The initial recommendation for the postoperative regime after uncemented total hip arthroplasty (THA) was 6-12 weeks of partial weight bearing (PWB) to obtain a stable implant position during bone ingrowth. In recent years patients with uncemented THA have increasingly practiced full weight bearing (FWB) after surgery, which has largely been based on clinical experience rather than on scientific evidence. The aim of this thesis was to investigate the effects of FWB versus PWB for 3 months on the stability of the implants and on bone mineral density (BMD), as well as body composition (BC) of the lower extremities. We used radiostereometric analysis (RSA) to measure implant micromotion and dual X-ray absorptiometry (DXA) to measure BMD and BC. Forty-six patients with strictly unilateral osteoarthritis of the hip (OAH) received uncemented THA. These patients were then randomized to the FWB or PWB groups and followed for 5 years. In a preoperative cross-sectional study the BMD of the hip and heel were compared between the OAH-affected side and the healthy side. The study showed an increase of BMD at the femoral neck and a decrease at the total hip and trochanter. The results of a RSA study of cup stability showed that there might be minimal movement in medial and proximal directions during the first postoperative week. These results indicate that the RSA baseline investigation of uncemented cups should be performed as early as possible after the first postoperative day. FWB had no adverse effects on the stability of the uncemented press-fit cups or the uncemented cementless Spotorno (CLS) femoral stems after a 5-year follow-up. There was no difference in periprosthetic BMD around the CLS stem regardless of the postoperative weight bearing regime. All zones around the femoral stem indicated a recovery in BMD toward baselines, except the calcar region, which showed progressive loss in BMD to -22% at 5 years post-surgery. FWB had no effect on the changes in BC after surgery. In conclusion, FWB is safe in uncemented THA in terms of stability, BMD and BC. Furthermore, THA apparently counteracts age-related changes in BC but not in BMD.

The use of nanotechnology to develop methods for fabrication and characterization of organized hybrid nanostructures that include integrated polymeric, biological and inorganic compounds has increased exponentially during the last decade. Such bio-nano-composite materials could be used in solving current biomedical problems spanning from nanomedicine to tissue engineering and biosensing. In this dissertation, a systematic study has been carried out on the synthesis, characterization, of two interfaces between naturally derived and synthetic nanostructures. Carbon nanotubes and porous silicon represent the synthetic nanostructures that were developed for the purpose of interfacing with the naturally derived bovine type I collagen and respiratory syncytial virus DNA respectively. Firstly, the synthesis of collagen-carbon nanotubes by two different techniques: fibrillogenesis through slow wet fiber drawing (gelation process) and electrospinning has been highlighted. Characterization of the novel nanocomposite was conducted using electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, nanoindentation, and Raman spectroscopy. The collagen-carbon nanotube gelation process was found to have superior nanoscale surface mechanical properties that were more conducive to higher osteoblast specific protein expression such as osteocalcin. Applications of the developed nanofibers are detailed in the fields of orthopaedics and tissue engineering. Secondly, an overview of porous silicon synthesized by hydrofluoric acid is presented. A parametric study was performed to determine the optimal pore size was carried out. The use of porous silicon as a biosensor to detect RSV virus by DNA hybridization was then provided and the importance of the interface chemistry was highlighted.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

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Conselho Nacional de Desenvolvimento Científico e Tecnológico / The hip joint is the more frequently joint injured in dogs for external traumatism or degenerative diseases. Many studies have been accomplished in the evaluation of new surgical techniques, however little has been describing about evaluations in long period Recent works have been using the force platform at gait as objective method in association to the other parameters consecrated in the evaluation of new orthopedics techniques. However, there are no studies using the platform in pattern ortostático as in the human medicine, for support evaluation and weight transfer. The propose of this work was to standardize the use of the force platform in ortostatic pattern in dogs, to test it at surgical orthopedics patients and to evaluate the patients' recovery with hip diseases of surgical resolution through the parameters clinic, and force platform for static collection. For this clinical evaluation (lameness degrees, thigh circumference, radiografic exam) was accomplished and biomechanical evaluation through of the force plate for static collection of 21 operated dogs of the hip joint with diagnosis of traumatic hip luxation , fracture of head and femoral lap or aseptic necrosis of the femoral head and 6 healthy dogs without report of orthopedics problems. The platform in pattern ortostático an efficient and more sensitive objective parameter was shown than the others in some situations, being his/her appropriate use in the evaluation of orthopedic patient. This association to others parameters turned the evaluation of the appraised patients' recovery more completes and trustworthy. The recovery of the animals was very good, demonstrating that most is (approximately 70%) with function of the affected member practically reestablished, with some individual variations, been their recovery classified between excellent and very good. The animals that presented recovery classification of reasonable to bad, didn't possess enough time for recovery, they presented complications or they had the late recovery due to the obesity. This way, it is concluded to be very good the prognostic in long period of these affections with surgical treatment through transacetabular pinning insertion and arthroplasty excision of the femoral head; and that the evaluation of animals recovery for clinic and biomechanical (in study pattern ortostático) is practice and efficient. / A articulação coxo-femoral em cães é a articulação mais freqüentemente lesionada, seja por traumatismo externo ou doenças degenerativas. Muitos estudos têm sido realizados na avaliação de novas técnicas cirúrgicas, porém, pouco há descrito sobre avaliações em longo prazo. Trabalhos recentes têm utilizado a plataforma de força em marcha como método objetivo em associação aos demais parâmetros consagrados na avaliação de novas técnicas ortopédicas. Porém, não há estudos utilizando a plataforma em padrão ortostático, como na medicina humana, para avaliação de apoio e transferência de peso. O objetivo deste trabalho foi padronizar o uso da plataforma de força em padrão ortostático em cães, testá-la em pacientes cirúrgicos ortopédicos, e avaliar a recuperação dos pacientes com afecções coxofemorais de resolução cirúrgica, através dos parâmetros clínico e biomecânico por coleta estática. Para isto foi realizada avaliação clínica (graus de claudicação, perimetria da coxa, exame radiográfico) e biomecânica na plataforma de força por coleta estática de 21 cães operados da articulação coxo-femoral com diagnóstico de luxação coxo-femoral traumática, fratura de cabeça e colo femorais ou necrose asséptica da cabeça femoral e 6 cães saudáveis sem histórico de problemas ortopédicos. A plataforma em padrão ortostático mostrou-se um parâmetro objetivo eficiente e mais sensível que os demais em algumas situações, sendo seu uso adequado na avaliação de pacientes ortopédicos. Sua associação aos demais parâmetros tornou a avaliação da recuperação dos pacientes avaliados mais completa e fidedigna. A recuperação dos animais foi muito boa, visto que a maioria (aproximadamente 70%) demonstrou estar com a função do membro afetado praticamente restabelecida, com algumas variações individuais, sendo sua recuperação classificada entre excelente e muito boa. Os animais que apresentaram classificação de recuperação de razoável a ruim, não possuíam tempo suficiente para recuperação, apresentaram complicações ou tiveram sua recuperação atrasada devido à obesidade. Desta forma, conclui-se ser muito bom o prognóstico em longo prazo destas afecções tratadas cirurgicamente através da inserção de pino transacetabular e excisão artroplástica da cabeça do fêmur; e que a avaliação da recuperação dos animais por estudo clínico e biomecânico (em padrão ortostático) é prática e eficiente.

abstract: Controlled release formulations for local, in vivo drug delivery are of growing interest to device manufacturers, research scientists, and clinicians; however, most research characterizing controlled release formulations occurs in vitro because the spatial and temporal distribution of drug delivery is difficult to measure in vivo. In this work, in vivo magnetic resonance imaging (MRI) of local drug delivery is performed to visualize and quantify the time resolved distribution of MRI contrast agents. I find it is possible to visualize contrast agent distributions in near real time from local delivery vehicles using MRI. Three dimensional T1 maps are processed to produce in vivo concentration maps of contrast agent for individual animal models. The method for obtaining concentration maps is analyzed to estimate errors introduced at various steps in the process. The method is used to evaluate different controlled release vehicles, vehicle placement, and type of surgical wound in rabbits as a model for antimicrobial delivery to orthopaedic infection sites. I are able to see differences between all these factors; however, all images show that contrast agent remains fairly local to the wound site and do not distribute to tissues far from the implant in therapeutic concentrations. I also produce a mathematical model that investigates important mechanisms in the transport of antimicrobials in a wound environment. It is determined from both the images and the mathematical model that antimicrobial distribution in an orthopaedic wounds is dependent on both diffusive and convective mechanisms. Furthermore, I began development of MRI visible therapeutic agents to examine active drug distributions. I hypothesize that this work can be developed into a non-invasive, patient specific, clinical tool to evaluate the success of interventional procedures using local drug delivery vehicles. / Dissertation/Thesis / Ph.D. Bioengineering 2013

This report presents three implementations for solving 3D puzzles of fractured bones: two semi-automatic ones and one which is automatic. These are compared using qualitative as well as quantitative tests to find out if less interaction can yield equal or better results. Qualitative tests are performed on real clinical data from CT-scans. A model created in Blender is used for quantitative tests. Test results have shown that each implementation has its own strengths and weaknesses which can make them usable for different types of fractures. It may be possible to combine automatic solutions and manual ones to increase the number of solvable cases. The conclusion is that it is possible to reduce fractures with less user interaction and still get equal or better results, but it depends on the fracture case as well as the user.

No description available.

Ce travail porte sur le comportement mécanique de la cupule acétabulaire de prothèse de hanche dans le milieu osseux. Un intérêt particulier est porté au développement d'une méthode d'analyse de signaux d'impacts visant à caractériser les propriétés biomécaniques de l'interface entre la cupule acétabulaire et l'os périacétabulaire. Dans un premier temps, l'insertion de la cupule par impacts reproductibles est étudiée expérimentalement. Il est démontré que les signaux de force des impacts sont sensibles aux conditions d'insertion de l'implant acétabulaire. Un modèle analytique empirique considérant une configuration poinçon plat est utilisé pour modéliser les conditions de contact entre l'os et l'implant. La stabilité de l'implant acétabulaire est ensuite évaluée dans différentes configurations osseuses. Une analyse des signaux d'impact permet d'estimer cette stabilité. Dans un deuxième temps, un marteau est instrumenté avec un capteur de force et utilisé pour enregistrer les signaux de force des impacts. La méthode d'analyse des signaux est adaptée et permet d'évaluer la stabilité primaire de l'implant acétabulaire. Pour permettre le transfert de l'approche vers une application clinique, une étude cadavérique est ensuite réalisée. Il est montré que la méthode est utile pour prévoir la stabilité primaire de la cupule acétabulaire dans des hanches cadavériques. Le troisième volet de cette thèse est composé d'études de simulation numérique pour mieux comprendre le comportement mécanique de la cupule acétabulaire. Un modèle est développé pour investiguer les procédés dynamiques ayant lieu lors de l'impaction de la cupule acétabulaire et pour estimer le potentiel de la méthode d'analyse d'impacts pour déterminer les conditions d'insertion de la cupule acétabulaire. Différentes conditions d'interférence et différentes vitesses d'impaction sont considérées. Il est montré que les signaux d'impacts sont sensibles à surface de contact entre l'os et l'implant. Un second modèle étudie l'influence des propriétés mécaniques de l'os périacétabulaire au comportement mécanique de la cupule / While hip arthroplasty has become a common surgical procedure, failures still happen due to inadequate mechanical behavior of the prosthesis. This work studies the behavior of the acetabular cup (AC) implant within bone tissue and develops an impact analysis method to assess its insertion conditions. In the first part, AC insertion within bovine bone tissue are performed using reproducible mass drops. The impact force signals are recorded and are shown to be sensitive to insertion conditions of the AC implant. An empirical analytical model considering a flat punch configuration to model the bone-implant contact conditions is used to understand the variations of the signals. The AC implant tangential stability is further evaluated for different bone cavity configurations. An impact signals analysis enables to assess the AC implant primary stability in vitro. In the second part, a hammeris instrumented with a force sensor and is used to record the impacts force signals. The impact signals analysis allows to evaluate the AC implant stability. In order to transfer the approach to a situation closer to the clinical application, tests are then realized with cadaveric hips. The method is found useful to predict the AC implant stability ex vivo. In the third part, finite element models are developed to improve the understanding of the AC implant mechanical behavior within bone tissue. A model investigates the dynamic processes occurring during the AC implant impaction. The impact signals analysis allows to evaluate the bone implant contact area. A second model studies the influence of the peri-implant anisotropic bone mechanical properties on the mechanical behavior of the AC implant. By coupling experimental and numerical approaches, this work provides new features concerning the mechanical processes responsible for the AC implant stability. Moreover, the feasibility of a medical device that could assess peroperatively the AC implant stability is proved

Despite the high success rates of hip replacements, implant-wear mediated periprosthetic osteolysis remains the most prominent cause of long-term implant failure. Other adverse tissue reactions including hypersensitivity reactions and pseudotumors have also recently been reported as a cause for short-term implant failures. The objectives of this thesis were: 1.) To analyze the effects of Co2+ and Cr3+ released from CoCrMo alloys used in hip implants on macrophage chemokine release; 2.) To determine if Co2+, Cr3+, and the chemokines in cultures of macrophages exposed to Co2+ and Cr3+ can induce migration of T and B lymphocytes; and 3) To analyze the potential modulation of macrophage response to Cr3+ using simvastatin as an anti-inflammatory agent. Results showed that the release of TNF–α and CC chemokines were ion-specific and dose-dependent. Results also suggested that Co2+ and Cr3+ may be capable of directly stimulating the migration of T cells, but not that of B cells, suggesting the potential of these ions to create a micro-environment that would favour a T cell-mediated response in vivo. Results also showed that simvastatin was capable of decreasing chemokine release in macrophages exposed to Cr3+, suggesting its potential to modulate the Cr3+-induced inflammatory response. Together, these studies improve the understanding of the role metal ions play in ion-mediated adverse tissue reactions and potential therapies that may modulate the immune response to metal ions.