Methods for medical applications

Background: The emergency for the COVID-19 pandemic has led to greater use of home telemonitoring devices. The aim of this study was to assess the usability of continuous home-monitoring care with an oxygen saturation device on post-COVID-19 patients. Method: The system consists of a digital continuous pulse oximeter and a smartphone with an App, which were provided to patients. A survey composed of a standard Post-Study System Usability Questionnaire, and a satisfaction questionnaire was exploited to conduct a usability and feasibility analysis of the service. Results: A total of 29 patients (17.2% female) with a mean age of 65 ± 11.5 years were enrolled: 20 patients were smartphone users (69%) with a mean age of 60.2 ± 9.5 years, and 9 patients (31%) did not own a smartphone (mean age 76.8 ± 5.9). The monitoring period was 1 month: a total of 444 recordings were conducted, 15 recordings per patient averagely. In total, 82% of the recordings performed did not require any intervention, while 18% led to the production of a report and subsequent intervention by a nurse who verified, together with the specialist, the need to intervene (i.e. the patient accessed the clinic for medical control and/or modification of oxygen therapy). A total of 17 patients compiled a usability questionnaire. The service was perceived as useful and well-structured, although it often required caregiver support. Conclusions: Using continuous home-monitoring care with an oxygen saturation device seems feasible and useful for patients who could be followed at home avoiding going back to the hospital every time a trend oximetry is needed. Further improvements in connections, data flow processes, and simplifications, based on patients' feedback, are needed to scale up the service.

Keywords: COVID-19 , digital oximeter , Telemonitoring , usability , wearable sensors

Featured Application: Future interactive devices. Additive Manufacturing (AM) facilitates product development due to the various native advantages of AM when compared to traditional manufacturing processes. Efficiency, customisation, innovation, and ease of product modifications are a few advantages of AM. This manufacturing process can therefore be applied to fabricate customisable devices, such as bespoke interactive devices for rehabilitation purposes. In this context, a two-day workshop titled Design for Additive Manufacturing: Future Interactive Devices (DEFINED) was held to discuss the design for AM issues encountered in the development of an innovative bespoke controller and supporting platform, in a Virtual Reality (VR)-based environment, intended for people with limited dexterity in their hands. The workshop sessions were transcribed, and a thematic analysis was carried out to identify the main topics discussed. The themes were Additive Manufacturing, Generative Design Algorithms, User-Centred Design, Measurement Devices for Data Acquisition, Virtual Reality, Augmented Reality, and Haptics. These themes were then discussed in relation to the available literature. The main conclusion of this workshop was that a coherent design for AM tools is needed by designers to take AM considerations throughout the design process, since they lack the AM knowledge required to develop bespoke interactive devices.

Keywords: design for AM knowledge , future interactive devices , user experiences

Background: Microtia is a congenital anomaly of the ear. We present an innovative technique using a 3D personalized framework that could simplify and standardize the sculpting phase, thanks to reverse engineering and additive manufacturing techniques. Methods: Three-dimensional models were realized by T3Ddy, a joint laboratory between the department of industrial engineering and Meyer Children's Hospital. Data were obtained retrospectively and included patient demographics, primary diagnosis, side of the affected ear, microtia classification, surgical time, length of hospitalization, type of skin approach and framework, complications, aesthetic results, and level of satisfaction using specific questionnaires. Data are reported as median and IQR. Results: A total of 17 children (female gender: four) underwent auricular reconstruction surgery with autologous cartilage in our center, between 2019 and 2022. Median age at surgery was 14 years [interquartile range (IQR), 13-17], and the median hospitalization length was 5 days (IQR, 3-5). Median surgical time was 420 minutes (IQR, 406-452). Complications occurred in four patients out of 19 procedures, with a complication rate of 21%. Aesthetic results were satisfactory in all cases. Conclusions: The three-dimensional models allow for an intuitive and precise approach. Having developed specific models for each component of the framework, we aimed to improve the aesthetic result and simplify the surgical intervention, guaranteeing a standardized yet personalized experience for each patient. The interprofessional partnership is fundamental to achieving this result.

Orbital exenteration is a radical and disfiguring operation. It is still under debate the absence of correlation between the term describing the resulting orbital defect and the type of reconstruction. Authors' goal was to propose a consistent and uniform terminology for Orbital Exenteration surgery in anticipation of patients' tailored management. Twenty-five patients who underwent orbital exenteration between 2014 and 2020 were reviewed. A parallel comprehensive literature review was carried on. Five different types of orbital exenteration where outlined. Multiple reconstructive procedures were enclosed. An algorithm for orbital reconstruction was proposed based on anatomic boundaries restoration. Eyelid removal was first considered as an independent reconstructive factor, and both orbital roof and floor were indicated as independent reconstructive goals, which deserve different defect classification. In our opinion, this algorithm could be a useful tool for patient counseling and treatment selection, which might allow a more tailored patient care protocol. Level of Evidence Level III.

Keywords: defect classification , orbital anatomy , orbital exenteration , orbital reconstruction , reconstructive flowchart

This article reports a study evaluating the effect of continuous assistance via an active exoskeleton during orientation tasks of the human wrist in a serious game. The proposed platform features a complete system that may be used for robot-assisted rehabilitation in clinics, offering support for both the therapist and the patient. It gives the possibility to customize the rehabilitation session by regulating the assigned task difficulty, the assistance level offered by the exoskeleton, and the wrist Degrees of Freedoms (DoFs) to be supported, providing a versatile, easy-to-use, rehabilitation station. The setup consists of a 3-DoFs wrist exoskeleton activated by three electric motors, connected to a wheeled station containing the control unit and the host PC to actuate the exoskeleton. The exoskeleton allows to monitor the positions of the human wrist joints and the force applied to the device by the user while performing a movement. Advanced software has been implemented to create a stimulating environment during therapy through virtual reality. The Flight Simulator serious game has been used to investigate the user's wrist Range of Motion (RoM) covered while reaching twenty targets. Thirteen healthy subjects tested the system under two different conditions, considering the device assistance on/off. Results show a significantly higher performance under assistance, rather than without it, on the exploitation of the wrist RoM and on the intuitiveness of movements during the orientation task. A reduction of around 30% of the overall muscle stress has been measured, highlighting the assistance efficacy of the system.

Keywords: Human-Robot Interaction , Mechanism Design , Medical and Rehabilitation Robots , Motor Control , Wearable Device , Wrist Exoskeleton

Background. Head and neck cancer (HNC) is the seventh most common neoplastic disorder at the global level. Contouring HNC lesions on [(Formula presented.) F] Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scans plays a fundamental role for diagnosis, risk assessment, radiotherapy planning and post-treatment evaluation. However, manual contouring is a lengthy and tedious procedure which requires significant effort from the clinician. Methods. We evaluated the performance of six hand-crafted, training-free methods (four threshold-based, two algorithm-based) for the semi-automated delineation of HNC lesions on FDG PET/CT. This study was carried out on a single-centre population of (Formula presented.) subjects, and the standard of reference was manual segmentation generated by nuclear medicine specialists. Figures of merit were the Sørensen–Dice coefficient (DSC) and relative volume difference (RVD). Results. Median DSC ranged between 0.595 and 0.792, median (Formula presented.) between −22.0% and 87.4%. Click and draw and Nestle's methods achieved the best segmentation accuracy (median DSC, respectively, 0.792 ± 0.178 and 0.762 ± 0.107; median RVD, respectively, −21.6% ± 1270.8% and −32.7% ± 40.0%) and outperformed the other methods by a significant margin. Nestle's method also resulted in a lower dispersion of the data, hence showing stronger inter-patient stability. The accuracy of the two best methods was in agreement with the most recent state-of-the art results. Conclusions. Semi-automated PET delineation methods show potential to assist clinicians in the segmentation of HNC lesions on FDG PET/CT images, although manual refinement may sometimes be needed to obtain clinically acceptable ROIs.

Keywords: head and neck cancer , positron emission tomography , radiomics , region of interest , segmentation

Purpose: To provide a comprehensive overview of the current literature on the applications of PET-based radiomics in patients affected by multiple myeloma (MM) and FDG-avid lymphomas. Methods: Relevant studies on the topic were selected by searching Pubmed/Medline. Retrospective or prospective cohort studies focusing on the clinical applications of PET-radiomics in lymphomas and MM were retrieved, analyzed, and discussed. Result: A total of 17 papers were ultimately selected, with 9 focusing on non-Hodgkin lymphomas, 6 on Hodgkin lymphomas, and 5 dealing with MM. Machine learning-derived models incorporating first-, second-, and third-order radiomic features extracted from baseline PET/CT scans demonstrated promising results in predicting outcomes, specifically the 2-year event-free survival (EFS) in lymphomas. Furthermore, models based on PET-radiomic features were effective in distinguishing between MM and bone metastases, as well as in assessing minimal residual disease, outperforming visual analysis. Conclusion: Preliminary results suggest that PET-radiomic features, which reflect the biological heterogeneity and spatial distribution of lesions, may play a prognostic role in both lymphomas and MM. Nevertheless, before implementing these findings in clinical practice, it is imperative to standardize the methodological approaches and validate them in large prospective trials.

Keywords: Artificial intelligence , FDG , Lymphomas , Machine learning , Multiple myeloma , PET/CT , Radiomics

Craniomaxillofacial surgeries are performed using custom-made physical cutting guides and resin dental splints that present several drawbacks (e.g. time and cost required for their design and production). The literature commonly provides augmented/mixed reality (AR/MR) solutions for assisting maxillofacial osteotomies and repositioning without any interactive guide. This work proposes a new MR application, useful for osteotomy and repositioning, providing interactive, fast, and intuitive feedback to the surgeon, who is then supported in performing the bone fragment resection and replacement frame by frame. The proposed application speeds up the surgery and reduces under/overshooting errors. Moreover, the idea of integrating osteotomy and repositioning assistance in the same MR application is rarely found in the literature. It is an entirely novel approach to craniomaxillofacial surgery. The MR application has been designed with a three-button menu. The “App Start” calibrates the app, the “Osteotomy Mode” visualises the holograms of the cutting lines and drilling points, and the “Repositioning Mode” visualises the step-by-step real-time feedback to precisely support the surgeon placing the osteotomised bone fragment towards the final pre-planned position. The MR app has been developed in Unity and deployed on Microsoft HoloLens V2. A laboratory test bench was realised to validate the accuracy of the proposed MR-based approach. The validation protocol consists of two tasks to test the osteotomy and repositioning modes using a 3D-printed skull phantom. For osteotomy, the accuracy is 0.89 mm (genioplasty), 1.24 mm (maxillary osteotomy), 1.33 mm (orthognathic surgery), and 2.89 mm (mandibular angle osteotomy). For repositioning, the accuracy is 0.6 mm (anteroposterior deviation), 0.7 mm (mediolateral deviation), and 0.6° (angular deviation).

Keywords: Augmented reality , Hololens , Maxillofacial surgery , Mixed reality , Surgical guide

Worldwide, life expectancy has steadily increased over the years. However, the integrity and the functionality of physiological systems reduce over time making older people more vulnerable to adverse events such as falls. Consequences of falls can include physical injuries (hip fractures), psychological issues (fear of falling) and social isolation (need for assistance) increasing the demand for healthcare services (hospitalization, rehabilitation, institutionalization). Despite many studies investigated the most predisposing factors to a fall risk, this study aimed at identifying those factors through a multidimensional health assessment of elderly people crossing over multiple health domains such as nutritional, clinical, psychological, social, and functional. The acquired variables were processed in terms of data cleaning and coding, to make them ready for subsequent statistical evaluation. Correlation and regression analyses were performed to find out the relevance of the variables with respect to the fall event. The most significant variables were accounted for the development of the predictive index. Each predictor was associated with a score according to specific weights so that the sum of the answers to each question of the index gave the final fall risk index. Its validation was assessed over the sample of the study by comparing the index output to that of the multidimensional evaluation and the one of a common fall risk test. Clinicians will benefit from this tool for a fast and easy screening of fall risk among community-dwelling seniors to act promptly on those subjects at increased risk, and preventively on low-risk subjects. This way, it is possible to optimize time, costs, and resources for sustainable and effective management of patient care.

Keywords: Data-driven approach , Fall-risk detection , Older adults , Predictive algorithm , Risk assessment , Risk prediction

Prosthetic socket for lower limb amputation needs to be customized based on the residual limb characteristics to satisfy functional and comfort requirements. One of the main causes for ill-fitting socket is the lack of appropriate application of material properties that match the characteristics of the amputee's biological tissue. Additive manufacturing has the ability to confer inhomogeneous properties to the printed object. This paper presents a digital workflow for the design and fabrication of a prosthetic socket based on the results of numerical simulations and the use of multi-material voxel printing. A voxel model of the socket is generated and the contact pressure between the residual limb and the socket derived from FEA is mapped to the voxels, which were correspondingly assigned a material. This allow to define a material distribution at the voxel level and to generate printing instructions as a stack of bitmap images for voxel printing. The goal is to obtain a socket characterized by a spatial variation of material stiffness, according to the pressure map extracted from simulation, in order to adapt the socket to the patient's anatomy and, consequently, to reduce contact pressure and discomfort.

Keywords: 3D Printing , FEA , Heterogeneous Objects , Prosthetic Socket , Voxel Printing

The development of comfortable, reliable and custom-made lower limb prostheses represents a crucial aspect, in order to improve the quality of life of amputees. In this context, the aim of this work is to study the donning phase of a custom-made prosthetic socket for transfemoral amputees, by means of numerical simulations. Finite Element Analyses (FEA) were performed to study contact pressures and stresses developed on the stump during the donning. Proper materials models and the presence of the friction and the liner were introduced, in order to analyze their impact on simulations results. Then, a sensitivity analysis to assess the influence of the stiffness of the liner was conducted. The proposed model was able to capture a comprehensive state of stress on the stump at the end of the donning phase. The beneficial effects linked to the introduction of the liner are properly described, too: this element is able to redistribute the stresses which are transmitted to the stump, thus obtaining a more homogenous state of stress. Finally, the sensitivity analysis showed that the variable stiffness of the liner mainly affects the maximum strains on the stump, whereas its influence on the maximum values of contact pressure seems to be limited.

Keywords: FEA , liner , prosthetic socket , transfemoral amputees

igital representations of anatomical parts are crucial for various biomedical applications. This paper presents an automatic alignment procedure for creating accurate 3D models of upper limb anatomy using a low-cost handheld 3D scanner. The goal is to overcome the challenges associated with forearm 3D scanning, such as needing multiple views, stability requirements, and optical undercuts. While bulky and expensive multi-camera systems have been used in previous research, this study explores the feasibility of using multiple consumer RGB-D sensors for scanning human anatomies. The proposed scanner comprises three Intel® RealSenseTM D415 depth cameras assembled on a lightweight circular jig, enabling simultaneous acquisition from three viewpoints. To achieve automatic alignment, the paper introduces a procedure that extracts common key points between acquisitions deriving from different scanner poses. Relevant hand key points are detected using a neural network, which works on the RGB images captured by the depth cameras. A set of forearm key points is meanwhile identified by processing the acquired data through a specifically developed algorithm that seeks the forearm's skeleton line. The alignment process involves automatic, rough 3D alignment and fine registration using an iterative-closest-point (ICP) algorithm expressly developed for this application. The proposed method was tested on forearm scans and compared the results obtained by a manual coarse alignment followed by an ICP algorithm for fine registration using commercial software. Deviations below 5 mm, with a mean value of 1.5 mm, were found. The obtained results are critically discussed and compared with the available implementations of published methods. The results demonstrate significant improvements to the state of the art and the potential of the proposed approach to accelerate the acquisition process and automatically register point clouds from different scanner poses without the intervention of skilled operators. This study contributes to developing effective upper limb rehabilitation frameworks and personalized biomedical applications by addressing these critical challenges.

Keywords: 3D optical scanning , automatic point cloud alignment , depth cameras , neural network , upper limb anatomy

(1) Background: The adoption of Virtual Surgical Planning (VSP) and 3D technologies is rapidly growing within the field of orthopedic surgery, opening the door to highly innovative and individually tailored surgical techniques. We present an innovative correction approach successfully used in a child affected by “windswept deformity” of the knees. (2) Methods: We report a case involving a child diagnosed with “windswept deformity” of the knees. This condition was successfully addressed through a one-stage bilateral osteotomy of the distal femur. Notably, the wedge removed from the valgus side was flipped and employed on the varus side to achieve the correction of both knees simultaneously. The surgical technique was entirely conceptualized, simulated, and planned in a virtual environment. Customized cutting guides and bony models were produced at an in-hospital 3D printing point of care and used during the operation. (3) Results: The surgery was carried out according to the VSP, resulting in favorable outcomes. We achieved good corrections of the angular deformity with an absolute difference from the planned correction of 2° on the right side and 1° on the left side. Moreover, this precision not only improved surgical outcomes but also reduced the procedure's duration and overall cost, highlighting the efficiency of our approach. (4) Conclusions: The integration of VSP and 3D printing into the surgical treatment of rare limb anomalies not only deepens our understanding of these deformities but also opens the door to the development of innovative, personalized, and adaptable approaches for addressing these unique conditions.

Keywords: 3D printing , autograft , cutting guide , in-hospital , patient-specific instruments , pediatric , point-of-care , VSP , windswept deformity

The design of scaffolds for multi-tissue regeneration is very complex in terms of material and structure, as a direct consequence of hierarchical and organizational features. TRIZ represents the Russian acronym for the “Theory of Inventive Problem Solving” (TIPS). TRIZ is able to identify and codify such principles, using them to make the creative process more predictable. It is a methodology for the identification of the system conflicts and contradictions in order to solve the inventive problems. Its multidisciplinary features and the general approach to product design can make TRIZ as an intriguing starting point for the biomimetic approach in a systematic and organized way. Biomimetics aims at a complete integration between nature and technology. In this scenario, BioTRIZ shares the contradiction resolution method of the Altshuller's theory, representing a systematic biomimetic approach towards the product design. In the current study, BioTRIZ was considered to systematize the process of bio-inspired design of 3D optimized scaffolds for the regeneration of complex tissue defects. A device for the regeneration of osteochondral tissue defects was considered as a case study. The technical solutions involved the design of a two-compartment, hybrid and functionally graded scaffold.

Keywords: Bio-inspired design , BioTRIZ , design for additive manufacturing , scaffolds for tissue engineering

Objectives: The aim of the present study was to design, produce and characterize composite substrates consisting of different formulations of poly(ε-caprolactone) (PCL), as a polymer matrix, and silver-containing mesoporous bioactive glasses (Ag-MBGs) with improved properties for bone tissue engineering. Methods: Ag-MBGs were synthesized by an evaporation-induced self-assembly process. Different polymer-to-particles weight ratios were considered (90/10, 80/20, 70/30 wt%). PCL/Ag-MBGs composites substrates were manufactured by melting and molding technique. The effect of Ag-MBGs embedded in the polymer matrix was investigated by morphological (field emission scanning electron microscopy (FE-SEM), SEM and contact angle measurement), structural/functional (small punch and tensile tests), antimicrobial, and in vitro biological analyses. Results: The obtained results highlighted that the inclusion of 10% by weight of Ag-MBGs improved the punching performances as well as the tensile Young's modulus (from 350.3 ± 32.0 MPa for PCL to 473.5 ± 41.0 MPa), without negatively altering the tensile strength of the neat PCL. Indeed, small punch test findings indicated that, over a threshold concentration (10% by weight), the Ag-MBGs acted as "weak points", rather than reinforcement, because the mechanical properties of the composite substrates decreased. The bacterial growth monitoring showed a clear antimicrobial effect against both Gram-negative and Gram-positive, confirmed by reduced cell viability registered after 24 h (2 ×105 CFU/mL for P. aeruginosa and 2.3 ×105 CFU/mL for S. aureus). The results were confirmed in terms of adhesion and adherent growth, reduced at day 3 on PCL samples with 10% of Ag/MBGs. Furthermore, this formulation induced a significant inhibition zone (21 mm for P. aeruginosa, 23 mm for S. aureus). In vitro biological assays confirmed that all formulations of PCL/Ag-MBGs supported periodontal ligament stem cells' viability and differentiation over time. Particularly, substrates with Ag-MBGs at a concentration of 10% and 20% by weight of Ag-MBGs provided higher values of the percentage of Alamar Blue reduction meanwhile, the highest Ag-MBGs concentration induced a higher expression of alkaline phosphatase activity. Significance: Ag-MBGs proved to be suitable candidates as filler at a specific threshold concentration (10% by weight), considering a compromise among physicochemical, antimicrobial, and pro-regenerative features. These findings provide useful data for the design and development of improved biomaterials with optimized properties, suggesting a potential application in maxillofacial bone and/or periodontal tissue repair.

Keywords: Antibacterial properties , Bone tissue engineering , Design of composite substrates , Mechanical analysis , Mesoporous bioactive glasses , PolycaprolactoneSilver

This paper focuses on the development of functionalized spongy chitosan scaffolds for bone tissue regeneration. Chitosan is a natural polymer that is readily available, biocompatible, and antibacterial. In this work, chitosan was covalently functionalized with two different bioactive peptide sequences, HVP (FRHRNRKGY) to improve cell adhesion, and GBMP1a (PFPLADHLNSTNHAIVQTLVNSF) to increase osteoblast proliferation and differentiation. HVP is an adhesive peptide mapped on human vitronectin, whereas GBMP1a reproduces a sequence derived from BMP-2 protein. Six different scaffolds were obtained by various combinations of both functionalized chitosan, also functionalizing the chitosan simultaneously with the two considered peptides. These matrices were then evaluated in in vitro biological assays with human jaw derived osteoblasts to assess their ability to induce modification of gene expression of characteristics proteins for this cell phenotype. Characterization of the matrices was completed with biomechanical tests, analysis by scanning electron microscope (SEM), and x-ray photoelectron spectroscopy (XPS).

Keywords: bone regeneration , chitosan , covalent functionalization , peptide

The study aims to optimize the topology of the complete disc replacement. In this paper, we present a stress-based topology optimization of a complete disc replacement for the lumbar spine using the finite element level set method (LS). The disc was optimized to reduce stress and strain at the level of two segments. The new modified pro disc design was proposed to increase the space for bone ingrowth and increase the stability of fixation. The intact model was tested in six degrees of freedom (compression, extension, flexion, lateral bending, and torsion). The volume of the intact model was reduced by 50% by optimizing the topology, and validation showed more significant results under biomechanical loading conditions. The Von Mises stress remains the same with minor differences. Topology optimization allows to increase bone ingrowth and reduces stress-shield effects in the cortical bone and cancellous bone.

Keywords: Complete Disc Replacement , Finite Element Method , Lumbar Spine , Topology Optimization

Background: Addressing intraoperative bleeding remains a significant challenge in the field of robotic surgery. This research endeavors to pioneer a groundbreaking solution utilizing convolutional neural networks (CNNs). The objective is to establish a system capable of forecasting instances of intraoperative bleeding during robot-assisted radical prostatectomy (RARP) and promptly notify the surgeon about bleeding risks. Methods: To achieve this, a multi-task learning (MTL) CNN was introduced, leveraging a modified version of the U-Net architecture. The aim was to categorize video input as either “absence of blood accumulation” (0) or “presence of blood accumulation” (1). To facilitate seamless interaction with the neural networks, the Bleeding Artificial Intelligence-based Detector (BLAIR) software was created using the Python Keras API and built upon the PyQT framework. A subsequent clinical assessment of BLAIR's efficacy was performed, comparing its bleeding identification performance against that of a urologist. Various perioperative variables were also gathered. For optimal MTL-CNN training parameterization, a multi-task loss function was adopted to enhance the accuracy of event detection by taking advantage of surgical tools' semantic segmentation. Additionally, the Multiple Correspondence Analysis (MCA) approach was employed to assess software performance. Results: The MTL-CNN demonstrated a remarkable event recognition accuracy of 90.63%. When evaluating BLAIR's predictive ability and its capacity to pre-warn surgeons of potential bleeding incidents, the density plot highlighted a striking similarity between BLAIR and human assessments. In fact, BLAIR exhibited a faster response. Notably, the MCA analysis revealed no discernible distinction between the software and human performance in accurately identifying instances of bleeding. Conclusion: The BLAIR software proved its competence by achieving over 90% accuracy in predicting bleeding events during RARP. This accomplishment underscores the potential of AI to assist surgeons during interventions. This study exemplifies the positive impact AI applications can have on surgical procedures.

Keywords: artificial intelligence , complications , prostate cancer , robotics

This paper explores how the examination of additively manufactured auxetic componentry can be applied in human-centred design settings with particular focus on biomedical products. Firstly, the design applications of auxetics are detailed followed by a review of the key problems facing practical researchers in the field with the treatment of boundary conditions identified as a key issue. The testing setup that is then introduced utilises a novel method of part mounting and facilitates optical analysis and real-time force–displacement measurements. A study is advanced that analyses three different auxetic structures (re-entrant, chiral, and semi-rigid), a set of samples of which were additively manufactured in flexible TPU material. A range of parameters were varied across the three designs including interior geometry and wall thicknesses in order to demonstrate the effectiveness of the setup for the examination of the different structures. The results from these examinations are subsequently discussed and a number of suggestions made regarding how this kind of analysis may be integrated into novel design development workflows for achieving human-centred biomedical devices which often require detailed consideration of ergonomic and usability factors.

Keywords: Auxetics , Biomedical applications , Human-centred design , Mechanical testing

Total knee arthroplasty (TKA) is the surgical procedure of choice for end-stage osteoarthritis. Even if it is widely performed, there is still dissatisfaction with the surgical procedure in about 20-30% of patients. Factors such as malalignment of the implant and the size of the components have been reported as the most common reasons for post-operative complaints. Custom-made prostheses have been introduced to replicate each individual joint geometry and kinematics. In this study, a novel approach is proposed to automate custom-made knee implant design. The aim is to create a pipeline, where customized implants can be designed automatically for a large number of patients, reducing the time for design. Firstly, a manual procedure for designing the implant is defined. The lower part of the femur is extruded with a thickness that matches with the natural anatomy of the patient and cut planes are used to design the customized femoral implant. Then, an automatic procedure is developed. For the purpose, a statistical shape model of femur, based on 33 patients, is created and employed. The procedure is tested with 5 study cases showing the potential of the methodology. Results will be furtherly validated on a larger scale.

Keywords: 3D Modelling , Customization , Human Modelling , Personalized , Statistical Shape Model , Total Knee Arthroplasty