Design and development of a MEMS-based capacitive bending strain sensor and a biocompatible housing for a telemetric strain monitoring system.

Lumbar arthrodesis or spinal fusion is usually performed to relieve back pain and regain functionality from ruptured discs, disc degenerative disease, trauma and scoliosis. Metal rods are often fixed to the spine with screws or hooks, while fusion develops on the affected vertebrae. Fusion is determined by visual examination of radiographic images (X-ray), computed tomography (CT) scans or magnetic resonance imaging (MRI), yet these inspection procedures are subjective methods of review. They do not objectively confirm the presence of spinal fusion, which can lead to exploratory surgery to determine if fusion has occurred. Therefore, a need has arisen to develop an objective method that will offer unbiased information for the determination of fusion. Discussed herein is a housing and sensor designed to be used in conjunction with telemetric circuitry that will attach to the spinal instrumentation rods. The housing will transmit strain to an internatal capacitive MEMS-based sensor that will relay strain magnitudes via telemetry. Observed reductions of bending strain will indicate a successful fusion. These objective assessments will reduce the incidence of costly exploratory surgeries where fusion is in question. The housing design was fabricated using Polyetheretherketone (PEEK) material, which was selected for its physical properties and its ability to be implanted for long durations. The housing was tested under cyclical, static and maximum strain transfer loading configurations in the Material Testing System (MTS). Results from these tests demonstrated that the housing transferred 102% of the bending strain and successfully met the design criteria. Additionally, a MEMS-based sensor was developed to change the capacitance with detected alterations in bending strain transmitted through the housing. Sensors were fabricated using microfabrication techniques and highly doped boron silicon wafers to create a transverse comb drive or an interdigitated finger array. The sensor was tested using similar methods that were used for the housing. Results from cyclical testing demonstrated the sensor\u27s response needed to be increased 50% and it did not exhibit any capacitance drift

Tribological Performance of Artificial Joints

Joint replacement is a very successful medical treatment. However, the survivorship of the implants could be adversely affected due to the loss of materials in the form of particles or ions as the bearing surfaces articulate against earch other. The consequent tissue and immune response to the wear products, remain one of the key factors of their failure. Tribology has been defined as the science and technology of interacting surfaces in relative motion and all related wear products (e.g., particles, ions, etc.). Over the last few decades, in an attempt to understand and improve joint replacement technology, the tribological performance of several material combinations have been studied experimentally and assessed clinically. In addition, research has focused on the biological effects and long term consequences of wear products. Improvements have been made in manufacturing processes, precision engineering capabilities, device designs and materials properties in order to minimize wear and friction and maximize component longevity in vivo

Die dritte Generation der Kyphoplastie: Entwicklung und Einführung am Beispiel des Vertebral Body Stenting (VBS)

Die Verwendung des VBS zur Augmentation von osteoporotischen Wirbelkörpern mit Kompressionsfrakturen ist ein innovatives Verfahren zur Frakturbehandlung. Das System ermöglicht die Reposition des Wirbels mit geringem Höhenverlust nach Ballondeflation und generiert einen Hohlraum zur sicheren Zementinjektion. Sowohl in vitro wie auch in vivo zeigten sich Vorteile gegenüber der Ballonkyphoplastie. In der Folge haben sich bis heute neben dem VBS bereits weitere implantatbasierte Systeme entwickelt, sodass diese neue Generation der Kyphoplastie im klinischen Alltag bereits jetzt etabliert ist

Revealing host factors important for hepatocyte : infection by plasmodium

Tese de doutoramento em Biologia (Biologia Celular), apresentada à Universidade de Lisboa através da Faculdade de Ciências, 200

Biomechanical risk factors and reduced bone health in lower limb amputees

Bone constantly adapts to its surroundings through the formation and resorption of material, controlled by bone modelling and remodelling. Strains produced by mechanical loading are one factor that drive these processes and thus determine bone health. Lower limb amputees (LLA) adopt an asymmetrical movement pattern to compensate for the loss of a limb, resulting in a change in mechanical loading and subsequently a degradation in bone health. The aetiology of the majority of amputations is vascular diseases, which affect bone health. Therefore, it is not clear whether the asymmetrical loading, or comorbidities cause the degradation in bone health in LLA. Finite element models (FEM) are used to generate strain plots and predict the bone's response to mechanical loading. To understand the relationship between the degradation in bone health and asymmetrical loads in LLAs the asymmetrical loads can be applied to a healthy bone using FEMs, or simulated within a healthy population using restrictive devices. Therefore, the overall aim was to investigate the relationship between asymmetrical loading, as observed in LLA’s, and bone health, through the use of semi-subject specific FEMs and restrictive lower limb devices. Study one established a novel image processing method to convert peripheral quantative computed tomography (pQCT) scan images into binary and segment the tibia. The outer perimeter of the tibia was identified and sectioned to produce landmarks. The outer geometry landmarks were used to morph a base FEM, constructed from open source scan images to create semi-subject tibia FEM. Study two applied subject-specific joint reaction and muscle forces to the semi-subject tibia FEM. The strain plots output from Study two were validated against longitudinal geometrical changes from Study three. Study three, used 3D motion capture, pQCT and dual energy x-ray absorptiometry (DXA) to investigate gait and tibial geometry within a lower limb amputee and able-bodied population across twelve months. The coefficient of variation (CV) for able bodied subjects was less than 10% for ground reaction force (GRF) in level walking and less than 4% for bone total area. Study four, used a rigid foot orthosis and a trans-femoral prosthesis, to restrict able-bodied gait. Results showed participants walked significantly slower (p<0.01) in the restricted conditions, with a longer non-restricted step length (p<0.001). The loading rate and maximum GRF were higher in the non-restricted limb (p<0.05). Larger knee adductor moments were shown in the un-restricted leg in the trans-tibial condition (p<0.05). This thesis presents a novel method of constructing semi-subject specific FEMs from pQCT scans. This can be used to further investigate the link between asymmetrical loading and bone health in LLA's and other populations with asymmetrical gait. The use of restrictive devices allow investigation into LLA's specifically, without the interference of prosthetic variability, or comorbidities

Patient-Specific Implants in Musculoskeletal (Orthopedic) Surgery

Most of the treatments in medicine are patient specific, aren’t they? So why should we bother with individualizing implants if we adapt our therapy to patients anyway? Looking at the neighboring field of oncologic treatment, you would not question the fact that individualization of tumor therapy with personalized antibodies has led to the thriving of this field in terms of success in patient survival and positive responses to alternatives for conventional treatments. Regarding the latest cutting-edge developments in orthopedic surgery and biotechnology, including new imaging techniques and 3D-printing of bone substitutes as well as implants, we do have an armamentarium available to stimulate the race for innovation in medicine. This Special Issue of Journal of Personalized Medicine will gather all relevant new and developed techniques already in clinical practice. Examples include the developments in revision arthroplasty and tumor (pelvic replacement) surgery to recreate individual defects, individualized implants for primary arthroplasty to establish physiological joint kinematics, and personalized implants in fracture treatment, to name but a few

Biomechanical studies of locomotion in pigs

PhD ThesisLameness is a major cause of lost productivity for the pig industry. The objective of this PhD was to develop an objective motion capture method for growing pigs and assess (1) the repeatability and sensitivity of the method (2) the gait characteristics of pigs housed on different floor types and (3) gait differences in pigs with conformational deficiencies, joint disease and/or clinical lameness. Infrared camera-based motion capture was applied to three different cohorts of pigs in three experiments, including an observational study following 84 gilts from grower- to second-parity stage. 3D coordinate data of reflective skin markers attached to head, neck, trunk and leg anatomical landmarks were collected. Temporal (time), linear (displacement) and angular (joint angles) kinematic gait parameters were calculated. Repeatability of the method varied with amount of overlying tissue and/or prominence of anatomical landmarks used for marker placement, but not necessarily with walking speed. Gait development of pigs reared on fully-slatted, partly-slatted or deep straw-bedded floors was not different. Lameness detection and evaluation was possible using relative linear and temporal kinematics. The within-stride trajectory of head and pelvic regions during walking differentiated pigs with front and multi-leg lameness from normal pigs, respectively. The ipsilateral swing-to-stance time ratio detected lameness in hind legs, but was not affected during multi-leg lameness. The frequency and magnitude of irregular steps was increased in lame pigs and in pigs with subclinical joint lesions of osteochondrosis diagnosed post slaughter. Step irregularity (as reflected in the step-to-stride length ratio) was also predictive of impending lameness. The step-to-stride length ratio is a dimensionless and ideal parameter to monitor pigs of different age and size, moving at a self-chosen walking speed. Flexion asymmetry and joint flexion patterns were indicative of locomotor problems in some cases. Gait analysis therefore offers potential for automated prediction and early detection of lameness.British Pig Executive (BPEX

De kwaliteit van implantaten in juridisch perspectief : reguleringsscenario's voor de totale heupprothese

Als iemand zich niet lekker voelt, gaat hij naar de dokter. In veel gevallen zal hij een pilletje, een poedertje of een zalfje voorgeschreven krijgen. Naast geneesmiddelen wordt bij de zorg voor patiënten echter ook gebruik gemaakt van een speciale groep produkten: 'medische hulpmiddelen'. Het betreft hier produkten variërend van verbandgaasjes en thermometers tot implantaten, niersteenvergruizers en röntgenapparatuur. Geneesmiddelen worden door de overheid aan een nauwkeurige controle onderworpen voordat ze in de medische praktijk mogen worden gebruikt. Het wekt misschien verbazing maar de situatie wat medische hulpmiddelen betreft is een geheèl andere

Applications of dynamical systems theory and 'complex' analyses to cricket fast bowling.

The aims of this thesis were to: (i) increase understanding of the biomechanical and motor control processes that underpin proficient fast bowling performance using dynamical systems theory and 'complex' analyses; and (ii) demonstrate the application of dynamical systems theory and the utility of 'complex' analyses to performance-oriented sports biomechanics research using cricket fast bowling as a representative task vehicle.Prior to analysing within- and between-bowler differences in coordination patterns at different levels of analysis and their relationship to ball release speed, the suitability of manual coordinate digitising for analysing intra- and inter-individual variability was examined. Both the reliability of time-discrete and time-continuous kinematic variables was considered. Of the 33 time-discrete kinematic variables examined, 31 exhibited between-participant variances and re-digitisation variances that accounted for the largest and smallest portions of total variance, respectively. Furthermore, re-digitisation variance accounted for less than 5% of total variance in 29 of these variables with 15 of these exhibiting less than 1%. For the 45 time-continuous kinematic variables, measurement error accounted for 17.2% of movement variability (range 4.3-41.0%). When considered together, these results indicated that manual coordinate digitising was sufficiently sensitive to reliably measure differences in technique within and between bowlers.Kohonen Self-Organising Maps (SOMs) were used to analyse coordination patterns in cricket fast bowling at a global whole-body level of analysis. Qualitative differences in SOM trajectories between bowlers signified participant-specific coordination patterns, which were attributed to differences in organismic constraints and intrinsic dynamics. A theoretical argument against the common optimal movement pattern concept was constructed and the utility of SOMs was evaluated. Several issues currently limiting their practical application, including the difficulty in linking the SOM trajectory to aspects of technique and the inability of biomechanists to identify optimal sports techniques, were highlighted.A combination of 'complex' analytical techniques was then applied to quantify intersegmental coordination among key limb and torso segments. Cross-correlation functions showed that moderate (0.5+) to very strong (0.9+) coupling relationships existed for the four segment couplings (NBA vs. FL, BA vs. NBA, BA vs. FL, UT vs.P) with the majority of these moving in synchrony. Statistically significant mean differences in both cross-correlation coefficients and average coupling angle for the four segment couplings throughout (0-100%), and during different phases (0-24%, 25-49%, 50-74%, 75-99%) of, the delivery stride provided further evidence of participant-specific coordination patterns. However, no associations between coupling relationships and ball release speed could be identified either within or between bowlers. This study further highlighted the difficulties in making associations between technique and outcomes.It was concluded that, based on the reported research findings, dynamical systems theory and its associated 'complex' analyses could make a substantive contribution to the enhancement of knowledge of cricket fast bowling techniques and also advance applied sports biomechanics research more generally. Further investigations into cricket fast bowling performance, focusing on the link between technique and outcomes using a combination of kinetic, energetic and coordination analyses, were identified as a research priority

Développement d'un protocole d’évaluation et d’un programme d’entraînement de la capacité cardiorespiratoire chez des usagers d’un fauteuil roulant manuel

Les usagers d’un fauteuil roulant (FR) manuel ont une capacité cardiorespiratoire habituellement fortement diminuée suite à aux déficiences physiques ayant mené à l’incapacité à la marche et à leur mode de vie souvent sédentaire. Cependant, peu d'outils sont disponibles pour l'évaluation et l'entraînement de la capacité cardiorespiratoire spécifique à la propulsion d’un FR manuel. Les objectifs principaux de cette thèse étaient 1) de proposer et d'évaluer un protocole d’épreuve d’effort en FR manuel sur un tapis roulant motorisé et 2) d’étudier la faisabilité, la sécurité et les effets d’un entraînement cardiorespiratoire par intervalles à haute intensité en FR manuel effectué dans la communauté. Trois projets distincts font partie de cette thèse. Projet #1 - Exigences cardiorespiratoires lors de la propulsion d'un FR manuel sur un tapis roulant motorisé: 17 usagers d'un FR manuel ont effectué 12 essais randomisés de propulsion composés d'une combinaison d'une pente (0°, 2,7°, 3,6° et 4,8°) et d'une vitesse (0,6, 0,8 et 1,0 m/s) sur un tapis roulant motorisé. Les réponses cardiorespiratoires ont été mesurées et l'effet de la pente et de la vitesse sur celles-ci fut calculé. Un nouveau protocole d’épreuve d’effort fut proposé en se basant sur l'effet de la pente et de la vitesse sur la consommation d'oxygène (VO2). Projet #2 - Qualités psychométriques de l’épreuve d’effort : Au total 28 usagers d'un FR manuel ont participé à ce projet. La fidélité test-retest et le changement minimal détectable ont été quantifiés en comparant les réponses cardiorespiratoires maximales mesurées lors de deux épreuves d’effort sur tapis roulant effectuées lors d’occasions différentes. La validité concomitante des réponses cardiorespiratoires maximales mesurées lors de l’épreuve sur tapis roulant a été vérifiée en les comparant avec celles obtenues lors d’une épreuve d’effort sur un ergocycle pour les membres supérieurs. Projet #3- Programme d'entraînement: Onze usagers d'un FR manuel ont été répartis aléatoirement entre un groupe effectuant un programme d'entraînement cardiorespiratoire par intervalles à haute intensité (HIIT) (N=6) et un groupe effectuant un programme d'entraînement cardiorespiratoire continu à intensité modérée (N=5). Ces programmes de 40 minutes/séance à raison de trois séances/semaine pendant six semaines étaient effectués en FR manuel dans la communauté sous la supervision indirecte d'un physiothérapeute. La faisabilité, la sécurité et l'efficacité sur l'amélioration de la capacité cardiorespiratoire et de la force des membres supérieurs ont été mesurées et comparées entre les deux programmes. Les résultats du projet #1 ont démontré que les réponses cardiorespiratoires augmentaient avec l’augmentation de la pente ou de la vitesse du tapis roulant pour presque toutes les conditions. L’équation de prédiction de la VO2 a permis de développer un protocole d’épreuve d’effort en propulsion d’un FR sur un tapis roulant motorisé fidèle et valide pour évaluer la capacité cardiorespiratoire des usagers d’un FR manuel. Aussi, le programme d’entraînement HIIT s’est avéré sécuritaire lorsqu’effectué dans la communauté bien que des précautions doivent être prises lorsque les individus présentent de la douleur aux membres supérieurs. De plus, les routes bien entretenues et les endroits peu achalandés sont des endroits sécuritaires et appréciés pour l’entraînement en FR manuel. Finalement, l’efficacité du programme d’entraînement HIIT n’a pas été démontrée après six semaines d’entraînement, mais les améliorations subjectives rapportées par les participants appuient sa pertinence.Manual wheelchair (MWC) users usually have a strongly reduced cardiorespiratory capacity due to both the physical disabilities which brought the need for a wheelchair and to their often sedentary lifestyle. However, very few tools are available for the evaluation and the training of the cardiorespiratory fitness aimed specifically at MWC users. The main goals of this thesis were to 1) propose and evaluate a MWC stress test protocol on a motorized treadmill and 2) to study the feasibility, the safety and the impacts of a community-based high-intensity interval MWC cardiorespiratory training. This thesis is composed of three distinct projects. Project #1 – Cardiorespiratory requirements during MWC propulsion on a motorized treadmill: 17 MWC users completed 12 randomized trials composed of a combination of a slope (0°, 2.7°, 3.6° and 4.8°) and a speed (0.6, 0.8 and 1.0 m/s) on a motorized treadmill. The cardiorespiratory responses have been measured and the effects of changes of slope and speed on them have been calculated. A new stress test protocol was then proposed according to the effects of the slope and the speed on oxygen consumption (VO2). Project #2 – Psychometric properties of the stress test: A total of 28 MWC users took part to this project. The test-retest reliability and the minimal detectable change (MDC) were quantified by comparing the maximal cardiorespiratory responses measured during two stress tests completed on two separate occasions. The verification of the concurrent validity was done by comparing the maximal cardiorespiratory responses measured during the treadmill stress tests with those measured during a stress test on an arm crank ergometer. Project #3: Training program: 11 MWC users were randomly assigned to either a group doing a high-intensity interval training (HIIT) (N=6) or a group doing a continuous, moderate-intensity cardiorespiratory training (N=5). These programs lasted 40 minutes/session, 3 days/weeks for a duration of 6 weeks and were executed in a MWC in a community setting under the indirect supervision of a physiotherapist. The feasibility, safety and effectiveness regarding an increase in cardiorespiratory capacity and upper extremity strength were measured and compared between programs. The results of project #1 did show higher cardiorespiratory responses with an increase in the treadmill slope or speed for almost all conditions. The prediction equation for the VO2 allowed for a stress test protocol to be developed and which can be used as a reliable and valid test of the cardiorespiratory capacity on a motorized treadmill for MWC users. Furthermore, the HIIT program was deemed safe while executed in a community setting, while precautions should be taken when individuals have upper extremity pain. Also, well-maintained roads and less crowded areas are popular and safe MWC training places. Finally, the effectiveness of the 6 weeks HIIT training program has not been confirmed, but the subjective improvements reported by the patients support the relevance of the program