Dissertations / Theses: 'Prosthesis simulator'

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Stokoe, Susan Marie. "A finger function simulator and surface replacement prosthesis for the metacarpophalangeal joint." Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6216/.

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Joint replacement surgery in the treatment of arthritic disease is now commonplace and on the whole very successful. Research into the design and development of prostheses has made major advances since the 1940s resulting in complex devices for almost all articulating joints of the body. In this thesis, a programme of work to design and test a surface replacement prosthesis for the metacarpophalangeal joint is presented. The anatomy and kinematics of the MCP joint are discussed for both normal and abnormal joint function and, based on these considerations, the design of a new surface replacement prosthesis is described. Various materials are explored with respect to their biocompatibility, durability and ease of fabrication with special attention being paid to one material - a new cross linked ultra-high molecular weight polyethylene - which is tested for wear and assessed for durability in long-term prototype tests. A finger function simulator is detailed which was designed and developed during this research programme, and results of tests on bone replicas, Swanson Silastic implants and prototypes of the new design are presented. The simulator can be easily modified to accept any MCP joint prosthesis for bench testing. Finally the stress response of the prototype design is studied using finite element analysis and modifications to the implant design and bone preparation are suggested.

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Ramakrishnan, Tyagi. "Asymmetric Unilateral Transfemoral Prosthetic Simulator." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5111.

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amputation, which includes reduced force generation at the knee and ankle, reduced control of the leg, and different mass properties relative to their intact leg. The physical change in the prosthetic leg leads to gait asymmetries that include spatial, temporal, or force differences. This altered gait can lead to an increase in energy consumption and pain due to compensating forces and torques. The asymmetric prosthesis demonstrated in this research aims to find a balance between the different types of asymmetries to provide a gait that is more symmetric and to make it overall easier for an amputee to walk. Previous research has shown that a passive dynamic walker (PDW) with an altered knee location can exhibit a symmetric step length. An asymmetric prosthetic simulator was developed to emulate this PDW with an altered knee location. The prosthetic simulator designed for this research had adjustable knee settings simulating different knee locations. The prosthetic simulator was tested on able-bodied participants with no gait impairments. The kinetic and kinematic data was obtained using a VICON motion capture system and force plates. This research analyzed the kinematic and kinetic data with different knee locations (high, medium, and low) and normal walking. This data was analyzed to find the asymmetries in step length, step time, and ground reaction forces between the different knee settings and normal walking. The study showed that there is symmetry in step lengths for all the cases in overground walking. The knee at the lowest setting was the closest in emulating a normal symmetric step length. The swing times for overground walking showed that the healthy leg swings at almost the same rate in every trial and the leg with the prosthetic simulator can either be symmetric, like the healthy leg or has a higher swing time. Step lengths on the treadmill also showed a similar pattern, and step length of the low knee setting were the closest to the step length of normal walking. The swing times for treadmills did not show a significant trend. Kinetic data from the treadmill study showed that there was force symmetry between the low setting and normal walking cases. In conclusion these results show that a low knee setting in an asymmetric prosthesis may bring about spatial and temporal symmetry in amputee gait. This research is important to demonstrate that asymmetries in amputee gait can be mitigated using a prosthesis with a knee location dissimilar to that of the intact leg. Tradeoffs have to be made to achieve symmetric step length, swing times, or reaction forces. A comprehensive study with more subjects has to be conducted in-order to have a larger sample size to obtain statistically significant data. There is also opportunity to expand this research to observe a wider range of kinetic and kinematic data of the asymmetric prosthesis.

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Estelle, Stephen. "Optimizing 3D Printed Prosthetic Hand and Simulator." Digital Commons at Loyola Marymount University and Loyola Law School, 2019. https://digitalcommons.lmu.edu/etd/661.

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The purpose of this study is to examine the position and use of an upper extremity prosthetic simulator on non-amputees. To see how a 3D printed prosthetic simulator can be optimized to serve the user correctly and accurately. In addition, this study examines the improvement of the Hosmer 5X Prosthetic Hook with the addition of newly designed trusses on to the prosthetic, as well as utilizing a new manufacturing method known as 3D printing. These topics are important because there is no standardized prosthetic simulator for schools and research facilities to use. Off the shelf prosthetic simulator cost upwards of $2000, often too expensive for early stage research. By optimizing the Hosmer 5X Prosthetic Hook with 3D printing, this new opportunity could allow amputees, from a range of income classes, to have access to a wide variety of prosthetics that are strong enough to support everyday living activities. A low-cost prosthetic that is easily distributable and accessible can give people a chance to regain their independence by giving them different options of efficient prosthetic devices, without having to spend so much. The devices in this project were design and analyzed on SOLIDWORKS, 3D scanned on the Artec Space Spider, and surfaced on Geomagic Wrap. Key results include developing a low-cost, robust prosthetic simulator capable of operating a Hosmer 5X Prosthetic hook, as well as developing a lighter version of the Hosmer 5X Prosthetic Hook that is more cost efficient and easily obtainable to the population around the world.

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Heying, Jamie John Gratton David G. "Flexural strength of interim fixed prosthesis materials after simulated function." [Iowa City, Iowa] : University of Iowa, 2009. http://ir.uiowa.edu/etd/377.

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Heying, Jamie John. "Flexural strength of interim fixed prosthesis materials after simulated function." Thesis, University of Iowa, 2009. https://ir.uiowa.edu/etd/377.

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Statement of Problem There are limited studies evaluating the effect of a cyclic load on interim fixed prosthetic materials and its effect on flexural strength. Purpose of Study 1) To verify the flexural strength of previously studied interim fixed prosthetic materials. 2) To establish the flexural strength of new, advanced generation and untested interim fixed prosthetic materials. 3) To determine the effect of cyclic load on the flexural strength of interim fixed prosthetic materials. Materials and Methods Bar-type specimens of Caulk Temporary Bridge Resin, VitaVM CC, Protemp 3 Garant and Radica were fabricated according to International Standards Organization 4049 and American National Standards Institute/American Dental Association specification 27. After being stored in distilled water for 10 days, specimens were divided into Noncycled and Cycled Groups. The Noncycled Group specimens were fractured under a 3-point loading in a Bose Electroforce 3300 testing instrument at a crosshead speed of 0.75 mm/min. Cycled Groups specimens underwent a 6-12 Newton 3 Hertz cyclic load for 20,000 cycles in a Bose Electroforce 3300 testing instrument. Immediately following completion of the cycles, the specimens were fractured under a 3-point loading. Maximal loads to fracture in Newtons were recorded and mean flexural strengths were calculated (n = 20 per group). Comparisons were made with analysis of variance and Tukey's Multiple Comparison Test. Results Noncycled (NC) and Cycled (C) groups order of mean flexural strengths (MPa) from lowest to highest mean were as follows: Caulk (Noncycled - 53.83; C - 60.02), Vita VM CC (NC - 65.96; C - 66.83), Protemp 3 Garant (NC - 75.85; C - 77.18), and Radica (NC - 106.1; C - 115.96). In the Noncycled and Cycled groups, Radica was statistically superior when compared to all materials and Protemp 3 Garant was statistically superior to Caulk Temporary Bridge Resin. There was no statistically significant difference between the material's flexural strengths before and after cycles. Conclusion Within the limitations of this study, 20,000 cyclic loads of 6-12 Newtons at 3 Hertz did not have a significant effect on the flexural strength of interim fixed prosthetic materials. Radica demonstrated significantly superior flexural strength over other materials tested.

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Smith, Simon Lawrence. "Design, development and applications of hip joint simulators." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/1132/.

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Anissian, H. Lucas. "In vitro evaluation of hip prostheses /." Stockholm, 2001. http://diss.kib.ki.se/2001/20010420anis/.

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Campbell, Neil. "Design of a knee simulator for the testing of total knee prostheses." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/3228.

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Brăileanu, Patricia-Isabela. "Research on optimizing customized prostheses." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI062.

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La thèse de doctorat intitulée " Research on optimizing customized prostheses " a pour objectif final de développer un logiciel qui modifie la géométrie d'une tige fémorale en fonction de paramètres prédéterminés après l’analyse des images tomographiques du patient. Afin d'obtenir des résultats, ont été réalisées les études suivantes : Des images tomographiques ont été obtenues de patients avec une hanche saine, de patients avec une hanche arthritique et de patients avec prothèse totale de hanche ; Une planification virtuelle de l'opération de remplacement total de la hanche a été réalisée pour construire une prothèse personnalisée et identifier les paramètres qui peuvent être optimisés ; Des études FEA ont été réalisées sur les tiges prothétiques standard et sur la tige prothétique personnalisée pour observer le comportement mécanique de la prothèse sujet à différentes charges externes ; Après avoir interprété les résultats, nous avons poursuivi le développement du logiciel, son objectif sera l’impression de la tige fémorale personnalisée par la technique de fabrication additive
This thesis aims to develop a virtual surgery planning methodology starting from the traditional Total Hip Replacement preoperative planning and having as final goal the realization of a template prosthesis that can be customized according to the femoral landmarks of each patient. Starting from the traditional preoperative planning of THR, which is done on the patients’ X-Ray and using the same principles of obtaining femoral landmarks, the CT scans of a patient with hip joint related disease that need to undergo a THR surgery were segmented by using specific algorithms in order to extract the patients’ femur and after that was imported in dedicated CAD software in which, with the help of evaluation instruments, all the patients’ femoral landmarks were identified. These femoral landmarks were used to develop a custom prosthesis starting from a standard anatomical femoral stem, which was validated using FEA simulations. Based on the information obtained, the development of a software coded in Python language was done to create somehow a tool that allows the analysis of patients’ CT scans in MPR view, but also in 3D view. It allows the bone segmentation of the affected area in order to obtain a CAD model file and perform the virtual preoperative planning in a CAD dedicated software, and finally use some of these dimensions in order to personalize a custom hip stem based on a pre-existing stem model used as basis for the desired geometrical transformations. The work is completed by printing it with FDM technology, using a biocompatible material to demonstrate the potential of this study, the versatility and the possibility of orienting the femoral stems used in THR towards personalization and AM, avoiding the use of standard prostheses that can lead to postoperative complications and thus leading to the elimination of prostheses “banks” due to the fact that they would no longer be necessary

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Lura, Derek J. "Modeling upper body kinematics while using a transradial prosthesis." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002751.

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Koelewijn, Anne D. "Predictive Simulations of Gait and Their Application in Prosthesis Design." Cleveland State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=csu1533901459119777.

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Wang, Lin. "Digital prototyping of a dental articular simulator to test prosthetic components." Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540870.

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Chen, Spencer Chin-Yu Graduate School of Biomedical Engineering Faculty of Engineering UNSW. "The perception and comprehension of prosthetic vison: patient rehabilitation and image processing considerations from simulated prosthetic vision psychophysics." Publisher:University of New South Wales. Graduate School of Biomedical Engineering, 2009. http://handle.unsw.edu.au/1959.4/44414.

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A successful restoration of vision should allow the blind to look, to see and to understand. The engineering of a microelectronic vision prosthesis has come a long way over the last forty years, but the understanding of how the restored form of vision would be interpreted and functionally applied to everyday living has made little progress until recent times. Prosthetic vision is not what most people think it would be; it is a visual scene composed of relatively large, isolated, spots of light so-called "phosphenes", very much like a magnified pictorial print. This thesis dissertation seeks to obtain a complete survey of the visual description of phosphenes from the human trial reports in the literature, simulate it, obtain a measure of the functional capacity of such visual perception, and explain the measured performance against design aspects of phosphene presentation, human perception, cognition and behaviour. Specifically, "visual acuity" (VA) was assessed on normally sighted subjects (N=15) administered with "simulated prosthetic vision". VA is a functional measure of vision highly correlated to many daily activities. Aggregating the results from the study with the other VA studies in prosthetic vision, it is shown that in general, the density of the phosphene field determines the affordable VA; however, design aspects relating to the phosphene field lattice (0.03 10gMAR with the hexagonal lattice as opposed to a square lattice) and image processing routines (0.15 10gMAR at optimised settings) can be further fine-tuned to improve VA performance. Significant performance improvement also arose from learning (0.13 10gMAR over ten visitations) and visual scanning adaptation (0.20 10gMAR with a circular scanning strategy). Performance improvements are likely related to various preferences and perceptual preferences of the human visual system. A rehabilitation program targeting the appropriate behavioural adaptation coupled with image processing routine optimised for image comprehension should provide a vision prosthesis recipient with the best functional experience to restored vision.

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Tatur, Guillaume. "Conception d'un système de vision par phosphènes." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20006.

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Ces travaux s'inscrivent dans le cadre plus général de la réalisation d'une prothèse visuelle, destinée aux personnes atteintes de cécité tardive due à une maladie dégénérative des cellules photo réceptrices de la rétine. Par la stimulation adéquate de certaines parties des voies optiques encore fonctionnelles, il est possible de transmettre à nouveau des perceptions visuelles, appelées phosphènes, dans le champ visuel du patient. Les études actuelles portant sur le contenu informationnel de cette vision prothétique proposent simplement de réduire la résolution de l'image d'une caméra embarquée. Notre étude propose une nouvelle approche basée sur le principe de la vision fonctionnelle, développée en collaboration avec les spécialistes de la rééducation fonctionnelle de l'institut ARAMAV. Par le biais de cette approche innovante, nous avons défini des méthodes d'extraction et de représentation des informations de la scène. L'objectif est d'améliorer l'autonomie en mobilité et de rendre possible la perception des expressions faciales. Pour évaluer la pertinence de ces propositions, nous avons développé un simulateur de vision prothétique, dont les paramètres sont basés sur les résultats d'essais cliniques. Pour la mobilité, nous mettons notamment en évidence l'intérêt de fournir un accès aux informations 3D, en substitution ou en complément de l'information de luminosité, ainsi que l'intérêt d'utiliser un oculomètre pour améliorer et faciliter la prise d'informations. Des expériences spécifiques à la mobilité, ainsi que certains résultats initiaux sont présentés. Pour la reconnaissance des expressions faciales, notre étude apporte la preuve que ces expressions sont correctement perçues si nous combinons des techniques de sélection de l'information et l'utilisation de certains prétraitements
This work falls within the broader framework of visual prostheses conception, designed for people suffering from late blindness due to degenerative diseases of retina photoreceptor cells. By stimulating certain part of the optical pathway that is still functional, it is possible to elicit visual perceptions, called phosphenes, in the subject's visual field. Recent studies on the problematic of informational content of prosthetic vision propose, in majority, a simple reduction in the resolution of grayscale images acquired from a single head worn camera. Our study proposes a new approach based on the principle of functional vision, developed in collaboration with specialists in functional rehabilitation of the ARAMAV institute. Through this innovative approach, we have defined methods for extraction and representation of scene informational content, which aim to improve autonomy in mobility and to make possible the perception of facial expressio ns. In order to evaluate these propositions, we have developed a prosthetic vision simulator, whose parameters are based on clinical trials results. For mobility, we present the usefulness of providing access to 3D information, in substitution or in addition with brightness information and the usefulness of an eye tracking device to improve and facilitate spatial knowledge acquisition. Experiments dedicated to mobility as well as some preliminary results are presented. For the recognition of facial expressions, our study provides evidence that these expressions are correctly perceived if we combined information selection and specific image processing techniques

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Wang, Feng. "Adaptive fuzzy network with application to neural prosthetic control, a computer simulation study." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0028/MQ40121.pdf.

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Lura, Derek James. "The Creation of a Robotics Based Human Upper Body Model for Predictive Simulation of Prostheses Performance." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4133.

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This work focuses on the use of 3D motion capture data to create and optimize a robotic human body model (RHBM) to predict the inverse kinematics of the upper body. The RHBM is a 25 degrees of freedom (DoFs) upper body model with subject specific kinematic parameters. The model was developed to predict the inverse kinematics of the upper body in the simulation of a virtual person, including persons with functional limitations such as a transradial or transhumeral amputation. Motion data were collected from 14 subjects: 10 non-amputees control subjects, 1 person with a transradial amputation, and 3 persons with a transhumeral amputation, in the University of South Florida's (USF) motion analysis laboratory. Motion capture for each subject consisted of the repetition of a series of range of motion (RoM) tasks and activities of daily living (ADLs), which were recorded using an eight camera Vicon (Oxford, UK) motion analysis system. The control subjects were also asked to repeat the motions while wearing a brace on their dominant arm. The RoM tasks consisted of elbow flexion & extension, forearm pronation & supination, shoulder flexion & extension, shoulder abduction & adduction, shoulder rotation, torso flexion & extension, torso lateral flexion, and torso rotation. The ADLs evaluated were brushing one's hair, drinking from a cup, eating with a knife and fork, lifting a laundry basket, and opening a door. The impact of bracing and prosthetic devices on the subjects' RoM, and their motion during ADLs was analyzed. The segment geometries of the subjects' upper body were extracted directly from the motion analysis data using a functional joint center method. With this method there are no conventional or segment length differences between recorded data segments and the RHBM. This ensures the accuracy of the RHBM when reconstructing a recorded task, as the model has the same geometry as the recorded data. A detailed investigation of the weighted least norm, probability density gradient projection method, artificial neural networks was performed to optimize the redundancy RHBM inverse kinematics. The selected control algorithm consisted of a combination of the weighted least norm method and the gradient projection of the null space, minimizing the inverse of the probability density function. This method increases the accuracy of the RHBM while being suitable for a wide range of tasks and observing the required subject constraint inputs.

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Sullins, Tyler Kayne. "The Development of a Prosthetic Training Software for Upper Limb Amputees." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6406.

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The purpose of this study was to develop an intuitive software that aids in the field of prosthetic training and rehabilitation by creating an individualized visualization of joint angles. This software is titled “the prosthetic training software (PTS) for individualized joint angle representation”, and it enables the individualized portrayal of predicted or pre-recorded joint angles. The PTS is an intuitive program for clinicians and prosthesis users that produces an animation of a virtual avatar reflecting the user’s segment lengths and amputation for rehabilitation and training purposes. The PTS consists of a graphical user interface (GUI) and a 3D visualization of the information input into the GUI. This software was developed in Microsoft Visual Studio (Microsoft, Redmond, Washington) as well as the Unity game engine (Unity Technologies, San Francisco, California) in the programming language C#. Four GUI tabs were created consisting of a patient input tab, a patient measurements tab, a prosthesis view and search tab, and a tab dedicated to editing a list of prostheses. Code was developed to take information input into these tabs to create an individualized 3D human model for the visualization. Twenty-four models were created in order to allow for unique portrayal of that input data. The models consisted of small, medium and large sizes, both male and female genders, and able-bodied, transradial left side, and transradial right side amputation variations. A generic transradial prosthesis was created for the use in the variations of these models. An additional six stick figure models were generated in order to give additional perspective of the portrayed joint angles. Code was also developed in order to animate these models accurately to the joint angles that are sent to them. Playback speed, viewing orientation, and perspective control functionalities were developed in order to assist in the comprehensiveness of the displayed joint angles. The PTS is not meant to be standalone software, however, the functionalities that it needed to encapsulate in order to work in conjunction with research currently being conducted at USF were tested. The intuitiveness of the GUI and visualization was evaluated by ease of use surveys, as well as volunteer commentary, in order to find how easily the interface that can be operated in a home setting without the oversight of an experienced operator. On average, subjects agreed that the PTS was intuitive to use, both for inputting information and utilizing the visualization. Feedback from these surveys will be used to further improve the PTS in the future. The feasibility of learning from the visualization output from the PTS was tested by comparing motions from five able-bodied subjects before and after having been taught three motions comprising pre-recorded joint angles animated by the PTS. Joint angles were calculated from recorded marker positions. It was found that after viewing the animation, the joint angles were markedly closer to the joint angles portrayed to them. This shows that the PTS is fully capable of showing joint angles in a comprehensive way. Future work will include additional testing of these functionalities, including the testing of prosthesis users, as well as the introduction and testing of new features of prosthesis recommendation and predictive joint angle production when later combined with future research.

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Ballit, Abbass. "Design and manufacturing process optimization for prosthesis of the lower limb." Thesis, Compiègne, 2020. http://www.theses.fr/2020COMP2589.

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Le socket prothétique (dit aussi emboiture prothétique), élément d'interface essentiel entre le moignon du patient et le dispositif prothétique, est le plus souvent le lieu où se définit le degré de réussite prothétique. C'est la partie la plus critique de la prothèse, personnalisée pour s'adapter au membre résiduel unique de l'amputé. Sans une forme et un ajustement approprié du socket, la prothèse devient inconfortable, voire inutilisable, et provoque des douleurs et des problèmes de peau. La production prothétique actuelle manque encore de normes numériques universelles pour concevoir un socket. La pratique actuelle est coûteuse et repose sur les raffinements manuels du technicien orthopédiste, et la qualité de l'ajustement est strictement corrélée à ses compétences ainsi qu'aux retours subjectifs du patient lors des phases d’essai de la prothèse fabriquée. La thèse vise à mener une analyse approfondie d'une conception optimale de l'emboîture prothétique en étudiant un processus alternatif de conception assistée par ordinateur. Ce processus est entièrement basé sur le modèle virtuel du membre résiduel du patient et repose sur le calcul de l’interaction emboîture-moignon. Un calcul rapide est favorable dans ce cas, c'est pourquoi nous proposons d'utiliser le système Mass-Spring (MSS) au lieu de la méthode FE largement utilisée pour modéliser les tissus mous du membre résiduel. Une nouvelle configuration du modèle MSS est proposée pour respecter la propriété de non compressibilité des tissus mous en ajoutant des « ressorts correctifs » non linéaires. Le modèle numérique doit être généré à partir du modèle scanné du moignon. À cette fin, nous proposons un schéma de fusion de quatre capteurs de profondeur à bas coût pour un scan rapide et économique avec des techniques de réduction des erreurs. Enfin, le membre résiduel virtuel est utilisé dans la phase de conception du socket. Une méthode de conception paramétrique est proposée et étudiée. Le problème de conception est transformé en problème de satisfaction des contraintes dérivées du calcul inverse de l'interaction socket-moignon. L'approche inverse a été choisie pour éliminer le besoin d'une formulation de contact coûteuse. Ce fait conduit à des calculs rapides, et par conséquent, permet de fournir des retours numériques en temps réel pendant le processus de conception. Le système a été implémenté pas programmation C++ avec une interface graphique où les retours numériques sont donnés sous forme d’une carte de radar. La validation a été faite en comparant les résultats de notre système avec la sortie des simulations FE. Le système a été implémenté avec une interface graphique conviviale et virtuellement testé et validé numériquement. Ce système réduit les limites des pratiques actuelles. Cependant, de nombreux travaux sont encore en cours pour affiner et développer le système et le valider par des expériences cliniques
The prosthetic socket, an essential interface element between the patient's stump and prosthetic device, is most often the place where the degree of prosthetic success is defined. It is the most critical part of the prosthesis, customized to fit with the unique residual limb of the amputee. Without a proper socket shape and fit, the prosthesis becomes uncomfortable, or even unusable, and causes pain and skin issues. The state-of-the-art prosthetic production is still missing universal numerical standards to design a socket. The current practice is expensive and relies on the manual refinements of the orthopedic technician, and the fit quality strictly correlates with his skills as well as the subjective feedback of the patient. The thesis aims to conduct a deep analysis of an optimal design of the prosthetic socket by studying and developing an alternative computer-aided design process. This process is fully based on the virtual model of the patient’s residual limb and relies on the calculation of the socket-stump interaction. A fast calculation is favorable in this case, that’s why we propose to use the Mass-Spring System (MSS) instead of the widely used FE method to model the soft tissues of the residual limb. A new configuration of the MSS model is proposed to respect the non-compressibility property of the soft tissues by adding non-linear “Corrective Springs”. The numeric model is to be generated from the scanned model of the stump. For this purpose, we propose a fusion scheme of four RGB-Depth sensors for a rapid and low-cost scan with error reduction techniques. Finally, the virtual residual limb is used in the socket designing phase. A parametric design method is proposed and investigated. The design problem is transformed into a constraint-satisfaction-problem whose constraints are derived from the inverse calculation of the stump-socket interaction. The inverse approach has been chosen to eliminate the need for expensive contact formulation. This fact leads to rapid calculations, and consequently, allows to provide real-time numerical feedback during the designing process. The validation was done by comparing the results of our system with the output of FE simulations. The system has been implemented with a user-friendly graphical interface and virtually tested and numerically validated. This system reduces the limitations of the current practices. However, a lot of works is still ahead to refine and develop the system and validate it with clinical experiments

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Sari-ali, Elhadi. "Experimental and computational simulation of micro-separation and its effect on ceramic-on-ceramic total hip prostheses." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515789.

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Keggen, Linda Anne. "Simulation techniques to study the potential for flow related thrombus deposition on prosthetic heart valves." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388707.

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Hallum, Luke Edward Graduate School of Biomedical Engineering Faculty of Engineering UNSW. "Prosthetic vision : Visual modelling, information theory and neural correlates." Publisher:University of New South Wales. Graduate School of Biomedical Engineering, 2008. http://handle.unsw.edu.au/1959.4/41450.

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Electrical stimulation of the retina affected by photoreceptor loss (e.g., cases of retinitis pigmentosa) elicits the perception of luminous spots (so-called phosphenes) in the visual field. This phenomenon, attributed to the relatively high survival rates of neurons comprising the retina's inner layer, serves as the cornerstone of efforts to provide a microelectronic retinal prosthesis -- a device analogous to the cochlear implant. This thesis concerns phosphenes -- their elicitation and modulation, and, in turn, image analysis for use in a prosthesis. This thesis begins with a comparative review of visual modelling of electrical epiretinal stimulation and analogous acoustic modelling of electrical cochlear stimulation. The latter models involve coloured noise played to normal listeners so as to investigate speech processing and electrode design for use in cochlear implants. Subsequently, four experiments (three psychophysical and one numerical), and two statistical analyses, are presented. Intrinsic signal optical imaging in cerebral cortex is canvassed appendically. The first experiment describes a visual tracking task administered to 20 normal observers afforded simulated prosthetic vision. Fixation, saccade, and smooth pursuit, and the effect of practice, were assessed. Further, an image analysis scheme is demonstrated that, compared to existing approaches, assisted fixation and pursuit (but not saccade) accuracy (35.8% and 6.8%, respectively), and required less phosphene array scanning. Subsequently, (numerical) information-theoretic reasoning is provided for the scheme's superiority. This reasoning was then employed to further optimise the scheme (resulting in a filter comprising overlapping Gaussian kernels), and may be readily extended to arbitrary arrangements of many phosphenes. A face recognition study, wherein stimuli comprised either size- or intensity-modulated phosphenes, is then presented. The study involved unpracticed observers (n=85), and showed no 'size' --versus--'intensity' effect. Overall, a 400-phosphene (100-phosphene) image afforded subjects 89.0% (64.0%) correct recognition (two-interval forced-choice paradigm) when five seconds' scanning was allowed. Performance fell (64.5%) when the 400-phosphene image was stabilised on the retina and presented briefly. Scanning was similar in 400- and 100-phosphene tasks. The final chapter presents the statistical effects of sampling and rendering jitter on the phosphene image. These results may generalise to low-resolution imaging systems involving loosely packed pixels.

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Dowling, Jason Anthony. "Mobility enhancement using simulated artificial human vision." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16380/1/Jason_Dowling_Thesis.pdf.

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The electrical stimulation of appropriate components of the human visual system can result in the perception of blobs of light (or phosphenes) in totally blind patients. By stimulating an array of closely aligned electrodes it is possible for a patient to perceive very low-resolution images from spatially aligned phosphenes. Using this approach, a number of international research groups are working toward developing multiple electrode systems (called Artificial Human Vision (AHV) systems or visual prostheses) to provide a phosphene-based substitute for normal human vision. Despite the great promise, there are currently a number of constraints with current AHV systems. These include limitations in the number of electrodes which can be implanted and the perceived spatial layout and display frequency of phosphenes. Therefore the development of computer vision techniques that can maximise the visualisation value of the limited number of phosphenes would be useful in compensating for these constraints. The lack of an objective method for comparing different AHV system displays, in addition to comparing AHV systems and other blind mobility aids (such as the long cane), has been a significant problem for AHV researchers. Finally, AHV research in Australia and many other countries relies strongly on theoretical models and animal experimentation due to the difficult of prototype human trials. Because of this constraint the experiments conducted in this thesis were limited to simulated AHV devices with normally sighted research participants and the true impact on blind people can only be regarded as approximated. In light of these constraints, this thesis has two general aims. The first aim is to investigate, evaluate and develop effective techniques for mobility assessment which will allow the objective comparison of different AHV system phosphene presentation methods. The second aim is to develop a useful display framework to guide the development of AHV information presentation, and use this framework to guide the development of an AHV simulation device. The first research contribution resulting from this work is a conceptual framework based on literature reviews of blind and low vision mobility, AHV technology, and computer vision. This framework incorporates a comprehensive number of factors which affect the effectiveness of information presentation in an AHV system. Experiments reported in this thesis have investigated a number of these factors using simulated AHV with human participants. It has been found that higher spatial resolution is associated with accurate walking (reduced veering), whereas higher display rate is associated with faster walking speeds. In this way it has been demonstrated that the conceptual framework supports and guides the development of an adaptive AHV system, with the dynamic adjustment of display properties in real-time. The second research contribution addresses mobility assessment which has been identified as an important issue in the AHV literature. This thesis presents the adaptation of a mobility assessment method from the blind and low vision literature to measure simulated AHV mobility performance using real-time computer based analysis. This method of mobility assessment (based on parameters for walking speed, obstacle contacts and veering) is demonstrated experimentally in two different indoor mobility courses. These experiments involved sixty-five participants wearing a head-mounted simulation device. The final research contribution in this thesis is the development and evaluation of an original real-time looming obstacle detector, based on coarse optical flow, and implemented on a Windows PocketPC based Personal Digital Assistant (PDA) using a CF card camera. PDA based processors are a preferred main processing platform for AHV systems due to their small size, light weight and ease of software development. However, PDA devices are currently constrained by restricted random access memory, lack of a floating point unit and slow internal bus speeds. Therefore any real-time software needs to maximise the use of integer calculations and minimise memory usage. This contribution was significant as the resulting device provided a selection of experimental results and subjective opinions.

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23

Dowling, Jason Anthony. "Mobility enhancement using simulated artificial human vision." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16380/.

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The electrical stimulation of appropriate components of the human visual system can result in the perception of blobs of light (or phosphenes) in totally blind patients. By stimulating an array of closely aligned electrodes it is possible for a patient to perceive very low-resolution images from spatially aligned phosphenes. Using this approach, a number of international research groups are working toward developing multiple electrode systems (called Artificial Human Vision (AHV) systems or visual prostheses) to provide a phosphene-based substitute for normal human vision. Despite the great promise, there are currently a number of constraints with current AHV systems. These include limitations in the number of electrodes which can be implanted and the perceived spatial layout and display frequency of phosphenes. Therefore the development of computer vision techniques that can maximise the visualisation value of the limited number of phosphenes would be useful in compensating for these constraints. The lack of an objective method for comparing different AHV system displays, in addition to comparing AHV systems and other blind mobility aids (such as the long cane), has been a significant problem for AHV researchers. Finally, AHV research in Australia and many other countries relies strongly on theoretical models and animal experimentation due to the difficult of prototype human trials. Because of this constraint the experiments conducted in this thesis were limited to simulated AHV devices with normally sighted research participants and the true impact on blind people can only be regarded as approximated. In light of these constraints, this thesis has two general aims. The first aim is to investigate, evaluate and develop effective techniques for mobility assessment which will allow the objective comparison of different AHV system phosphene presentation methods. The second aim is to develop a useful display framework to guide the development of AHV information presentation, and use this framework to guide the development of an AHV simulation device. The first research contribution resulting from this work is a conceptual framework based on literature reviews of blind and low vision mobility, AHV technology, and computer vision. This framework incorporates a comprehensive number of factors which affect the effectiveness of information presentation in an AHV system. Experiments reported in this thesis have investigated a number of these factors using simulated AHV with human participants. It has been found that higher spatial resolution is associated with accurate walking (reduced veering), whereas higher display rate is associated with faster walking speeds. In this way it has been demonstrated that the conceptual framework supports and guides the development of an adaptive AHV system, with the dynamic adjustment of display properties in real-time. The second research contribution addresses mobility assessment which has been identified as an important issue in the AHV literature. This thesis presents the adaptation of a mobility assessment method from the blind and low vision literature to measure simulated AHV mobility performance using real-time computer based analysis. This method of mobility assessment (based on parameters for walking speed, obstacle contacts and veering) is demonstrated experimentally in two different indoor mobility courses. These experiments involved sixty-five participants wearing a head-mounted simulation device. The final research contribution in this thesis is the development and evaluation of an original real-time looming obstacle detector, based on coarse optical flow, and implemented on a Windows PocketPC based Personal Digital Assistant (PDA) using a CF card camera. PDA based processors are a preferred main processing platform for AHV systems due to their small size, light weight and ease of software development. However, PDA devices are currently constrained by restricted random access memory, lack of a floating point unit and slow internal bus speeds. Therefore any real-time software needs to maximise the use of integer calculations and minimise memory usage. This contribution was significant as the resulting device provided a selection of experimental results and subjective opinions.

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24

Sushko, John. "Asymmetric Passive Dynamic Walker Used to Examine Gait Rehabilitation Methods." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3373.

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Testing gait rehabilitation devices on humans can be a difficult task, due to the effects of the neurological controls of the human body. This thesis advances the use of a passive dynamic walker (PDW) tuned to have asymmetric gait patterns similar to those with physical impairments to test rehabilitation devices. A passive dynamic walker is a multipendulum system that has a stable gait pattern when walking down a slope without any energy inputs except the forces due to gravity. A PDW model is better suited for testing rehabilitation devices because it has been shown to resemble human gait and separates the human neurological controls from the purely dynamic aspects of walking. This research uses different asymmetric gait patterns based on an asymmetric PDW to aid in the design of current and future rehabilitation methods. There are four major parts to this research: (1) the derivation of the current nine mass PDW model, (2) the effects of changing the moment of inertia and center of mass on each leg, (3) the effects of having a leg that is longer than the other and adding masses on the opposite leg to generate a symmetric gait, and (4) the design of a theoretical prosthesis that will break the assumption that the knee on the prosthetic leg should be in the same location as the intact leg. The result of changing the moment of inertia and center of mass on each leg in the nine mass model showed that it is an improvement over the previously used five mass model. This is because the five mass model forces the center of mass to change with the moment of inertia, while the nine mass model allows these to be changed independently of each other. A theoretical prosthesis has been developed in this research that is is significantly lighter while maintaining a symmetric gait. This was accomplished by moving the knee of the prosthetic limb below the location of the intact knee.

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25

Chun, Eliseo Pablo [UNESP]. "Análise microestrutural e da resistência à fadiga de zircônia monolítica submetida a protocolos de ajuste simulado." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150134.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O objetivo deste trabalho foi investigar as propriedades microestruturais e a resistência à fadiga de amostras de zircônia parcialmente estabilizada por óxido de ítrio (Y-TZP) para uso em forma monolítica (Vita YZ HT, Vita Zahnfabrik, Alemanha) após diferentes protocolos de ajuste clínico simulado. 162 discos de Y-TZP HT (12 mm de diâmetro, 0,8 mm de altura) foram confeccionados e aleatoriamente divididos em 6 grupos de acordo com as simulações (n=27): S- Y-TZP sinterizada (sem desgaste, sem glaze); G- Y-TZP sinterizada (sem desgaste) e glazeada; PdG- ajuste simulado da Y-TZP com ponta diamantada seguido por aplicação de glaze; GPd- ajuste simulado com ponta diamantada da Y-TZP já glazeada; PdBdG- ajuste simulado com ponta diamantada, seguido por borracha diamantada e aplicação do glaze; GPdBd- ajuste simulado com ponta diamantada, seguido por borracha diamantada da Y-TZP já glazeada. Após teste monotônico sob flexão biaxial (n=3, célula de carga de 1000 kgf, velocidade de 1 mm/min), os espécimes restantes foram distribuídos na proporção 3:2:3 e testados sob fadiga acelerada (step stress) em três perfis de carregamento (leve, moderado e agressivo), variando-se os incrementos de carga e número de ciclos. Os espécimes representativos fraturados foram avaliados em estereomicroscopio e microscópio eletrônico de varredura (MEV) e as características microestruturais das superfícies obtidas com os diferentes protocolos foram analisadas quanto a difração de raios-X, rugosidade média (Ra), perfilometria e MEV. Os dados de sobrevivência ou fratura foram utilizados para cálculo do valor beta (β) de Weibull e da confiabilidade para missões de 300.000 e 600.000 ciclos a 200 N. Os espectros obtidos pela difração foram comparados com espectros padrão de bancos de dados. Os dados de Ra foram analisados estatisticamente por ANOVA 1 fator e teste de Tukey (ambos, a=5%). As imagens foram analisadas qualitativamente e descritas. Não houve alteração significativa na cristalografia da zircônia após as simulações de ajuste clínico. A zircônia HT não tratada (S) apresentou menor probabilidade de sobrevivência, após 600.000 ciclos a 200 N, em comparação com a Y-TZP HT desgastada com ponta diamantada e glazeada (PdG) e após o polimento final com borracha diamantada (GPdBd). Apesar dos protocolos de ajuste simulado não alterarem a cristalografia da zircônia, o polimento final com borracha diamantada (GPdBd) resultou em uma superfície mais homogênea em comparação com amostras glazeadas (G, PdG e PdBdG). O glaze se acumulou em “ilhas” sobre todas as superfícies analisadas. Concluiu-se que a Y-TZP HT tem maior probabilidade de sobrevivência quando glazeada após desgaste com ponta diamantada (PdG) ou com polimento finalizado por borrachas diamantadas (GPdBd).
The objective of this study was to investigate the microstructural properties and fatigue resistance of zirconia partially stabilized by yttrium oxide (Y-TZP) for use in monolithic form (Vita YZ HT, Vita Zahnfabrik, Germany) after different clinical adjustment protocols simulation. 162 disc of Y-TZP HT (12 mm diameter, 0.8 mm high) were made and randomly divided into 6 groups according to the adjustment protocol (n = 27): S- Y-TZP as sintered (without adjustment and glaze); G- glazed Y-TZP (without adjustment); PdG- Y-TZP with adjustment simulation procedure with diamond bur followed by glaze application; GPd- glazed Y-TZP followed by adjustment simulation procedure with diamond bur; PdBdG- Y-TZP with adjustment simulation procedure with diamond bur and polishing kit, followed by glaze application; GPdBd- glazed Y-TZP with adjustment simulation procedure with bur followed by polishing kit. After monotonic testing under biaxial flexure (n=3, 1000 kgf load cell, 1 mm/min speed), the remaining specimens were distributed into 3:2:3 ratio and tested under step-stress in three profiles (light, moderate and aggressive), varying the load, increments and number of cycles. The fractured representative specimens were evaluated in a stereomicroscope and scanning electron microscope (SEM) and the microstructural characteristics of the surfaces obtained with different protocols were analyzed by X-ray diffraction, mean roughness (Ra), profilometry and SEM. Survival or fracture data were used to calculate Weibull's beta (β) value and reliability for 300,000 and 600,000 cycles at 200 N. The spectra obtained by the diffraction were compared with standard spectra from databases. Ra data were statistically analyzed by 1-way ANOVA and Tukey’s test (both, a=5%). The images were analyzed and qualitatively described. There was no significant change in zirconia crystallography after the simulations of clinical adjustment. The untreated Y-TZP HT (S) presented a lower probability of survival after 600,000 cycles at 200 N, compared to Y-TZP HT adjusted with diamond bur and glazed (PdG). and after final polishing with polishing kit (GPdBd). Although the simulated adjustment protocols did not alter the crystallography of the Y-TZP HT, the final polishing with diamond rubber (GPdBd) resulted in a more homogeneous surface compared to glazed samples (G, PdG and PdBdG). The glaze was accumulated in "islands" on all analyzed surfaces. It could be concluded that Y-TZP HT is more likely to survive when glazed after diamond adjustments (PdG) or when it is finished with polishing kit (GPdBd).

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26

Chien, Chih-Hao. "POTENTIAL OPTIMAL GAIT PERFORMANCE OF MAUCH S-N-S PROSTHETIC KNEE CONFIGURATIONS AS PREDICTED BY DYNAMIC MODELING." Cleveland State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=csu1417068842.

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27

Drapeau, Guy. "Comparative numerical study of the intra-vessel flow characteristics between a flat and a cylindrical configuration in a stented wall region." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112566.

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Mechanical stresses and flow dynamics alteration in a stented artery region are known to stimulate intimal thickening and increase the risk of restenosis, the closure of a revascularized artery. Particle imaging velocimetry (PIV) is an optical flow visualization technique that can be used to characterize the local flow dynamics around different stent structures. However, the usual cylindrical stent geometries present visualization difficulties when using an optical measurement technique such as the PIV technique. Using a flat configuration of a stent model presents advantages over the usual cylindrical model. A planar stent model makes data acquisition easier in planes cutting through the model due to its flat geometry that is compatible with the PIV planar flow investigation technique. Furthermore, with the planar stent configuration model velocity measurements and their associated flow features can be done without inducing refraction of the laser light sheet occurring with the cylindrical model's curvature. The refraction of light should be avoided since measurement errors and reflections are the resulting effects of this laser light plane deviation when passing through the curvature of a cylindrical stent model.
The spatial and temporal distribution of the Wall Shear Stress (WSS), which is believed to be of primary importance in the development of restenosis should be comparable between the flat and the cylindrical stent configuration models. The velocity and shear strain rate distributions will be compared between the flat and cylindrical stent configurations using computational fluid dynamics (CFD) simulations in order to analyse the feasibility of using a flat instead of a cylindrical version of the stent model for PIV experiments. It will be shown that for a physiological pulsatile flow the flat model yields results in shear strain rate spatial and temporal distribution that is comparable to the cylindrical model. A more PIV compatible, efficient and less refractive error prone validated flat model would be advantageous when several stent designs influence on the local hemodynamics around the strut geometries have to be studied quantitatively and optimized.

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28

Jedenmalm, Anneli. "Assessment of acetabular cup wear with computed tomography and influence of surface roughness on wear of materials for hip prostheses." Licentiate thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4157.

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29

Van, Schalkwyk Etienne P. "Determining femoral component goodness-of-fit using computer segmentation and numerical simulation." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4320.

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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: The c2 goodness-of-fit (GOF) test was used to determine which standard femoral component would achieve the best geometrical fit for a specific patient. This was done by creating 3D models from computerized tomography scan data through computer segmentation using Materialise MIMICS. The second step was to measure the morphological dimensions of the distal femur whereof twelve were selected and compared to the dimensions of two commercial femoral prosthesis designs. Thirdly, cadaveric femurs were scanned with a 3D desktop scanner to create a database with the dimensions of healthy knees. The 3D model database of the cadaveric femurs included cartilage layer. A cartilage thickness was added to the CT knee dimensions using a self-organizing map (SOM) calculation based on the healthy knee database. The developed method calculated alignment angles with higher accuracy than presently used and determined preoperatively which size to implant. Kinematic simulations of total knee arthroplasty (TKA) knees were compared to normal knee simulations created in LifeMOD. The articulating surface was the only variable changed between the two simulations and the kinematics of different sizes were evaluated. A method was created to scale the femoral component using the standard available sizes. The completed project will be used as foundation for customization of TKA prostheses.
AFRIKAANSE OPSOMMING: Die c2 graad van passing toets metode was gebruik om te bereken watter standaard femorale komponent ’n patiënt die beste geometries pas. Dit was gedoen deur eerstens 3D modelle gemaak vanaf CT skandeer data deur rekenaar segmentasie met Materialise MIMICS. Daarna was morfologiese dimensies gemeet vanaf die distale femur, waarvan twaalf gekies en vergelyk was teen two kommersiële femorale prostesis ontwerpe. Laastens was kadawer femurs geskandeer met ‘n 3D skandeerder om ’n databasis van gesonde knieë te maak. Die 3D modelle van die kadawer bene het die kraakbeen laag bevat. Die kraakbeen dikte was by die CT knie dimensies gevoeg d.m.v. SOM en die gesonde knie databasis. Die nuwe metode bereken die belynings hoeke met hoër akkuraatheid as wat huidiglik gebruik word en bereken voor die operasie watter grote om te gebruik. Kinematiese simulasies van knie prostesis was vergelyk met ’n normale knie simulasies gemaak in LifeMOD. Die artikulêre oppervlakte was die enigste veranderlike tussen die twee simulasies en kinematika van verskillende grotes was ondersoek. ‘n Metode was geskep om die standaard femorale komponent se skaal te verander vir ’n beter passing.

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Chun, Eliseo Pablo. "Análise microestrutural e da resistência à fadiga de zircônia monolítica submetida a protocolos de ajuste simulado /." São José dos Campos, 2017. http://hdl.handle.net/11449/150134.

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Orientador: Marco Antonio Bottino
Coorientadora: Lilian Costa Anami
Banca: Guilherme de Siqueira Ferreira Anzaloni Saavedra
Banca: Fernanda Campos
Resumo: O objetivo deste trabalho foi investigar as propriedades microestruturais e a resistência à fadiga de amostras de zircônia parcialmente estabilizada por óxido de ítrio (Y-TZP) para uso em forma monolítica (Vita YZ HT, Vita Zahnfabrik, Alemanha) após diferentes protocolos de ajuste clínico simulado. 162 discos de Y-TZP HT (12 mm de diâmetro, 0,8 mm de altura) foram confeccionados e aleatoriamente divididos em 6 grupos de acordo com as simulações (n=27): S- Y-TZP sinterizada (sem desgaste, sem glaze); G- Y-TZP sinterizada (sem desgaste) e glazeada; PdG- ajuste simulado da Y-TZP com ponta diamantada seguido por aplicação de glaze; GPd- ajuste simulado com ponta diamantada da Y-TZP já glazeada; PdBdG- ajuste simulado com ponta diamantada, seguido por borracha diamantada e aplicação do glaze; GPdBd- ajuste simulado com ponta diamantada, seguido por borracha diamantada da Y-TZP já glazeada. Após teste monotônico sob flexão biaxial (n=3, célula de carga de 1000 kgf, velocidade de 1 mm/min), os espécimes restantes foram distribuídos na proporção 3:2:3 e testados sob fadiga acelerada (step stress) em três perfis de carregamento (leve, moderado e agressivo), variando-se os incrementos de carga e número de ciclos. Os espécimes representativos fraturados foram avaliados em estereomicroscopio e microscópio eletrônico de varredura (MEV) e as características microestruturais das superfícies obtidas com os diferentes protocolos foram analisadas quanto a difração de raios-X, rugosidade média ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The objective of this study was to investigate the microstructural properties and fatigue resistance of zirconia partially stabilized by yttrium oxide (Y-TZP) for use in monolithic form (Vita YZ HT, Vita Zahnfabrik, Germany) after different clinical adjustment protocols simulation. 162 disc of Y-TZP HT (12 mm diameter, 0.8 mm high) were made and randomly divided into 6 groups according to the adjustment protocol (n = 27): S- Y-TZP as sintered (without adjustment and glaze); G- glazed Y-TZP (without adjustment); PdG- Y-TZP with adjustment simulation procedure with diamond bur followed by glaze application; GPd- glazed Y-TZP followed by adjustment simulation procedure with diamond bur; PdBdG- Y-TZP with adjustment simulation procedure with diamond bur and polishing kit, followed by glaze application; GPdBd- glazed Y-TZP with adjustment simulation procedure with bur followed by polishing kit. After monotonic testing under biaxial flexure (n=3, 1000 kgf load cell, 1 mm/min speed), the remaining specimens were distributed into 3:2:3 ratio and tested under step-stress in three profiles (light, moderate and aggressive), varying the load, increments and number of cycles. The fractured representative specimens were evaluated in a stereomicroscope and scanning electron microscope (SEM) and the microstructural characteristics of the surfaces obtained with different protocols were analyzed by X-ray diffraction, mean roughness (Ra), profilometry and SEM. Survival or fracture data were used to calculate Weibull's beta (β) value and reliability for 300,000 and 600,000 cycles at 200 N. The spectra obtained by the diffraction were compared with standard spectra from databases. Ra data were statistically analyzed by 1-way ANOVA and Tukey's test (both, a=5%). The images were analyzed and qualitatively described. There was no significant change in zirconia crystallography ....(Resumo completo, clicar acesso eletrônico abaixo)
Mestre

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31

Narang, Yashraj S. (Yashraj Shyam). "Identification of design requirements for a high-performance, low-cost, passive prosthetic knee through user analysis and dynamic simulation." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82357.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references.
In January 2012, a partnership was initiated between the Massachusetts Institute of Technology and Bhagwan Mahaveer Viklang Sahayata Samiti (BMVSS, a.k.a., Jaipur Foot) to design a high-performance, low-cost, passive prosthetic knee for transfemoral amputees in India. The knee was primarily intended to improve the walking gait of amputees relative to existing low-cost devices. This thesis aimed to identify detailed design requirements for the prosthetic knee through user analysis and dynamic simulation. User analysis identified the needs and constraints of numerous stakeholders in the prosthesis development process. Members of the Indian biomechanics, prosthetics, and rehabilitation communities were interviewed to identify general requirements for the design, manufacturing, evaluation, and fitting of a prosthetic knee, and a structured survey of Indian amputees was conducted to quantify the demographics, functional capabilities, and functional needs of future end users. Dynamic simulation identified methods to enable transfemoral amputees to walk with reduced energy expenditure and normative gait kinematics. 2-dimensional inverse dynamics simulations were used to calculate the effects of inertial alterations of a prosthetic leg on the energy expenditure required to walk with normative kinematics. In addition, simulations were performed to compute the effects of inertial alterations on the knee moment required to walk with normative kinematics. Mechanical power analysis, sensitivity analysis, and optimization were used to formulate a passive mechanical model that could accurately reproduce the specified knee moment. The effects of walking cadence on critical results were also examined. Through the identification of user-centered and biomechanical requirements, the thesis provides a blueprint for the mechanism design comprising the next phase of the project.
by Yashraj S. Narang.
S.M.

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32

Vergnieux, Victor. "Naviguer en vision prothétique simulée : apport de la vision par ordinateur pour augmenter les rendus prothétiques de basse résolution." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30323/document.

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La cécité touche 39 millions de personnes dans le monde et génère de nombreuses difficultés dans la vie quotidienne. Plus précisément, les capacités de navigation (incluant orientation et mobilité) sont fortement diminuées, ce qui amène les personnes non-voyantes à limiter, voire à cesser leurs déplacements. Pour restaurer des sensations "visuelles", et par-delà, une certaine autonomie, il est possible de stimuler directement le système visuel résiduel d'une personne non-voyante à l'aide d'un implant administrant des micro-stimulations électriques. Le dispositif complet se compose d'une micro-caméra portée sur des lunettes et reliée à un ordinateur de poche, qui lui-même est connecté à l'implant. Lors des micro-stimulations, les sujets perçoivent des tâches grises, blanches ou jaunâtres appelées phosphènes. Ainsi la qualité de la vision restaurée est directement dépendante de la résolution et de la position de l'implant. Le nombre d'électrodes étant faible pour les implants en développement (moins d'une centaine), il est nécessaire de réduire drastiquement la résolution du flux vidéo pour la faire correspondre à la faible résolution de l'implant. Actuellement, l'Argus II de la société Second Sight est l'implant dont le développement est le plus avancé et sa résolution est de 60 électrodes, ce qui permet aux patients implantés de percevoir 60 phosphènes différents. Cette vision restaurée est donc très pauvre et un travail d'optimisation du signal est nécessaire pour pouvoir utiliser l'implant de manière fonctionnelle. Les sujets implantés sont impliqués dans des protocoles cliniques fermés ne permettant pas de les inclure dans d'autres expériences. Malgré cela, il est possible d'étudier les possibilités offertes par ces implants visuels en simulant la vision prothétique dans un casque de réalité virtuelle porté par des sujets voyants. Il s'agit du domaine de la vision prothétique simulée (VPS). La navigation n'a jamais été étudiée chez les patients implantés et très rarement en VPS. Il s'avère qu'avec des implants de très faible résolution, elle pose de grandes difficultés liées à la mobilité mais également des difficultés liées à l'orientation. Les travaux entrepris dans ce doctorat se concentrent sur l'étude de la navigation en VPS. Différentes théories en psychologie nous ont permis d'identifier les éléments importants pour les sujets afin qu'ils se repèrent et se construisent une représentation mentale fiable de l'environnement lors de la navigation. À partir de ces modèles, différents rendus prothétiques utilisant la vision par ordinateur ont été conçus et testés dans une tâche de navigation réalisée dans un environnement virtuel. Les expérimentations effectuées avaient pour objectif d'optimiser la perception et la compréhension de l'espace parcouru avec un implant de faible résolution. Ces évaluations reposaient sur la performance de temps des sujets pour effectuer la tâche de navigation et sur leur représentation mentale de l'environnement. Après la tâche de navigation, il leur était demandé de dessiner la carte des environnements explorés, afin d'évaluer ces représentations. Cette double évaluation a permis d'identifier les indices importants permettant de faciliter la perception et la mémorisation de la structure des environnements dans une tâche de navigation en VPS. Pour améliorer les performances des personnes non-voyantes implantées, il apparaît notamment nécessaire de limiter la quantité d'information présentée, tout en préservant la structure de l'environnement grâce à des algorithmes de vision par ordinateur. Lorsque l'accès à des patients implantés sera plus ouvert, il deviendra nécessaire de valider ces différents résultats en les faisant naviguer en environnement virtuel puis en environnement réel
Blindness affects thirty nine millions people in the world and generates numerous difficulties in everyday life. Specifically, navigation abilities (which include wayfinding and mobility) are heavily diminished. This leads blind people to limit and eventually to stop walking outside. Visual neuroprosthesis are developed in order to restore such "visual" perception and help them to get some autonomy back. Those implants generate electrical micro-stimulations which are focused on the retina, the optic nerve or the visual cortex. Those stimulations elicit blurry dots called "phosphenes". Phosphenes can be mainly white, grey or yellow. The whole stimulation device contains a wearable camera, a small computer and the implant which is connected to the computer. The implant resolution and position impact directly the quality of the restored visual perception. Current implants include less than a hundred electrodes so it is mandatory to reduce the resolution of the visual stream to match the implant resolution. For instance, the already commercialized Argus II implant from the company Second Sight (Seymar, California) is the leading visual implant worldwide and uses only sixty electrodes. This means that Argus II blind owners can perceive only sixty phosphenes simultaneously. Therefore this restored vision is quite poor and signal optimization is required to get to a functional implant usage. Blind people with implants are involved in restricted clinical trials and are difficult to reach. Yet, studying those implant possibilities is at our reach by simulating prosthetic vision and displaying it in a head mounted display for sighted subjects. This is the field of simulated prosthetic vision (SPV). Navigation was never studied with people with implant, and only a few studies approached this topic in SPV. In this thesis, we focused on the study of navigation in SPV. Computer vision allowed us to select which of the scene elements to display in order to help subjects to navigate and build a spatial representation of the environment. We used psychological models of navigation to conceive and evaluate SPV renderings. Subjects had to find their way and collect elements in a navigation task in SPV inspired by video games for the blind. To evaluate their performance we used a performance index based on the completion time. To evaluate their mental representation, we asked them to draw the environment layout after the task for each rendering. This double evaluation lead us to spot which elements can and should be displayed in low resolution SPV in order to navigate. Specifically those results show that to be understandable in low vision, a scene must be simple and the structure of the environment should not be hidden. When blind people with implant will become available we will be able to confirm or deny those results by evaluating their navigation in virtual and real environments

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Hasan, Istabrak [Verfasser]. "Computational Simulation of Trabecular Bone Distribution around Dental Implants and the Influence of Abutment Design on the Bone Reaction for Implant-Supported Fixed Prosthesis / Istabrak Hasan." Bonn : Universitäts- und Landesbibliothek Bonn, 2011. http://d-nb.info/1016151403/34.

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De, Jongh Cornel. "Critical evaluation of predictive modelling of a cervical disc design." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/601.

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Giovannelli, Luca. "Direct creation of patient-specific Finite Element models from medical images and preoperative prosthetic implant simulation using h-adaptive Cartesian grids." Doctoral thesis, Universitat Politècnica de València, 2018. http://hdl.handle.net/10251/113644.

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Se cree que la medicina in silico supondrá uno de los cambios más disruptivos en el futuro próximo. A lo largo de la última década se ha invertido un gran esfuerzo en el desarrollo de modelos computacionales predictivos para mejorar el poder de diagnóstico de los médicos y la efectividad de las terapias. Un punto clave de esta revolución, será la personalización, que conlleva en la mayoría de los casos, la creación de modelos computacionales específicos de paciente, también llamados gemelos digitales. Esta práctica está actualmente extendida en la investigación y existen en el mercado varias herramientas de software que permiten obtener modelos a partir de imágenes. A pesar de eso, para poderse usar en la práctica clínica, estos métodos se necesita reducir drásticamente el tiempo y el trabajo humano necesarios para la creación de los modelos numéricos. Esta tésis se centra en la propuesta de la versión basada en imágenes del Cartesian grid Finite Element Method (cgFEM), una técnica para obtener de forma automática modelos a partir de imágenes y llevar a cabo análisis estructurales lineales de huesos, implantes o materiales heterogéneos. En la técnica propuesta, tras relacionar la escala de los datos de la imágen con valores de propiedades mecánicas, se usa toda la información contenida en los píxeles para evaluar las matrices de rigidez de los elementos que homogenizan el comportamiento elástico de los grupos de píxeles contenidos en cada elemento. Se h-adapta una malla cartesiana inicialmente uniforme a las características de la imágen usando un procedimiento eficiente que tiene en cuenta las propiedades elásticas locales asociadas a los valores de los píxeles. Con eso, se evita un suavizado excesivo de las propiedades elásticas debido a la integración de los elementos en áreas altamente heterogéneas, pero, no obstante, se obtienen modelos finales con un número razonable de grados de libertad. El resultado de este proceso es una malla no conforme en la que se impone la continudad C0 de la solución mediante restricciones multi-punto en los hanging nodes. Contrariamente a los procedimientos estandar para la creación de modelos de Elementos Finitos a partir de imágenes, que normalmente requieren la definición completa y watertight de la geometrá y tratan el resultado como un CAD estandar, con cgFEM no es necesario definir ninguna entidad geométrica dado que el procedimiento propuesto conduce a una definición implícita de los contornos. Sin embargo, es inmediato incluirlas en el modelo en el caso de que sea necesario, como por ejemplo superficies suaves para imponer condiciones de contorno de forma más precisa o volúmenes CAD de dispositivos para la simulación de implantes. Como consecuencia de eso, la cantidad de trabajo humano para la creación de modelos se reduce drásticamente. En esta tesis, se analiza en detalles el comportamiento del nuevo método en problemas 2D y 3D a partir de CT-scan y radiográfias sintéticas y reales, centrandose en tres clases de problemas. Estos incluyen la simulación de huesos, la caracterización de materiales a partir de TACs, para lo cual se ha desarrollado la cgFEM virtual characterisation technique, y el análisis estructural de futuros implantes, aprovechando la capacidad del cgFEM de combinar fácilmente imágenes y modelos de CAD.
Es creu que la medicina in silico suposarà un dels canvis més disruptius en el futur pròxim. Al llarg de l'última dècada, s'ha invertit un gran esforç en el desenvolupament de models computacionals predictius per millorar el poder de diagnòstic dels metges i l'efectivitat de les teràpies. Un punt clau d'aquesta revolució, serà la personalització, que comporta en la majoria dels casos la creació de models computacionals específics de pacient. Aquesta pràctica està actualment estesa en la investigació i hi ha al mercat diversos software que permeten obtenir models a partir d'imatges. Tot i això, per a poder-se utilitzar en la pràctica clínica aquests métodes es necessita reduir dràsticament el temps i el treball humà necessaris per a la seva creació. Aquesta tesi es centra en la proposta d'una versió basada en imatges del Cartesian grid Finite Element Method (cgFEM), una técnica per obtenir de forma automàticament models a partir d'imatges i dur a terme anàlisis estructurals lineals d'ossos, implants o materials heterogenis. Després de relacionar l'escala del imatge a propietats macàniques corresponents, s'usa tota la informació continguda en els píxels per a integrar les matrius de rigidesa dels elements que homogeneïtzen el comportament elàstic dels grups de píxels continguts en cada element. Es emphh-adapta una malla inicialment uniforme a les característiques de la imatge usant un procediment eficient que té en compte les propietats elàstiques locals associades als valors dels píxels. Amb això, s'evita un suavitzat excessiu de les propietats elàstiques a causa de la integració dels elements en àrees altament heterogénies, però, tot i això, s'obtenen models finals amb un nombre raonable de graus de llibertat. El resultat d'aquest procés és una malla no conforme en la qual s'imposa la continuïtat C0 de la solució mitjançant restriccions multi-punt en els hanging nodes. Contràriament als procediments estàndard per a la creació de models d'Elements finits a partir d'imatges, que normalment requereixen la definició completa i watertight de la geometria i tracten el resultat com un CAD estàndard, amb cgFEM no cal definir cap entitat geométrica. No obstant això, és immediat incloure-les en el model en el cas que sigui necessari, com ara superfícies suaus per imposar condicions de contorn de forma més precisa o volums CAD de dispositius per a la simulació d'implants. Com a conseqüéncia d'això, la quantitat de treball humà per a la creació de models es redueix dràsticament. En aquesta tesi, s'analitza en detalls el comportament del nou métode en problemes 2D i 3D a partir de CT-scan i radiografies sintétiques i reals, centrant-se en tres classes de problemes. Aquestes inclouen la simulació d'ossos, la caracterització de materials a partir de TACs, per a la qual s'ha desenvolupat la cgFEM virtual characterisation technique, i l'anàlisi estructural de futurs implants, aprofitant la capacitat del cgFEM de combinar fàcilment imatges i models de CAD.
In silico medicine is believed to be one of the most disruptive changes in the near future. A great effort has been carried out during the last decade to develop predicting computational models to increase the diagnostic capabilities of medical doctors and the effectiveness of therapies. One of the key points of this revolution, will be personalisation, which means in most of the cases creating patient specific computational models, also called digital twins. This practice is currently wide-spread in research and there are quite a few software products in the market to obtain models from images. Nevertheless, in order to be usable in the clinical practice, these methods have to drastically reduce the time and human intervention required for the creation of the numerical models. This thesis focuses on the proposal of image-based Cartesian grid Finite Element Method (cgFEM), a technique to automatically obtain numerical models from images and carry out linear structural analyses of bone, implants or heterogeneous materials. In the method proposed in this thesis, after relating the image scale to corresponding elastic properties, all the pixel information will be used for the integration of the element stiffness matrices, which homogenise the elastic behaviour of the groups of pixels contained in each element. An initial uniform Cartesian mesh is h-adapted to the image characteristics by using an efficient refinement procedure which takes into account the local elastic properties associated to the pixel values. Doing so we avoid an excessive elastic property smoothing due to element integration in highly heterogeneous areas, but, nonetheless obtain final models with a reasonable number of degrees of freedom. The result of the process is non-conforming mesh in which C0 continuity is enforced via multipoint constraints at the hanging nodes. In contrast to the standard procedures for the creation of Finite Element models from images, which usually require a complete and watertight definition of the geometry and treat the result as a standard CAD, with cgFEM it is not necessary to define any geometrical entity, as the procedure proposed leads to an implicit definition of the boundaries. Nonetheless, they are straightforward to include in the model if necessary, such as smooth surfaces to impose the boundary conditions more precisely or CAD device volumes for the simulation of implants. As a consequence, the amount of human work required for the creation of the numerical models is drastically reduced. In this thesis, we analyse in detail the new method behaviour in 2D and 3D problems from CT-scans and X-ray images and synthetic images, focusing on three classes of problems. These include the simulation of bones, the material characterisation of solid foams from CT scans, for which we developed the cgFEM virtual characterisation technique, and the structural analysis of future implants, taking advantage of the capability of cgFEM to easily mix images and CAD models.
Giovannelli, L. (2018). Direct creation of patient-specific Finite Element models from medical images and preoperative prosthetic implant simulation using h-adaptive Cartesian grids [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/113644
TESIS

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Lamb, Christopher John. "Computer simulation of the action of a mechanical prosthetic heart valve and investigation of aortic flow field characteristics by magnetic resonance velocimetry." Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312718.

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Delventhal, Brooke. "Simulation-Based Stability Tests in Total Knee Arthroplasty: Are Component Alignment, KneeLaxity, and Tibiofemoral Contact Forces Related?" The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574422948246589.

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Warner, Holly E. "Simulation and Control at the Boundaries Between Humans and Assistive Robots." Cleveland State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=csu1577719990967925.

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Burkett, Brendan J. "A biomechanical analysis of running for trans-femoral amputees." Thesis, Queensland University of Technology, 1998. https://eprints.qut.edu.au/36739/1/36739_Digitised%20Thesis.pdf.

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Lower limb amputation results in changes to the usual pattern of human locomotion. Previous research has shown that amputees walk more slowly due to asymmetries In their movement patterns and that trans-femoral amputee gait was also found to be sensitive to the inertia of the prosthesis. As the majority of previous studies on amputee gait have been confined to walking the aim of this study was to develop an understanding of the blomechanical processes that occur when a trans-femoral amputee runs, with the primary objective to enhance performance. The research hypothesis was; "There is a knee axis location which optimizes the inertial characteristics of the trans-femoral amputee's prosthesis, and therefore improves the running performance". With the specific objectives of this study as follows: (a) To collect baseline biomechanical data (kinematic, kinetic and temporal) on the walking and running gait for a group of elite athletes with trans-femoral amputations; (b) To evaluate the performance of the standard prosthesis at walking and running speeds; (c) To develop a mathematical model that simulated the swing phase of the trans-femoral prosthesis, so that the effect of inertial changes to the prosthesis on swing time could be predicted (d) To compare the performance of configurations suggested by the model with physical tests on the modified prosthesis when used for running. The subject group consisted of highly active trans-femoral amputees who were members of the Australian Paralymplc squad for the 1996 Atlanta Paralymplc Games. Their running performance was analysed with their standard prosthesis and then repeated for a total of three modified prosthetic configurations. Each modification was based on the predictions of a mathematlcal model which was developed using the MATALB software. In addition to the objective biomechanical data collection, a subjective written survey was completed by the subjects. With each subject using their same prosthetic components this research found a significantly (p<0.001) faster running velocity for all subjects when they ran with the prosthetic knee axis lower than the standard anatomical configuration. Due to this technological advancement a 15 to 40 percent range of Improvement in running velocity was achieved. This finding was supported by improved indices of symmetry between lnterlimb performance as well as positive subject feedback.

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Girod, Loïc. "Développement et modélisation d'éléments de prothèse pour la main." Thesis, Nancy 1, 2010. http://www.theses.fr/2010NAN10076/document.

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Comme toute articulation fonctionnelle, l’articulation interphalangienne proximale(IPP) est la cible de lésions ou de pathologies pouvant compromettre les fonctions globales de la main. Les principaux objectifs d’une arthroplastie digitale sont de restituer la fonction et la stabilité de l’articulation et de réduire ou supprimer la douleur de manière durable. Le présent travail de thèse porte sur le développement et la modélisation de deux concepts prothétiques pour l’articulation IPP : une prothèse semi-contrainte en alliage de nickel-titane et une prothèse de resurfaçage. Outre le travail de dimensionnement, des essais de fatigue et d’usure sont conduits sur les deux implants. Des études complémentaires à chaque concept sont présentées. Celles-ci portent en premier lieu sur la mise en forme et les traitements thermiques de la prothèse semi-contrainte accompagnées d’une étude de relargage de nickel et une investigation sur les mécanismes mis en jeu. Enfin, une modélisation par éléments finis de l’interaction entre une prothèse articulaire et son environnement osseux est présentée de manière à évaluer la stabilité primaire des implants
As any functional joint, the proximal interphalangeal joint (PIP) is the target of hurts or of pathologies which can compromise the global functions of the hand. The main objectives of a digital arthroplasty are to restore the function and the stability of the joint and to reduce or suppress the pain in a long-lasting way. The present work of thesis concerns the development and the modeling of two concepts of PIP prostheses: a semiconstrained prosthesis made of nickel-titanium alloy and a resurfacing prosthesis. Besides the work of sizing, fatigue and wear tests are done on both implants. Additional studies are presented for each concept. First, we focus on the shaping and the heat treatments of the semi-constrained prosthesis accompanied with a study nickel ion release and an investigation on the involved mechanisms. Eventually, a finite element modeling of the interaction between the prosthesis and the surrounding bone is presented to estimate the primary stability of implants

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Лозінський, Владислав Валентинович. "Моделювання звукопровідної системи середнього вуха людини в Comsol." Master's thesis, КПІ ім. Ігоря Сікорського, 2020. https://ela.kpi.ua/handle/123456789/33851.

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Дослідження слухових властивостей слухової системи людини є актуальною проблемою сьогодення, адже здоровий слух це запорука нормального життя. Серед об’єктивних методів, таких як імпендасометрія, дослідження проводять з застосуванням пневмосистеми, що робить неможливим проведення процедури для немовлят. Саме тому запропоновано дослідження на основі ехо-спектрометру, який є вдосконаленим об’єктивного методу без використання пневмосистеми та з простою процедурою вимірювань і обробки для розширення вікової групи та покращенням точності результатів. При наявності великого спектру можливостей для діагностики слуху, майже нічого не відомо про акустичні характеристики звукопровідної системи людини, вже десятки років вчені займаються вивченням середнього вуха. Також широке застосування набуло використання протезів для реконструкції вуха при пошкодженнях його органів слуху. Проте сказати наскільки ці методи ефективні важко. Тому ця робота присвячена моделюванню звукопровідної системи, замінника, порівнянням цих моделей та оцінці ефективності запропонованого методу діагностики слуху. Основною задачею є отримання коефіцієнту проходження, який дасть змогу відповісти на питання як саме себе поводить звукопровідна система та наскільки протези є ефективними для реконструкції слуху.
The study of the auditory properties of the human auditory system is an urgent problem today, because healthy hearing is the key to a normal life. Among the objective methods, such as impedancemetry, research is performed using a pneumatic system, which makes it impossible to perform the procedure for infants. That is why the study is based on an echo spectrometer, which is an improved objective method without the use of a pneumatic system and with a simple measurement and processing procedure to expand the age group and improve the accuracy of the results. With a wide range of opportunities for the diagnosis of hearing, almost nothing is known about the acoustic characteristics of the human sound system, for decades, scientists have been studying the middle ear. The use of prostheses for the reconstruction of the ear in case of damage to its hearing organs has also become widely used. However, it is difficult to say how effective these methods are. Therefore, this work is devoted to modeling the sound conduction system, substitute, comparing these models and evaluating the effectiveness of the proposed method of hearing diagnosis. The main task is to obtain the transmittance, which will answer the question of how the sound system behaves and how effective prostheses are for the reconstruction of hearing.

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内藤, 尚., 和徳長谷, 剛伸井上, 孝訓相川, 伸也山崎, 基. 諏訪, 五郎大日方, et al. "神経・筋骨格系を有する3次元股義足歩行シミュレーションモデルの開発." バイオメカニズム学会, 2005. http://hdl.handle.net/2237/10875.

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Hannoun, Amira. "Tribological role of pyrocarbon in articular cartilage regeneration. Application in the shoulder arthroplasty." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI025.

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Les pathologies dégénératives de l’épaule sont traitées par arthroplastie totale ou hémiarthroplastie. Malgré le succès de ce traitement, le taux d’échec augmente à 22 %. Dans ce cadre, pour des patients ayant un stock osseux très limité, une nouvelle génération d'implants d'interposition a été développée. L’implant, dont l’originalité est la forme sphérique, est introduit sans fixation dans l’articulation. Il est en contact direct avec le cartilage de l’omoplate et une cavité humérale osseuse créée chirurgicalement. Bien que le chrome-cobalt (CrCo) soit le matériau le plus utilisé pour l’arthroplastie de l’épaule, le pyrocarbone (PyC) a été choisi pour le nouvel implant car il a un module d’élasticité proche de celui de l’os. Les résultats cliniques à court terme ont montré une usure minimale du cartilage et un bon remodelage osseux au contact avec l’implant. Cependant, l’origine de ces résultats n’est pas encore bien comprise. Dans ce contexte, les précédents travaux au laboratoire ont montré que le remodelage osseux côté humérus implique la synthèse d’un tissu néocartilagineux expliquant en partie les bons résultats cliniques. En revanche, ces résultats du côté de l’omoplate sont beaucoup plus controversés. Par conséquent, des interrogations se posent sur l’effet du PyC et de la géométrie de l’implant sur le remodelage des tissus adjacents. Cette thèse vise donc à comprendre l’origine de ce remodelage coté humérus et omoplate. Pour cela, notre stratégie est d’effectuer en première étape trois études parallèles pour découpler le rôle de la biologie (réponse cellulaire), du matériau (PyC vs CrCo) et de la transmission des contraintes mécaniques (triplet tribologique vivant). En deuxième étape, notre stratégie consiste à coupler les différents aspects dans un modèle in vitro s'appuyant sur les principes de la bio-ingénierie tissulaire. Pour ce faire notre méthodologie a été basée sur : 1) l’expertise d’explants in vivo (analyses histologiques et lipidomiques), 2) le développement in vitro des cultures cellulaires primaires de chondrocytes murins en contact avec les deux matériaux, 3) les simulations bio-tribologiques in vitro et 4) la conception et la validation d’un simulateur qui a permis de combiner les résultats biologiques, physicochimiques et tribologiques obtenus précédemment. Les résultats ont montré une meilleure activité cellulaire chondrogénique et ostéogénique dans le cas du PyC par rapport au CrCo. Cela a été corrélé d’une part à une meilleure adsorption des molécules lubrifiantes, les phospholipides, sur la surface du PyC et d’autre part à une transmission optimale des contraintes mécaniques due à ses propriétés et à sa géométrie. Par ailleurs, le contrôle de la transmission des contraintes mécaniques in vivo est essentiel pour garantir de bons résultats à long terme. De plus, cette thèse ouvre des perspectives vers le contrôle de cette transmission via les biomatériaux et leurs géométries afin de régénérer le cartilage
Degenerative shoulder pathologies are currently treated by total shoulder arthroplasty (joint replacement) or hemiarthroplasty. Despite the success of this treatment, the complication rate reaches 22 % due to the complex nature of joint mechanics and limited bone stock. In this context, for young patients with degenerative glenohumeral joints, a new generation of interposition implant has been developed. The implant, designed with an original spherical shape, is inserted without fixation between the glenoid cartilage and a surgically created humeral bone cavity. Cobalt-chromium (CoCr) is the most used biomaterial in shoulder arthroplasty; however, Pyrocarbon (PyC) is selected for the new implant for its elastic modulus similar to that of cortical bone. Short-term clinical results showed minimal bone and cartilage wear and good bone remodelling in contact with the implant. However, the origin of these results is not yet well understood. In this framework, the previous study on human explants in the laboratory showed that humeral bone remodelling involves the synthesis of a neocartilaginous tissue, which partly explains the favourable clinical results. However, these results are more controversial on the scapula side because of cartilage erosion. Therefore, the effect of PyC and the geometry of the implant on the remodelling of the surrounding tissues need investigation. Thus, this thesis aims to understand the origin of tissue remodelling on the bone and cartilage side. The first step of our strategy is to carry out three parallel studies to dissociate the role of the biology (cellular response), the impact of the material (PyC vs CoCr), and the involvement of mechanical stresses transmission (living tribological triplet). The second step is to validate the results thus obtained by associating the different aspects in an in vitro model based on tissue bioengineering principles. Consequently, our methodology was based on 1) the expertise of retrieved explants; 2) the analysis of murine primary chondrocytes cultures in contact with PyC and CoCr; 3) the testing of in vitro biotribological simulations; and 4) the design and validation of a simulator allowing to combine the biological, physicochemical and tribological results obtained previously. The final results showed better chondrogenic and osteogenic cell activity in the case of PyC compared to CoCr. They were correlated on the one hand with better adsorption of the lubricating molecules, phospholipids, on the surface of PyC and the other hand with an optimal transmission of the mechanical stress due to its properties and geometry. Furthermore, the in vivo control of transmission of mechanical stresses is essential to guarantee good results in the long term. Besides, this thesis opens up fresh perspectives on the control of this transmission through biomaterials and their geometries for cartilage regeneration

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Araujo, Carlos Eduardo de. "Implante neural controlado em malha fechada." Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1687.

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Um dos desafios propostos por pesquisadores em neurociência aos engenheiros biomédicos é a interação cérebro-máquina. O sistema nervoso comunica-se interpretando sinais eletroquímicos, e circuitos implantáveis podem tomar decisões de modo a interagir com o meio biológico. Sabe-se também que a doença de Parkinson está relacionada a um déficit do neurotransmissor dopamina. Para controlar a concentração de dopamina diferentes técnicas tem sido empregadas como estimuladores elétricos, magnéticos e drogas. Neste trabalho obteve-se o controle da concentração do neurotransmissor de maneira automática uma vez que atualmente isto não é realizado. Para tanto, projetou-se e desenvolveu-se quatro sistemas: a estimulação cerebral profunda ou deep brain stimulation (DBS), a estimulação transmagnética ou transmagnetic stimulation (TMS), um controle de bomba de infusão ou infusion pump control (IPC) para a entrega de drogas e um sistema de voltametria cíclica de varredura rápida ou fast scan ciclic voltammetry (FSCV) (circuito que detecta variações de concentração de neurotransmissores como a dopamina - DA). Também foi necessário o desenvolvimento de softwares para a visualização de dados e análises em sincronia com acontecimentos ou experimentos correntes, facilitando a utilização destes dispositivos quando emprega-se bombas de infusão e a sua flexibilidade é tal que a DBS ou a TMS podem ser utilizadas de maneira manual ou automática além de outras técnicas de estimulação como luzes, sons, etc. O sistema desenvolvido permite controlar de forma automática a concentração da DA. A resolução do sistema é de 0.4 µmol/L podendo-se ajustar o tempo para correção da concentração entre 1 e 90 segundos. O sistema permite controlar concentrações entre 1 e 10 µmol/L, com um erro de cerca de +/- 0,8 µmol/L. Embora desenhado para o controle da concentração de dopamina o sistema pode ser utilizado para controlar outros neurotransmissores. Propõe-se continuar o desenvolvimento em malha fechada empregando FSCV e DBS (ou TMS, ou infusão), utilizando modelos animais parkinsonianos.
One of the challenges to biomedical engineers proposed by researchers in neuroscience is brain machine interaction. The nervous system communicates by interpreting electrochemical signals, and implantable circuits make decisions in order to interact with the biological environment. It is well known that Parkinson’s disease is related to a deficit of dopamine (DA). Different methods has been employed to control dopamine concentration like magnetic or electrical stimulators or drugs. In this work was automatically controlled the neurotransmitter concentration since this is not currently employed. To do that, four systems were designed and developed: deep brain stimulation (DBS), transmagnetic stimulation (TMS), Infusion Pump Control (IPC) for drug delivery, and fast scan cyclic voltammetry (FSCV) (sensing circuits which detect varying concentrations of neurotransmitters like dopamine caused by these stimulations). Some softwares also were developed for data display and analysis in synchronously with current events in the experiments. This allowed the use of infusion pumps and their flexibility is such that DBS or TMS can be used in single mode and other stimulation techniques and combinations like lights, sounds, etc. The developed system allows to control automatically the concentration of DA. The resolution of the system is around 0.4 µmol/L with time correction of concentration adjustable between 1 and 90 seconds. The system allows controlling DA concentrations between 1 and 10 µmol/L, with an error about +/- 0.8 µmol/L. Although designed to control DA concentration, the system can be used to control, the concentration of other substances. It is proposed to continue the closed loop development with FSCV and DBS (or TMS, or infusion) using parkinsonian animals models.

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Poujade, Mylène. "Apport des dispositifs de restauration de la vision et de la résolution temporelle." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS319.

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La rétinite pigmentaire est une maladie neurodégénérative héréditaire de la rétine entraînant la cécité. Des technologies restaurant la vision ont vu le jour comme les neuroprothèses visuelles et la thérapie optogénétique. Leur limitation est la résolution spatiale. La neuroprothèse visuelle IRIS I de Pixium Vision et la thérapie optogénétique de Gensigth Biologics permettent une stimulation à haute fréquence temporelle. Or, augmenter la résolution temporelle mène à une stimulation plus naturelle pouvant compenser la résolution spatiale limitée. Notre étude évalue l’apport de la vision restaurée de ces dispositifs et de la résolution temporelle. Des sujets sains portant des lunettes de stimulation simulant la vision restaurée ont réalisé des tâches quotidiennes à 60 Hz et 1440 Hz et différentes qualité de restauration. Les dispositifs permettent la réalisation des tâches proposées, avec plus de facilité pour les patients traités par thérapie optogénétique. Les patients pourraient donc recouvrir une autonomie dans la réalisation de tâches quotidiennes. Nous montrons que la qualité de la stimulation inﬂuence les performances des tâches nécessitant une acuité relativement bonne. La réalisation des tâches n’a pas été facilitée par l’augmentation de la résolution temporelle. Selon la littérature, cette dernière améliore la qualité de la perception. Nous avons élaboré une tâche de discrimination de direction de mouvement à trois vitesses. Dès 120 Hz, la résolution temporelle facilite la tâche à vitesse moyenne et élevée. Par conséquent, les vitesses des scènes visuelles de notre précédente étude étaient trop faibles pour que la résolution temporelle améliore la perception
Retinitis Pigmentosa is an inherited retinal degenerative disease leading to blindness. Vision restoration techniques have been developed as visual neuroprostheses and optogenetic therapy. The limitation of these devices is their spatial resolution. The visual neuroprosthesis IRIS I developed by Pixium vision and Gensight Biologics’ optogenetic therapy allow the visual information to be captured and stimuled with a high temporal resolution. Increasing the temporal resolution leads to a more natural vision, and should overcome the low spatial resolution. Our study evaluate the contribution to these techniques and the temporal resolution, towards usefull vision. Healthy subjects wearing goggles simulating vision arising from the devices were asked to perform everyday tasks at 60Hz and 1440Hz. The devices allow the tasks to be carried out, with greater ease for patients who would be treated with optogenetic therapy. Patients could then regain autonomy in performing daily tasks. We also show that the quality of stimulation inﬂuences tasks requiring relatively sharpness. We have not identiﬁed any facilitation in the accomplishment of these tasks through increased temporal resolution. According to the literature, an improvement in visual perception should accompany the increase in temporal resolution. As such, we set up a parametric study of the temporal frequency through a task of directional discrimination at three different speeds. From 120 Hz, the temporal resolution facilitates the task at medium and high speed. Based on these results, speeds of the visual scenes from our previous experiment were too low for temporal resolution to improve the perception

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Alleau, Thibaut. "Development of a numerical platform to model the mitral valve." Thesis, Compiègne, 2021. http://www.theses.fr/2021COMP2649.

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L’insuffisance mitrale est la valvulopathie mondiale la plus fréquente avec une prévalence de 2%. Lorsque le patient n’est pas en mesure d’être opéré à cœur ouvert, un implant percutané est utilisé pour aider la fermeture des feuillets. Le seul implant actuellement disponible est basé sur la réparation bord à bord de la valve mitrale. Il réduit le reflux vers l’oreillette lors de la systole, mais n’est pas adapté pour les patients souffrant d’insuffisance mitrale fonctionnelle, chez qui la pathologie provient du ventricule et non des éléments de la valve. L’objectif de la thèse est de fournir une plateforme numérique permettant d’aider au développement d’un implant adapté pour ces patients. Plusieurs géométries de valve ont été réalisées au moyen d’un modèle paramétrique, en utilisant des données anatomiques. La dynamique de la valve a été modélisée avec le logiciel ADINA par des simulations éléments finis en grandes déformations. Des modèles structurels de la valve ont permis de représenter la fermeture de la valve sous une pression uniforme. Les lois de comportement de matériaux ont été développé dans le but d’obtenir une fermeture réaliste de la valve. Cela a nécessité la prise en compte de l’hyperélasticité et de l’anisotropie des tissus. Des pathologies valvulaires, telles que la dilatation de l’anneau mitrale ou la rupture des cordages tendineux ont été modélisées, et plusieurs méthodes ont été testées pour y apposer des systèmes médicaux. En utilisant une description ALE et un couplage monolithique, les interactions fluide-structure ont été simulées pour une valve mitrale bi-dimensionnelle. La fermeture hermétique de la valve pendant la systole a pu être reproduite et l’ouverture de la valve étudiée pendant la diastole. La plateforme numérique développée permet de modéliser la fonction de la valve mitrale et peut être utilisée pour aider au développement d’un implant mitral grâce au modèle paramétrique reproduisant différentes géométries de valve et aux lois matériaux anisotropes. Une perspective reste la création d’un modèle 3D des interactions fluide-structure de la valve mitrale
Mitral insufficiency is the first valvular disease worldwide, with a 2% prevalence. When open-heartsurgery is impossible for the patient, surgeons use percutaneous devices to help the mitral leaflets coapt. However, the only device currently available is based on the edge-to-edge mitral valve repair technique. This type of implant is not adapted for patients suffering from functional mitral insufficiency, where the ventricle is responsible for the lack of coaptation of the leaflets. This thesis aims to provide a numerical platform to help the development of a mitral valve implant adapted for those patients. Several mitral valve geometries were created from a parametric model using anatomical measurements. Finite element simulations of the mitral valve were performed using ADINA to determine the valve closure under constant pressure. Several material models were developed in large strain and large deformation to model the valve closure accurately. Pathological behaviour such as annulus dilatation and chordae rupture were modelled, and several methods were tested to implement medical devices. Fluid-structure interaction of a 2D mitral valve was obtained using an ALE description and a monolithic coupling approach. Both the systole and the diastole were reproduced and studied, and the hermetic seal of the valve was detailed. The numerical platform developed is suited to model mitral valve function and can be used to help the development of mitral implants. In addition, the parametric geometry model and the anisotropic material model will be useful to depict with realism the valve function. A 3D fluid-structure interaction of the mitral valve could be developed

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Alnu'man, Nasim. "Advanced Simulation of an Adaptive Lower Limb Prosthesis." Phd thesis, 2010. http://tuprints.ulb.tu-darmstadt.de/2149/1/Dissertation_Nasim_Alnuman.pdf.

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The normal daily human activities include different levels of energy and strength needs, and this applies also for walking such that walking at high speeds needs more stiff muscles compared with walking slowly, and walking during carrying heavy loads or on inclined surfaces needs more energy than during doing the light housekeeping activities. For a healthy individual the human foot has already the ability to change its stiffness and to store and return a part of the elastic energy in a compliant structure of muscle fibres and series elastic elements. In the case of amputations in the lower limbs the amputated limbs are replaced with artificial limbs. A problem appears by this replacement that the new artificial limbs are designed to satisfy some described tasks and any change in these tasks or in the boundary conditions leads to an incompliance and unsatisfactory motion of the amputees. For example, the use of soft foot for walking at high speeds leads to a larger motion of the body centre of mass compared with walking at the preferred walking speed. In order to overcome these problems or reduce their effects, the need arises to design adaptive prostheses that have the ability to change their properties according to the surrounding conditions. This work has the goal to evaluate the usefulness of using adaptive elastic foot prosthesis, through the numerical modelling and simulation of the human gait of an above-knee amputee with an adaptive elastic foot. The body of the amputee is divided into a limited number of rigid bodies (segments) connected together by hinge joints. A two dimensional model of the human body is built from these segments using a commercial multibody simulation program. The initial conditions of the system, some of the body segments relative motions and forces are given as inputs in the model. In order to integrate the adaptive elastic foot in the rigid bodies system a numerical model of the foot is built using the finite element method and then reduced by static condensation. The reduced elastic model is then integrated in the rigid bodies’ model of the human gait. This model is used to simulate the stance period of the human gait. Four parameters, the vertical ground reaction force (GRF), the body centre of mass (BCoM), the ankle joint moment and the hip joint rotation are considered as defining characteristics of the human gait. These characteristics are used in the evaluation of the model results and latterly in the evaluation of the adaptive foot usefulness. The simulation model is validated through comparison with experimental results of the human gait. The model shows good consistency with experimental results and can be further used in simulating the human gait using prosthetic feet with different mechanical properties and positions. Different prosthetic foot properties and walking conditions are studied for the adaptive elastic prosthetic foot. The stiffness of the foot sole is changed for normal walking on level and inclined surfaces and for fast walking on level surfaces. The changes in stiffness show changes in the vertical BCoM motion which improve the gait form for walking faster than the normal walking speed but show no significant changes on the other parameters. The ankle joint inclination is also changed for walking on uphill inclined surfaces; the results show that increasing the inclination angle reduces the vertical GRF and increases the horizontal motion of the BCoM and relatively the step size, which improves the uphill motion on inclined surfaces. Also designs of beam elements with changeable stiffness that could be used in an adaptive prosthetic foot’s sole are considered. In this part two concepts are developed and studied theoretically then two models are manufactured and proved experimentally. The results show good changes in the stiffness of the models, then the first model consisting of two plates sliding one in the other shows experimentally a change of ± 8.5% in the stiffness and the second model consisting of two plates screwed together gives experimentally an average change of ±18% in the stiffness. Since these models are designed to be used as replacements for human limbs (where the available external energy sources are limited) attention was given to model a light weight system with minimum energy consumption for controlling and driving it. Also attention was given to design a system that could be used with the different commercially available prosthetic feet without the need to make large changes in the original models designs and sizes.

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Lai, Y. C., and 賴育誠. "Laboratory Simulation and Assessment of Total Hip Prosthesis on Loosening Problem." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/06523258534424900308.

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碩士
中原大學
醫學工程學系
88
For patients inserted total hip joint prostheses, clinical findings on implant detachment, malfunction, and loosening-associate problems are frequently observed after a period of time. To evaluate various potential factors caused fixation failure, laboratory-assisted assessments are required. Present study using cup-on-ball hip wear simulator approaches to comply with gait analysis of hip, accelerates in-vitro tests by entering maximum angular setting and obtains relative abrasive condition at the interface. Morphologies and concentrations of wear debris may affect the attachment of peri-prosthetic tissues; consequently, this work deals with three main topics: (1) To improve wear resistance of UHMW polyethylene acetabular cup as the bearing part, the load-bearing properties of polyethylene are enhanced by nitrogen ion implantation; the doses with low current density differ from 1013 ions.cm-2 to 1016 ions.cm-2. (2) Wear debris generated from simulator is compared with in vivo particles taken from tissues surrounded the failure implant. (3) Initiation of fixation failure with musculo-skeletal system rises with fluctuations of stress-strain relation at the implant/tissue interface. Because of varied materials’ characteristic at the contact surfaces, relative friction causes mobility between adhesive components and gradual increase of plastic strain, and eventually brings about macro-scale dislocation between implant and surrounding tissues. This study is to propose a possible mechanism, using micro-motion tester to simulate the occurrence of implant displacement at the inserted interface before loosening. Experimental result on the ion-implanted polyethylene has demonstrated that an important surface-hardening transformation at polyethylene surface is found. Using cup-on-ball hip joint simulator, the release rate and the sequence of wear debris are detectable from the accumulated filters varied with testing cycles up to 1.3 M, e.g. weight loss of non-treated polyethylene is ca. 74.7 mg; similarly, for the 1013 ions.cm-2 implanted polyethylene is 17 mg, while for the 1016 ions.cm-2 implanted polyethylene is ca. 8 mg. Wear rate of ion-implanted polyethylene significantly decreases owing to the formation of a hardened (or cross-linked) layer at surface. Analytical result supports that morphologies and concentrations of wear debris vary with testing cycles, which include delaminated species and carbonates from the scission of polyethylene in foam- or plate-like dimension. On the other hand, because of varied materials’ characteristic at the contact surfaces, their bearing capabilities to keep in the elastic region are different. Micro-motion at the fixed interface eventually provokes macro-scale dislocation between implant and surrounding tissues. Present methodology proposes a possible mechanism occurred at the inserted interface before loosening. The parameters used are correlated with Ti-based femoral stem with respect to bone cement; the range of micro-motion is assigned as ±40μm per cycle with constant speed of 0.0014 mm/s, moving forward for 10,000 cycles each, and under a bearing load of 100 N. Experimental result on micro-motion has indicated that boundary friction causes plowing effect and thus reduced contact area; a localized edge effect occurs. Further SEM observations and roughness tests provide that the edge-effected width on bone cement is ca. 80m (due to ±40μm movement each cycle); some 20μm are caused by the accumulation of wear debris. Along partial edge of Ti-base pin, small amount of PMMA particles are adhered. The roughness at both surfaces after micro-motion tests is corresponded to friction-to-wear mechanics. When the inserted stem loses mechanical interlocks with bone cement, a gradual slip at the interface decreases their adherence. The released species may facilitate and accelerate their detachment and diminish the initial elastic range of bone cement. This may create loosening or shrinking effect on the inserted stem. A conclusion for both behaviors suggest that a variation of relative and dynamic interface in use.

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Patarata, Vasco Santos. "Structural simulation of 3D limb prostheses using meshless methods." Master's thesis, 2017. https://hdl.handle.net/10216/107686.

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Patarata, Vasco Santos. "Structural simulation of 3D limb prostheses using meshless methods." Dissertação, 2017. https://hdl.handle.net/10216/107686.

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Dissertations / Theses on the topic 'Prosthesis simulator'

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