capabilities. Virtually tested against three case studies the procedure demonstrated its effectiveness.

Keywords: Biomedical devices | CAD | Design for additive manufacturing | Medical imaging

Abstract: Te design of bone scafolds for tissue regeneration is a topic of great interest, which involves diferent issues related to geometry of architectures, mechanical behavior, and biological requirements, whose optimal combination determines the success of an implant. Additive manufacturing (AM) has widened the capability to produce structures with complex geometries, which should potentially satisfy the diferent requirements. These architectures can be obtained by means of refned methods and have to be assessed in terms of geometrical and mechanical properties. In this paper a triply periodic minimal surface (TPMS), the Schwarz's Primitive surface (P-surface), has been considered as scafold unit cell and conveniently parameterized in order to investigate the efect of modulation of analytical parameters on the P-cell geometry and on its properties. Several are the cell properties, which can afect the scafold performance. Due to the important biofunctional role that the surface curvature plays in mechanisms of cellular proliferation and diferentiation, in this paper, in addition to properties considering the cell geometry in its whole (such as volume fraction or pore size), new properties were proposed. Tese properties involve, particularly, the evaluation of local geometrical-diferential properties of the P-surface. Te results of this P-cell comprehensive characterization are very useful for the design of customized bone scafolds able to satisfy both biological and mechanical requirements. A numerical structural evaluation, by means of fnite element method (FEM), was performed in order to assess the stifness of solid P-cells as a function of the changes of the analytical parameters of outer surface and the thickness of cell. Finally, the relationship between stifness and porosity has been analyzed, given the relevance that this property has for bone scafolds design.

Abstract: The research reported in this paper applies an explicit non-linear FEA solver to simulate the interaction between a clamp and a hyper-elastic material that aims to mimic the biological tissue of the colon. More in detail, the paper provides new results as a continuation of a previous works aimed at the evaluation of this solver to manage contact and dynamic loading on complex, multiple shapes. Results concern with the evaluation of the contact force during clamping, thus to the assessment of the force-feedback. The analysis is carried out on two geometries, using the hyper-elastic Mooney-Rivlin model for the mechanical behavior of the soft tissues. A pressure is applied on the colon to simulate the surgical clamp, which goes progressively in contact with tissue surface. To assess FEA criticality, and, then, its feasibility, the stress-strain and the contact force are analysed according to geometrical model and thickness variation, leaving the pressure constant. Doing so, their effect on the force-feedback can be foreseen, understanding their role on the accuracy of the final result.

Keywords: Computer assisted surgical planning | Finite element analysis | Segmentation | Soft tissues simulations

Abstract: Blepharospasm (BSP) is an adult-onset focal dystonia with phenomenologically heterogeneous effects, including, but not limited to, blinks, brief or prolonged spasms, and a narrowing or closure of the eyelids. In spite of the clear and well-known symptomatology, objectively rating the severity of this dystonia is a rather complex task since BSP symptoms are so subtle and hardly perceptible that even expert neurologists can rate the gravity of the pathology differently in the same patients. Software tools have been developed to help clinicians in the rating procedure. Currently, a computerised video-based system is available that is capable of objectively determining the eye closure time, however, it cannot distinguish the typical symptoms of the pathology. In this study, we attempt to take a step forward by proposing a neural network-based software able not only to measure the eye closure, time but also to recognise and count the typical blepharospasm symptoms. The software, after detecting the state of the eyes (open or closed), the movement of specific facial landmarks, and properly implementing artificial neural networks with an optimised topology, can recognise blinking, and brief and prolonged spasms. Comparing the software predictions with the observations of an expert neurologist allowed assessment of the sensitivity and specificity of the proposed software. The levels of sensitivity were high for recognising brief and prolonged spasms but were lower in the case of blinks. The proposed software is an automatic tool capable of making objective ‘measurements’ of blepharospasm symptoms.

Keywords: Blepharospasm | Blepharospasm rating scale | Eye closure time | Focal dystonia | Neural network topology optimisation

Abstract: Scaffolds are porous biomaterials that serve to replace missing portions of bone. Scaffolds must possess a proper geometry and hence have to be adequately designed to correctly undergo to the load and to favor the differentiation of the mesenchymal stem cells invading it, into osteoblasts. It is commonly known that scaffold geometry affects the quality of the regenerated bone creating within the scaffold pores. Scaffold properly designed trigger favorable values of biophysical stimuli that are responsible for the reactions cascade leading to the bone formation. In this paper an optimization algorithm is proposed that, based on mechano-regulation criteria, identifies the optimal geometry of scaffolds, i.e. the geometry that favors the formation of the largest amounts of bone in the shortest time. In detail, the algorithm, written in the Matlab environment, incorporates parametric finite element models of different scaffold types, a computational mechanobiological model and structural optimization routines. The scaffold geometry is iteratively perturbed by the algorithm until the optimal geometry is computed, i.e. the geometry that triggers the most favorable values of the biophysical stimulus which lead to the formation of mature bone. Mesenchymal stem cells were hypothesized to spread within the fracture domain and uniformly occupy the scaffold pores.

Keywords: Hexahedron unit cell | Mechanobiology | Rhombicuboctahedron unit cell | Unit cell geometry

Abstract: Purpose: Orbital fractures are the most commonly encountered midfacial fractures, and usually, the fracture involves the floor and/or the medial wall of the orbit. This paper aims to present an innovative approach for primary and secondary reconstructions of fractured orbital walls through the use of computer-assisted techniques and additive manufacturing. Design/methodology/approach: First, through the 3D anatomical modelling, the geometry of the implant is shaped to fill the orbital defect and recover the facial symmetry. Subsequently, starting from the modelled implant, a customised mould is designed taking into account medical and technological requirements. Findings: The selective laser sintered mould is able to model and form several kind of prosthetic materials (e.g. titanium meshes and demineralised bone tissue), resulting in customised implants and allowing accurate orbital cavity reconstructions. The case study proved that this procedure, at the same time, reduces the morbidity on the patients, the duration of surgery and the related costs. Originality/value: This innovative approach has great potential, as it is an easy and in-office procedure, and it offers several advantages over other existing methods.

Keywords: Customized implant | Orbital cavity reconstruction | Reverse engineering | Selective laser sintering | Surgery | Surgical guide

Abstract: This study defines a methodological procedure for the design and manufacturing of a prosthetic implant for the reconstruction of a midsagittal bony-deficiency of the skull due to the Apert congenital disorder. Conventional techniques for craniofacial defects reconstruction rely on the mirrored-image technique. When the cranial lesion extends over the midline or in case of bilateral defects, other approaches based on thin plate spline interpolation or constrained anatomical deformation are applied. The proposed method uses the anthropometric theory of cranial landmarks identification for the retrieval of a template healthy skull, useful as a guide in the successive implant design. Then, anatomical deformation of the region of interest and free-form modelling allow to get the customized shape of the implant. A full bulk and a porous implant have been provided according to the surgeon advises. The models have been 3D printed for a pre-surgical analysis and further treatment plan. They fulfilled the expectancies of the surgeon thus positive results are predictable. This methodology results to be reproducible to any other craniofacial defect spanning over the entire skull.

Keywords: Additive Manufacturing | Apert Syndrome | Biomedical design | Design process | Implant design

Abstract: To date, standard methods for assessing the severity of chest wall deformities are mostly linked to X-ray and CT scans. However, the use of radiations limits their use when there is a need to monitor the development of the pathology over time. This is particularly important when dealing with patients suffering from Pectus Carinatum, whose treatment mainly requires the use of corrective braces and a systematic supervision. In recent years, the assessment of severity of chest deformities by means of radiation-free devices became increasingly popular but not yet adopted as standard clinical practice. The present study aims to define an objective measure by defining a severity index (named External Pectus Carinatum Index) used to monitor the course of the disease during treatment. Computed on the optical acquisition of the patients’ chest by means of an appositely devised, fast and easy-to-use, body scanner, the proposed index has been validated on a sample composed of a control group and a group of Pectus Carinatum patients. The index proved to be reliable and accurate in the characterization of the pathology, enabling the definition of a threshold that allows to distinguish the cases of patients with PC from those of healthy subjects. [Figure not available: see fulltext.]

Keywords: Index | Optical imaging | Pectus Carinatum | Severity assessment | Three-dimensional

Abstract: The final subject position is often the only evidence in the case of the fall of a human being from a given height. Foreseeing the body trajectory and the respective driving force may not be trivial due to the possibility of rotations and to an unknown initial position and momentum of the subject. This article illustrates how multibody models can be used for this aim, with specific reference to an actual case, where a worker fell into a stair well, prior to stair mounting, and he was found in an unexpected posture. The aim of the analysis was establishing if this worker was dead in that same place, if he had been pushed, and which was his initial position. A multibody model of the subject has been built (“numerical android”), given his stature and his known mass. Multiple simulations have been performed, following a design of experiments where various initial positions and velocity as well as pushing forces have been considered, while the objective function to be minimized was the deviation of the numerical android position from the actual worker position. At the end of the analysis, it was possible to point how a very limited set of conditions, all including the application of an external pushing force (or initial speed), could produce the given final posture with an error on the distance function equal to 0.39 m. The full analysis gives a demonstration of the potentiality of multibody models as a tool for the analysis of falls in forensic inquiries.

Keywords: accident | android | biomechanics | crime | doe | fall | forensic | multibody

Abstract: The development of systems for supporting neuro-rehabilitation is of primary importance, due to the high number of people in need of rehabilitation and the limited effectiveness of most of the current developed systems. Our research work aims at developing more engaging interaction modalities for neuro rehabilitation systems, through virtual reality, music based on harp therapy and fragrance feedback modalities and which are also fun and motivational for the patients. The proposed interaction modalities consist of a set of virtual immersive environments which includes an olfactory feedback, where odours are used to increase the sense of presence and the attention of the patients during the execution of the exercises. While the patient performs the rehabilitation exercise, the harp therapist plays the harp accordingly to the patient emotional condition. The system shows a virtual scenario, including virtual objects and/or 360 videos used to increase his sense of presence in the scenario. Odours are associated with virtual scenarios.

Abstract: Background Preclinical training in perforator flap harvesting is typically conducted on living animal models; however, repeated training is not possible with these models because of ethical and/or economical constraints. We describe an anterolateral thigh flap (ALT flap) training model using chicken thigh that seems to be an appropriate training model prior, for example, to raise a perforator flap in a living rat or swine model. Methods A total of 10 chicken legs were used in this study. Six chicken legs were anatomically dissected to confirm the presence of the perforator and to identify the main vascular tree. In four chicken legs, a skin flap was planned based on the perforator and intramuscular dissection was performed under magnification. Results The perforator was identified in all dissections and was consistently found 3 cm above the line extending from the patella to the head of the femur in its third proximal. Proximally, the mean diameter of the artery and vein was 0.56 (σ = 0.04) and 0.84 (σ = 0.06) mm, respectively. The mean dissection time to raise the flap was 88 (σ = 7) min. Conclusion This is the first description of a nonliving biological simulation model for training in perforator flap dissection that mimics an ALT flap. As an ex vivo chicken model, it is a cost effective and readily accessible model suitable for repeated practice.

Keywords: ALT | chicken | perforator flap | training

Abstract: Background: Autotransplantation of cryopreserved ovarian tissue is currently the main option to preserve fertility for cancer patients. To avoid cancer cell reintroduction at transplantation, amulti-step culture systemhas been proposed to obtain fully competent oocytes for in vitro fertilization. Current in vitro systems are limited by the low number and health of secondary follicles produced during the first step culture of ovarian tissue fragments. To overcome such limitations, bioreactor designs have been proposed to enhance oxygen supply to the tissue, with inconsistent results. This retrospective study investigates, on theoretical grounds, whether the lack of a rational design of the proposed bioreactors prevented the full exploitation of follicle growth potential. Methods: Models describing oxygen transport in bioreactors and tissue were developed and used to predict oxygen availability inside ovarian tissue in the pertinent literature. Results: The proposed theoretical analysis suggests that a successful outcome is associated with enhanced oxygen availability in the cultured tissue in the considered bioreactor designs. This suggests that a rational approach to bioreactor design for ovarian tissue culture in vitro may help exploit tissue potential to support follicle growth.

Keywords: Design | In vitro culture | Ioreactor | Ovarian tissue | Oxygen | Transport

Abstract: This paper presents the application of a low-cost 3D printing technology in pre-operative planning and intra-operative decision-making. Starting from Computed Tomography (CT) scans, we were able to reconstruct a 3D model of the area of interest with a very simple and rapid workflow, using open-source software and an entry level 3D printer. The use of High Temperature Poly-Lactic Acid (HTPLA) by ProtoPasta allowed fabricating sterilizable models, which could be used within the surgical field. We believe that our method is an appealing alternative to high-end commercial products, being superior for cost and speed of production. It could be advantageous especially for small and less affluent hospitals that could produce customized sterilizable tools with little investment and high versatility.

Keywords: 3D printing | Computed tomography | Diagnostic imaging | Mesh reconstruction | Rapid prototyping | Surgical planning

Abstract: 3D reconstruction of human anatomy from cross-sectional imaging has recently gained increasing importance in several medical fields thus designating the 3D bones reconstruction accuracy, critical for the success of the whole surgical intervention. The 3D anatomic model quality depends on the quality of the reconstructed image, on the quality of the images segmentation step and on the error introduced by the iso-surface triangulation algorithm. The influence of image processing procedures and relative parametrization has been largely studied in the scientific literature; however, the analysis of the direct impact of the quality of the reconstructed medical images is still lacking. In this paper, a comparative study on the influence of both image reconstruction algorithm (standard and iterative) and applied kernel is reported. Research was performed on the 3D reconstruction of a pig tibia, by using Philips Brilliance 64 CT scanner. At the stage of scanning and at the stage of 3D reconstruction, the same procedures were followed, while only image reconstruction algorithm and kernel were changed. The influence of such selection on the accuracy of bone geometry was assessed by comparing it against the 3D model obtained with a professional 3D scanner. Results show an average error in reconstructing the geometry of around 0.1 mm with a variance of 0.08 mm. The presented study highlights new opportunities to control the deviations on the geometry accuracy of the bones structures at the stage of cross sectional imaging generation.

Keywords: 3D model reconstruction | Accuracy | Computed tomography | Kernel reconstruction

Abstract: Recently, robotics has increasingly become a companion for the human being and assisting physically impaired people with robotic devices is showing encouraging signs regarding the application of this largely investigated technology to the clinical field. As of today, however, exoskeleton design can still be considered a hurdle task and, even in modern robotics, aiding those patients who have lost or injured their limbs is surely one of the most challenging goal. In this framework, the research activity carried out by the Department of Industrial Engineering of the University of Florence concentrated on the development of portable, wearable and highly customizable hand exoskeletons to aid patients suffering from hand disabilities, and on the definition of patient-centered design strategies to tailor-made devices specifically developed on the different users' needs. Three hand exoskeletons versions will be presented in this paper proving the major taken steps in mechanical designing and controlling a compact and lightweight solution. The performance of the resulting systems has been tested in a real-use scenario. The obtained results have been satisfying, indicating that the derived solutions may constitute a valid alternative to existing hand exoskeletons so far studied in the rehabilitation and assistance fields.

Keywords: Biomechanical engineering | Hand exoskeleton | Kinematic analysis | Mechanism design and optimization | Mechatronics | Wearable robotics

Abstract: This study proposes a novel occlusions detection and restoration strategy. The aim is to success with 3D face recognition even when faces are partially occluded by external objects. The method, which relies on geometrical facial properties, is designed for managing two types of facial occlusions (eye and mouth occlusions due to hands). First occlusions are detected and (if present) classified, by considering their effects on the 3D points cloud. Then, the occluded regions are progressively removed, and finally, the non-occluded symmetrical regions are used to restore the missing information. After the restoration process, face recognition is performed relying on the restored facial information and on the localized landmarks. The landmarking methodology relies on derivatives and on 12 differential geometry descriptors. The discriminating features adopted for facial comparison include shape index histograms, Euclidean and geodetical distances between landmarks, facial curves, and nose volume. Obtained recognition rates, evaluated on the whole Bosphorus database and on our private dataset, ranging from 92.55 to 97.20% depending on the completeness of data.

Keywords: 3D face | Differential geometry | Face analysis | Face recognition | Feature extraction

Abstract: Three-dimensional technologies have had a wide diffusion in several fields of application throughout the last decades; medicine is no exception and the interest in their introduction in clinical applications has grown with the refinement of such technologies. We focus on the application of 3D methodologies in maxillofacial surgery, where they can give concrete support in surgical planning and in the prediction of involuntary facial soft-tissue changes after planned bony repositioning. The purpose of this literature review is to offer a panorama of the existing prediction methods and software with a comparison of their reliability and to propose a series of still pending issues. Various software are available for surgical planning and for the prediction of tissue displacements, but their reliability is still an unknown variable in respect of the accuracy needed by surgeons. Maxilim, Dolphin and other common planning software provide a realistic result, but with some inaccuracies in specific areas of the face; it also is not totally clear how the prediction is obtained by the software and what is the theoretical model they are based on.

Keywords: 3D face analysis | Orthognathic surgery | Prediction methods | Soft tissue prediction | Surgical planning

Abstract: In recent years, facial expression analysis and recognition (FER) have emerged as an active research topic with applications in several different areas, including the human-computer interaction domain. Solutions based on 2D models are not entirely satisfactory for real-world applications, as they present some problems of pose variations and illumination related to the nature of the data. Thanks to technological development, 3D facial data, both still images and video sequences, have become increasingly used to improve the accuracy of FER systems. Despite the advance in 3D algorithms, these solutions still have some drawbacks that make pure three-dimensional techniques convenient only for a set of specific applications; a viable solution to overcome such limitations is adopting a multimodal 2D+3D analysis. In this paper, we analyze the limits and strengths of traditional and deep-learning FER techniques, intending to provide the research community an overview of the results obtained looking to the next future. Furthermore, we describe in detail the most used databases to address the problem of facial expressions and emotions, highlighting the results obtained by the various authors. The different techniques used are compared, and some conclusions are drawn concerning the best recognition rates achieved.

Keywords: 2D/3Dcomparison | 3Dface analysis | Action units | Deep learning-based FER | Facial action coding system | Facial expression recognition

Abstract: Nowadays, facial mimicry studies have acquired a great importance in the clinical domain and 3D motion capture systems are becoming valid tools for analysing facial muscles movements, thanks to the remarkable developments achieved in the 1990s. However, the face analysis domain suffers from a lack of valid motion capture protocol, due to the complexity of the human face. Indeed, a framework for defining the optimal marker set layout does not exist yet and, up to date, researchers still use their traditional facial point sets with manually allocated markers. Therefore, the study proposes an automatic approach to compute a minimum optimized marker layout to be exploited in facial motion capture, able to simplify the marker allocation without decreasing the significance level. Specifically, the algorithm identifies the optimal facial marker layouts selecting the subsets of linear distances among markers that allow to automatically recognizing with the highest performances, through a k-nearest neighbours classification technique, the acted facial movements. The marker layouts are extracted from them. Various validation and testing phases have demonstrated the accuracy, robustness and usefulness of the custom approach.

Keywords: 3D face | Face analysis | Feature extraction | Marker optimization | Motion capture

Abstract: As the potentials of technology grow, the embedding of IT advances in different fields and applications increases. A recent example is virtual reality and in particular the virtual product. The possibility of having a product in a virtual form allows creators and designers to efficiently manage the cycle of a product generation and evolution. The key advantage of the “virtual” is to have the product in advance, even in the conceptualization phase, with clear benefits in terms of consumptions of resources and, hence, sustainability. A potential customer could thus interact with a product-to-be and provide feedback about its look and feel, its usability, and, most of all, give an emotional response. In this context, the interaction between the virtual product and the future customer becomes a core point for the new approaches related to user-centred and user experience design, giving birth to a design methodology called “emotional design”. In particular, the study of facial expressions seems to be the more reliable and attractive aspect of it.

Keywords: 3D | Concept design | Emotional design | Facial expression recognition | PLM | Virtual reality

Abstract: Surgical interventions for jaw reconstruction require the design and the production of surgical guides that allow the surgeon to operate quickly and accurately. In some cases, the reconstruction is performed by inserting a prothesis, thus operating exclusively on the jaw, while in other cases the reconstruction is performed by withdrawing and inserting part of the fibula in place of the original jaw bone. This project aims to develop a procedure that allows 3D modeling of the surgical guides necessary for surgical intervention. The idea is to find a surgical guide archetype, a starting shape for the surgeon so that the cutting planes can be oriented without the surgical guide having to be redesigned from scratch for every single patient. The first step of the procedure is the segmentation, performed applying the thresholding operation on the images provided by magnetic resonance MR in order to identify the region of interest (ROI). The second step is the reconstruction of the 3D model, so that a mesh is obtained from 2D images. Subsequently the mesh is post-processed and the cutting plans along which the surgeon will intervene are defined.

Keywords: 3D modeling | 3D reconstruction | Maxillofacial surgery | Surgical guides

Abstract: The pre-operative planning of a hip arthroplasty entails the choice of the prosthetic hip model and of the position of both joint components with reference to bone. Assessing the impact of geometrical factors on the final hip range of motion (ROM) is not trivial, since it requires performing 3D evaluations. Nonetheless, it deserves to be studied since hip impingement and dislocation are still relevant complications in hip arthroplasty.This work pertains a numerical model for the assessment of the hip ROM in relation to cotyle position. External/internal rotation is considered as a benchmark, and multiple combinations of acetabular anteversion/inclination are considered.According to results, over two hundred different geometric configurations can be examined in few minutes, and the cotyle position can be so optimized with relevant benefits in term of hip ROM.

Abstract: When a new material for the realization of an implantable device in the bone is being studied, in addition to its chemical-physical-mechanical characterization, tests regarding osteointegration are performed. Usually, researchers evaluate the ability of biomaterials to bind to the bone under load-bearing conditions, through animal experiments in the phase of a preclinical study, provided the respective authorization by the ethics committee. In more detail, plugs made of the material under investigation are prepared and implanted into a weight-bearing portion of the skeleton of animals (typically into the knee joint of goats, pigs, rabbits or dogs); after a pre-set time, the animal is sacrificed, the bone element is extracted, it is tested mechanically – generally by means of a pull-out test – and finally it is examined histologically. Mechanical tests often require demanding specimen preparation, which could bias results. In the scope of a research regarding the interface behaviour of a ceramic plug (two different ceramic plugs) compared to a titanium one, the authors have suggested a novel testing technique which allows to perform ‘push-in’ tests, instead of the more common pull-out tests. This methodology has been followed here to compare titanium versus ceramic plugs at different times from implant (0, 3 months, 1 year) into goat knees. As a result, the study reports the shear resistance of bone–plug interfaces. The statistical analysis of the data allowed us to establish that titanium plugs systematically exhibit a higher resistance (p&lt;0.10); this resistance undergoes a significant increment as time passes (p&lt;0.07) due to progressive osteointegration.

Keywords: Biomaterial interface | Bone | Mechanical test | Osteointegration

Abstract: In recent years the science of dental materials and implantology have taken many steps forward. In particular, it has tended to optimize the implant design, the implant surface, or the connection between implant and abutment. All these features have been improved or modified to obtain a better response from the body, better biomechanics, increased bone implant contact surface, and better immunological response. The purpose of this article, carried out by a multidisciplinary team, is to evaluate and understand, through the use also of bioengineering tests, the biomechanical aspects, and those induced on the patient’s tissues, by dental implants. A comparative analysis on different dental implants of the same manufacturer was carried out to evaluate biomechanical and molecular features. Von Mises analysis has given results regarding the biomechanical behavior of these implants and above all the repercussions on the patient’s tissues. Knowing and understanding the biomechanical characteristics with studies of this type could help improve their characteristics in order to have more predictable oral rehabilitations

Keywords: biomechanical phenomena | bone tissue | dental implants | dental occlusion | dental prosthesis design | finite element analysis | immunological | osseointegrated implants | osseointegration | wound healing

Abstract: HoloLens is the most recent and advanced forms of wearable Mixed Reality (MR) technology. It enables the user wearing a head-mounted device to experience 3D holographic objects “inside” the visualization of the real environment where he or she is located. Existing HoloLens applications have been developed in domains such as data visualization, entertainment, industrial training, education, and tourism, but the use of this technology in the arena of mental health is largely unexplored. The paper presents a HoloLens-based system called MemHolo that addresses persons with mild Alzheimer’s Disease (AD). AD is associated to a chronic progressive neurodegenerative process that severely affects cognitive functioning (especially memory) and some motor functions. MemHolo is intended to be used as a cognitive training tool to practice short-term and spatial memory in a safe and controlled virtual environment, and to mitigate the effects of mental decline. The paper discusses the design process of MemHolo, and describes three evaluation studies on progressive prototypes. To our knowledge, MemHolo is the first HoloLens application designed natively for persons with AD. Our empirical work sheds a light on how these people experience HoloLens applications, highlights some challenges and potential benefits of using MR technology in the AD arena, and may pave the ground towards new forms of treatment.

Keywords: Alzheimer disease (AD) | Augmented reality | Cognitive training | Elderly | HoloLens | Mixed reality

Abstract: HoloLearn is a Mixed Reality (MR) application that exploits Microsoft HoloLens to help people with Cognitive Disability improve autonomy in everyday life. Using HoloLearn, the user is immersed in a MR environment based on the surrounding space, in which s/he can learn simple daily tasks in an engaging way, with the help of a virtual assistant if needed.

Keywords: Augmented Reality | Cognitive Disability | Holograms | HoloLens | Mixed Reality | Virtual Assistant

Abstract: Objective: To investigate the influence of implant design on the change in the natural frequency of bone-implant system during osseointegration by means of a modal 3D finite element analysis. Methods: Six implants were considered. Solid models were obtained by means of reverse engineering techniques. The mandibular bone geometry was built-up from a CT scan dataset through image segmentation. Each implant was virtually implanted in the mandibular bone. Two different models have been considered, differing in the free length of the mandibular branch (‘long branch’ and ‘short branch’) in order to simulate the variability of boundary conditions when performing vibrometric analyses. Modal analyses were carried out for each model, and the first three resonance frequencies were assessed with the respective vibration modes. Results: With reference to the ‘long branch’ model, the first three modes of vibration are whole bone vibration with minimum displacement of the implant relative to bone, with the exception of the initial condition (1% bone maturation) where the implant is not osseointegrated. By contrast, implant displacements become relevant in the ‘short branch’ model, unless osseointegration level is beyond 20%. The difference between resonance frequency at whole bone maturation and resonance frequency at 1% bone maturation remained lower than 6.5% for all modes, with the exception of the third mode of vibration in the ‘D’ implant where this difference reached 9.7%. With reference to the ‘short branch’ considering the first mode of vibration, 61–68% of the frequency increase was achieved at 10% osseointegration; 72–79% was achieved at 20%; 89–93% was achieved at 50% osseointegration. The pattern of the natural frequency versus the osseointegration level is similar among different modes of vibration. Significance: Resonance frequencies and their trends towards osseointegration level may differ between implant designs, and in different boundary conditions that are related to implant position inside the mandible; tapered implants are the most sensitive to bone maturation levels, small implants have very little sensitivity. Resonance frequencies are less sensitive to bone maturation level beyond 50%.

Keywords: Bone properties | CAD | Dental materials | Endosteal implants | Finite element analysis | Implant stability | Material properties | Osseointegration | Reverse engineering

Abstract: Objectives: To assess conceptual designs of dental posts consisting of polyetherimide (PEI) reinforced with carbon (C) and glass (G) glass fibers in endodontically treated anterior teeth. Methods: 3D tessellated CAD and geometric models of endodontically treated anterior teeth were generated from Micro-CT scan images. Model C-G/PEI composite posts with different Young's moduli were analyzed by Finite Element (FE) methods post A (57.7 GPa), post B (31.6 GPa), post C (from 57.7 to 9.0 GPa in the coronal–apical direction). A load of 50 N was applied at 45° to the longitudinal axis of the tooth, acting on the palatal surface of the crown. The maximum principal stress distribution was determined along the post and at the interface between the post and the surrounding structure. Results: Post C, with Young's modulus decreasing from 57.7 to 9.0 GPa in the coronal–apical direction, reduced the maximum principal stress distribution in the restored tooth. Post C gave reduced stress and the most uniform stress distribution with no stress concentration, compared to the other C-G/PEI composite posts. Significance: The FE analysis confirmed the ability of the functionally graded post to dissipate stress from the coronal to the apical end. Hence actual (physical) C-G/PEI posts could permit optimization of stress distributions in endodontically treated anterior teeth.

Keywords: CAD | Dental materials | Design | Endodontic treatment | Finite Element analysis | Image analysis

Abstract: Over the last three decades, it has been frequently reported that the properties of dental restorative composites cured with argon laser are similar or superior to those achieved with conventional halogen and light emitting diode (LED) curing units. Whereas laser curing is not dependent on the distance between the curing unit and the material, such distance represents a drawback for conventional curing units. However, a widespread clinical application of this kind of laser remains difficult due to cost, heavy weight, and bulky size. Recently, with regard to the radiation in the blue region of the spectrum, powerful solid-state lasers have been commercialized. In the current research, CAD (computer-aided design)/CAM (computer-aided manufacturing) assisted solid-state lasers were employed for curing of different dental restorative composites consisting of micro- and nanoparticle-reinforced materials based on acrylic resins. Commercial LED curing units were used as a control. Temperature rise during the photopolymerisation process and bending properties were measured. By providing similar light energy dose, no significant difference in temperature rise was observed when the two light sources provided similar intensity. In addition, after 7 days since curing, bending properties of composites cured with laser and LED were similar. The results suggested that this kind of laser would be suitable for curing dental composites, and the curing process does not suffer from the tip-to-tooth distance.

Keywords: Composites | Computer-aided design/computer-aided systems | Dental materials | Laser | Mechanical properties | Thermal properties

Abstract: Objective: To assess the influence of implant thread shape and inclination on the mechanical behaviour of bone-implant systems. The study assesses which factors influence the initial and full osseointegration stages. Methods: Point clouds of the original implant were created using a non-contact reverse engineering technique. A 3D tessellated surface was created using Geomagic Studio® software. From cross-section curves, generated by intersecting the tessellated model and cutting-planes, a 3D parametric CAD model was created using SolidWorks® 2017. By the permutation of three thread shapes (rectangular, 30° trapezoidal, 45° trapezoidal) and three thread inclinations (0°, 3° or 6°), nine geometric configurations were obtained. Two different osseointegration stages were analysed: the initial osseointegration and a full osseointegration. In total, 18 different FE models were analysed and two load conditions were applied to each model. The mechanical behaviour of the models was analysed by Finite Element (FE) Analysis using ANSYS® v. 17.0. Static linear analyses were also carried out. Results: ANOVA was used to assess the influence of each factor. Models with a rectangular thread and 6° inclination provided the best results and reduced displacement in the initial osseointegration stages up to 4.58%. This configuration also reduced equivalent VM stress peaks up to 54%. The same effect was confirmed for the full osseointegration stage, where 6° inclination reduced stress peaks by up to 62%. Significance: The FE analysis confirmed the beneficial effect of thread inclination, reducing the displacement in immediate post-operative conditions and equivalent VM stress peaks. Thread shape does not significantly influence the mechanical behaviour of bone-implant systems but contributes to reducing stress peaks in the trabecular bone in both the initial and full osseointegration stages.

Keywords: Bone properties | CAD | Dental materials | Endosteal implants | Finite element analysis | Material properties | Osseointegration | Plateau implants

Abstract: The use of intraoral scanners and Additive Manufacturing (AM) techniques in dentistry is increasing, and such technologies are integrated in daily workflows for the production of various types of dental restorations. Thus, it is clinically sensible to assess the accuracy of these systems. This in vivo study presents a comparison, in term of accuracy, among three commercially available AM systems, used to rapid prototype models obtained from intraoral scans data. Eight patients with a complete dentition were selected. Complete-arch scans of both upper and lower jaws were obtained using the 3Shape Trios 3 color intraoral scanner. The corresponding CAD models were created by means of the 3Shape Dental System software, and three AM systems, Photocentric LC10 (AM1), Zortrax M 200 (AM2) and Prusa I3 (AM3) were used to manufacture them. The manufactured fourty-eight models were scanned with the 3Shape Trios 3 color scanner, by the same operator. Scans of the manufactured models were aligned and compared to the reference intraoral scan by means of a Reverse Engineering software (Geomagic Studio). The comparison between the scans of the manufactured models and the reference intraoral scans, for the eight patients, shows a standard deviation (SD) in the range 0.11 – 0.27 mm for AM1, in the range 0.04 – 0.26 mm for AM2 and in the range 0.07 – 0.26 mm for AM3. The results of this research show that Prusa I3 and Zortrax M 200 are statistically more accurate than Photocentric LC10. Nevertheless, if we consider the amount of difference in accuracy, this may be not relevant from a clinical point of view. Thus, the three AM systems can be used in some dental applications which are compatible with the reported accuracy.

Keywords: Additive manufacturing | Dental models | Dentistry | Intraoral scans | Orthodontic appliances

Abstract: Additive Manufacturing technologies allow for the direct fabrication of lightweight structures with improved properties. In this context, Fused Deposition Modelling (FDM) has also been considered to design 3D multifunctional scaffolds with complex morphology, tailored biological, mechanical and mass transport properties. As an example, poly(ε-caprolactone) (PCL), surface-modified PCL and PCL-based nanocomposite scaffolds were fabricated and analysed. The effects of structural and morphological features (i.e., sequence of stacking, fiber spacing distance, pore size and geometry), surface modification and nanoparticles on the in vitro biological and mechanical performances were investigated.

Keywords: Additive Manufacturing | Design | Mechanical and Functional Analyses | Scaffolds

Abstract: In this chapter, authors provide a description of boundary element method (BEM) applications in biomechanics, with a focus on advantages and limitations of BEM versus other numerical methods such as finite element method, finite difference method, and meshless methods. In addition to a general overview, the chapter focus on how the BEM approach can be advantageous in those biomechanical problems involving fracture mechanics and contact modeling. To this aim, its preprocessing flexibility to tackle sharp geometric changes and complex remeshing is highlighted. The comparison among BEM and other numerical approaches proceeds through the evaluation of inherent accuracy, preprocessing and postprocessing efforts, and run times. Bio-CAD models with complex shapes are usually created from medical images acquisition, computer tomography or magnetic resonance scan, with different modeling techniques, which result in different accuracy and usability of the generated tessellated or surface computer-aided design (CAD) geometry. Special attention must be drawn to the mathematical reconstruction of bio-CAD model to facilitate the meshing process in the BEM environment and reduce the geometrical imperfections generated during the CAD to computer-aided engineering translation phase. BEM is best suited to reproduce accurately high surface stress gradients that are generally a modeling issue (e.g., in bone-implant contact simulations). Working with 3D models, the mesh refinement in the neighboring areas where high stress gradients are expected is much facilitated when using BEM, also because it is possible to use discontinuous elements and circumvent the constraint of a continuous mesh. BEM approach is certainly more accurate for linear analysis but, on the other hand, less versatile in some areas like those of highly nonlinear material behavior. A short description of some case studies showing the described advantages of BEM approach is reported.

Keywords: Bio-CAD | Biomechanics | Boundary element method | Dual boundary element method | Fracture

Abstract: Background and objective: The purpose of the present paper is to pave the road to the systematic optimization of complex craniofacial surgical intervention and to validate a design methodology for the virtual surgery and the fabrication of cranium vault custom plates. Recent advances in the field of medical imaging, image processing and additive manufacturing (AM) have led to new insights in several medical applications. The engineered combination of medical actions and 3D processing steps, foster the optimization of the intervention in terms of operative time and number of sessions needed. Complex craniofacial surgical intervention, such as for instance severe hypertelorism accompanied by skull holes, traditionally requires a first surgery to correctly “resize” the patient cranium and a second surgical session to implant a customized 3D printed prosthesis. Between the two surgical interventions, medical imaging needs to be carried out to aid the design the skull plate. Instead, this paper proposes a CAD/AM-based one-in-all design methodology allowing the surgeons to perform, in a single surgical intervention, both skull correction and implantation. Methods: A strategy envisaging a virtual/mock surgery on a CAD/AM model of the patient cranium so as to plan the surgery and to design the final shape of the cranium plaque is proposed. The procedure relies on patient imaging, 3D geometry reconstruction of the defective skull, virtual planning and mock surgery to determine the hypothetical anatomic 3D model and, finally, to skull plate design and 3D printing. Results: The methodology has been tested on a complex case study. Results demonstrate the feasibility of the proposed approach and a consistent reduction of time and overall cost of the surgery, not to mention the huge benefits on the patient that is subjected to a single surgical operation. Conclusions: Despite a number of AM-based methodologies have been proposed for designing cranial implants or to correct orbital hypertelorism, to the best of the authors’ knowledge, the present work is the first to simultaneously treat osteotomy and titanium cranium plaque.

Keywords: Additive manufacturing | CAD | Cranium surgery | Image processing

Abstract: Background: Current approaches to quantifying the severity of pectus excavatum require internal measurements based on cross-sectional imaging. The aim of this study is to exploit a novel index evaluated on the external surface of the chest with a three-dimensional (3D) optical scanner. Methods: Fifty-one children (41 male, 10 female) between 2 and 17 years of age were evaluated with a 3D optical scanner. Pectus excavatum severity was calculated by using an ad hoc instant 3D scanner and defining an automatic procedure to generate an optical 3D correction index (CI3D). For the latter, an ideal threshold was derived from a statistical analysis, and five blind surveys were collected from pediatric specialists on chest wall deformities. The CI3D was then correlated with blind clinical assessments of PE severity. Results: The cutoff thresholds were determined to optimally discriminate between six degrees of severity of PE patients by a correlation analysis. The correlation coefficient obtained by matching the CI3D with the average subjective severity shows that the proposed method outperforms traditional approaches. Conclusions: The optical 3D index has a good match with the average subjective assessment in distinguishing patients with mild to severe PE. This innovative approach offers several advantages over existing indices, as it is repeatable and does not require cross-sectional imaging. The index might be particularly suitable for monitoring the efficacy of nonoperative treatment and, in the future, for designing an optimal personalized usage of therapeutic devices.

Abstract: The percutaneous interventions in the treatment of structural heart diseases represent nowadays a viable option for patients at high risk for surgery. However, unlike during the traditional open heart surgery, the heart structures to be corrected are not directly visualized by the physician during the interventions. The interpretation of the available medical images is often a demanding task and needs specific skills i.e. clinical experience and complex radiological and echocardiographic analysis. The new trend for cardiovascular diagnosis, surgical planning and intervention is, today, mutually connected with most recent developments in the field of 3D acquisition, interactive modelling and rapid prototyping techniques. This is particularly true when dealing with complex heart diseases since 3D-based techniques can really help in providing an accurate planning of the intervention and to support surgical intervention. To help the research community in confronting with this new trend in medical science, the present work provides an overview on most recent approaches and methodologies for creating physical prototypes of patient-specific cardiac structures, with particular reference to most critical phases such as: 3D image acquisition, interactive image segmentation and restoration, interactive 3D model reconstruction, physical prototyping through additive manufacturing. To this purpose, first, recent techniques for image enhancement to highlight anatomical structures of interest are presented together with the current state of the art of interactive image segmentation. Finally, most suitable techniques for prototyping the retrieved 3D model are investigated so as to derive a number of criteria for manufacturing prototypes useful for planning the medical intervention.

Keywords: 3D modelling | Cardiovascular diseases | Heart | Medical imagery | Rapid prototyping | Surgical planning

Abstract: Pectus Excavatum, one of the most frequent chest wall deformities, is characterized by a depression of the sternum and costal cartilages. Patients with mild deformities are generally treated conservatively by using the so called Vacuum Bell (VB) i.e. a suction cup to be placed on the patient's sternal region. Three different sizes, as well as a model fitted for young women, of VB are available on the market. Unfortunately, the variability of the surface to be treated, the possible asymmetry of the caved-in area and the prolonged use, can make the device uncomfortable and, in some cases, ineffective for the patient. In order to cope with these issues, the present paper proposes a computer-aided method for customized vacuum bell design to be used by non-expert user, e.g. by medical staff. In particular, the present work entails the development of a system comprising: 1) a dedicated software capable of acquiring the 3D chest geometry - by using a low-cost range sensor, i.e. Kinect v2 - and of processing the point cloud so to generate NURBS surfaces of the chest; 2) a procedural CAD modeling of a personalized VB implemented within Siemens NX 11 CAD environment. Using the devised method, the medical staff is required only to use the 3D scanning system for acquiring the patient chest and to sketch, in a CAD-based interface, the boundary of the area to be treated. Once these tasks are performed, the system automatically builds the personalized VB model, ready to be manufactured.

Keywords: design customization | Procedural CAD modeling | reverse engineering | vacuum bell

Abstract: In tissue engineering, biocompatible porous scaffolds that try to mimic the features and function of the bone are of great relevance. In this paper, an effective method for the design of 3D porous scaffolds is applied to the modelling of structures with variable architectures. These structures are of interest since they are more similar to the stochastic configuration of real bone with respect to architectures made of a unit cell replicated in three orthogonal directions, which are usually considered for this kind of applications. This property configures them as, potentially, more suitable to satisfy simultaneously the biological requirements and those relative to the mechanical strength. The procedure implemented is based on the implicit surface modelling method and the use of a triply periodic minimal surface (TPMS), specifically, the Schwarz's Primitive (P) minimal surface, whose geometry was considered for the development of scaffolds with different configurations. The representative structures modelled were numerically analysed by means of finite element analysis (FEA), considering them made of a biocompatible titanium alloy. The architectures considered were thus assessed in terms of the relationship between the geometrical configuration and the mechanical response to compression loading.

Keywords: Design | FEA | Scaffold | Tissue engineering | TPMS

Abstract: Background/Aim. We retrospectively investigated the prognostic potential (correlation with overall survival) of 9 shape and 21 textural features from non-contrast-enhanced computed tomography (CT) in patients with non-small-cell lung cancer. Materials and Methods. We considered a public dataset of 203 individuals with inoperable, histologically- or cytologically-confirmed NSCLC. Three-dimensional shape and textural features from CT were computed using proprietary code and their prognostic potential evaluated through four different statistical protocols. Results. Volume and grey-level run length matrix (GLRLM) run length non-uniformity were the only two features to pass all four protocols. Both features correlated negatively with overall survival. The results also showed a strong dependence on the evaluation protocol used. Conclusion: Tumour volume and GLRLM run-length non-uniformity from CT were the best predictor of survival in patients with non-small-cell lung cancer. We did not find enough evidence to claim a relationship with survival for the other features.

Keywords: Computed tomography | Non-small-cell lung cancer | Radiomics. | Shape | Texture

Abstract: In this paper, we aim at providing results concerning the application of desktop systems for rapid prototyping of medical replicas that involve complex shapes, as, for example, folds of a colon. Medical replicas may assist preoperative planning or tutoring in surgery to better understand the interaction among pathology and organs. Major goals of the paper concern with guiding the digital design workflow of the replicas and understanding their final performance, according to the requirements asked by the medics (shape accuracy, capability of seeing both inner and outer details, and support and possible interfacing with other organs). In particular, after the analysis of these requirements, we apply digital design for colon replicas, adopting two desktop systems. The experimental results confirm that the proposed preprocessing strategy is able to conduct to the manufacturing of colon replicas divided in self-supporting segments, minimizing the supports during printing. This allows also to reach an acceptable level of final quality, according to the request of having a 3D presurgery overview of the problems. These replicas are compared through reverse engineering acquisitions made by a structured-light system, to assess the achieved shape and dimensional accuracy. Final results demonstrate that low-cost desktop systems, coupled with proper strategy of preprocessing, may have shape deviation in the range of ±1 mm, good for physical manipulations during medical diagnosis and explanation.

Abstract: Finite Element Analysis (FEA) has gained an extensive application in the medical field, such as soft tissues simulations. In particular, colorectal simulations can be used to understand the interaction with the surrounding tissues, or with instruments used in surgical procedures. Although several works have been introduced considering small displacements, as a result of the forces exerted on adjacent tissues, FEA applied to colorectal surgical scenarios is still a challenge. Therefore, this work aims to provide a sensitivity analysis on three geometric models, taking in mind different bioengineering tasks. In this way, a set of simulations has been performed using three mechanical models named Linear Elastic, Hyper-Elastic with a Mooney-Rivlin material model, and Hyper-Elastic with a YEOH material model.

Keywords: Computer assisted surgical planning | Finite element analysis | Soft tissues simulation | Surface modeling

Abstract: Enhancing the performance of scaffolds for bone regeneration requires a multidisciplinary approach involving competences in the fields of Biology, Medicine and Engineering. A number of studies have been conducted to investigate the influence of scaffolds design parameters on their mechanical and biological response. The possibilities offered by the additive manufacturing techniques to fabricate sophisticated and very complex microgeometries that until few years ago were just a geometrical abstraction, led many researchers to design scaffolds made from different unit cell geometries. The aim of this work is to find, based on mechanobiological criteria and for different load regimes, the optimal geometrical parameters of scaffolds made from beam-based repeating unit cells, namely, truncated cuboctahedron, truncated cube, rhombic dodecahedron and diamond. The performance, -expressed in terms of percentage of the scaffold volume occupied by bone-, of the scaffolds based on these unit cells was compared with that of scaffolds based on other unit cell geometries such as: hexahedron and rhombicuboctahedron. A very intriguing behavior was predicted for the truncated cube unit cell that allows the formation of large amounts of bone for low load values and of very small amounts for the medium-high ones. For high values of load, scaffolds made from hexahedron unit cells were predicted to favor the formation of the largest amounts of bone. In a clinical context where medical solutions become more and more customized, this study offers a support to the surgeon in the choice of the best scaffold to be implanted in a patient-specific anatomic region.

Keywords: Beam-based scaffolds | Bone tissue engineering | Diamond | Mechanobiology | Rhombic dodecahedron | Truncated cube | Truncated cuboctahedron | Unit cell

Abstract: Background: New sources of stem cells in adult organisms are constantly emerging. Postnatal Mesenchymal Stem Cells (MSCs), are the most promising support to perform an effective regenerative medicine: such cells have the ability to differentiate into several lineages, such as osteoblasts and chondroblasts, providing novel strategies to improve different complex treatments, during bone regeneration. 3D-printed biomaterials can be designed with geometry aimed to induce stem cells to differentiate towards specific lineage. Objective: The interaction between stem cells easy to isolate and engineered 3D-printed scaffolds can translate the tissue bio-engineering into bone regenerative surgery. For those reasons, to better identify the complexity represented by the activities and responses of MSCs requires the advance of new target therapies which are not current in endocrine, metabolic and immune disorders and yet to be developed. Method: This topical review briefly focuses on the new approaches of translational medicine with the use of MSCs and scaffolds engineered with the aid of 3D-printing technology, highlights the osteogenic functions and addresses their applications across the breadth of regenerative medicine. Results: The application of bone constructs consisting of the engineered scaffold and MSCs as well as the aspects related to the optimal scaffold geometry that favours the best MSCs differentiation and the improvement of concepts as “sensing surface” were also discussed. Conclusion: Regenerative surgery is largely growing in the field of translational medicine. The use of new sources of MSCs and the improvement of new concepts of bio-engineered scaffolds will certainly be the next step of customized medicine.

Keywords: 3D-printed scaffolds | Customized medicine | Mesenchymal stem cells | Regenerative medicine | Tissue engineering | Translational medicine

Abstract: The optimization of loading protocols following dental implant insertion requires setting up patient-specific protocols, customized according to the actual implant osseointegration, measured through quantitative, objective methods. Various devices for the assessment of implant stability as an indirect measure of implant osseointegration have been developed. They are analyzed here, introducing the respective physical models, outlining major advantages and critical aspects, and reporting their clinical performance. A careful discussion of underlying hypotheses is finally reported, as is a suggestion for further development of instrumentation and signal analysis.

Keywords: Damping | Early loading | Functional loading | Implant stability | Modal analysis | Osseointegration | Resonance frequency | Reverse torque | Ultrasound

Abstract: OBJECTIVE The aim of this study is the evaluation of the temporomandibular joint stress distribution during the use of a Mandibular Advancement Device. MATERIALS AND METHODS This study is made using Finite Element Method (FEM). Dental casts, advancement bite, CBCT and MRI were taken in a 27-year-old woman. A Somnodent device was scanned and associated with a three-dimensional cranium. FEM analysis was made using ANSYS software with 1 and 2 mm of advancement. RESULTS The articular disc showed values range between 0.099-6.39 and 0.5-2.02 MPa for an advancement of 1 and 2 mm respectively. The condyle load distribution showed values range between 0.0037-7.50 and 0.0020-10.0 MPa for an advancement of 1 and 2 mm respectively. CONCLUSIONS Values obtained are significantly lower than limit values of the condyle and articular disc. Slight mandibular advancement can be consider a safe procedure even for the long period and should not cause permanent side effects.

Keywords: CBCT | Finite Element Method | Mandibular advancement device | OSAS | Temporomandibular joint

Abstract: The paper aims to evaluate the effects caused by a Mandibular Advancement Device (MAD) for Obstructive Sleep Apnoea Syndrome (OSAS) treatment. This study is based on Finite Element Method (FEM) for evaluating the load distribution on temporomandibular joint, especially on the mandibular condyle and disc, and on periodontal ligaments. The stress values on condyle and periodontal ligaments lead authors to consider MAD a safe procedure even for a long period. The obtained results also show the relationship between MAD material and load distribution at the periodontal ligaments. The paper is a step toward future analyses for studying and comparing the effects of MAD features, such as material, shape and dimensions, in order to allow the clinician prescribing the most fitting device.

Keywords: Finite element method | mandibular advancement device | obstruction sleep apnea syndrome | periodontal ligament | temporomandibular joint

Abstract: This paper presents a knowledge-based method and relative multi-user web platform to prescribe Custom Made Insoles (CMI) involving the various stakeholders (patients/customers, practitioners, manufacturers and controllers) in an integrated approach that covers the entire process. The CMI prescription and design are carried out by using configuration rules, which combine foot parameters with insoles features. The platform also offers functionalities to collect and monitor the patients feedbacks, to control the clinician work and to obtain an electronic insole order used by manufactures.

Keywords: Co-design | Custom-made insole | Design knowledge | Healthcare design | Knowledge-based process

Abstract: Wrist injuries are one of the most common fractures, specifically around 25% of fractures among the pediatric population and up to 18% in the elderly age group are distal radius fractures. To date, the standard treatment entails the use of a tailor-made plaster of Paris cast. Although it is a simple and reliable treatment, it presents several disadvantages: its weight generally causes discomfort, it cannot be taken off without breaking it, it can cause skin rashes and prevents ventilation of the treated area. To overcome the limitations of the above mentioned treatment, 3D printed orthopaedic casts based on reverse engineering (RE) and additive manufacturing (AM) techniques have been proposed in literature. Despite these solutions prove to be a valid alternative to the standard treatment, the clinical use of AM-based devices is not trivial due to the need of expert CAD modelers to design the 3D model of the orthosis starting from the patient’s anatomy 3D acquisition. In this work, the authors identify a systematic procedure to create an orthosis model, compliant with medical guidelines, using common CAD tools. The systematic procedure, even still manually performed, envisages a set of tasks, grouped into five main blocks, that will be easy to be automatized in the future, thus eliminating the necessity of designing expertise to model the orthosis. The proposed procedure allows to design a device composed of two halves, to ease the application, locked through a zip tie-based mechanism. A preliminary ventilation pattern is proposed and tested with a FEM analysis to ensure structural resistance. The procedure has been tested on six case studies: all the orthoses models were correctly generated without major complications and positive user feedbacks were generally obtained throughout the tests.

Keywords: Cad | Cast modeling | Orthosis modelling | Personalized medicine | Reverse engineering

Abstract: The surgical process adopted to repair cranial defects using an implant, typically called Cranioplasty, has seen an abrupt increase in recent years due to the introduction of Reverse Engineering (RE) and Additive Manufacturing (AM) techniques. By adopting these techniques, CT/MRI data can be used to reconstruct, in a pre-operative stage, the 3D anatomy of the defective skull in order to design a patient-specific digital model of the prosthesis. The so-designed cranial plate can be then fabricated via AM, in a suitable metal alloy, and implanted. This allows for a perfect fit of the implant during the actual surgery, reducing the risks for the patient and increasing the efficacy of the treatment. This paper reviews existing approaches for the virtual reconstruction of defective skulls, and a basic classification, proposing four different classes of strategies (Mirroring, Surface Interpolation, Template-Based and Slice-based techniques) is provided. The findings of the study suggest that the reconstruction of skull defects is still an open problem, due to the complexities imposed by surface that needs to be retrieved (i.e. the human anatomy). All the presented approaches share weaknesses and limits, which are discussed in the article. Finally, possible directions to improve the existing techniques are briefly presented.

Keywords: Biomedical engineering | Cranioplasty | Reverse engineering | Skull reconstruction

Abstract: This paper analyse and compare the methods to detect and represent the human symmetry line. In the last years, the development of 3D scanners has allowed to replace the traditional techniques (marking based methods) with modern methodologies that, starting from a 3D valid discrete geometric model of the back, perform the posture and vertebral column detection based on a complex processing of the acquired data. The purpose of the paper is a critical discussion of the state of the art in order to highlight real potentialities and limitations of the most important methodologies proposed for human symmetry line detection.

Keywords: Anatomical landmarks | Back shape analysis | Posture prediction | Rasterstereography | Symmetry line

Abstract: The aim of this ex vivo study was to test a novel three-dimensional (3D) automated computer-aided design (CAD) method (aCAD) for the computation of femoral angles in dogs from 3D reconstructions of computed tomography (CT) images. The repeatability and reproducibility of three manual radiography, manual CT reconstructions and the aCAD method for the measurement of three femoral angles were evaluated: (1) anatomical lateral distal femoral angle (aLDFA); (2) femoral neck angle (FNA); and (3) femoral torsion angle (FTA). Femoral angles of 22 femurs obtained from 16 cadavers were measured by three blinded observers. Measurements were repeated three times by each observer for each diagnostic technique. Femoral angle measurements were analysed using a mixed effects linear model for repeated measures to determine the levels of intra-observer agreement (repeatability) and inter-observer agreement (reproducibility). Repeatability and reproducibility of measurements using the aCAD method were excellent (intra-class coefficients, ICCs ≥ 0.98) for all three angles assessed. Manual radiography and CT exhibited excellent agreement for the aLDFA measurement (ICCs ≥ 0.90). However, FNA repeatability and reproducibility were poor (ICCs < 0.8), whereas FTA measurement showed slightly higher ICCs values, except for the radiographic reproducibility, which was poor (ICCs < 0.8). The computation of the 3D aCAD method provided the highest repeatability and reproducibility among the tested methodologies.

Keywords: Canine | Computed tomography | Femur | Repeatability | Reproducibility | Three-dimensional constructions

Abstract: The impairment of finger movements after a stroke results in a significant deficit in hands everyday performances. To face this kind of problems different rehabilitation techniques have been developed, nevertheless, they require the presence of a therapist to be executed. To overcome this issue have been designed several apparatuses that allow the patient to perform the training by itself. Thus, an easy to use and effective device is needed to provide the right training and complete the rehabilitation techniques in the best way. In this paper, a review of state of the art in this field is provided, along with an introduction to the problems caused by a stroke and the consequences for the mobility of the hand. Then follows a complete review of the low cost home based exoskeleton project design. The objective is to design a device that can be used at home, with a lightweight and affordable structure and a fast mounting system. For implementing all these features, many aspects have been analysed, starting from the rehabilitation requirements and the ergonomic issues. This device should be able to reproduce the training movements on an injured hand without the need for assistance by an external tutor.

Keywords: Hand rehabilitation | Post stroke | Tele-Rehabilitation

Abstract: In the present work, sheet-forming processes, i.e. super plastic forming and single-point incremental forming, have been adopted for the manufacturing of custom prostheses, instead of subtractive and additive techniques that are time- and cost-consuming for a single-piece production. Regarding concerns of the material, three different titanium alloys were used: pure titanium and two grades of the alloy Ti-6Al-4V (the standard one and the extra low interstitial one). Since no standard protocol exists to assess the mechanical performance of cranial implants, an experimental procedure has been designed and used in this work for producing polymethylmethacrylate supports, on which the cranial prostheses were firmly connected and subjected to impact puncture tests (drop tests). An experimental campaign could thus be conducted to investigate the effect on the mechanical response of (a) the titanium alloy, (b) the initial blank thickness and (c) the manufacturing process. Drop tests, carried out according to the proposed procedure, have shown no failure of the prostheses, neither in the area of the impact nor in the anchoring region and have revealed that, irrespective of the adopted manufacturing process, which does not alter the material, the amount of energy absorbed by the implants is always larger than 70%.

Keywords: Drop test | Pure titanium | SPF | SPIF | Ti-6Al-4V | Ti-6Al-4V-ELI

Abstract: Versatile, cheap and non-invasive 3D acquisition techniques have received attention and interest in the field of biomedicine in recent years as the accuracy of developed devices permits the acquisition of human body shapes in detail. Interest in these technologies derives from the fact that they have the potential to overcome some limitations of invasive techniques (CT, X-rays, etc.) and those based on 2D photographs for the acquisition of 3D geometry. However, the data acquired from the 3D scanner cannot be directly used but need to be processed as they consist of 3D coordinates of the acquired points. Therefore, many researchers have proposed different algorithms which recognise the shape of human body and/or its features when starting from a 3D point cloud. Among all possible human body features to be evaluated, symmetry results the most relevant one. Accordingly, this survey systematically investigates the methods proposed in the literature to recognise 2D symmetry by the symmetry line and bilateral symmetry by the symmetry plane. The paper also analyses qualitative comparisons among the proposed methods to provide a guide for both practitioners and researchers.

Keywords: 3D scan | Digital human model | Symmetry line | Symmetry plane

Abstract: Meniscectomy significantly change the kinematics of the knee joint by reducing the contact area between femoral condyles and the tibial plateau, but the shift in the contact area has been poorly described. The aim of our investigation was to measure the shift of the tibiofemoral contact area occurring after meniscectomy. We used laser scans combined to surface texturing for measuring the 3D position and area of the femoral and tibial surfaces involved in the joint. In particular, natural condyles (porcine model) were analysed and the reverse engineering approach was used for the interpretation of the results from compression tests and local force measurements in conjunction with staining techniques. The results suggested that laser scans combined to surface texturing may be considered as a powerful tool to investigate the stained contours of the contact area. Beside the largely documented reduction of contact area and local pressure increase, a shift of the centroid of the contact area toward the intercondylar notch was measured after meniscectomy. As a consequence of the contact area shift and pressure increase, cartilage degeneration close to the intercondylar notch may occur.

Keywords: Biomechanics | Centroid | Image analysis | Laser scanning | Surface texturing | Tibiofemoral contact area

Abstract: Material structure-property relationship is strongly related to the employed process technology. Over the past years, laser processing of engineering materials has been proposed in many fields and different uses for diode lasers have been found in dentistry. In this contest, the potential of GaN- and InGaN-based laser diodes to cure dental materials was analysed. Two wavelengths of 405 nm and 445 nm were used as heat or light sources for warm condensation of gutta-percha, light transmission in dental posts and brackets or light curing of dental composites. Additive manufacturing approach was considered to fabricate 3D root analogues, suitable supports, positioning systems and moulds for optical measurements. A three-axis CAD/CAM system was implemented for positioning and aligning the laser beam. The ability of diode-pumped solid-state lasers to cure dental materials or to transmit light was compared to that of a traditional instrument. Temperature profile at the apex of an additive manufactured root canal sealed with gutta-percha, light transmission through translucent quartz fiber post or through aesthetic ceramic bracket, bending properties and morphological features of light cured dental composites (Gradia Direct - GC Corporation and Venus Diamond - Heraeus Kulzer) were measured. Results showed a very high potential of diode-pumped solid-state lasers to be used in endodontics, orthodontics and restorative dentistry.

Keywords: CAD/CAM system | Ceramic bracket | Dental materials | Laser diode | Mechanical analysis

Abstract: The ability to engineer scaffolds that resemble the transition between tissues would be beneficial to improve repair of complex organs, but has yet to be achieved. In order to mimic tissue organization, such constructs should present continuous gradients of geometry, stiffness and biochemical composition. Although the introduction of rapid prototyping or additive manufacturing techniques allows deposition of heterogeneous layers and shape control, the creation of surface chemical gradients has not been explored on three-dimensional (3D) scaffolds obtained through fused deposition modelling technique. Thus, the goal of this study was to introduce a gradient functionalization method in which a poly(ε-caprolactone) surface was first aminolysed and subsequently covered with collagen via carbodiimide reaction. The 2D constructs were characterized for their amine and collagen contents, wettability, surface topography and biofunctionality. Finally, chemical gradients were created in 3D printed scaffolds with controlled geometry and porosity. The combination of additive manufacturing and surface modification is a viable tool for the fabrication of 3D constructs with controlled structural and chemical gradients. These constructs can be employed for mimicking continuous tissue gradients for interface tissue engineering.

Keywords: collagen | functionalization | interface tissue engineering | poly(ε-caprolactone) | scaffold

Abstract: This study proposes a novel automatic method for facial landmark localization relying on geometrical properties of 3D facial surface working both on complete faces displaying different emotions and in presence of occlusions. In particular, 12 descriptors coming from Differential Geometry including the coefficients of the fundamental forms, Gaussian, mean, principal curvatures, shape index and curvedness are extracted as facial features and their local geometric properties are exploited to localize 13 soft-tissue landmarks from eye and nose areas. The method is deterministic and is backboned by a thresholding technique designed by studying the behaviour of each geometrical descriptor in correspondence to the locus of each landmark. Occlusions are managed by a detection algorithm based on geometrical properties which allows to proceed with the landmark localization avoiding the covered areas. Experimentations were carried out on 3132 faces of the Bosphorus database and of a 230-sized internal database, including expressive and occluded ones (mouth, eye, and eyeglasses occlusions), obtaining 4.75 mm mean localization error.

Keywords: 3D face | Differential geometry | Face analysis | Feature extraction | Landmark localization

Abstract: The Marchetti-Vicenzi's nail is an intramedullary device where six curved nails are kept straight by a closing ring in order to allow their insertion into the medullary canal of a long bone; in a following step, these nails stabilize the fracture due to the ring withdrawal and to the consequent elastic expansion of the nails. Pre-clinical testing of this sort of device is strongly advocated in order to be able to foresee their stability inside the medullary canal and to quantify their stiffening action on a broken bone. In this numerical work, an MB (Multi Body) model of the device has been developed, with the dual purpose of evaluating forces between the bone and the systemcomponents during its progressive opening and verifying the behavior of the stabilized bone when it undergoes external loading. Different solutions, for flexible body modeling (discretization with lumped parameters, "flexible body," "FE Part"), have been analyzed and compared in terms of accuracy of results and required computational resources. Contact parameters have been identified and criteria to simplify geometries and therefore to reduce simulation times have been given. Results have allowed to demonstrate how amoderate lateral force is able to dislocate the fracture and how the final position of the retention nut can be optimized. On the whole, a tool for the pre-clinical testing of elastic intramedullary nails has been given.

Keywords: FE analysis | Flexible bodies | Intramedullary nails | Marchetti-Vicenzi's nail | Multibody analysis | Sliding contacts

Abstract: Our research explores the potential of wearable Mixed Reality (MR) for people with Neuro-Developmental Disorders (NDD). The paper presents HoloLearn, a MR application designed in cooperation with NDD experts and implemented using HoloLens technology. The goal of HoloLearn is to help people with NDD learn how to perform simple everyday tasks in domestic environments and improve autonomy. An original feature of the system is the presence of a virtual assistant devoted to capture the user's attention and to give her/him hints during task execution in the MR environment. We performed an exploratory study involving 20 subjects with NDD to investigate the acceptability and usability of HoloLearn and its potential as a therapeutic tool. HoloLearn was well-accepted by the participants and the activities in the MR space were perceived as enjoyable, despite some usability problems associated to HoloLens interaction mechanism. More extensive and long term empirical research is needed to validate these early results, but our study suggests that HoloLearn could be adopted as a complement to more traditional interventions. Our work, and the lessons we learned, may help designers and developers of future MR applications devoted to people with NDD and to other people with similar needs.

Keywords: Augmented Reality | Holo Lens | Holograms | Mixed Reality | Neuro-developmental Disorders | Virtual assistant

Abstract: Objective To assess the effect of a ferrule design with specific post material-shape combinations on the mechanical behavior of post-restored canine teeth. Methods Micro-CT scan images of an intact canine were used to create a 3-D tessellated CAD model, from which the shapes of dentin, pulp and enamel were obtained and geometric models of post-endodontically restored teeth were created. Two types of 15 mm post were evaluated: a quartz fiber post with conical–tapered shape, and a carbon (C) fiber post with conical–cylindrical shape. The abutment was created around the coronal portion of the posts and 0.1 mm cement was added between prepared crown and abutment. Cement was also added between the post and root canal and a 0.25 mm periodontal ligament was modeled around the root. Four models were analysed by Finite Element (FE) Analysis: with/without a ferrule for both types of post material and shape. A load of 50 N was applied at 45° to the longitudinal axis of the tooth, acting on the palatal surface of the crown. The maximum normal stress criterion was adopted as a measure of potential damage. Results Models without a ferrule showed greater stresses (16.3 MPa) than those for models with a ferrule (9.2 MPa). With a ferrule, stress was uniformly distributed along the abutment and the root, with no critical stress concentration. In all models, the highest stresses were in the palatal wall of the root. Models with the C-fiber post had higher stress than models with the quartz fiber posts. The most uniform stress distribution was with the combination of ferrule and quartz fiber post. Significance The FE analysis confirmed a beneficial ferrule effect with the combination of ferrule and quartz fiber post, with tapered shape, affording no critical stress concentrations within the restored system.

Keywords: CAD | Dental materials | Endodontic treatment | Finite element analysis | Image analysis | Materials properties

Abstract: This paper deals with additive manufacturing techniques for the creation of 3D fetal face models starting from routine 3D ultrasound data. In particular, two distinct themes are addressed. First, a method for processing and building 3D models based on the use of medical image processing techniques is proposed. Second, the preliminary results of a questionnaire distributed to future parents consider the use of these reconstructions both from an emotional and an affective point of view. In particular, the study focuses on the enhancement of the perception of maternity or paternity and the improvement in the relationship between parents and physicians in case of fetal malformations, in particular facial or cleft lip diseases.

Abstract: For the purpose of reducing uncertainties in the measurements of morphologically complex biological objects, the authors present a new automatic method, which takes advantage from the representation of the object in the form of the 3D geometric model obtained from CT-scans or 3D scanning. In this paper, the method is verified in real cases and compared with the traditional approaches.

Keywords: 3D biomedical image analysis | measurement accuracy | measurement protocols in biomedicine | shape segmentation

Abstract: This work explores the use of an industry-oriented digital human modelling tool for the estimation of the musculoskeletal loads corresponding to a simulated human activity. The error in using a static analysis tool for measuring articulations loads under not-static conditions is assessed with reference to an accurate dynamic model and data from real experiments. Results show that, for slow movements, static analysis tools provide good approximation of the actual loads affecting human musculoskeletal system during walking.

Keywords: Biomechanics | Dynamics | Gait analysis | Kinematics | Virtual simulation

Abstract: This paper concerns the design and manufacture of medical devices, such as lower limb prosthesis, integrating low cost industrial technologies. In particular, it focuses the attention on the custom-fit component of a lower limb prosthesis, i.e., the socket, that is the interface with the residual limb. The considered process starts from the 3D reconstruction of patients’ limb and ends with the manufacture of the socket with a 3D printer using a multi-material approach. The process counts three steps: 3D modeling, testing (both experimental and numer-ical) and manufacturing. For each step adopted solutions and tools are described. Finally, conclusions are drawn mainly concerning the challenge of multi-material 3D printing of the socket.

Keywords: 3D printing | Lower limb prosthesis | Socket Modelling Assistant

Abstract: 3D body scanners are nowadays used in a range of applications spanning from health, fashion and fitness to reverse engineering applications for robotics and computer vision. Nowadays very good performances are achievable when using commercial 3D body scanners; however, focusing on relative complex shape of some body details, the results still lack precision and acceptable accuracy. Such critical issue remains unsolved also when dealing with the instantaneous acquisition of the hand-wrist-arm (HWA) anatomy. In this paper, we present a new approach that leverages the emerging 3D depth cameras technologies to design a compact low cost 3D dedicated HWA scanner system capable of delivering almost instantaneous full 3D measurement.

Keywords: 3D body scanner | 3D surface | calibration | depth sensors | hand-wrist-arm anatomy

Abstract: Cardiovascular diagnosis, surgical planning and intervention are among the most interested in recent developments in the field of 3D acquisition, modelling and rapid prototyping techniques. In case of complex heart disease, to provide an accurate planning of the intervention and to support surgical planning and intervention, an increasing number of Hospitals make use of physical 3D models of the cardiac structure, including heart, obtained using additive manufacturing starting from the 3D model retrieved with medical imagery. The present work aims in providing an overview on most recent approaches and methodologies for creating physical prototypes of patient-specific heart and cardiac structures, with particular reference to most critical phases such as segmentation and aspects concerning converting digital models into physical replicas through rapid prototyping techniques. First, recent techniques for image enhancement to highlight anatomical structures of interest are presented together with the current state of the art of semi-automatic image segmentation. Then, most suitable techniques for prototyping the retrieved 3D model are investigated so as to draft some hints for creating prototypes useful for planning the medical intervention.

Keywords: 3D modelling | 3D printing | Cardiovascular diseases | Heart | Medical imagery | Rapid prototyping | Surgical planning

Abstract: In orthopaedics, cellular structures can be used as three-dimensional porous biomaterials that try to mimic the characteristics and function of the bone. The progress in manufacturing techniques, mainly in the field of additive manufacturing, can potentially allow the production of highly controlled pore architectures and customized implants that, however, need more sophisticated design methodologies. In this paper, the design of porous biocompatible structures based on mathematically defined surfaces (triply periodic minimal surfaces) has been considered in respect of the approach that considers unit cells entirely modelled in CAD environment. Two types of unit cell have been here considered: the cubic and the P-cell. The cubic cell is created by a 3D CAD s/w from solid features that are combined together. The P-cell is modelled using an implicit function to describe the outer surface of the cell. Two are the design parameters of the P-cell: thickness and radius. The variation of these parameters allows modifying the architecture of the basic unit of the scaffold. The modification of the radius is carried out by a procedure, based on scaling and truncation operations. The thickness of the cell is modified by thickening and closure operations on the P-isosurface. The effect of these variations on the mechanical behaviour of the scaffold has been numerically evaluated by the estimation of the stiffness of each structure considered. The results demonstrated the huge potentiality of the method and stiffness values compatible with those required for biomechanical applications.

Keywords: Bone implants | Design | Porous materials | Scaffolds

Abstract: This work concerns the growing interest in accessible tourism and describes the early stages of development of Gölem project. In particular, it takes into account accompanying activities of disabled people in mountain areas. Although literature and market analysis highlight the presence of different technical solutions used for the movement of disabled persons on rough terrains, there are only a couple of solutions based on the help of guides: Joëlette© and TrailRider©. Even if the use of these devices is generally satisfactory, our analysis has highlighted the presence of some limitations such as the difficulty of maintaining the lateral balance of the devices (which involves a considerable physical effort for the guides) and their reduced comfort for the passenger. This article describes the activities developed within the Gölem project. Its main goals are to design and to test an improved model of trekking/hiking wheelchair taking into account passengers comfort and better functionality of the device. At this moment, the design and modeling phases with the definition of dynamic parameters and of the suspension system of the device have been completed. The prototype implementation phase is in progress. Future activities will provide validation and field testing of the new solution with users.

Keywords: Accessible tourism | Comfort design | Disabled people | Mountain | Suspension system design | Trekking/hiking wheelchair

Abstract: This paper presents an immersive virtual reality system (IVRS) that has been designed for unilateral amputees in order to reduce the phantom limb pain (PLP). The patient's healthy limb is tracked by using a motion sensor. Data of the limb in motion are used as input parameters to move the phantom limb in the immersive virtual reality system. In this way, the patient has the illusion of moving the phantom limb while moving the real and contra-lateral limb. The system has been implemented by using low cost and open technologies, and combines the Oculus Rift SDK2 device, the LeapMotion device, a motion sensor, and an engine for interactive 3D content and gaming generation (Unity 3D). The Oculus Rift head mounted display is used to provide the immersive experience.

Abstract: Many foot pathologies are prevented or treated with Custom Made Insoles (CMIs). Although a strong computerization has characterized the shoe development process during the last decade, the CMI sector still lacks a software platform integrating the design and diagnosis tools used by the stakeholders of this area. Moreover, the prescription of CMIs is only based on the experience of skilled podiatrists rather than on a common and shared knowledge (e.g. guidelines, best practices, rules, etc.). This paper presents a multi-users and knowledge-based platform, called Smart Prescription Platform (SPP), covering the whole CMI development phases, from foot diagnosis to the production, involving clinicians, patients, manufacturers and controllers. The web-based platform is fully integrated with the technologies available in the orthopaedic sector, which are 3D/4D scanners, baropodometric platforms, footwear virtual catalogues, plantar pressure simulators, Augmented Reality devices and 3D CAD systems. The use of standard file formats (e.g.stl,.bmp,.xml) allows an electronic dataflow among the tools. The main module of the platform, called Prescription System (PS), is used for prescribing custom-made insoles for patients with different health conditions, satisfying the needs of all actors and optimizing the data exchange. PS is a knowledge-based prescription system integrating the best practices related to the prescription of CMIs. The PS output is a XML file representing the electronic order, used to exchange data with the other tools of the SPP. The proposed platform has been tested with a twofold aim: to validate the usability of the Prescription System and the inter-operability of the platform tools. The positive results gathered during the validation, led the experts to start using the web platform for their daily work.

Keywords: Collaborative platform | Custom Made Insole | Insole prescription | Knowledge-based platform | Web-based platform

Abstract: Diagnosis and treatment of orbital wall fractures are based on both physical examination and computed tomography scan of the orbital cavity. The present paper reports on the secondary reconstruction of the skeletal orbit following untreated orbital floor fracture in a patient wearing an ocular prosthesis because of an orbital trauma. A computer-assisted approach, based on anatomical modelling and custom-made mould fabrication via selective laser sintering, is proposed for manufacturing a preformed orbital implant. Such a procedure offers precise and predictable results for orbital reconstructions. This protocol proved an effective reduction of operating time, patient morbidity and a fast and low-cost preoperative planning procedure. Such an approach can be used for immediate and in-office manufacturing of custom implants in trauma and reconstructive patients.

Keywords: computer aided surgery | ocular prosthesis | Orbital wall reconstruction | surgical tools

Abstract: The custom-made insole is largely recognized as the most important orthotics for decreasing the foot plantar pressure, using additions or cutouts, which modify the geometry of the insole. This paper proposes a procedure for supporting the clinicians in prescribing innovative custom made insoles for offloading the plantar pressure by using specific combinations of materials for the foot peak-pressure areas, without modifying the geometry of the insole. The process starts with the acquisition of the plantar pressure map of the customer and ends with the definition of the customised insole. The aim of the procedure is choosing the best combination of materials for each foot anatomical area for reducing the plantar pressure peaks below a maximum admissible pressure value decided by the physician. The positions and dimensions of the inserts are defined through analyzing the customer plantar pressure while the inserts materials are defined using FEM simulations of the insole-foot interaction. The case study showed a plantar pressure reduction congruent with the FEM simulations results. This procedure is applicable both for subtractive and additive manufacture techniques.

Keywords: Biomedical design | Custom made insole | Design process | Pressure offloading | Simulation

Abstract: Many diseases of the spine require surgical treatments that are currently performed based on the experience of the surgeon. For pedicle arthrodesis surgery, two critical factors must be addressed: Screws must be applied correctly and exposure to harmful radiation must be avoided. The incorrect positioning of the screws may cause operating failures that lead to subsequent reoperations, an increase in the overall duration of surgery and, therefore, more harmful, real-time X-ray checks. In this paper, the authors solve these problems by developing a method to realize a customized surgical template that acts as a drilling template. The template has two cylindrical guides that follow a correct trajectory previously calculated by means of an automatic algorithm generated on the basis of a vertebra CAD model for a specific patient. The surgeon sets the template (drilling guides) on the patient’s vertebra and safely applies the screws. Three surgical interventions for spinal stabilization have been performed using the template. These have had excellent results with regard to the accuracy of the screw positioning, reduction of the overall duration of the intervention, and reduction of the number of times the patient was exposed to X-rays.

Keywords: Pedicle arthrodesis | Screw direction optimization | Spine surgery | Surgical template | X-ray minimization

Abstract: This work shows the practical application and the experimental validation of a procedure based on an algorithm, running in a finite element environment, able to operate inside a convex three-dimensional solid by replacing the continuous mass with an appropriate cancellous bone-inspired space frame sharing, with the solid, the border and organized for having the fibres oriented according to the boundary conditions. The purpose is to reach the maximum mechanical efficiency realizing a load adaptive space frame optimized in terms of weight. Young's moduli of a cubic virtual specimen were numerically estimated. Fifteen specimens were printed by a 3D printer using a titanium alloy. Numerical results were compared with experimental ones obtained by tensile tests. The simulation results confirmed the validity of the FEM “beam element-based” space frame.

Keywords: 3-Dimensional printing | Directional orientation | Fibres | Finite element analysis (FEA) | Mechanical testing

Abstract: HoloLens technology enables mixed reality experiences that integrate holographic objects into the real world in which the mixed reality head-mounted device is used. Since HoloLens' launch in March 2016, some mixed-reality applications of this technology have been announced or showcased, addressing different fields, including education, data visualization, tourism, entertainment, and professional training e.g., in medicine, architecture, manufacturing, and engineering. Still, a limited number of reported research provide examples of user experience designs and evaluations for applications using HoloLens. We are interested in the use of HoloLens as therapeutic tool for people with the Alzheimer's Disease. The paper describes a set of therapeutic activities that have been designed in cooperation with neurologists and aim at stimulating short term memory and spatial memory in this target group. We also report a preliminary study of the usability of these activities among the elderly subjects.

Keywords: Alzheimer's | Augmented reality | Cognitive training | Hologram | HoloLens | Memory | Mixed reality | Rehabilitation

Abstract: The aim of regenerative medicine is replacing missing or damaged bone tissues with synthetic grafts based on porous interconnected scaffolds, which allow adhesion, growth, and proliferation of the human cells. The optimal design of such scaffolds, in the Bone Tissue Engineering field, should meet several geometrical requirements. First, they have to be customized to replicate the skeletal anatomy of the patient, and then they have to provide the proper trabecular structure to be successfully populated by the cells. Therefore, for modelling such scaffolds, specific design methods are needed to conceive extremely complex structures by controlling both macro and micro shapes. For this purpose, in the last years, the Computer Aided Design of Triply Periodic Minimal Surfaces has received considerable attention, since their presence in natural shapes and structures. In this work, we propose a method that exploit Triply Periodic Minimal Surfaces as unit cell for the development of customized trabecular scaffolds. The aim is to identify the mathematical parameters of these surfaces in order to obtain the target requirements of the bone grafts. For that reason, the method is implemented through a Generative Design tool that allow to interactively controlling both the porosity and the pores size of the scaffolds.

Keywords: Bone tissue engineering | Generative design | Scaffold design | Triple periodic minimal surfaces

Abstract: Titanium and its alloys are widely used in cranioplasty because they are biocompatible with excellent mechanical properties and favor the osseointegration with the bone. However, when Titanium alloys have to be worked several problems occurred from a manufacturing point of view: the standard procedure for obtaining Titanium prostheses is represented by the machining processes, which result time and cost consuming. The aim of this research consist to introduce alternative flexible sheet forming processes, i.e. Super Plastic Forming (SPF) and Single Point Incremental Forming (SPIF), for the manufacturing of patient-oriented titanium prostheses. The research activities have already highlighted the potentiality of the investigated forming processes that can be alternatively used taking into account both the damage morphology and the need of urgency operation. In the present work, the way of manufacturing the Ti prostheses by SPF and SPIF is described. A comparative analysis has been performed, thus highlighting the peculiarities of the investigated processes and the prostheses feasibility.

Keywords: Single Point Incremental Forming | Super Plastic Forming | Titanium alloy

Abstract: Over the past few years, the influence of static or dynamic magnetic fields on biological systems has become a topic of considerable interest. Magnetism has recently been implicated to play significant roles in the regulation of cell responses and, for this reason, it is revolutionizing many aspects of healthcare, also suggesting new opportunities in tissue engineering. The aim of the present study was to analyze the effect of the application mode of a time-dependent magnetic field on the behavior of human mesenchymal stem cells (hMSCs) seeded on 3D additive-manufactured poly(ɛ-caprolactone)/iron-doped hydroxyapatite (PCL/FeHA) nanocomposite scaffolds.

Keywords: Additive manufacturing | Cell-material interaction | Magnetic field | Scaffold

Abstract: Bone tissue engineering is strongly dependent on the use of three-dimensional scaffolds that can act as templates to accommodate cells and support tissue ingrowth. Despite its wide application in tissue engineering research, polycaprolactone presents a very limited ability to induce adhesion, proliferation and osteogenic cell differentiation. To overcome some of these limitations, different calcium phosphates, such as hydroxyapatite and tricalcium phosphate, have been employed with relative success. This work investigates the influence of nano-hydroxyapatite and micro-hydroxyapatite (nHA and mHA, respectively) particles on the in vitro biomechanical performance of polycaprolactone/hydroxyapatite scaffolds. Morphological analysis performed with scanning electron microscopy allowed us to confirm the production of polycaprolactone/hydroxyapatite constructs with square interconnected pores of approximately 350 μm and to assess the distribution of hydroxyapatite particles within the polymer matrix. Compression mechanical tests showed an increase in polycaprolactone compressive modulus (E) from 105.5 ± 11.2 to 138.8 ± 12.9 MPa (PCL-nHA) and 217.2 ± 21.8 MPa (PCL-mHA). In comparison to PCL-mHA scaffolds, the addition of nano-hydroxyapatite enhanced the adhesion and viability of human mesenchymal stem cells as confirmed by Alamar Blue assay. In addition, after 14 days of incubation, PCL-nHA scaffolds showed higher levels of alkaline phosphatase activity compared to polycaprolactone or PCL-mHA structures.

Keywords: bioactive materials | Biomanufacturing | bone tissue engineering | hydroxyapatite | mesenchymal stem cells | scaffold development

Abstract: The success of Tissue Engineering (TE) based approaches is strongly dependent on the development of novel biomaterials for the design of 3D matrices with tailored biomechanical properties to promote the regeneration of human tissues and organs. This review covers the critical aspects related with the preparation of new unsaturated polyester (UP) resin formulations with suitable biological, chemical, thermal and morphological properties for the additive manufacturing (AM) of TE constructs. In this context, the basic principles of available AM technologies, with a special focus on novel stereolithography processes such as microstereolithography (micro-SLA), stereo-thermal-lithography (STLA), two-photon polymerization (TPP) and nanostereolithography (nano-SLA), are also presented and discussed. Ultimately, the present review will provide a better insight into the limitations and potential of combining UP and AM towards the rationale design/fabrication of complex artificial tissue substitutes.

Keywords: Additive manufacturing | Stereolithography processes | Structure/properties relationships | Tissue engineering | Unsaturated polyesters

Abstract: Background: A variety of antiinflammatory therapies are employed to promote corneal wound healing. The effects of steroidal and nonsteroidal antiinflammatory drugs on the biomechanical properties of rabbit cornea were investigated over time using tensile tests. Methods: Full-thickness incisions were made and used to analyze the effects of dexamethasone sodium phosphate 0.1% and diclofenac sodium 0.1% on corneal biomechanical properties during wound healing at 7, 14 and 21 days after surgery. Results: The full-thickness incision deeply modified all of the mechanical properties. At 3 weeks after incision, regardless of the drug therapy, the tensile modulus was about 70% of the value for the intact cornea. Conclusions: Topical treatment with dexamethasone was particularly effective during the first week after surgery; the second week after surgery, a similar result was observed in the corneas treated with diclofenac. Low doses of steroidal and nonsteroidal antiinflammatory drugs would seem to have the potential to improve biomechanical properties only during the early stage of the healing process of the cornea.

Keywords: Biomechanics | Corneal wound healing | Nonsteroidal drugs | Steroidal drugs | Stress-strain

Abstract: Background: In recent years, the tissue engineering (TE) field has significantly benefited from advanced techniques such as additive manufacturing (AM), for the design of customized 3D scaffolds with the aim of guided tissue repair. Among the wide range of materials available to biomanufacture 3D scaffolds, poly(ε-caprolactone) (PCL) clearly arises as the synthetic polymer with the greatest potential, due to its unique properties – namely, biocompatibility, biodegradability, thermal and chemical stability and processability. This study aimed for the first time to investigate the effect of pore geometry on the in vitro enzymatic chain cleavage mechanism of PCL scaffolds manufactured by the AM extrusion process. Methods: Methods: Morphological properties of 3D printed PCL scaffolds before and after degradation were evaluated using Scanning Electron Microscopy (SEM) and micro-computed tomography (μ-CT). Differential Scanning Calorimetry (DSC) was employed to determine possible variations in the crystallinity of the scaffolds during the degradation period. The molecular weight was assessed using Size Exclusion Chromatography (SEC) while the mechanical properties were investigated under static compression conditions. Results: Morphological results suggested a uniform reduction of filament diameter, while increasing the scaffolds’ porosity. DSC analysis revealed and increment in the crystallinity degree while the molecular weight, evaluated through SEC, remained almost constant during the incubation period (25 days). Mechanical analysis highlighted a decrease in the compressive modulus and maximum stress over time, probably related to the significant weight loss of the scaffolds. Conclusions: All of these results suggest that PCL scaffolds undergo enzymatic degradation through a surface erosion mechanism, which leads to significant variations in mechanical, physical and chemical properties, but which has little influence on pore geometry.

Keywords: Biomanufacturing | Enzymatic degradation | Polycaprolactone | Scaffolds | Tissue engineering

Abstract: Ultrasound scans, Computed Axial Tomography, Magnetic Resonance Imaging are only few examples of medical imaging tools boosting physicians in diagnosing a wide range of pathologies. Anyway, no standard methodology has been defined yet to extensively exploit them and current diagnoses procedures are still carried out mainly relying on physician's experience. Although the human contribution is always fundamental, it is self-evident that an automatic procedure for image analysis would allow a more rapid and effective identification of dysmorphisms. Moving toward this purpose, in this work we address the problem of feature extraction devoted to the detection of specific diseases involving facial dysmorphisms. In particular, a bounded Depth Minimum Steiner Trees (D-MST) clustering algorithm is presented for discriminating groups of individuals relying on the manifestation/absence of the labio-schisis pathology, commonly called cleft lip. The analysis of three-dimensional facial surfaces via Differential Geometry is adopted to extract landmarks. The extracted geometrical information is furthermore elaborated to feed the unsupervised clustering algorithm and produce the classification. The clustering returns the probability of being affected by the pathology, allowing physicians to focus their attention on risky individuals for further analysis.

Keywords: Artificial intelligence | Clustering | D-MST | Decision support | Diagnosis | Facial dysmorphism | Feature extraction | Labio-schisis | Landmarking

Abstract: 3D face was recently investigated for various applications, including biometrics and diagnosis. Describing facial surface, i.e. how it bends and which kinds of patches is composed by, is the aim of studies of Face Analysis, whose ultimate goal is to identify which features could be extracted from three-dimensional faces depending on the application. In this study, we propose 105 novel geometrical descriptors for Face Analysis. They are generated by composing primary geometrical descriptors such as mean, Gaussian, principal curvatures, shape index, curvedness, and the coefficients of the fundamental forms, and by applying standard functions such as sine, cosine, and logarithm to them. The new descriptors were mapped on 217 facial depth maps and analysed in terms of descriptiveness of facial shape and exploitability for localizing landmark points. Automatic landmark extraction stands as the final aim of this analysis. Results showed that some newly generated descriptors were sounder than the primary ones, meaning that their local behaviours in correspondence to a landmark position is thoroughly specific and can be registered with high similarity on every face of our dataset.

Keywords: 3D face | Face analysis | Face expression recognition | Face recognition | Geometry | Landmarks

Abstract: This work proposes a methodology to automatically diagnose and formalize prenatal cleft lip with representative key points and identify the type of defect (unilateral, bilateral, right, or left) in three-dimensional ultrasonography (3D US). Differential Geometry has been used as a framework for describing facial shapes and curvatures. Then, descriptors coming from this field are employed for identifying the typical key points of the defect and its dimensions. The descriptive accurateness of these descriptors has allowed us to automatically extract reference points, quantitative distances, labial profiles, and to provide information about facial asymmetry. Seventeen foetal faces, nine of healthy foetuses and eight with different types of cleft lips, have been obtained through a Voluson system and used for testing the algorithm. In case no defect is present, the algorithm detects thirteen standard facial soft-tissue landmarks. This would help ultrasonographists and future mothers in identifying the most salient points of the forthcoming baby. This algorithm has been designed to support practitioners in identifying and classifying cleft lips. The gained results have shown that differential geometry may be a valuable tool for describing faces and for diagnosis.

Keywords: 3D ultrasound | Cleft lip | Dysmorphisms | Landmarking | Syndrome diagnosis

Abstract: As the interest in human face grows, facial landmarks become more and more important for a large variety of fields and applications. Multipurpose medical is evidently leading in this sense, but others such as skull study for crime scenes, sex estimation, and attractiveness quantification, morphological and cephalometric analyses are present. A cluster analysis of the examined papers is performed depending on scope, landmarking method, and facial database features. The purpose is to face these topics by providing the reader with a comprehensive view of what 3D facial landmarks are and what "they have been up to" in 2014 and 2015. The aim is to offer to users the very up-todate scenario, the best outcomes, i.e., the latest frontier of landmarks' talents and skills. The third dimension allowed to select the most prominent contributions, especially in terms of scientific advance innovativeness.

Keywords: 3D face | Cluster analysis | Fiducial point | Landmarks | Soft-tissue landmark, hard-tissue landmark

Abstract: 3D face was recently investigated for various applications, including biometrics and diagnosis. Describing facial surface, i.e. how it bends and which kinds of patches is composed by, is the aim of studies in Face Analysis, whose ultimate goal is to identify which features could be extracted from three-dimensional faces depending on the application. In this study, we propose 54 novel geometrical descriptors for Face Analysis. They are generated by composing primary geometrical descriptors such as mean, Gaussian, principal curvatures, shape index, curvedness, and the coefficients of the fundamental forms. The new descriptors were mapped on 217 facial depth maps and analysed in terms of descriptiveness of facial shape and exploitability for localizing landmark points. Automatic landmark extraction stands as the final aim of this analysis. Results showed that the newly generated descriptors are suitable to 3D face description and to support landmark localization procedures.

Keywords: 3D Face | Face Analysis | Face Recognition | Geometry | Landmarks

Abstract: Understanding the mechanisms of traumatic ocular injury is helpful to make accurate diagnoses before the symptoms emerge and to develop specific eye protection. The comprehension of the dynamics of primary blast injury mechanisms is a challenging issue. The question is whether the pressure wave propagation and reflection alone could cause ocular damage. To date, there are dissenting opinions and no conclusive evidence thereupon. A previous numerical investigation of blast trauma highlighted the dynamic effect of pressure propagation and its amplification by the geometry of the bony orbit, inducing a resonance cavity effect and a standing wave hazardous for eye tissues. The objective of the current work is to find experimental evidence of the numerically identified phenomenon. Therefore, tests aimed at evaluating the response of porcine eyes to blast overpressure generated by firecrackers explosion were performed. The orbital cavity effect was considered mounting the enucleated eyes inside a dummy orbit. The experimental measurements obtained during the explosion tests presented in this paper corroborate the numerical evidence of a high-frequency pressure amplification, enhancing the loading on the ocular tissues, attributable to the orbital bony walls surrounding the eye.

Keywords: Amplification | Experimental study | Orbital cavity | Pressure standing wave | Primary blast injury

Abstract: Background: Double pelvic osteotomy (DPO) planning is usually performed by hip palpation, and on radiographic images which give a poor representation of the complex three-dimensional manoeuvre required during surgery. Furthermore, bone strains which play a crucial role cannot be foreseen. Objective: To support surgeons and designers with biomechanical guidelines through a virtual model that would provide bone stress and strain, required moments, and three-dimensional measurements. Methods: A multibody numerical model for kinematic analyses has been coupled to a finite element model for stress/strain analysis on deformable bodies. The model was parametrized by the fixation plate angle, the iliac osteotomy angle, and the plate offset in ventro-dorsal direction. Model outputs were: acetabular ventro-version (VV) and lateralization (L), Norberg (NA) and dorsal acetabular rim (DAR) angles, the percentage of acetabular coverage (PC), the peak bone stress, and moments required to deform the pelvis. Results: Over 150 combinations of cited parameters and their respective outcome were analysed. Curves reporting NA and PC versus VV were traced for the given patient. The optimal VV range in relation to NA and PC limits was established. The 25° DPO plate results were the most similar to 20° TPO. The output L grew for positive iliac osteotomy inclinations. The 15° DPO plate was critical in relation to DAR, while very large VV could lead to bone failure. Clinical significance: Structural models can be a support to the study and optimization of DPO as they allow for foreseeing geometrical and structural outcomes of surgical choices.

Keywords: Finite elements | Hip dysplasia | Multibody analysis | Pelvic osteotomies | Preoperative planning

Abstract: This paper proposes a new automatic approach to determine the accurate measure of human teeth. The aim of the proposed computer based method is to reduce inaccuracy of measurement with respect to traditional approaches. Starting from a 3D model of the teeth which is obtained from 3D scanning, the method algorithmically evaluates the most important dimensional features detectable in central incisors. For this purpose, specific rules are put forward and implemented in original software with a view to identifying repere points, from which to detect dimensional features both unambiguously and accurately. The automatic method which is proposed here is verified by means of the analysis of real teeth and is then compared with the current state-of-the-art methods for teeth measurement.

Keywords: 3D biomedical image analysis | Computer methods for tooth analysis | Dental dimensions | Measurement accuracy | Measurement protocols in biomedicine

Abstract: In this paper performance evaluation and experimental characterization of a new automatic method for measuring vertebrae are analysed. Starting to a discrete valid geometric model of the vertebra, obtained from CT-scans or 3D scanning, the method measures algorithmically vertebrae. The proposed study is performed by analysing the most used dimensional features of lumbar and thoracic real vertebrae in anthropological investigations. The results are compared with the state-of-the-art methods for vertebra measurement.

Abstract: This paper describes a new motion analysis protocol for race-walking. The protocol has been tested under laboratory conditions on a real athlete of the Italian national race-walking team. The experimental setup included a motion capture system and a force platform to record both kinematic and dynamic aspects of the athletic action. Thus, any infringement of the rules can be detected, based on the measure of knee flexion-extension and the loss of ground contact. The biomechanical efficiency can be determined from the joint angles and the temporal components of gait. The results of experiments show that the protocol can be a valuable tool to assist athletes and trainers in improving race-walking technique.

Keywords: Biomechanics | Dynamics | Experimental protocol | Gait Analysis | Kinematics | Motion Capturing | Race-walking

Abstract: Digital Human Modelling (DHM) is becoming a simple way to study the ergonomic behaviour of devices interacting with the human body. In particular, innovative technologies per- mit to manage big amount of data coming from several IT devices in order to better understand the correlation be- tween technical aspects and human factors. In the medical field DHM can be exploited to combine in a unique applica- tion many data types coming from several inputs (e.g. 3D scan, motion capture). In this research work, the attention is focused on the design of lower limb prosthesis around the digital human model of the patient. We present an appli- cation, which allows visualizing pressure on patient's limb while evaluating his/her gait in a unique virtual knowledge- guided environment. Such application is conceived to be usable by non IT experts, and all information are directly visualized on the digital human model of the amputee. The first part of the paper describes the platform to design lower limb prosthesis with particular attention on the use of low- cost technologies. Then, the virtual gait analysis tool is described. Finally, tests and conclusion are discussed.

Keywords: Digital human modelling | Gait analysis | Lower limb prosthesis | Pressure mapping

Abstract: In this work we present a preliminary study on a system able to design automatically sockets for lower-limb prosthesis. The socket is the most important part of the whole prosthesis and requires a custom design specific for the patient’s characteristics and her/his residuum morphology. The system takes in input the weight and the lifestyle of the patient, the tonicity level and the geometry file of the residuum, and creates a new model applying the correct geometric deformations needed to create a functional socket. In fact, in order to provide the right fit and prevent pain, we need to create on the socket load and off-load zones in correspondence of the critical anatomical areas. To identify the position of such critical areas, several neural networks have been trained using a dataset generated from real residuum models.

Keywords: CAD | Lower limb prosthesis | Neural network | Prosthetic socket

Abstract: The socket for lower limb prosthesis is the central element of artificial leg that needs to be optimize with the aim to increase comfort and reduce pain. Nowadays, the modeling of this part is completely manual and based on prosthetist skills. The key parameter determining if the socket is properly designed is the pressure distribution in the interface between the skin of residual limb and the internal surface of the socket. In this paper, we expose a method to measure this pressure thought resistive pressure sensors and we illustrate a case study of a transfemoral amputee patient. A visualization tool has been developed to dynamically show pressure data on the 3D model of the residual limb during topic moments of the gait by a color scale. Achieved results and future work will be discussed in the paper.

Keywords: Gait | Lower limb prosthesis | Pressure mapping

Abstract: Endocanalar posts are necessary to build up and retain coronal restorations but they do not reinforce dental roots. It was observed that the dislodgement of post-retained restorations commonly occurs after several years of function and long-term retention may be influenced by various factors such as temperature changes. Temperature changes, in fact, produce micrometric deformations of post and surrounding tissues/materials that may generate high stress concentrations at the interface thus leading to failure. In this study we present an optical system based on the projection moiré technique that has been utilized to monitor the displacement field of endocanalar glass-fibre posts subjected to temperature changes. Measurements were performed on forty samples and the average displacement values registered at the apical and middle region were determined for six different temperature levels. A total of 480 displacement measurements was hence performed. The values of the standard deviation computed for each of the tested temperatures over the forty samples appear reasonably small which proves the robustness and the reliability of the proposed optical technique. The possible implications for the use of the system in the applicative context were discussed.

Keywords: Dental materials | Endocanalar post | Projection moiré | Thermal deformation | Thermal stress

Abstract: Complexity of scaffold geometries and biological mechanisms involved in the bone generation process make the design of scaffolds a quite challenging task. The most common approaches utilized in bone tissue engineering require costly protocols and time-consuming experiments. In this study we present an algorithm that, combining parametric finite element models of scaffolds with numerical optimization methods and a computational mechano-regulation model, is able to predict the optimal scaffold microstructure. The scaffold geometrical parameters are perturbed until the best geometry that allows the largest amounts of bone to be generated, is reached. We study the effects of the following factors: (1) the shape of the pores; (2) their spatial distribution; (3) the number of pores per unit area. The optimal dimensions of the pores have been determined for different values of scaffold Young’s modulus and compression loading acting on the scaffold upper surface. Pores with rectangular section were predicted to lead to the formation of larger amounts of bone compared to square section pores; similarly, elliptic pores were predicted to allow the generation of greater amounts of bone compared to circular pores. The number of pores per unit area appears to have rather negligible effects on the bone regeneration process. Finally, the algorithm predicts that for increasing loads, increasing values of the scaffold Young’s modulus are preferable. The results shown in the article represent a proof-of-principle demonstration of the possibility to optimize the scaffold microstructure geometry based on mechanobiological criteria.

Keywords: Mechano-regulation algorithm | Mechanobiology | Numerical optimization | Scaffold microstructure

Abstract: Abstract: The aim of this work is to show a quick and simple procedure able to identify the geometrical parameters of the intervertebral disc that strongly affect the behavior of the FEM model. First, we allocated a selection criterion for the minimum number of geometrical parameters that describe, with a good degree of approximation, a healthy human vertebra. Next, we carried out a sensitivity analysis using the ‘Taguchi orthogonal array’ to arrive at a quick identification of the parameters that strongly affect the behavior of the Fem model.

Keywords: geometrical parameters | intervertebral disc | Spine | subject-specific finite element models | Taguchi method

Abstract: In regenerative medicine, 3D scaffolds are used to sustain the regeneration of tissues in removed or damaged parts of the human body. As such practices are being widely experimented in clinical applications, the design, the materials and the manufacturing process to obtain efficient 3D biocompatible lattices are being significantly investigated. Nevertheless, most of the proposed designs are based on regular 3D shapes obtained from the repetition of unit cells disposed in a three-dimensional array. This approach does not exploit the whole potential of computer-aided design tools coupled with manufacturing capabilities for freeform shapes. In this paper, we propose a method to model biomimetic lattices controlling the porosity and the pores size of scaffolds to be integrated with the anatomical shape of the defect. The method has been implemented in bone tissue case study and implements a generative design approach based on Voronoi diagrams.

Keywords: 3D scaffolds | generative design | Voronoi diagram

Abstract: The present work collects some results of the three-years Research Program "BioForming", funded by the Italian Ministry of Education (MIUR) and aimed to investigate the possibility of using flexible sheet forming processes, i.e. Super Plastic Forming (SPF) and Single Point Incremental Forming (SPIF), for the manufacturing of patient-oriented titanium prostheses. The prosthetic implants used as case studies were from the skull; in particular, two different Ti alloys and geometries were considered: one to be produced in Ti-Gr23 by SPF and one to be produced in Ti-Gr2 by SPIF. Numerical simulations implementing material behaviours evaluated by characterization tests were conducted in order to design both the manufacturing processes. Subsequently, experimental tests were carried out implementing numerical results in terms of: (i) gas pressure profile able to determine a constant (and optimal) strain rate during the SPF process; (ii) tool path able to avoid rupture during the SPIF process. Post forming characteristics of the prostheses in terms of thickness distributions were measured and compared to data from simulations for validation purposes. A good correlation between numerical and experimental thickness distributions has been obtained; in addition, the possibility of successfully adopting both the SPF and the SPIF processes for the manufacturing of prostheses has been demonstrated.

Abstract: Cranioplasty is a surgery in which a prosthesis must be anchored on skull bone to repair a defect. One of the most used materials is the titanium. However, titanium prostheses could be made using the incremental sheet forming (ISF). Since titanium and bone are characterized by different Young modules, a detailed design of anchoring system is required to avoid cranial rupture. Aim of this study was to present a design procedure in order to identify the optimal anchoring system in case of craniofacial prostheses made with ISF. In detail, an optimization process and a predictive model for bone stress were used, choosing the numerical outputs of different FEM analyses as input data. The results indicate that our predictive and optimization models are accurate and, so, that this procedure could be very helpful for the prosthesis design, as demonstrated by the application of the procedure to a real case study.

Keywords: Anchoring system | Design procedure | Incremental sheet forming | Titanium prosthesis

Abstract: Recent Face Analysis advances have focused the attention on studying and formalizing 3D facial shape. Landmarks, i.e. typical points of the face, are perfectly suited to the purpose, as their position on visage shape allows to build up a map of each human being’s appearance. This turns to be extremely useful for a large variety of fields and related applications. In particular, the forensic context is taken into consideration in this study. This work is intended as a survey of current research advances in forensic science involving 3D facial landmarks. In particular, by selecting recent scientific contributions in this field, a literature review is proposed for in-depth analyzing which landmarks are adopted, and how, in this discipline. The main outcome concerns the identification of a leading research branch, which is landmark-based facial reconstruction from skull. The choice of selecting 3D contributions is driven by the idea that the most innovative Face Analysis research trends work on three-dimensional data, such as depth maps and meshes, with three-dimensional software and tools. The third dimension improves the accurateness and is robust to colour and lightning variations.

Keywords: 3D face | Fiducial point | Forensic | Landmarks | Reconstruction

Abstract: In this paper, we propose a forearm rehabilitation system based on a serious game in Augmented Reality (AR). We designed and developed a simplified AR arcade brick breaking game to induce rehabilitation of the forearm muscles. We record the electromyographic signals using a low cost device to evaluate the applied force. We collected and analysed data in order to find a relationship between the applied force and the difficulty of the game. This research focuses on the dehospitalization of subjects in the middle or final stages of their rehabilitation where the new technologies, like Virtual and Augmented Reality, may improve the experience of repetitive exercises. The results achieved prove that the force applied by the user to hit the virtual sphere with real cardboard cube is related to sphere speed. In a rehabilitation scenario the results could be used to evaluate the improvements analysing the performance history.

Keywords: Brick serious games | Rehabilitation | Virtual and Augmented Reality

Abstract: A 3D automatic facial expression recognition procedure is presented in this work. The method is based on point-by-point mapping of seventeen Differential Geometry descriptors onto the probe facial depth map, which is then partitioned into seventy-nine regions. Then, features such as mean, median, mode, volumes, histograms are computed for each region and for each descriptor, to reach a varied large set of parameters representing the query face. Each set of parameters, given by a geometrical descriptor, a region, and a feature, form a trio, whose featuring numerical values are compared with appropriate thresholds, set via experimentation in a previous phase by processing a limited portion of the public facial Bosphorus database. This allows the identification of the emotion-based expression of the query 3D face among the six basic ones (anger, disgust, fear, joy, sadness, surprise). The algorithm was tested on the Bosphorus database and is suitable for applications in security, marketing, medical. The three-dimensional context has been preferred due to its invariance to different lightening/make-up/camouflage conditions.

Keywords: 3D face | Differential geometry | Emotions | Face expression recognition (FER) | Facial expression recognition | Shape index

Abstract: The aim of this work is to automatically diagnose and formalize prenatal cleft lip with representative key points and identify the type of defect (unilateral, bilateral, right, or left) in three-dimensional ultrasonography (3D US). Geometry has been used as a framework for describing facial shapes and curvatures. Then, descriptors coming from this field are employed for identifying the typical key points of the defect and its dimensions. The descriptive accuracy of these descriptors has allowed us to automatically extract reference points, quantitative distances, labial profiles, and to provide information about facial asymmetry. Eighteen foetal faces, ten of healthy foetuses and eight with different types of cleft lips, have been obtained through a Voluson system and used for testing the algorithm. Cleft lip has been diagnosed and correctly characterized in all cases. Transverse and cranio-caudal length of the cleft have been computed and upper lip profile has been automatically extract to have a visual quantification of the overall labial defect. The asymmetry information obtained is consistent with the defect. This algorithm has been designed to support practitioners in identifying and classifying cleft lips. The gained results have shown that geometry might be a proper tool for describing faces and for diagnosis.

Keywords: 3D ultrasound | Cleft lip | Dysmorphisms | Landmarking | Syndrome diagnosis

Abstract: Bone tissue engineered 3-D constructs customized to patient-specific needs are emerging as attractive biomimetic scaffolds to enhance bone cell and tissue growth and differentiation. The article outlines the features of the most common additive manufacturing technologies (3D printing, stereolithography, fused deposition modeling, and selective laser sintering) used to fabricate bone tissue engineering scaffolds. It concentrates, in particular, on the current state of knowledge concerning powder-based 3D printing, including a description of the properties of powders and binder solutions, the critical phases of scaffold manufacturing, and its applications in bone tissue engineering. Clinical aspects and future applications are also discussed.

Keywords: 3D printing | Additive manufacturing technologies | Binder | Bone | Depowdering | Powder | Scaffold | Sintering

Abstract: Many systems have been developed to facilitate upper limb rehabilitation procedures in human subjects affected by trauma or pathologies and to retrieve information about patient performance. The Microsoft Kinect sensor can be used in this context to track body motion and detect objects. In order to evaluate the usability of this device in the upper limb rehabilitation field, a comparison with a marker-based system is presented in this paper. The upper limb motion is specifically considered and the performance on its detection and tracking is evaluated. The effect of the relative location between the Kinect and the observed subject is also investigated through experimental tests performed in different configurations.

Keywords: Kinect V2 | Upper limb joints tracking | Upper limb rehabilitation

Abstract: In this work an hypothesis of modeling nanofibers network of Poly-L-lactide (PLLA) scaffolds loaded with hydroxyapatite (HA) nanoparticles, suitable for tissue engineering applications, is presented to investigate the mechanical properties by FEM analysis. Scaffolds were produced by Supercritical CO2 drying of polymeric gels. FEM modeling of nanoporous biomaterials involves computational problems such as: the reproduction of the nano-morphology by means of different techniques, such as molecular dynamics simulations that hardly lead to results adherent to the experimental evidence; the reverse engineering to extrapolate geometric information; the identification of a periodic representative volume element (RVE) to reach more coherent results and to reduce the simulation computational effort. Basic modeling assumptions are: a) polymer particles are small enough to exhibit Brownian motion; b) scaffold SEM images show that the porous structure consists of curved fibers that depart from punctiform nuclei realizing a space frame; c) scaffold experimental compressive tests show that the porous material behaves as a soft isotropic material. On the basis of these assumptions, a parametric algorithm that creates a cubic RVE, showing a nanofibers network and having the same porosity of the real material, has been written; RVE size has been optimized on the bases of its material isotropic degree measured by an ad hoc created iterative algorithm for generating a rod spaceframe; RVE mechanical behavior has been optimized by curving appropriately each fiber according to the experimental data and on the basis of SEM imaging diagnostic. Linear FEM simulations on mechanical behavior have given qualitatively and quantitative satisfactory results when compared to the experimental ones.

Abstract: Purpose: The purpose of this study was to characterize the biomechanical effect of two grasping suture techniques used during ligament reconstruction: the modified rolling-hitch (MRH) and the modified finger-trap (MFT). Methods: Flexor profundus tendons were harvested from fresh pig hind-leg trotters. Each specimen was mounted on an electro-mechanic universal testing machine (Instron 3367). In half of all tendons (15 specimens), the suture was passed around the tendon following the MRH knot (Group 1). In the remaining half of all tendons (15 specimens), the suture was passed over a distance of 30 mm according to the MFT suture technique (Group 2). As per standard intra-operative technique, a 1 cm residual tendon stub was left free from suture in all samples. All specimens were preconditioned to a load of 50 N for 10 min, followed by three cycles loading between 50 and 120 N. At this point, each sample was cyclically tensioned between 35 and 240 N, at 1 Hz for 200 cycles. Load-to-failure test was then carried out at a rate of 200 mm/min. Results: Rupture of the suture material at the knot was the mode of failure in all specimens during the loaded to failure test. Significant difference was found between Group 1 vs Group 2 for the elongation between the 0th cycle and 10th cycle, the elongation between the 10th cycle and 200th cycle, the mean stiffness at the 10th cycle, and the mean stiffness at the 190th cycle. No significant differences were noted between Group 1 and Group 2 concerning the ultimate load-to-failure. Conclusion: This study showed that both suture methods appear to be biomechanically effective in a porcine tendon model. However, the single-knot grasping technique (MRH) provided superior biomechanical properties compared with the MFT technique.

Keywords: Biomechanics grasping suture | FiberWire suture | Grasping suture | Modified finger-trap | Rolling-hitch | Suture ligament

Abstract: In this paper a new automatic approach to determine the accurate measure of human vertebrae is proposed. The aim is to speed up the measurement process and to reduce the uncertainties that typically affect the measurement carried out by traditional approaches. The proposed method uses a 3D model of the vertebra obtained from CT-scans or 3D scanning, from which some characteristic dimensions are detected. For this purpose, specific rules to identify morphological features, from which to detect dimensional features unambiguously and accurately, are put forward and implemented in original software. The automatic method which is here proposed is verified by analysing real vertebrae and is then compared with the state-of-the-art methods for vertebra measurement.

Keywords: 3D medical-image analysis | Computer methods for vertebra analysis | Measurement accuracy | Measurement protocols in biomedicine | Shape segmentation | Vertebral dimensions

Abstract: The diffusion of depth sensors to sense people and objects constitutes an outstanding opportunity in those fields in which the benefits of optical marker-less solutions for scanning or tracking are requested. This paper shows how two different applications based on MS Kinect device can be accomplished in the domain of lower limb prosthesis design and test. The first one refers to the use of a depth camera as a three-dimensional scanner to acquire the geometry of residual limbs or of custom-fit components. The second application is related to the motion capture of patients' gait with the prosthesis. In both cases, the technology resulted to be better than many traditional ones mainly for its limited invasivity, interesting performance, portability and low cost.

Keywords: 3D scanner | Digital human modelling | Lower limb prosthesis | Motion capture | RGB-D cameras

Abstract: The diffusion of depth sensors to sense people and objects constitutes an outstanding opportunity in those fields in which the benefits of optical marker-less solutions for scanning or tracking are requested. This paper shows how two different applications based on MS Kinect device can be accomplished in the domain of lower limb prosthesis design and test. The first one refers to the use of a depth camera as a three-dimensional scanner to acquire the geometry of residual limbs or of custom-fit components. The second application is related to the motion capture of patients' gait with the prosthesis. In both cases, the technology resulted to be better than many traditional ones mainly for its limited invasivity, interesting performance, portability and low cost.

Keywords: 3D scanner | Digital human modelling | Lower limb prosthesis | Motion capture | RGB-D cameras

Abstract: The research work presented in this paper is part of an innovative framework that deals with the design process of lower limb prostheses. The quality of the whole prosthesis depends on the comfort of the socket, which realizes the interface between the patient body and the mechanical parts. We developed a CAD system, named Socket Modelling Assistant that guides the user during the design of the socket, exploiting domain knowledge and design rules. In this work we present a preliminary study that describes the implementation of a software module able to automatically identify the critical areas of the residuum to adequately modify the socket model and reach the optimal shape. Once the critical areas have been identified, the Socket Modelling Assistant can apply proper geometry modifications, in order to create the load and off-load zones for a good pressure distribution over the residual limb.

Keywords: CAD | Lower limb prosthesis | Neural network | Prostheses socket

Abstract: The paper concerns the use of integrated methodologies and tools to perform innovative human centered development of products. Digital simulation of ergonomics by means of DHM is shown together with advanced tools for design, taking into account Knowledge-based systems, Design Automation and design of highly customized goods. Two different applications of the proposed approach are described, the first refers to an industrial product, the second to the medical domain. Both applications, even if belonging to completely different fields benefit from putting the human at the center of the developing paradigm from the very first step of product development. Some results and discussion highlight benefits and limitation of the approach and of the adopted tools.

Keywords: Design Automation | Digital human modelling | Ergonomics | Human centered design | Knowledge-based systems | Lower limb prosthesis

Abstract: Carotid artery phantoms (CaPs) can be used as test objects to explore novel ways of enhancing the ultrasound based carotid atherosclerosis diagnosis. To achieve this goal CaPs should be anatomically realistic both in terms of geometry, acoustic and physical properties, and should allow to reproduce different pathological conditions. We propose a framework for designing CaPs of healthy and diseased arteries. To verify the framework effectiveness we constructed three CaPs: healthy, with a hard/soft plaque causing a 30%/65% vessel narrowing. Then we acquired CaPs B-mode images and performed their geometric characterization and echogenicity analysis demonstrating the framework effectiveness at realizing anthropomorphic CaPs at low cost, easily reproducing different atherosclerotic conditions.

Abstract: Purpose - The purpose of this paper is to describe two different approaches for manufacturing pre-formed titanium meshes to assist prosthetically guided bone regeneration of atrophic maxillary arches. Both methods are based on the use of additive manufacturing (AM) technologies and aim to limit at the minimal intervention the bone reconstructive surgery by virtual planning the surgical intervention for dental implants placement. Design/methodology/approach - Two patients with atrophic maxillary arches were scheduled for bone augmentation using pre-formed titanium mesh with particulate autogenous bone graft and alloplastic material. The complete workflow consists of four steps: three-dimensional (3D) acquisition of medical images and virtual planning, 3D modelling and design of the bone augmentation volume, manufacturing of biomodels and pre-formed meshes, clinical procedure and follow up. For what concerns the AM, fused deposition modelling (FDM) and direct metal laser sintering (DMLS) were used. Findings - For both patients, a post-operative control CT examination was scheduled to evaluate the progression of the regenerative process and verify the availability of an adequate amount of bone before the surgical intervention for dental implants placement. In both cases, the regenerated bone was sufficient to fix the implants in the planned position, improving the intervention quality and reducing the intervention time during surgery. Originality/value - A comparison between two novel methods, involving AM technologies are presented as viable and reproducible methods to assist the correct bone augmentation of atrophic patients, prior to implant placement for the final implant supported prosthetic rehabilitation.

Keywords: CAD/CAM | Computed tomography | Implant surgery | Rapid prototyping | Titanium mesh

Abstract: The production of prostheses is still not completely optimized, especially for those districts where both functional and aesthetic requirements have to be combined with the urgency of intervention. The prostheses manufactured by machining using CAD/CAM techniques represent the conventional way to obtain a "custom-made" part. However, the above-mentioned solutions are penalized by the too long manufacturing time. This limit can be overcome by using an innovative metal-forming process, i.e. the Incremental Sheet Forming (ISF), which also allows to obtain complex patient-specific geometries even if characterized by a lower precision compared to the conventional process. In this paper, alternative approaches to manufacture a skull prosthesis (i.e. conventional milling and ISF) are compared from technological and economical points of view.

Keywords: Anchoring system design | Prostheses modelling | Skull manufacturing

Abstract: Patients affected by serious foot pathologies often require special orthotics to stand and walk correctly. Skilled operators obtain such insoles on the basis of manual procedures and following the prescriptions of orthopaedic technicians. The process is handicraft and time consuming. The paper presents a virtual prototyping approach which is based on dedicated foot scanners, CAD-based design tool and milling machines to obtain the bespoke footwear orthotics. The major contribution is a geometric procedure to design complex insole shapes starting from the foot scan and highly customized shoe lasts which are required in case of important deformities. The approach has been tested on several patients thanks to the collaboration with a partner insole producer and some orthopaedic centers. Patients have generally reported positive feedbacks on the comfort and functionality of the insoles.

Keywords: Foot orthotics | Insole design | Orthopaedic custom-made insoles

Abstract: Intervertebral disc (IVD) degeneration is one of the main causes of low back pain. Current surgical treatments are complex and generally do not fully restore spine mobility. Development of injectable extracellular matrix-based hydrogels offers an opportunity for minimally invasive treatment of IVD degeneration. Here we analyze a specific formulation of collagen-low molecular weight hyaluronic acid (LMW HA) semi-interpenetrating network (semi-IPN) loaded with gelatin microspheres as a potential material for tissue engineering of the inner part of the IVD, the nucleus pulposus (NP). The material displayed a gel-like behavior, it was easily injectable as demonstrated by suitable tests and did not induce cytotoxicity or inflammation. Importantly, it supported the growth and chondrogenic differentiation potential of mesenchymal stem cells (MSC) and nasal chondrocytes (NC) in vitro and in vivo. These properties of the hydrogel were successfully combined with TGF-β3 delivery by gelatin microspheres, which promoted the chondrogenic phenotype. Altogether, collagen-LMW HA loaded with gelatin microspheres represents a good candidate material for NP tissue engineering as it combines important rheological, functional and biological features.

Keywords: Chondrocyte | Collagen | Hydrogel | Intervertebral disc | Mesenchymal stem cell

Abstract: In the past few years, researchers have focused on the design and development of three-dimensional (3D) advanced scaffolds, which offer significant advantages in terms of cell performance. The introduction of magnetic features into scaffold technology could offer innovative opportunities to control cell populations within 3D microenvironments, with the potential to enhance their use in tissue regeneration or in cell-based analysis. In the present study, 3D fully biodegradable and magnetic nanocomposite scaffolds for bone tissue engineering, consisting of a poly(ε-caprolactone) (PCL) matrix reinforced with iron-doped hydroxyapatite (FeHA) nanoparticles, were designed and manufactured using a rapid prototyping technique. The performances of these novel 3D PCL/FeHA scaffolds were assessed through a combination of theoretical evaluation, experimental in vitro analyses and in vivo testing in a rabbit animal model. The results from mechanical compression tests were consistent with FEM simulations. The in vitro results showed that the cell growth in the magnetized scaffolds was 2.2-fold greater than that in non-magnetized ones. In vivo experiments further suggested that, after only 4 weeks, the PCL/FeHA scaffolds were completely filled with newly formed bone, proving a good level of histocompatibility. All of the results suggest that the introduction of magnetic features into biocompatible materials may confer significant advantages in terms of 3D cell assembly.

Keywords: Bone tissue engineering | Experimental/theoretical analysis | Nanocomposite | Rapid prototyping | Scaffold

Abstract: In this research work, the authors developed and tested a low cost wearable and portable hand exoskeleton to assist people with physical disabilities in their everyday lives. Focusing on hand opening disabilities, the proposed actuated orthoses could support and enable daily gestures such as shacking hands or grasping objects. The Hand Exoskeleton System (HES) prototype is based on a cable-driven architecture applied to a single-phalanx mechanism. The preliminary prototype of the system has been successfully built and is currently under testing with a patient to verify its performance from a patient viewpoint.

Abstract: Scaffolds have been produced by supercritical CO<inf>2</inf> drying of Poly-L-Lactid Acid (PLLA) gels loaded with micrometric fructose particles used as porogens. These structures show a microporous architecture generated by the voids left in the solid material by porogen leaching, while they maintain the nanostructure of the gel, consisting of a network of nanofilaments. These scaffolds have also been loaded with Hydroxyapatite (HA) nanoparticles, from 10 to 50% w/w with respect to the polymer, to improve the mechanical properties of the PLLA structure.Based on miscroscopic and mechanical considerations, we propose a parametric Finite Element Method (FEM) model of PLLA-HA composites that describes the microporous structure as a close-packing of equal spheres and the nanoscale structure as a space frame of isotropic curved fibers. The effect of HA on the mechanical properties of the scaffolds has been modeled on the basis of SEM images and by taking into consideration the formation of concentric cylinders of HA nanoparticles around PLLA nanofibers. Modeling analysis confirms that mechanical properties of these scaffolds depend on nanofibrous network connections and that bending is the major factor causing deformation of the network. The FEM model also takes into account the formation of HA multi-layer coating on some areas in the nanofiber network and its increase in thickness with HA percentage. The Young modulus tends to a plateau for HA percentages larger than 30% w/w and when the coverage of the nanofibers produced by HA nanoparticles reaches a loaded surface index of 0.14 in the FEM model.

Keywords: FEM modeling | Hydroxyapatite nanoparticles | Poly(L-Lactic Acid) nanofibers | Scaffold | Supercritical fluids

Abstract: Purpose: A suture passed along the part of the graft that will be inserted into the femoral tunnel is widely used by surgeons, because it could prevent the graft sliding on the femoral fixation device during pulling from the tibial side. The aim of this study was to evaluate the biomechanical effects of suturing the intratunnel femoral part of the graft during an anterior cruciate ligament (ACL) reconstruction. Methods: Bovine digital extensor tendons and tibias were harvested from 20 fresh-frozen mature bovine knees ranging in age from 18 to 24 months. Quadruple-strand bovine tendons were passed through the tibial tunnel and secured distally with a bioabsorbable interference screw. In one half of all grafts (N = 10), the looped-over part of the graft was sutured in a whipstitch technique over a distance of 30 mm (Group 1). In one half of all grafts (N = 10), the looped-over part was left free from any suture (Group 2). The grafts were preconditioned at 50 N for 10 min, followed by cyclic loading at 1 Hz between 50 N and 250 N for 1,000 cycles. Load-to-failure test was then carried out at a rate of 1 mm/s. Results: There was no statistically significant difference between mean stiffness at pullout and yield load between the two groups. In all specimens on Group 1, failure occurred following to partial breaking and then slipping of the tendons between the screw and the tunnel. Concerning Group 2, in six cases failure occurred as described for Group 1 specimens. In the remaining four cases, failure occurred entirely through the ligament mid-substance. Conclusions: Suturing in a whipstitch fashion the femoral portion of the graft doesn't affect the mechanical proprieties of the ACL graft. When suspension fixation device is used, suturing the looped-over part of the graft could be helpful in order to provide equal tension in all of the strands of the graft at time of tibial fixation. © 2013 Springer-Verlag Berlin Heidelberg.

Keywords: ACL graft | ACL reconstruction | Anterior cruciate ligament | Biomechanics | Graft properties

Abstract: This paper presents a new mirroring-and-registration method for the automatic symmetry plane detection of 3D asymmetrically scanned human faces. Once the mirroring of the original data is carried out with respect to the first-attempt symmetry plane, which is estimated by the PCA method, the source point cloud and the mirrored data are registered by the ICP algorithm that minimises a new weighted function. The final symmetry plane obtained approximates in the least-squares sense the midpoints of the lines connecting homologous points randomly chosen. This method is validated by analysing some specifically-designed test cases. The obtained results show that the method is quite insensitive to asymmetries of data resulting from the acquisition process. © 2013 © 2013 CAD Solutions, LLC.

Keywords: iterative closest points | mirroring | rasterstereography | registration | symmetry plane

Abstract: In this work a commercial reverse shoulder prosthesis has been redesigned to improve performances in terms of range of movements of the implant and stability to dislocation. A kinematic and mechanic study has been performed using a realistic solid model of the prothesised shoulder: in particular, all the components of the prosthesis have been acquired via a 3D laser scanner and inserted in a virtual humerus-glenoid system by reproducing the common surgical procedure. The final model has been used to measure the maximum angles of abduction and rotation of the arm and the shear forces that cause dislocation. Modifications proposed to the commercial prosthesis are: a different orientation of the cutting plane of the glenoid component and the interposition of a spacer to move the center of rotation of the arm.

Keywords: CAD modelling | Digital shape acquisition | Reverse shoulder prosthesis

Abstract: Aim of this paper is to setup a novel procedure able to analyze performances of a reverse shoulder prosthesis when different geometrical configurations are assumed. Nowadays, such a prosthesis is widely used but, because of its novelty, data in literature give poor information about performances and limits to its applicability. The activity has been divided into the following steps. At the beginning the shape of the prosthesis has been digitally acquired via a 3D scanner. Then, CAD models of all prosthetic components have been geometrically optimized in a way to obtain final entities suitable for numerical simulations. After that, CAD assemblies have been created between prosthetic components and bones (humerus and scapula) involved in the shoulder joint. Following step has been the setup of numerical finite element method models to simulate use conditions. To this scope, analyses have been performed in accordance with experimental conditions found in literature. Stability conditions have been verified under the action of horizontal and vertical instability loads with different version angles between humerus and the humeral implant. In particular, the stability ratios of the prosthesis have been calculated for the analysed loading conditions. Obtained results show how the positioning has a great influence on the shoulder stability and allow the definition of guidelines for the application of this prosthesis. © 2014 Springer-Verlag France.

Keywords: 3D scanner acquisition | Non linear FEM analyses | Reversed shoulder prosthesis | Shoulder stability ratio

Abstract: Nowadays, it is widely recognized that a large number of phenomenological degrees of freedom basically rule the functionality of bone tissue scaffolds. As a consequence of this, the design of scaffolds for tissue engineering involves multidisciplinary and multi-scale aspects, the latter being the subject of intensive investigation by the research community. In this chapter we present an overview on the computational aspects of bone tissue engineering, with particular emphasis on the recent mechanobiological based finite element models, as well as on novel aspects regarding the numerical characterization of the network of scaffold voids.

Keywords: Bone tissue engineering | Finite element modelling | Mechanobiology | Percolation analysis | Scaffold

Abstract: Minimally invasive percutaneous fixation techniques play a role of crucial relevance in the clinical practice. In spite of their consolidated use, little is reported in the literature to provide a mechanobiological explanation on how design of fixation devices can affect the healing process within fractured vertebrae. The aim of the study is to develop a multi-scale mechano-regulation model capable of predicting how the patterns of tissue differentiation within a vertebral fracture change in the presence or in the absence of fixation devices and how the dimensions of the device, and the materials it is made from, can affect the outcome of the healing process. To this purpose, a multi-scale mechano-regulation model is developed that combines a macro-scale model representing the spinal segment L3-L4-L5 including the fractured body of the L4 vertebra, and a micro-scale model of a fractured portion of cancellous bone. The macro-scale model includes also a minimally invasive percutaneous fixation device. The above mentioned model allows us to investigate how spatial and temporal patterns of tissue differentiation in the fracture gap change for different dimensions of the fixation device components and for different materials (Ti-6A1-4V alloy and Co-Cr alloy). Furthermore, the model provides information on the stress state in the fixation device and hence allows the risk of failure of the device itself to be estimated. The mechanical properties of the forming tissue change as the healing process progresses. In order to validate the mechano-regulation model, displacement fields will be measured with moiré and holography and compared with numerical computations. The model predicts that fixation devices significantly shorten healing times. Increasing values of the rod diameter D and decreasing values of its radius of curvature R lead to shorter durations of the healing period. Manufacturing the rods in Cobalt-Chrome alloy is predicted to reduce slightly the healing period by providing greater mechanical stability within the fracture callus. © The Society for Experimental Mechanics, Inc. 2014.

Keywords: Mechanobiology | Minimally invasive percutaneous fixation | Moiré | Tissue differentiation | Vertebral fracture

Abstract: The perception of haptic textures depends on the mechanical interaction between a surface and a biological sensor. A texture is apprehended by sliding one’s fingers over the surface of an object. We describe here an apparatus that makes it possible to record the mechanical fluctuations arising from the friction between a human fingertip and easily interchangeable samples. Using this apparatus, human participants tactually scanned material samples. The analysis of the results indicates that the biomechanical characteristics of individual fingertips clearly affected the mechanical fluctuations. Nevertheless, the signals generated for a single material sample under different conditions showed some invariant features. We propose that this apparatus can be a valuable tool for the analysis of natural haptic surfaces.

Keywords: Apparatus | Biomechanics | Biotribology | Humans | Texture

Abstract: In oral implantology, proper execution of the holes for the installation of dental implants is directly related to the correct functioning and durability of the system itself. For this reason, the procedure discussed here, which was once performed freehand in all its phases, is now being implemented through aids with more precision. Masks currently in use are created in resin ad hoc; surgical stents are inserted into the holes that will then be used as a guide. These aids are fixed into the jaw by means of micro bone screws in order to prevent movement during surgery. Despite this, we still use the guides as they are, centered properly with the help of drilling jigs. The same technique is also used in partially edentulous cases through smaller jig fixed on teeth near to the implant zone. In this article, we propose a guidance system for milling cutters used in partially edentulous cases involving from one to three adjacent installations. The purpose of the study was to realize a modular model adaptable to most dental implants, as well as efficient, quick, and low cost by pouring the resin into a plaster mold of the teeth, and then drilling the masks into position in the plants at the required angle.

Keywords: Dental implants | Drilling aid

Abstract: This study aimed at investigating the effects of titanium implants and different configurations of full-arch prostheses on the biomechanics of edentulous mandibles. Reverse engineered, composite, anisotropic, edentulous mandibles made of a poly(methylmethacrylate) core and a glass fibre reinforced outer shell were rapid prototyped and instrumented with strain gauges. Brånemark implants RP platforms in conjunction with titanium Procera one-piece or two-piece bridges were used to simulate oral rehabilitations. A lateral load through the gonion regions was used to test the biomechanical effects of the rehabilitations. In addition, strains due to misfit of the one-piece titanium bridge were compared to those produced by one-piece cast gold bridges. Milled titanium bridges had a better fit than cast gold bridges. The stress distribution in mandibular bone rehabilitated with a one-piece bridge was more perturbed than that observed with a two-piece bridge. In particular the former induced a stress concentration and stress shielding in the molar and symphysis regions, while for the latter design these stresses were strongly reduced. In conclusion, prosthetic frameworks changed the biomechanics of the mandible as a result of both their design and manufacturing technology.

Keywords: Composite | Dental implants | Mandible | Stress concentration | Stress shielding

Abstract: Purpose: The main purpose of this research work is to study the effect of poly lactic acid (PLA) addition into poly (e-caprolactone) (PCL) matrices, as well the influence of the mixing process on the morphological, thermal, chemical, mechanical and biological performance of the 3D constructs produced with a novel biomanufacturing device (BioCell Printing). Design/methodology/ approach: Two mixing processes are used to prepare PCL/PLA blends, namely melt blending and solvent casting. PCL and PCL/PLA scaffolds are produced via BioCell Printing using a 300-mm nozzle, 0/908 lay down pattern and 350-μm pore size. Several techniques such as scanning electron microscopy (SEM), simultaneous thermal analyzer (STA), nuclear magnetic resonance (NMR), static compression analysis and Alamar BlueTM are used to evaluate scaffold's morphological, thermal, chemical, mechanical and biological properties. Findings: Results show that the addition of PLA to PCL scaffolds strongly improves the biomechanical performance of the constructs. Additionally, polymer blends obtained by solvent casting present better mechanical and biological properties, compared to blends prepared by melt blending. Originality/value: This paper undertakes a detailed study on the effect of the mixing process on the biomechanical properties of PCL/PLA scaffolds. Results will enable to prepare customized PCL/PLA scaffolds for tissue engineering applications with improved biological and mechanical properties, compared to PCL scaffolds alone. Additionally, the accuracy and reproducibility of by the BioCell Printing enables to modulate the micro/macro architecture of the scaffolds enhancing tissue regeneration. © Emerald Group Publishing Limited.

Keywords: Biological analysis and testing | Fused deposition modelling | Polymers | Scaffolds

Abstract: The application of three-dimensional (3D) facial analysis and landmarking algorithms in the field of maxillofacial surgery and other medical applications, such as diagnosis of diseases by facial anomalies and dysmorphism, has gained a lot of attention. In a previous work, we used a geometric approach to automatically extract some 3D facial key points, called landmarks, working in the differential geometry domain, through the coefficients of fundamental forms, principal curvatures, mean and Gaussian curvatures, derivatives, shape and curvedness indexes, and tangent map. In this article we describe the extension of our previous landmarking algorithm, which is now able to extract eyebrows and mouth landmarks using both old and new meshes. The algorithm has been tested on our face database and on the public Bosphorus 3D database. We chose to work on the mouth and eyebrows as a separate study because of the role that these parts play in facial expressions. In fact, since the mouth is the part of the face that moves the most and affects mainly facial expressions, extracting mouth landmarks from various facial poses means that the newly developed algorithm is pose-independent.

Keywords: 3D face | 3D scanner | Differential geometry | Face morphology | Medical diagnosis | Soft-tissue landmarks

Abstract: In the last decade, three-dimensional landmarking has gained attention for different applications, such as face recognition for both identification of suspects and authentication, facial expression recognition, corrective and aesthetic surgery, syndrome study and diagnosis. This work focuses on the last one by proposing a geometrically-based landmark extraction algorithm aimed at diagnosing syndromes on babies before their birth. Pivotal role in this activity is the support provided by physicians and 3D ultrasound tools for working on real faces. In particular, the landmarking algorithm here proposed only relies on descriptors coming from Differential Geometry (Gaussian, mean, and principal curvatures, derivatives, coefficients of first and second fundamental forms, Shape and Curvedness indexes) and is tested on nine facial point clouds referred to nine babies taken by a three-dimensional ultrasound tool at different weeks' gestation. The results obtained, validated with the support of four practitioners, show that the localization is quite accurate. All errors lie in the range between 0 and 3.5 mm and the mean distance for each shell is in the range between 0.6 and 1.6 mm. The landmarks showing the highest errors are the ones belonging to the mouth region. Instead, the most precise landmark is the pronasal, on the nose tip, with a mean distance of 0.55 mm. Relying on current literature, this study is something missing in the state-of-the-art of the field, as present facial studies on 3D ultrasound do not work on automatic landmarking yet.

Keywords: 3D echography | 3D face | 3D ultrasound | Dysmorphisms | Landmarking | Syndrome diagnosis

Abstract: In the last decades, several three-dimensional face recognition algorithms have been thought, designed, and assessed. What they have in common can be hardly said, as they differ in theoretical background, tools, and method. Here we propose a new 3D face recognition algorithm, entirely developed in Matlab ® ,whose framework totally comes from differential geometry. First, 17 soft-tissue landmarks are automatically extracted relying on geometrical properties of facial shape. We made use of derivatives, coefficients of the fundamental forms, principal, mean, and Gaussian curvatures, and shape and curvedness indexes. Then, a set of geodesic and Euclidean distances, together with nose volume and ratios between geodesic and Euclidean distances, has been computed and summed in a final score, used to compare faces. The highest contribution of this work, we believe, is that its theoretical substratum is differential geometry with its various descriptors, which is something totally new in the field.

Keywords: 3D face | Face recognition | Geodesic distance | Geometry | Landmark | Shape index

Abstract: Mini-invasive surgery deserves increasing attention to lower the post-operative stay in hospital and lessen falls-off complications. This leads to the trends in robots, as innovative integrated computer-aided implements. Out of front-end haptic effectors, the background support is turning to inclusive on-duty functions, e.g., surgical planners, operation assistants, etc., making possible the rethinking of protocols to progressively embed the innovations offered by the micro- and nano-technologies. The chapter brings in surgical robotics, with focus on technology and design issues of the remote-mode operation assistants. The investigation leads to define the technical characteristics of a CRHA, Co-Robotic Handling Appliance, to be purposely developed, to support the duty-split approach surgical planner. The expected features are outlined, including analysis of operation potential of special-purpose contrivances (i.e., automatic changing device of the surgical tools) and of scope-driven enhancers (i.e., exploration of the intervention theatre, IT).

Abstract: The goal of the study is investigating the odd claim of the human civilisation, which modifies the wild natural surrounds by synthetic alterations, defined improvements, bestowing 〈value added〉. Indeed, the history seems sanctioning that the 〈life-quality〉 on the earth has been expanding, with enhanced chances and increased resources, compared to the native prospects of the wilderness. Only at the millennium turnover, the ecology globalisation shows the impeding threats of over-depletion/pollution, exceeding the extant recovery and reclamation capabilities of the environment. The new imperative turns to be the 〈sustainable growth〉, with caginess in defining if the trends can be positive, being conditioned by the empowered recycling, retrieval and renovation measures. In fact, sustainability requires lifecycle supply-chain visibility, resource bookkeeping and revamp planning. The lifecycle starts when the idea of a product is born and lasts until complete disposal after realisation and operation. In the musts' specification/analysis, the crucial policy (global plans, detailed design, assembly plots, etc.) are followed by manufacturing, testing, delivery, diagnostics and operation, advertising, service, maintenance, etc.; then, disassembly and firing are scheduled, requiring reclamation and recovery, via re-cycling (material reprocessing) or re-using (part refurbishing). The present study summarises pilot cues for understanding the product-process agendas, using the TYPUS metrics and the KILT model, prospected by the authors, in previous works. © J.UCS.

Keywords: Eco-project | Ecology globalisation | Economy globalisation | Lifecycle management | Sustainable growth

Abstract: In this work, a new technique for symmetry line detection for non-erected postures, which can not be investigated with the other methods presented in the literature, is proposed. It evaluates the symmetry line by means an adaptive process in which a first attempt is modified step by step until the solution converges to the best estimation. The method here proposed is validated by analysing four different non-erected postures in which the spine does not lie onto sagittal plane, by the comparison with the traditional approach to symmetry line detection, having as reference the cutaneous marking. Results are analysed and critically discussed. © 2012 Springer-Verlag France.

Keywords: Anatomical landmarks | Back shape analysis | Posture prediction | Rasterstereography | Symmetry line

Abstract: This paper proposes a new method for the identification of the symmetry plane of the human face, working from 3D high-density scanned data. The method being proposed is an original variant of a typical mirroring and registration method. This method is validated by analysing some specifically designed test cases. The obtained results show that the method is quite insensitive to local asymmetries, whether they be near or far from the symmetry plane, and is also repeatable and slightly conditioned by the acquisition process. © 2012 Springer-Verlag France.

Keywords: Asymmetry | Mirroring | Rasterstereography | Registration | Symmetry plane

Abstract: The methods for symmetry line detection presented in the literature are typically suited to analyse symmetric upright postures, both standing and seated. The proposed method focuses on the symmetry line detection in subjects assuming asymmetric postures in which this line falls far outside the sagittal plane. The proposed approach evaluates the symmetry line by means of an autoregressive process in order to determine the set of planes suited to slice the back coherently with its geometric spatial configuration. The method is analysed assuming the cutaneous marking as reference and it is compared with a previous one, also developed by these authors. Results are analysed and critically discussed. © 2013 Taylor & Francis.

Keywords: anatomical landmarks | back shape analysis | posture prediction | rasterstereography | symmetry line

Abstract: It was reported that next to style, comfort is the second key aspect in purchasing footwear. One of the most important components of footwear is the shoe sole, whose design is based on many factors such as foot shape/size, perceived comfort and materials. The present paper focuses on the parametric analysis of a shoe sole to improve the perceived comfort. The sensitivity of geometric and material design factors on comfort degree was investigated by combining real experimental tests and CAD-FEM simulations. The correlation between perceived comfort and physical responses, such as plantar pressures, was estimated by conducting real tests. Four different conditions were analyzed: subjects wearing three commercially available shoes and in a barefoot condition. For each condition, subjects expressed their perceived comfort score. By adopting plantar sensors, the plantar pressures were also monitored. Once given such a correlation, a parametric FEM model of the footwear was developed. In order to better simulate contact at the plantar surface, a detailed FEM model of the foot was also generated from CT scan images. Lastly, a fractional factorial design array was applied to study the sensitivity of different sets of design factors on comfort degree. The findings of this research showed that the sole thickness and its material highly influence perceived comfort. In particular, softer materials and thicker soles contribute to increasing the degree of comfort. © 2012 IPEM.

Keywords: CAD-FEM modeling | Comfort assessment | Fractional factorial design | Numerical-physical correlation | Pressure map | Shoe sole

Abstract: Aim of this work is to compare two different total knee prostheses that differ mainly in the shape of the polyethylene (PE) component inserted between the femoral and tibial plates. The best solution between them has been originally reshaped in order to reduce stress peaks. The study procedure has been divided into the following steps. First step is the digitalisation of the shape of the prostheses by means of a 3D laser scanner. The morphology of two prototypes of the prostheses has been acquired by elaborating multiple Moirè fringe patterns projected on their surfaces. Second step consisted on the manipulation of these data in a CAD module, that is the interpolation of raw data into NURBS surfaces, reducing singularities due to the typical scattering of the acquiring system. Third step has been the setting up of FEM simulations to evaluate the prostheses behaviour under benchmark loading conditions given in literature. The CAD model of the prostheses has been meshed into solid finite elements. Different flexion angles configurations have been analysed, the load being applied along the femoral axis. FEM analyses have returned stress fields in the PE insert and, in particular, in the stabilizing cam which function is to avoid dislocation. Last step has been the integrated use of CAD and FEM to modify the shape of the stabilizing cam of the best prosthesis, in order to reduce the stress peaks in the original prosthesis without affecting kinematics of the joint. Good results have been obtained both in terms of stress and contact pressure peaks reduction. © 2012 Springer-Verlag.

Keywords: Contact analysis | FEM simulation | Total knee replacement

Abstract: This article concerns the design of lower limb prosthesis, both belowand above knee. It describes a newcomputer-based design framework and a digital model of the patient around which the prosthesis is designed and tested in a completely virtual environment. The virtual model of the patient is the backbone of the whole system, and it is based on a biomechanical generalpurpose model customized with the patient's characteristics (e.g. anthropometric measures). The software platform adopts computer-aided and knowledge-guided approaches with the goal of replacing the current development process, mainly hand made, with a virtual one. It provides the prosthetics with a set of tools to design, configure and test the prosthesis and comprehends two main environments: the prosthesis modelling laboratory and the virtual testing laboratory. The first permits the three-dimensional model of the prosthesis to be configured and generated, while the second allows the prosthetics to virtually set up the artificial leg and simulate the patient's postures and movements, validating its functionality and configuration. General architecture and modelling/simulation tools for the platform are described as well as main aspects and results of the experimentation. © 2013 The Author(s) Published by the Royal Society. All rights reserved.

Keywords: Digital patient | Human modelling | Lower limb prosthesis | Virtual prototyping

Abstract: This paper concerns a research project that aims at developing an innovative platform to design lower limb prosthesis. The platform is centered on the virtual model of the amputee and is based on a computer-aided and knowledge-guided approach. In particular, the paper focuses on the module, named Socket Modeling Assistant-SMA, conceived to design the socket, the most critical component of the whole prosthesis. The underlining idea is to experiment low-cost devices, such the Leap Motion, to manipulate the 3D virtual model of the socket using hands as traditional done by the prosthetist. The goal is to make available a modeling tool that permits to replicate/emulate manual operations usually performed by the prosthetist during the traditional development process. First, we first describe the traditional socket development process; then the SMA software architecture and the guidelines used to develop the interaction algorithms (integrated within SMA) that exploit the Leap Motion and Falcon devices. Finally preliminary tests and results will be illustrated. © 2013 ACM.

Keywords: 3D modeling | hand tracking | haptic interaction | lower limb prosthesis

Abstract: In this paper, we propose a knowledge-based approach to design lower limb prostheses; in particular, we focus on the 3D modelling of the socket, the most critical component. First, the architecture of a dedicated design framework is described, detailing features of the main design steps. Then, the paper discusses the acquisition and formalisation of the knowledge related both to the prosthesis manufacturing process and to the considered component. Finally, we present the computer-aided module, named socket modelling assistant-SMA, we specifically developed to design the socket. It is a virtual laboratory where the socket virtual prototype is generated directly on the digital model of patient's residual limb. It guides and supports the designer during each step in an automatic and/or semi-automatic way applying design rules and procedures. The modelling steps and available interactive tools that emulate orthopaedic technician's operations are described. Results of the experimentation phase are described. At current state of the prototype development, they are encouraging and have permitted to preliminarily validate the proposed approach and envisage future improvements. Copyright © 2013 Inderscience Enterprises Ltd.

Keywords: 3D socket modelling | Knowledge-based design | Lower limb prosthesis | Virtual prototyping

Abstract: In this paper we report the application of CAD/CAM based technologies for the innovative development of customized surgical devices to assist the mandibular rehabilitation in both primary surgery (resection and reconstruction) and secondary surgery (only reconstruction). Design and manufacturing of such customized surgical device are conducted according to the virtual pre-operative planning of the surgeon and with the aim to transferring this planning into the operating theatre. In the case of primary surgery, a cutting guide is developed to assist the resection step while a bone plate is developed to assist the reconstruction step. Instead, in the case of secondary surgery, in addition to the bone plate to support the reconstruction, also a repositioning guide is designed to bring back to the original position the resected stumps according to the original shape of the mandible. Finally, the components of the surgical devices are manufactured by DMLS in alloys suitable for biomedical applications. © 2012 Springer-Verlag France.

Keywords: 3D Reconstruction | Computed tomography | Computer aided design | Direct metal laser sintering | Rapid prototyping

Abstract: The protocol presented here is intended to minimise the intervention in bone reconstruction surgery when severe atrophy or deformity is present in the maxillary arches. A patient underwent augmentation of an atrophic maxillary arch using titanium mesh and particulate autogenous plus bovine demineralised bone. After computed tomography data elaboration, computer-aided design and computer-aided machining were used to plan the augmentation of bone volume to improve the implant position needed to support the final dental prosthesis. The augmented maxilla was rapidly prototyped in plastic, and the titanium mesh was tested on this model before the surgical intervention. Then, the preformed titanium mesh was implanted in the maxillary arch with bone grafting. The bone was augmented relative to the position of the implants for the definitive fixed implant-supported rehabilitation. The protocol presented here is a viable, reproducible way to determine the correct bone augmentation for the final implant-supported prosthetic rehabilitation. © 2013 Copyright Taylor and Francis Group, LLC.

Keywords: bone augmentation | bone graft | computed tomography | dental implants | rapid prototyping

Abstract: In the context of a research program aiming at defining a framework to acquire patient data and support the whole shoe design and manufacturing process, this paper presents new CAD tools to design and validate lasts for shoes designed specifically for people with diabetes. Shoe last customising systems have already been proposed in the literature. However, tools for designing shoes for people with diabetes do not currently have the capacity to modify the last in order to reduce the risk of foot ulceration, whilst at the same time preserving the style of the shoe. The main contributions of the work are given by a method to identify the required design features to guarantee the footwear preventive function, the determination of a systematic protocol for orienting and measuring the virtual models of the feet and the lasts, and the definition of geometrical operators to modify the last shape according to its original aesthetic and the required footwear parameters. Such variables are computed by a knowledge based system on the basis of the patient's pathology. The paper presents the implementation of two CAD tools and describes the procedures and the geometrical algorithms to handle the last geometry. Finally a case study is reported to show the advantages provided by the proposed approach in terms of achieved quality of the design process and expected footwear performance. © 2013 Elsevier Ltd. All rights reserved.

Keywords: Diabetic foot | Foot-last fitting | Last design | Last measurement

Abstract: Ideal scaffolds for tissue engineering should mimic the complex characteristics of natural tissues and their mechanical performance. This work presents a new concept of hybrid scaffolds produced through the combination of electrospinning and an additive bioextruder system. The obtained results have shown that the hybrid structures present improved mechanical properties. © (2013) Trans Tech Publications, Switzerland.

Keywords: Bioextrusion | Electrospinning | Hybrid scaffolds | Polycaprolactone | Tissue engineering

Abstract: This paper investigates the use of PCL and PCL/PLA scaffolds, produced using a novel additive biomanufacturing system called BioCell Printing, for bone tissue engineering applications. Results show that the BioCell Printing system produces scaffolds with regular and reproducible architecture, presenting no toxicity and enhancing cell attachment and proliferation. It was also possible to observe that the addition of PLA to PCL scaffolds strongly improves the biomechanical performance of the constructs. © (2013) Trans Tech Publications, Switzerland.

Keywords: Additive biomanufacturing | Bone tissue regeneration | Cells | Polymers | Scaffolds

Abstract: Non-woven scaffolds, with fiber dimensions at a nanometer scale, can mimic the physical structure of natural extracellular matrices, being ideal construts for Tissue Engineering applications. This research work explores solution electrospinning to produce nanoscale meshes. Different Poly (ε-caprolactone) (PCL) solutions were considered and the influence of both polymer concentration and type of solvent studied regarding the fabrication of polymeric meshes and their mechanical and biological properties. PCL solutions were prepared using two different solvents: glacial acetic acid with triethylamine (AA/TEA)) and Acetone (DMK) at different concentrations. PCL/AA/TEA meshes present better mechanical properties and good cell viability and proliferation. © (2013) Trans Tech Publications, Switzerland.

Keywords: Electrospinning | Nanofibers | Polycaprolacone | Tissue engineering

Abstract: In biomedicine, magnetic nanoparticles provide some attractive possibilities because they possess peculiar physical properties that permit their use in a wide range of applications. The concept of magnetic guidance basically spans from drug delivery and hyperthermia treatment of tumours, to tissue engineering, such as magneto-mechanical stimulation/activation of cell constructs and mechanosensitive ion channels, magnetic cell-seeding procedures, and controlled cell proliferation and differentiation. Accordingly, the aim of this study was to develop fully biodegradable and magnetic nanocomposite substrates for bone tissue engineering by embedding irondoped hydroxyapatite (FeHA) nanoparticles in a poly(1-caprolactone) (PCL) matrix. X-ray diffraction analyses enabled the demonstration that the phase composition and crystallinity of the magnetic FeHA were not affected by the process used to develop the nanocomposite substrates. The mechanical characterization performed through small punch tests has evidenced that inclusion of 10 per cent by weight of FeHA would represent an effective reinforcement. The inclusion of nanoparticles also improves the hydrophilicity of the substrates as evidenced by the lower values of water contact angle in comparison with those of neat PCL. The results from magnetic measurements confirmed the superparamagnetic character of the nanocomposite substrates, indicated by a very low coercive field, a saturation magnetization strictly proportional to the FeHA content and a strong history dependence in temperature sweeps. Regarding the biological performances, confocal laser scanning microscopy and AlamarBlue assay have provided qualitative and quantitative information on human mesenchymal stem cell adhesion and viability/proliferation, respectively, whereas the obtained ALP/DNA values have shown the ability of the nanocomposite substrates to support osteogenic differentiation. © 2013 The Authors.

Keywords: Bone tissue regeneration | Magnetic hydroxyapatite | Nanocomposite | Poly(ε-caprolactone) | Scaffold

Abstract: This paper investigates the use of PCL and PCL/PLA scaffolds produced using a novel additive biomanufacturing system called BioCell Printing. PCL/PLA blends were prepared using melt blend and solvent casting techniques. Scaffolds with 0/90° architecture and 350 μm of pore size were morphologically evaluated using scanning electron microscopy and atomic force microscopy. Biological tests, using osteosarcoma cell line G-63, were performed using the Alamar Blue Assay and Alkaline Phosphatase Activity. Results show that the BioCell Printing system produces scaffolds with regular and reproducible architecture, presenting no toxicity and enhancing cell attachment and proliferation. It was also possible to observe that the addition of PLA to PCL scaffolds strongly improves the biomechanical performance of the constructs. © 2013 The Authors.

Keywords: Biomanufacturing | Polymer blends | Scaffolds | Tissue Engineering

Abstract: Cellular adhesion and proliferation inside three-dimensional synthetic scaffolds represent a major challenge in tissue engineering. Besides the surface chemistry of the polymers, it is well recognized that scaffold internal architecture, namely pore size/shape and interconnectivity, has a strong effect on the biological response of cells. This study reports for the first time how polycaprolactone (PCL) scaffolds with controlled micro-architecture can be effectively produced via bioextrusion and used to enhance the penetration of plasma deposited species. Low-pressure nitrogen-based coatings were employed to augment cell adhesion and proliferation without altering the mechanical properties of the structures. X-ray photoelectron spectroscopy carried out on different sections of the scaffolds indicates a uniform distribution of nitrogen-containing groups throughout the entire porous structure. In vitro biological assays confirm that plasma deposition sensitively promotes the activity of Saos-2 osteoblast cells, leading to a homogeneous colonization of the PCL scaffolds. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Keywords: Biofabrication | Osteoblast cells | Scaffolds | Surface modification | Tissue engineering

Abstract: Face study and description through landmarks is a key activity in many fields, in particular the medical one for both corrective and esthetic surgery purposes. In a previous work, we used a geometric approach to automatically extract landmarks working in the Differential Geometry domain, through the coefficients of the Fundamental Forms, the Principal Curvatures, Mean and Gaussian Curvatures, derivatives, and Shape and Curvedness Indexes. In this paper we describe the improvements made to our previously developed algorithm by using a new parameterization of the mesh, new geometrical descriptors, and new conditions. © 2013 Elsevier B.V. All rights reserved.

Keywords: 3D face | 3D scanner | Differential Geometry | Face morphology | Soft-tissue landmark extraction

Abstract: Mini-invasive surgery deserves increasing attention to lower the post-operative stay in hospital and lessen falls-off complications. This leads to the trends in robots, as innovative integrated computer-aided implements. Out of front-end haptic effectors, the background support is turning to inclusive on-duty functions, e.g., surgical planners, operation assistants, etc., making possible the rethinking of protocols to progressively embed the innovations offered by the micro- and nano-technologies. The chapter brings in surgical robotics, with focus on technology and design issues of the remote-mode operation assistants. The investigation leads to define the technical characteristics of a CRHA, Co-Robotic Handling Appliance, to be purposely developed, to support the duty-split approach surgical planner. The expected features are outlined, including analysis of operation potential of special-purpose contrivances (i.e., automatic changing device of the surgical tools) and of scope-driven enhancers (i.e., exploration of the intervention theatre, IT).

Abstract: Objective: In the paper laser scanning was used to evaluate, by indirect methods, the accuracy of computer-designed surgical guides in the oral implant supported rehabilitation of partially or completely edentulous patients. Materials and methods: Five implant supported rehabilitations for a total of twenty-three implants were carried out by computer-designed surgical guides, performed with the master model developed by muco-compressive and muco-static impressions. For all cases the surgical virtual planning, starting from 3D models obtained by dental scan DICOM data, was performed. The implants were inserted on the pre-surgical casts in the position defined in the virtual planning. These positions were acquired by three-dimensional optical laser scanning and compared with the laser scans of the intraoral impressions taken post-operatively. Results: The comparison between the post-surgical implant replica positions and the positions in the pre-operative cast, for the five patients, shows a maximum distance in the range 1.02-1.25 mm, an average distance in the range 0.21-0.41 mm and a standard deviation in the range 0.21-0.29 mm. Significance: The results of this research demonstrate accurate transfer of implant replica position by virtual implant insertion into a pre-operative cast and a post-operative cast obtained from impressioning. In previous studies the evaluation of the implant positions have required a post-surgical CT scan. With the indirect methods by laser scanning technique, proposed in the paper, this extra radiation exposure of the patient can be eliminated. © 2012 Academy of Dental Materials.

Keywords: Dental implants | Guided implant surgery | Impressions | Laser scan | Virtual modeling

Abstract: Objective: To investigate the influence of implant design factors in terms of bone integrity and implant stability. Materials and methods: A 3D parametric CAD model was developed. Then, once domain settings and boundary conditions were defined, a 3D FEM model was created. To simulate the physical interaction at the bone-implant interface, identity pairs were introduced. After generating different design scenarios with a DOE approach, the most significant design factors were obtained. Results: This study showed that the geometry of the screw thread highly influenced the implant stability. In particular the degree of bone damage became minimal when adopting 0.40 mm for the thread width and 0.05 mm for the thickness. Significance: Thread width and thickness play a crucial role to reduce induced stresses and damage in bone. Considering these preliminary results, future improvements should focus on investigating also two-factor and higher interactions to better understand the implant loading mechanism. © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Keywords: Bone-stress distribution | Dental implants | DOE design | FEM modeling | Osseo-integration | Thread parameterization | Titanium implants

Abstract: In this work, a new technique for symmetry line detection for asymmetric postures, which can not be investigated with the other methods presented in the literature, is proposed. It evaluates the symmetry line by means an adaptive process in which a first attempt is modified step by step until the solution converges to the best estimation. The method here proposed is validated by analysing four different asymmetric postures in which the spine lies far outside the sagittal plane, having as reference the cutaneous marking. Results are analysed and critically discussed. © 2012 Springer-Verlag.

Keywords: Anatomical landmarks | Back shape analysis | Posture prediction | Raster stereography | Symmetry line

Abstract: The aim of this work is the analysis of the contact area in a knee prosthesis using two different approaches. In particular, the interface between the femoral component and the polyethylene insert has been studied both numerically and experimentally. The interest in studying the contact area is related to the fact that the wear of the polyethylene insert, due to the high contact pressures, represents one of the major causes of failure of the total knee prosthesis. The possibility to evaluate the contact area at different loads and mutual position between femur and tibia is, therefore, of fundamental importance to study the service life of a prosthesis and to improve its performance. The finite element numerical approach has required the acquisition, through reverse engineering, and CAD modelling of the prosthetic components. Then the FEM simulations have been developed considering two different load conditions. In order to compare the calculated data, the same load configurations have been used for experimental tests based on ultrasonic method. In this case, some preliminary tests were required to calibrate the system depending on the particular characteristics of materials, geometries and surface finish of the prosthesis. The results show a good correlation between the data obtained with the two different approaches and, consequently, a good level of reliability of the procedures developed for the numerical and experimental evaluation of the contact area. The numerical procedure can be used to determine the area for different angles and loads, but especially in the design phase. The ultrasonic technique can be used to validate the numerical data.

Abstract: Computer-aided tools can help to realize custom-fit products characterized by a strict interaction with human body and definitely improve quality of life, in particular of people with disabilities. The paper refers to this context and to a specific custom-fit product, the lower limb prosthesis. It presents an innovative framework centred on virtual models of the patient's body, to design and configure lower limb prosthesis, both transfemoral and transtibial. The framework integrates virtual prototyping and knowledge-based tools to support the orthopaedic technician during all the steps of the lower limb prosthesis design, suggesting rules and procedures for each task. First, the considered product is introduced, and then, the new design framework is described as well as main steps and related tools, from socket modelling to standards component selection and final prosthesis assembly. Results of preliminary experimentation and final remarks conclude the paper. © 2012 Springer-Verlag.

Keywords: Custom-fit products | Knowledge-based systems | Lower limb prosthesis | Socket | Virtual prototyping

Abstract: In spite of the consolidated clinical use of minimally invasive percutaneous fixation techniques, little is reported in the literature providing a mechanobiological explanation for how the design of fixation devices can affect the healing process within fractured vertebrae. The aim of this study was to develop a multi-scale mechano-regulation model capable of predicting how the patterns of tissue differentiation within a vertebral fracture change in the presence or in the absence of fixation devices and how the dimensions of the device, and the materials it is made from (Ti-6Al-4V alloy and cobalt chrome alloy) can affect the outcome of the healing process. The macro-scale model simulates the spinal segment L3-L4-L5, including the fractured body of the L4 vertebra, while the micro-scale model represents a fractured portion of cancellous bone. The macro-scale model also includes a minimally invasive percutaneous fixation device. The model predicts that fixation devices significantly shorten healing times. Increasing values of the rod diameter D and decreasing values of its radius of curvature R lead to shorter durations of the healing period. Manufacturing the rods in cobalt chrome alloy is also predicted to reduce slightly the healing period by providing greater mechanical stability within the fracture callus. © International Federation for Medical and Biological Engineering 2012.

Keywords: Mechanobiology | Minimally invasive percutaneous fixation | Spine | Tissue differentiation | Vertebral fracture

Abstract: This study represents a preliminary activity for the biomechanical numerical modeling aimed at the prediction of the human foot behavior and the deformation under different load conditions. It also represents the starting point to develop a scientific approach for the functional mass customization aimed at the optimization of comfort in footwear. Reverse Engineering (RE) methodologies developed for building up the external shape of the human foot are presented and discussed. Aim of this work is to study the problem of the digitalization of human feet under different conditions using three technologies: shape from stereo, from silhouette and from shading. The foot is one of the most difficult human parts to reconstruct taking into account the complex surface and the high curvature. In this article the disadvantage and advantage of each technique are analyzed. In particular tests about reliability and precision of the measure are considered. ©2010 Society for Experimental Mechanics Inc.

Abstract: Background: It is common practice to prescribe customised footwear to people with diabetes to reduce the risk of foot ulceration. Although shoe customising systems have been proposed, effective tools for designing shoe lasts for diabetic patients are lacking. The shape of the lasts must meet certain biomechanical objectives, while maintaining the style of the shoe.Method: The main contributions of this work are as follows: the creation of an artificial-neural-network-based framework to correlate foot measurements and medical data to required footwear features; the definition of repeatable geometrical procedures to measure foot and last scans; and the definition of geometrical operators to modify the last shape according to its original aesthetic and specific footwear parameters. These parameters are computed by a knowledge-based system on the basis of the patient's pathology and best practices of experienced technicians.Results: Dedicated software systems integrated in a common platform are implemented to support the last design process. Test case studies and a survey show the advantages provided by the proposed approach in terms of achieved quality and shoe developing time (72% time savings).Conclusions: A design framework with dedicated tools is proposed for the customisation of shoe lasts for diabetic patients. Further research should be focused on tools to design the insole, outsole and other shoe components. © 2012 Copyright Taylor and Francis Group, LLC.

Keywords: diabetic foot | foot-last fitting | last design | last measurement

Abstract: Hydrogels currently represent a powerful solution to promote the regeneration of soft and hard tissues. Primarily, they assure efficient bio-molecular interactions with cells, also regulating their basic functions, guiding the spatially and temporally complex multi-cellular processes of tissue formation, and ultimately facilitating the restoration of structure and function of damaged or dysfunctional tissues. In order to overcome basic drawbacks of traditional synthesized hydrogels, many recent strategies have been implemented to realize multi-component hydrogels based on natural and/or synthetic materials with tailored chemistries and different degradation kinetics. Here, a critical review of main strategies has been proposed based on the use of hydrogels-based devices for the regeneration of complex tissues, i.e., osteo-chondral tissues and intervertebral disc. © 2012 by the authors.

Keywords: Disc nucleus | Hydrogels | Osteochondral tissue | Scaffolds | Tissue regeneration

Abstract: An Additive Manufacturing technique for the fabrication of three-dimensional polymeric scaffolds, based on wet-spinning of poly(ε-caprolactone) (PCL) or PCL/hydroxyapatite (HA) solutions, was developed. The processing conditions to fabricate scaffolds with a layer-by-layer approach were optimized by studying their influence on fibres morphology and alignment. Two different scaffold architectures were designed and fabricated by tuning inter-fibre distance and fibres staggering. The developed scaffolds showed good reproducibility of the internal architecture characterized by highly porous, aligned fibres with an average diameter in the range 200-250 μm. Mechanical characterization showed that the architecture and HA loading influenced the scaffold compressive modulus and strength. Cell culture experiments employing MC3T3-E1 preosteoblast cell line showed good cell adhesion, proliferation, alkaline phosphatase activity and bone mineralization on the developed scaffolds. © 2012 Springer Science+Business Media, LLC.

Keywords: Additive manufacturing | Polycaprolactone | Scaffolds | Tissue engineering | Wet-spinning

Abstract: As reported in the literature, scaffolds for soft and hard tissue regeneration should satisfy several requirements. In the present work, the potential of 3D fiber deposition technique to design morphologically controlled scaffolds consisting of poly(ε-caprolactone) reinforced with sol-gel synthesized organic-inorganic hybrid fillers was demonstrated, also benefiting from a basic study carried out on 2D composite substrates. Finite element analysis, biological and mechanical tests were properly performed to assess the effects of the inclusion of the hybrid fillers on the performances of 2D substrates and 3D structures. © 2012 American Institute of Physics.

Keywords: Alamar Blue™ assay | Composite scaffolds | Finite element analysis | Mechanical properties | Organic-inorganic hybrid | Poly(e-caprolactone) | Tissue engineering

Abstract: Hydrogels are considered promising for disc regeneration strategies. However, it is currently unknown whether the destruction of the natural interface between nucleus and surrounding structures caused by nucleotomy and an inadequate annulus closure diminishes the mechanical competence of the disc. This in vitro study aimed to clarify these mechanisms and to evaluate whether hydrogels are able to restore the biomechanical behaviour of the disc.Nucleus pressure in an ovine intervertebral disc was measured in vivo during day and night and adapted to an in vitro axial compressive diurnal (15min) and night (30min) load. Effects of different defects on disc height and nucleus pressure were subsequently measured in vitro using 30 ovine motion segments. Following cases were considered: intact; annulus incision repaired by suture and glue; annulus incision with removal and re-implantation of nucleus tissue; and two different hydrogels repaired by suture and glue.The intradiscal pressure in vivo was 0.75. MPa during day and 0.5. MPa during night corresponding to an in vitro axial compressive force of 130 and 58. N, respectively. The compression test showed that neither the implantation of hydrogels nor the re-implantation of the natural nucleus, assumed as being the ideal implant, was able to restore the mechanical functionality of an intact disc.Results indicate the importance of the natural anchorage of the nucleus with its surrounding structures and the relevance of an appropriate annulus closure. Therefore, hydrogels that are able to mimic the mechanical behaviour of the native nucleus may fail in restoring the mechanical behaviour of the disc. © 2012 Elsevier Ltd.

Keywords: Compression test | Disc regeneration | Hydrogels | In vitro | In vivo | Intervertebral disc | Nucleus replacement

Abstract: Currently, numerous hydrogels are under examination as potential nucleus replacements. The clinical success, however, depends on how well the mechanical function of the host structure is restored. This study aimed to evaluate the extent to and mechanisms by which surgery for nucleus replacements influence the mechanical behaviour of the disc. The effects of an annulus defect with and without nucleus replacement on disc height and nucleus pressure were measured using 24 ovine motion segments. The following cases were considered: intact; annulus incision repaired by suture and glue; annulus incision with removal and re-implantation of nucleus tissue repaired by suture and glue or plug. To identify the likely mechanisms observed in vitro, a finite-element model of a human disc (L4-L5) was employed. Both studies were subjected to physiological cycles of compression and recovery. A repaired annulus defect did not influence the disc behaviour in vitro, whereas additional nucleus removal and replacement substantially decreased disc stiffness and nucleus pressure. Model predictions demonstrated the substantial effects of reductions in replaced nucleus water content, bulk modulus and osmotic potential on disc height loss and pressure, similar tomeasurements. In these events, the compression load transfer in the disc markedly altered by substantially increasing the load on the annulus when compared with the nucleus. The success of hydrogels for nucleus replacements is not only dependent on the implantmaterial itself but also on the restoration of the environment perturbed during surgery. The substantial effects on the disc response of disruptions owing to nucleus replacements can be simulated by reduced nucleus water content, elastic modulus and osmotic potential. © 2012 The Royal Society.

Keywords: Disruptions | Finite-element method | Hydrogels | In vitro | Interface | Intervertebral disc

Abstract: The intervertebral disc is a complex structure consisting of different tissues (nucleus pulposus, annulus fibrosus and cartilage endplate) that differ chemically, histologically and physiologically. Its degeneration represents a serious medical problem which affects many people worldwide. Discectomy and spinal fusion compromise the biomechanics of the spine, whilst current disc prostheses do not properly reproduce the static mechanical behaviour, as well as the viscoelastic, transport and biological properties of the natural structure. This clearly stresses the importance of biological approaches to disc repair. Considering the structure-function relationship, biomimetic structures able to mimic the multi-scale structural hierarchy of complex tissues are extremely important for tissue engineering applications. This chapter first describes the structure, anatomy and function of the intervertebral disc, then it briefly introduces the mechanics-biology interrelation. In particular, the chapter underlines the several approaches considered in the field of tissue engineering of annulus, nucleus and entire intervertebral disc, also trying to evidence key functional features. Injectable materials, polymers, electrospun scaffolds and several cell sources are also discussed alone or in combination. © 2012 Woodhead Publishing Limited. All rights reserved.

Keywords: Annulus fibrosus | Intervertebral disc | Nucleus pulposus | Polymers | Scaffolds | Tissue engineering

Abstract: Purpose - This paper aims to report a detailed study regarding the influence of process parameters on the morphological/mechanical properties of poly(1-caprolactone) (PCL) scaffolds manufactured by using a novel extrusion-based system that is called BioExtruder. Design/methodology/approach - In this study the authors focused investigations on four parameters, namely the liquefier temperature (LT), screw rotation velocity (SRV), deposition velocity (DV) and slice thickness (ST). Scaffolds were fabricated by employing three different values of each parameter. Through a series of trials, scaffolds were manufactured varying iteratively one parameter while maintaining constant the other ones. The morphology of the structures was investigated using a scanning electron microscope (SEM), whilst the mechanical performance was assessed though compression tests. Findings - Experimental results highlight a direct influence of the process parameters on the PCL scaffolds properties. In particular, DV and SRV have the highest influence in terms of road width (RW) and consequently on the porosity and mechanical behaviour of the structures. Research limitations/implications - The effect of process and design parameters on the biological response of scaffolds is currently under investigation. Originality/value - The output of this work provides a major insight into the effect of process parameters on the morphological/mechanical properties of PCL scaffolds. Moreover, the potential and feasibility of this novel extrusion-based system open a new opportunity to study how structural features may influence the characteristics and performances of the scaffolds, enabling the development of integrated biomechanical models that can be used in CAD systems to manufacture customized structures for tissue regeneration. © Emerald Group Publishing Limited.

Keywords: Biomanufacturing | Biotechnology | Mechanical properties of materials | Morphological properties | Process parameters | Scaffolds

Abstract: Recently, 3D landmark extraction has been widely researched and experimented in medical field, for both corrective and aesthetic purposes. Automation of these procedures on three-dimensional face renderings is something desirable for the specialists who work in this field. In this work we propose a new method for accurate landmark localization on facial scans. The method relies on geometrical descriptors, such as curvatures and Shape Index, for computing candidate and initial points, and on a statistical model based on Procrustes Analysis and Principal Component Analysis, which is fitted to candidate points, for extracting the final landmarks. The elaborated method is independent on face pose. © 2012 Elsevier Ireland Ltd.

Keywords: 3D face | Differential Geometry | Landmark extraction | PCA | Procrustes Analysis

Abstract: In this work a new method for symmetry line recognition, from 3D scanned data of a subject's back, is presented. The new method is validated by comparison with traditional techniques based on cutaneous marking. For this purpose, the upright standing and sitting postures of a sample of 75 subjects, who usually perform different sports activities, are analysed. Error in symmetry line detection is measured as the distance between the estimated symmetry line and the position of the markers. The proposed method is compared with another one described in literature which has been validated in clinical field. Results are analysed and critically discussed. © 2011 CAD Solutions, LLC.

Keywords: Back shape analysis | Posture prediction | Symmetry line

Abstract: This paper concerns the usage of virtual humans to validate lower limb prosthesis design. In particular, we are developing an innovative design framework centered on digital models of the whole patient or of his/her anatomical districts, which constitute the backbone of the design process. The framework integrates a set of virtual "assistants" to guide the technicians during each design task providing specific knowledge and design rules. In this paper, we focus the attention on the last step of the prosthesis deign process, i.e., the final set-up with the patient using a biomechanical model of the amputee. First, we describe the state of art on virtual humans and main features of the new design framework. Then, the application of virtual humans for the prosthesis set-up is presented as well as preliminary results. Copyright © 2011 by ASME.

Keywords: Lower limb prosthesis | Product development | Virtual humans | Virtual prototyping

Abstract: In this study a multi-scale mechano-regulation model was developed in order to investigate the mechanobiology of trabecular fracture healing in vertebral bodies. A macro-scale finite element model of the spinal segment L3-L4-L5, including a mild wedge fracture in the body of the L4 vertebra, was used to determine the boundary conditions acting on a micro-scale finite element model simulating a portion of fractured trabecular bone. The micro-scale model, in turn, was utilized to predict the local patterns of tissue differentiation within the fracture gap and then how the equivalent mechanical properties of the macro-scale model change with time. The patterns of tissue differentiation predicted by the model appeared consistent with those observed in vivo. Bone formation occurred primarily through endochondral ossification. New woven bone was predicted to occupy the majority of the space within the fracture site approximately 7-8 weeks after the fracture event. Remodeling of cancellous bone architecture was then predicted, with complete new trabeculae forming due to bridging of the microcallus between the remnant trabeculae. Copyright © 2010 Orthopaedic Research Society.

Keywords: finite element analysis | fracture repair | mechanobiology | tissue differentiation | vertebral body

Abstract: Techniques of bone reconstructive surgery are largely based on conventional, non-cell-based therapies that rely on the use of durable materials from outside the patient's body. In contrast to conventional materials, bone tissue engineering is an interdisciplinary field that applies the principles of engineering and life sciences towards the development of biological substitutes that restore, maintain, or improve bone tissue function. Bone tissue engineering has led to great expectations for clinical surgery or various diseases that cannot be solved with traditional devices. For example, critical-sized defects in bone, whether induced by primary tumor resection, trauma, or selective surgery have in many cases presented insurmountable challenges to the current gold standard treatment for bone repair. The primary purpose of bone tissue engineering is to apply engineering principles to incite and promote the natural healing process of bone which does not occur in critical-sized defects. The total market for bone tissue regeneration and repair was valued at $1.1 billion in 2007 and is projected to increase to nearly $1.6 billion by 2014. Usually, temporary biomimetic scaffolds are utilized for accommodating cell growth and bone tissue genesis. The scaffold has to promote biological processes such as the production of extra-cellular matrix and vascularisation, furthermore the scaffold has to withstand the mechanical loads acting on it and to transfer them to the natural tissues located in the vicinity. The design of a scaffold for the guided regeneration of a bony tissue requires a multidisciplinary approach. Finite element method and mechanobiology can be used in an integrated approach to find the optimal parameters governing bone scaffold performance. In this paper, a review of the studies that through a combined use of finite element method and mechano-regulation algorithms described the possible patterns of tissue differentiation in biomimetic scaffolds for bone tissue engineering is given. Firstly, the generalities of the finite element method of structural analysis are outlined; second, the issues related to the generation of a finite element model of a given anatomical site or of a bone scaffold are discussed; thirdly, the principles on which mechanobiology is based, the principal theories as well as the main applications of mechano-regulation models in bone tissue engineering are described; finally, the limitations of the mechanobiological models and the future perspectives are indicated. © Ivyspring International Publisher.

Keywords: Bone tissue engineering | Finite element analysis | Mechano-regulation algorithms | Mechanobiology | Scaffold

Abstract: In order to mimic the behaviors of natural tissue, the optimal approach for designing novel biomaterials has to be inspired to nature guidelines. One of the major challenge consists in the development of well-organized structures or scaffolds with controlled porosity in terms of pore size, pore shape and interconnection degree able to guide new tissue formation during the in vivo degradation following the scaffold implantation. Scaffolds endowed with molecular cues together to a controlled degradation profile should contribute to cell proliferation and differentiation, controlled vascularization, promoting the remodeling of neo tissue through a gradual transmission of biochemicals and biophysical signals as performed by the extracellular matrix (ECM). Here, different polymers and composites have been investigated to design scaffolds with peculiar micro and/or nanometric morphological features in order to satisfy all these requirements: a) bioactive scaffolds, with tailored porosity and high pores interconnectivity were developed by integrating PLA fibres, Calcium Phosphates particles or Hyaff11 phases into a Poly(ε-caprolactone) (PCL) matrix by the combination of filament winding technology and phase inversion/salt leaching technique as mineralised ECM analogue for bone regeneration; b) custom made PCL/hydroxyapatite scaffolds were designed by imaging and rapid prototyping technologies for the osteochondral defect. c) Ester of Hyaluronic Acid reinforced with degradable fibres were processed by composite technology, phase inversion and salt leaching technique, to obtain scaffolds for meniscus regeneration. d) PCL and gelatin nanofibres were obtained by highly customized fibre deposition via electrospinning to guide the nerve outgrowth in nerve regeneration. All the proposed approaches offer the chance of realizing tailor-made platforms with micro/nanoscale architecture and chemical composition suitable for the regeneration of the extracellular matrix of a large variety of natural tissues (i.e, bone, menisci, osteochondral and peripheral nervous tissues). © (2011) Trans Tech Publications, Switzerland.

Keywords: Composite | Polycaprolactone | Scaffold | Tissue engineering

Abstract: The goal of this study was to produce and characterize the scaffolds by combining the advantages of both natural and synthetic polymers for engineering fibro-cartilaginous tissues. Porous three-dimensional composite scaffolds were produced based on glycosaminoglycans and hyaluronic acid (HYAFF11) reinforced with polycaprolactone. The mechanical properties of scaffolds were evaluated as a function of time and compared with those of scaffolds seeded with human chondrocytes (constructs) and cultured in vitro up to 6 weeks. The composite scaffolds had a porosity of 68% with interconnected macropores with average pore sizes of 200 μm, an equilibrium swelling of 350%, and a predominant elastic behavior, typical of a macromolecular gel. The composite constructs maintained chondrocyte phenotype and degraded with the deposition of macromolecules synthesized by the cells. The scaffold presented mechanical properties and the ability to dissipate energy similar to the fibro-cartilaginous tissue. © The Author(s) 2011.

Keywords: cartilage tissue engineering | hyaluronic acid derivatives | mechanical properties | PCL | scaffolds

Abstract: Spinal disease due to intervertebral disc degeneration represents a serious medical problem which affects many people worldwide. Disc arthroplasty may be considered the future "gold standard" of back pain treatment, even if problems related to available disc prostheses are considered. Hence, the aim of the present study was to improve the artificial disc technology by proposing the engineering of a pilot-scale device production process for a total multi-component intervertebral disc prosthesis. The device is made up of a poly(2-hydroxyethyl methacrylate)/poly(methyl methacrylate) (PHEMA/PMMA) (80/20 w/w) semi-interpenetrating polymer network (s-IPN) composite hydrogel reinforced with poly(ethylene terephthalate) (PET) fibers as annulus/nucleus substitute, and two hydroxyapatite-reinforced polyethylene composite (HAPEXTM) endplates in order to anchor the multi-component device to the vertebral bodies. Static and dynamic-mechanical characterization show appropriate mechanical behavior. An example of engineering of a suitable pilot-scale device production process is also proposed in order to manufacture custom made implants. © 2010 The Author(s).

Keywords: customized prosthesis | fiber-reinforced hydrogel | intervertebral disc | mechanical testing. | multi-component model | reverse engineering | technologies

Abstract: Low back pain, a common cause of disability in individuals - especially between 20 and 50 years old - with enormous socioeconomic consequences, may be strongly associated with the degeneration of the intervertebral disc (IVD). The traditional IVD treatments, such as spinal fusion, even though they provide amelioration of the pain, present different drawbacks; consequently there is a lot of research interest in replacing the damaged disc with an artificial one. In this chapter, after an introductory part on IVD and the pathologies and treatment related to it, an overview of the IVD traditional prostheses is given, followed by the presentation of new hydrogels-based prostheses designed according to a biomimetic approach. Finally, the hydrogels-based systems aimed to replace the nucleus pulposus (NP) and to act as scaffolds to carry cells to engineer the IVD tissues are described.

Keywords: Hydrogels | Intervertebral disc prostheses | Nucleus pulposus | Tissue engineering

Abstract: Mini-invasive surgery deserves increasing attention to lower post-operative stays in hospitals and to lessen fall-off complications. This new book is devoted to surgical robotics, with a focus on technology and design issues of the remote-mode operation assistants. The investigation leads to define the technical characteristics of a CRHA, co-robotic handling appliance, to be purposely developed, to support the duty-split approach surgical planner. © 2010 by Nova Science Publishers, Inc. All rights reserved.

Abstract: In this work a new method for symmetry line recognition, from 3D scanned data of a subject’s back, is presented. The new method is validated by comparison with traditional techniques based on cutaneous marking. For this purpose, the upright standing and sitting postures of a sample of 75 subjects, who usually perform different sports activities, are analysed. Error in symmetry line detection is measured as the distance between the estimated symmetry line and the position of the markers. The proposed method is compared with another one described in literature which has been validated in clinical field. Results are analysed and critically discussed. © 2010 Taylor & Francis Group, LLC.

Keywords: Back shape analysis | Posture prediction | Symmetry line

Abstract: In this paper, we propose a knowledge-based approach to design lower limb prostheses; in particular, we focus on the 3D modelling of the socket, the most critical component. First, the architecture of a dedicated knowledge based engineering framework is described, detailing features of the main design steps. Then, the paper discusses the acquisition and formalization of the knowledge related both to the prosthesis manufacturing process and to the considered component. Finally, we present a computer-aided module, named Socket Modelling Assistant-SMA, to design the socket; it is a virtual laboratory where the socket virtual prototype is generated directly on the digital model of patient's residual limb. It guides and supports the designer during each step in an automatic and/or semi-automatic way applying design rules and procedures. The guided modelling steps and available tools are described. Work in progress and future developments conclude the paper. © Organizing Committee of TMCE 2010 Symposium.

Keywords: 3d socket modelling | Knowledge-based design | Lower limb prosthesis | Virtual prototyping

Abstract: This paper presents a new 3D design paradigmfor the development of specific custom-fit products, such as the soft socket of prostheses for lower limb amputees. It is centered on the digitalmodel of the human body and, contrarily to the traditional process almost manually based, it considers the integration of methods and tools coming from different research and application fields: Reverse Engineering, Medical Imaging, Virtual Prototyping, Physics-based Simulation, and Rapid Prototyping. The paper describes the techniques adopted to acquire and create the digital model of the residual limb, the procedure to generate the socket model, the strategy developed for the functional simulation of the socket-stump interaction and, finally, the realization of the physical prototype. Each design step is described with the related problems and the obtained results. Both trans-tibial and trans-femoral amputees have been considered; however, for now the complete process has been validated for trans-tibial prostheses. Major outcomes of the proposed approach stand in a better quality of the final product, in a shorter involvement of the amputee implying a lower psychological impact, in a limited use of physical prototypes, and in a shorter development time. Moreover, the resulting paradigm answers to the Collaborative Engineering guidelines by optimizing the interaction between different domains and enhancing their contributions in a homogeneous development framework. © 2010 Elsevier B.V. All rights reserved.

Keywords: Custom-fit products | Human-centric soft product design | Physics-based modeling for soft products | Prosthesis development process

Abstract: This study represents a preliminary activity for the biomechanical numerical modeling aimed at the prediction of the human foot behavior and the deformation under different load conditions. It also represents the starting point to develop a scientific approach for the functional mass customization aimed at the optimization of comfort in footwear. Reverse Engineering (RE) methodologies developed for building up the external shape of the human foot are presented and discussed. Aim of this work is to study the problem of the digitalization of human feet under different conditions using three technologies: shape from stereo, from silhouette and from shading. The foot is one of the most difficult human parts to reconstruct taking into account the complex surface and the high curvature. In this article the disadvantage and advantage of each technique are analyzed. In particular tests about reliability and precision of the measure are considered. © 2010 Society for Experimental Mechanics Inc.

Abstract: Scaffolds should possess suitable properties to play their specific role. In this work, the potential of 3D fiber deposition technique to develop multifunctional and well-defined magnetic poly(ε-caprolactone)/iron oxide scaffolds has been highlighted, and the effect of iron oxide nanoparticles on the biological and mechanical performances has been assessed. © 2010 American Institute of Physics.

Keywords: 3D fiber deposition | Iron oxide nanoparticles | Poly(ε-caprolactone) | Scaffolds | Tissue engineering

Abstract: Tissue engineering may be defined as the application of biological, chemical and engineering principles toward the repair, restoration or regeneration of living tissue using biomaterials, cells and biologically active molecules alone or in combinations. The rapid restoration of tissue biomechanical function represents a great challenge, highlighting the need to mimic tissue structure and mechanical behavior through scaffold designs. For this reason, several biodegradable and bioresorbable materials, as well as technologies and scaffold designs, have been widely investigated from an experimental and/or clinical point of view. Accordingly, this review aims at stressing the importance of polymer-based composite materials to make multifunctional scaffolds for tissue engineering, with a special focus on bone, ligaments, meniscus and cartilage. Moreover, polymer-based nanocomposites will also be briefly introduced as an interesting strategy to improve the biological and mechanical performances of polymer scaffolds, especially for bone tissue engineering. © 2010 Società Italiana Biomateriali.

Keywords: Bone | Cartilage | Composites | Ligaments | Meniscus | Polymers | Scaffolds

Abstract: The tissue engineering of tendon was studied using highly elastic poly(L-lactide-co-&epsi;-caprolactone) (PLCL) scaffolds and focusing on the effect of dynamic tensile stimulation. Tenocytes from rabbit Achilles tendon were seeded (1.0 × 106 cells/scaffold) onto porous PLCL scaffolds and cultured for periods of 2 weeks and 4 weeks. This was performed in a static system and also in a bioreactor equipped with tensile modulation which mimicked the environmental surroundings of tendons with respect to tensile extension. The degradation of the polymeric scaffolds during the culture was relatively slow. However, there was an indication that cells accelerated the degradation of PLCL scaffolds. The scaffold/cell adducts from the static culture exhibited inferior strength (at 2 weeks 350 kPa, 4 weeks 300 kPa) compared to the control without cells (at 2 weeks 460 kPa, 4 weeks 340 kPa), indicating that the cells contributed to the enhanced degradation. On the contrary, the corresponding values of the adducts from the dynamic culture (at 2 weeks 430 kPa, 4 weeks 370 kPa) were similar to, or higher than, those from the control. This could be explained by the increased quantity of cells and neo-tissues in the case of dynamic culture compensating for the loss in tensile strength. Compared with static and dynamic culture conditions, mechanical stimulation played a crucial role in the regeneration of tendon tissue. In the case of the dynamic culture system, cell proliferation was enhanced and secretion of collagen type I was increased, as evidenced by DNA assay and histological and immunofluorescence analysis. Thus, tendon regeneration, indicated by improved mechanical and biological properties, was demonstrated, confirming the effect of mechanical stimulation. It could be concluded that the dynamic tensile stimulation appeared to be an essential factor in tendon/ligament tissue engineering, and that elastic PLCL co-polymers could be very beneficial in this process. © 2010 Koninklijke Brill NV, Leiden.

Keywords: BIOREACTOR | MECHANICAL STIMULATION | PLCL | TENDON | TISSUE ENGINEERING

Abstract: Objective: To evaluate volumetric variations in the palate following rapid expansion, both immediately after treatment and over time. Materials and Methods: The sample was composed of 30 patients in early mixed dentition treated with a Haas-type device cemented onto the primary second molars. The mean age of the patients upon commencement of expansion was 7 years and 6 months (standard deviation [SD], 12 months). Measurement of palatal volume was conducted via 3D acquisition of plaster models using laser scanning before treatment (T1), upon device removal (T2), and 2.6 years afterward (T3). Results: The volume of the palate increased in a statistically significant fashion from T1 to T2 and from T1 to T3, and it decreased in a nonsignificant fashion from T2 to T3. Conclusions: Palatal volume significantly increases with rapid maxillary expansion (RME) treatment with insignificant relapse. The use of virtual 3D models with the aid of Apposite software permits evaluation of the morphologic and volumetric changes induced by orthodontic treatment. © 2010 by The EH Angle Education and Research Foundation, Inc.

Keywords: Laser | Palate | RME | Volume

Abstract: We developed a model to test new bone constructs to replace spare skeletal segments originating from new generation scaffolds for bone marrow-derived mesenchymal stem cells. Using computed tomography (CT) data, scaffolds were defined using computer-aided design/computer-aided manufacturing (CAD/CAM) for rapid prototyping by three-dimensional (3D) printing. A bone defect was created in pig mandible ramus by condyle resection for CT and CAD/CAM elaboration of bone volume for cutting and scaffold restoration. The protocol produced a perfect-fitting bone substitute model for rapid prototyped hydroxyapatite (HA) scaffolds. A surgical guide system was developed to accurately reproduce virtually planned bone sectioning procedures in animal models to obtain a perfect fit during surgery. © 2008 Elsevier Ltd. All rights reserved.

Keywords: Bone regeneration | CAD-CAM | Maxillofacial prosthesis | Rapid prototyping | Scaffold

Abstract: At present, computer assisted surgery systems help orthopaedic surgeons both plan and perform surgical procedures. To enable these systems to function, it is crucial to have at one's disposal 3D models of anatomical structures, surgical tools and prostheses (if required). This paper analyses and compares three methods for generating 3D digital models of anatomical structures starting from X-ray images: parametric solid modelling/reconfiguration, global shape modelling and free-form deformation. Seven experiences involving the generation of a femur model were conducted by software developers and different skilled users. These experiences are described in detail and compared at different stages and from different points of view. © 2009 Taylor & Francis.

Keywords: 3D modelling of anatomical structures | CAS systems | Orthopaedic surgery | Surgical planning

Abstract: Repairing critical human skull injuries requires the production and use of customized cranial implants and involves the integration of computer aided design and manufacturing (CAD and CAM). The main causes for large cranial defects are trauma, cranial tumors, infected craniotomy bone flaps and external neurosurgical decompression. The success of reconstructive cranial surgery depends upon: the preoperative evaluation of the defect, the design and manufacturing of the implant, and the skill of the operating surgeon. Cranial implant design is usually carried out manually using CAD although this process is very time-consuming and the quality of the end product depends wholly upon the skill of the operator. This paper presents an alternative automated method for the design of custom-made cranial plates in a PHANToM®-based haptic environment, and their direct fabrication in biocompatible metal using electron beam melting (EBM) technology. © 2008 Elsevier Ltd. All rights reserved.

Keywords: Custom cranial implant | Electron beam melting (EBM) | Haptic environment | PHANToM-based tools

Abstract: Tissue engineering represents an interesting approach which aims to create tissues and organs de novo. In designing scaffolds for tissue engineering applications, the principal goal is to mimic the function of the natural extracellular matrix, providing a temporary template for the growth of target tissues. For this reason, scaffolds should possess suitable mechanical properties and architecture to play their specific role. In this paper, limitations of conventional scaffold fabrication methods will be briefly introduced, and rapid prototyping techniques will be described as advanced processing methods to realize customized scaffolds with controlled internal microarchitecture. Among the rapid prototyping techniques, the potential and challenges of 3D fiber deposition to create multifunctional and tailor-made scaffolds will be reviewed. © Società Italiana Biomateriali.

Keywords: 3D fiber deposition | Bioplotter | Rapid prototyping | Scaffolds | Tissue engineering

Abstract: Mandibular symphyseal distraction osteogenesis is a common clinical procedure to modify the geometrical shape of the mandible for correcting problems of dental overcrowding and arch shrinkage. In spite of consolidated clinical use, questions remain concerning the optimal latency period and the influence of mastication loading on osteogenesis within the callus prior to the first distraction of the mandible. This work utilized a mechano-regulation model to assess bone regeneration within the callus of an osteotomized mandible. A 3D model of the mandible was reconstructed from CT scan data and meshed using poroelastic finite elements (FE). The stimulus regulating tissue differentiation within the callus was hypothesized to be a function of the strain and fluid flow computed by the FE model. This model was then used to analyse tissue differentiation during a 15-day latency period, defined as the time between the day of the osteotomy and the day when the first distraction is given to the device. The following predictions are made: (1) the mastication forces generated during the latency period support osteogenesis in certain regions of the callus, and that during the latency period the percentage of progenitor cells differentiating into osteoblasts increases; (2) reducing the mastication load by 70% during the latency period increases the number of progenitor cells differentiating into osteoblasts; (3) the stiffness of new tissue increases at a slower rate on the side of bone callus next to the occlusion of the mandibular ramus which could cause asymmetries in the bone tissue formation with respect to the middle sagittal plane. Although the model predicts that the mastication loading generates such asymmetries, their effects on the spatial distribution of callus mechanical properties are insignificant for typical latency periods used clinically. It is also predicted that a latency period of longer than a week will increase the risk of premature bone union across the callus. © International Federation for Medical and Biological Engineering 2007.

Keywords: Finite element modelling | Mandibular distraction osteogenesis | Mechanobiology | Orthodontic devices | Tissue differentiation

Abstract: Computed tomography is a medical instrument that can be useful not only for diagnostic purposes, but also for surgical planning, thanks to the fact that it offers volumetric information which can be translated in three dimensional models. These models can be visualized, but also exported to Rapid Prototyping (RP) systems, that can produce these structures thanks to the rapidity and versatility of the technologies involved. The literature reports various cases of stereolithographic models used in orthopedic, neurological, and maxillo-facial surgery. In these contexts, the availability of a copy of the real anatomy allows not only planning, but also the practical execution of surgical operations, within the limitations of the materials. Nevertheless, the Rapid Prototyping model also presents some disadvantages that can be reduced if practical simulation is accompanied by virtual simulation, performed on a digital model. The purpose of this work is to examine and present the use of Virtual Reality (VR) and Rapid Prototyping for surgical planning in Maxillo-Facial surgery. ©2008Muntaz B. Habal, MD.

Keywords: Osteogenesis distraction | Rapid prototyping | Reverse engineering | Surgical planning | Virtual reality

Abstract: Quality of service, in terms of improvement in patient satisfaction, is an increasingly important objective in all medical fields, and is especially imperative in orthodontics due to the high numbers of patients treated. Information technology can provide a meaningful contribution to bettering treatment processes, and we maintain that systems such as CAD, CAM and CAE, although initially conceived for industrial purposes, should be evaluated, studied and customized with a view to use in medicine. The present study aims to evaluate Reverse Engineering (RE) and Rapid Prototyping (RP) in order to define an ideal chain of advanced technological solutions to support the critical processes of orthodontic activity.

Abstract: Purpose: Low back pain related to intervertebral disc (IVD) degeneration represents a socio-economic problem which affects quality of life. In order to solve this problem the current gold standard techniques such as spinal arthroplasty and arthrodesis (or fusion) are considered. As for spinal arthroplasty, over the past 40 yrs, IVD prostheses have been designed to maintain the correct IVD spacing and to allow for motion, while providing stability. However, there are many difficulties in incorporating important features such as viscoelastic and shock absorber behavior of natural IVDs in a prosthetic disc design. Moreover, in some cases, the use of IVD prostheses does not represent the ideal solution. Consequently, the aim of this study was to improve the design of alternative devices for spinal fusion, which overcome the problems related to metal ones currently available on the market, such as stress shielding, stress concentration effects and eventual bone corrosive or inflammatory reaction. Methods: Accordingly, a novel polyetherimide (PEI)-based cage reinforced with carbon fibers through filament winding and compression molding technologies was realized. Results: The characterization through a porcine model has produced very interesting results. The small values obtained from local compression tests have suggested that a reduction in mobility occurred, whereas distributed compression tests on IVDs prosthesized by employing the PEI-based cage reinforced with carbon fibers have highlighted a compressive stiffness of 100 MPa. This stiffness is lower than that of the IVD prosthesized through the titanium cage (146 MPa), and closer to the stiffness of natural porcine IVDs (90 MPa). Conclusions: Through a suitable composite cage design it is possible to control stress-strain distributions and the mechanical signals to bone, thus avoiding the stress-shielding phenomena, but also corrosion and metal ions release which are typical of the metallic implants. © Società Italiana Biomateriali.

Keywords: Composite interbody fusion device | Intervertebral disc | Mechanical behavior | Porcine model | Prosthesized segments

Abstract: Tissue engineered scaffolds must have an organized and repeatable microstructure which enables cells to assemble in an ordered matrix that allows adequate nutriental perfusion. In this work, to evaluate the reciprocal cell interactions of endothelial and osteoblast-like cells, human osteoblast-like cells (MG63) and Human Umbilical Vein Endothelial Cells (HUVEC) were co-seeded onto 3D geometrically controlled porous poly(ε-caprolactone) (PCL) and cultured by means of a rotary cell culture system (RCCS-4DQ). In our dynamic co-culture system, the lack of significant enhancement of osteoblast ALP activity and ECM production indicated that the microgravity conditions of the rotary system affected the cells by favoring their proliferation and cellular cross-talk. These results emphasize how osteoblasts increase endothelial cell proliferate and endothelial cells amplify the growth of osteoblasts but decrease their differentiation. This dynamic seeding of osteoblasts and endothelial cells onto a 3D polymeric scaffold may represent a unique approach for studying the mechanisms of interaction of endothelial and osteoblast cells as well as achieve a functional hybrid in which angiogenesis, furnished by neo-vascular organization of endothelial cells may further support osteoblasts growth. Furthermore, this in vitro model may be useful in examining the applicability of novel material structures for tissue engineering. © SAGE Publications 2008.

Keywords: 3D scaffolds | Dynamic co-culture | Poly-ε- caprolactone | Rapid prototyping | Tissue engineering

Abstract: Purpose - The purpose of this paper is to consider surgical robotics, with a focus on technology and design issues for remote-mode operation assistance. The investigation leads to the definition of the technical characteristics of a co-robotic positioning device (CRPD), to be developed in support of a split-duty approach to planning. The expected characteristics and advantages are outlined, including the operation potential of special-purpose devices (e.g. an automatic changer for surgical tools) and of scope-driven enhancers (e.g. the exploration of the intervention theatre). Design/methodology/approach - The paper addresses example developments based on projects performed with the co-operation of other robot laboratories in Munich and Paris. The CRPD concept is applied in relation to the DLR KineMedic® arm (developed by the Munich laboratory), and with the LRP prototype mini-arm (built by the Paris laboratory). Findings - Minimally-invasive surgery deserves increasing attention to reduce post-operative hospital stays and to reduce complications. This leads to new trends in robotics, to facilitate safe, fast and accurate remote manipulation, and integrated computer-aided implements. The features of the example CRPD design are summarised for the two cases. Practical implications - The overall comments consider minimally-invasive robotic surgery as a given intervention practice in the near future, and the split-duty approach, supported by the CRPD technology, as a valuable aid for human-robot co-operation, according to the "best-of-skills" idea, supporting intervention under the surgeon's control. Originality/value - This investigation shows new results aimed at expanding the operation versatility of robotics with integrated intelligence, to enhance scope-driven alternatives and out-of-reach handling with improved dexterity and safe autonomic processing. © Emerald Group Publishing Limited.

Keywords: Remote handling devices | Robotics | Surgery

Abstract: Mandibular distraction osteogenesis is a clinical procedure used for modifying the mandibular geometry when problems of dental overcrowding and arch shrinkage occur. The objective of this study is to use a computational model of tissue differentiation to examine the influence of the rate of distraction on bone re-growth within the fracture callus of a human mandible submitted to symphyseal distraction osteogenesis. A 3D model of the mandible is reconstructed from CT scan data and meshed into finite elements. Two different mastication loadings have been investigated: a 'full' mastication load and a 'reduced' mastication load where the action of each muscle was reduced by 70%. Four different distraction rates were analyzed: 0.6, 1.2, 2, and 3 mm/day, allowing a total displacement of 6 mm. In the early stages of the distraction process it is predicted that there is a decrease in the amount of bone tissue forming within the center of the fracture gap for all distraction rates. After the initial phases of expansion, the bone tissue within the callus increases for the slower rate of distraction or continues to decrease at the faster rates of distraction. At the end of the simulated maturation period, 47% of the distracted callus was predicted to consist of bone tissue for a distraction rate of 0.6 mm/day, decreasing to 22% for a distraction rate of 3 mm/day. Significantly higher amounts of bone formation were predicted for all distraction rates for the case of reduced mastication loading. Disparities between the model predictions and what is observed in vivo were found. For instance, during the latency period, the distraction period and beyond, the model is predicting larger than expected amounts of cartilage tissue formation within the callus. This and other limitations of the proposed model are discussed and possible specific explanations for these disparities are provided in the paper. The model predicts a distraction rate of around 1.2 mm/day to be optimal as higher rates produce less bone tissue while the risk of a premature bone union is greater at slower rates of distraction because in the latter stages of the distraction process bone tissue is predicted to form between the left and right side of the bone callus. © 2007 Biomedical Engineering Society.

Keywords: Finite element analysis | Mandibular distraction osteogenesis | Mechanobiology | Osteotomized human mandible | Tissue differentiation

Abstract: Repairing severe human skull injuries requires customized cranial implants. Trauma, cranial tumors, infected craniotomy bone flaps and neurosurgical external decompression are the main causes for large cranial defects. The success of the reconstructive cranial surgery depends on diverse aspects regarding the preoperative evaluation of the defect, the design and manufacturing of the implant and the execution of the operation. Currently, the design of membranes is mainly a manual work, even with the use of CAD facilities, and results in a time-consuming and user-dependent skull reconstruction. This paper presents an automated design methodology for custom-made cranioplasty plates in a PHANToM®-based haptic environment and the possibility to manufacture the same using Solid Freeform Fabrication technologies.

Keywords: Custom-made cranial plates | Haptic environment | PHANToM®-based tools | Solid freeform fabrication

Abstract: A review of recent literature revealed a very high success rate of implants used to support a mandibular overdenture as an alternative to the conventional removable dentistry. Today there are already several prosthetic solutions for the same clinical situations: in particular, the implant support can be different depending on the type of implants used and their layout. It is well known that the success or the failure of implants interfaced with bone depends, taking into account a favourable biological reaction, on the structural condition of the biomechanical system constituted by the bone structure and the implant. Knowledge of the strain/stress pattern can allow one to establish if bone maintenance, resorption or addition is more likely to take place. In this work two different kinds of implant supports for overdenture retention were compared by means of FEM: they differed in the number of implants, their dimension, their location inside the mandible and, finally, in the presence/absence of a beam connecting all implants and making them all linked. Clinical follow-up was assessed by means of technetium 99m-MDP scintigraphy. The obtained results agree with the clinical experience.

Keywords: Biomechanics | Bone remodelling | Bone scintigraphy | Dental implants | FEM | Nuclear medicine

Abstract: The paper presents an innovative approach totally based on digital data to optimize lower limb socket prosthesis design. This approach is based on a stump's detailed geometric model and provides a substitute to plaster cast obtained through the traditional manual methodology with a physical model, realized with Rapid Prototyping technologies; this physical model will be used for the socket lamination. The paper discusses a methodology to reconstruct a 3D geometric model of the stump able to describe with high accuracy and detail the complete structure subdivided into bones, soft tissues, muscular masses and dermis. Some different technologies are used for stump acquisition: non contact laser technique for external geometry, CT and MRI imaging technologies for the internal structure, the first one dedicated to bones geometrical model, the last for soft tissues and muscles. We discuss problems related to 3D geometric reconstruction: the patient and stump positioning for the different acquisitions, markers' definition on the stump to identify landmarks, alignment's strategies for the different digital models, in order to define a protocol procedure with a requested accuracy for socket's realization. Some case-studies illustrate the methodology and the results obtained. © 2006 SPIE-IS&T.

Keywords: 3D geometrical model | Human body scanning | Lower limb prosthesis | Medical imaging | Rapid prototyping | Reverse engineering

Abstract: Incremental Forming processes have been introduced in the recent past as an alternative to the money consuming stamping technology, when small batches have to be manufactured. Anyway, they introduce some advantages in terms of flexibility and material formability but, also, some problems such as the dimensional accuracy decreasing. In this paper, a particular application is carried out taking into account the development of an innovative technique to produce a customised ankle support. In this way Incremental Forming process has been selected for the sheet profiling, exalting the role that this technology may play when single complex product has to be manufactured. The producing procedure finishes with a measure of the dimensional accuracy that shown a good result for the desired application. © 2005 Elsevier B.V. All rights reserved.

Keywords: Ankle support | Incremental Forming | Reverse engineering

Abstract: The purpose of the present work was to develop a tool for preoperatively planning the Total Hip Replacement (THR). Starting from the MR images, the 3D surface model of both the pelvis and the femur was built and the surgical operation was virtually performed. Data coming from gait analysis were added to visualize the physiologic movement of the hip joint. The resulting triangular mesh was sufficiently accurate to allow the building of the stereolithographic model of the joint by means of rapid prototyping technique. The plastic bones allow the user to have an enhanced vision of the surgical procedure to be performed. © 2005 CARS and Elsevier B.V.

Keywords: Magnetic resonance imaging | Rapid prototyping | Surgical planning | Total hip replacement

Abstract: This article presents the use of stereolithography in oral implantology. Stereolithography is a new technology that can produce physical models by selectively solidifying an ultraviolet-sensitive liquid resin using a laser beam, reproducing the true maxillary and mandibular anatomic dimensions. With these models, it is possible to fabricate surgical guides that can place the implants in vivo in the same places and same directions as those in the planned computer simulation. A 70-year-old woman, in good health, with severe mandibular bone atrophy was rehabilitated with an overdenture supported by 2 Branemark implants. Two different surgical planning methods were considered: 1) the construction of a surgical guide evaluating clinical aspects, and 2) the surgical guide produced by stereolithographic study. The accuracy of surgical planning can reduce the problems related to bone density and dimensions. Furthermore, the stereolithographic study assured the clinicians of a superior location of fixtures in bone. Surgical planning based on stereolithographic technique is a safe procedure and has many advantages. This technologic advance has biologic and therapeutic benefits because it simplifies anatomic surgical management for improved implant placement. Copyright © 2004 by Lippincott Williams & Wilkins.

Keywords: Anatomic models | Jaw atrophy | Rapid prototyping | Surgical planning

Abstract: The planning of the hip prosthesis surgical operation is usually performed manually by the surgeon, who 'draws' on a patient's X-ray image the outline of the prosthetic stem in order to choose the one most suitable for the case at hand. In an attempt to give some repeatability and objectivity to the planning phase, a procedure has been devised for hip prosthesis' stem selection based on the extraction of the femoral relevant outlines. This work presents a computer aided method aimed at automatically extracting the medulla duct outlines from a human femur radiographic image. The outlines are retrieved by referring to a suitable geometric model of the generic femoral cross-section; the projection function obtained by simulating the radiographic acquisition of such a model is fitted on the grey-level functions corresponding to the rows of the actual digitised radiographic image by means of a least squares algorithm. The resulting outlines are used in a software tool performing the hip prosthesis pre-operational planning. © 2003 Published by Elsevier B.V.

Keywords: Medical images processing | Model-based image processing | Surgery aiding tools

Abstract: This work presents a procedure aimed at automatically extracting the medulla duct outlines from a human femur radiographic image. The outlines are retrieved by referring to a suitable geometric model of the generic femoral cross section; the projection function deriving from such a model is fitted on the grey level values corresponding to the rows of the digitised radiographic image by means of a least square algorithm. The resulting outlines are used in a software system performing the hip prosthesis pre-operational planning.

Abstract: This work illustrates a computer program designed to aid surgeons in selecting the hip prosthesis femoral component during the preoperation planning stage of hip replacement surgery. Starting from the processing of the patient's coxo-femoral region X-ray image, the program, called Hippin, interacts with the user to outline the femoral region, including the head and the inner contour of the proximal femur. It automatically examines all possible couplings with the patient's femur outlines from a database containing the outlines of the available prostheses created by digitizing the templates normally used in preoperation planning. The resulting images enable the surgeon to visually compare all the alternatives. In addition, the program provides numerical values for the distances between the physiological rotation and prosthesis centers, helping the surgeon in selecting from among the possibilities. The program has been validated by comparing the computer results with actual surgeon selections. (C) 2000 Elsevier Science Ireland Ltd.

Keywords: Hip prosthesis | Image processing | Preoperation planning

Abstract: Hip joint simulators were developed for predicting, by attempting to duplicate in vitro physiological loads and motion, the wear rate that total hip replacements are likely to show in vivo. From a theoretical point of view, loading and motion cycles of hip joints could be closely reproduced by three rotation actuators and three force actuators. However existing devices have been designed assuming that some of these degrees of freedom are negligible, in order to reduce the complexity of the equipment. The present study singles out some preliminary indications on the design choices regarding the spatial configuration of loading and motion actuators. The aim is to define theoretically a simplified simulator but still able to apply the most physiologically realistic loading cycle to the specimen.

Keywords: Biomechanics | Hip joint simulator | Wear