Dissertations / Theses on the topic 'Femoral implants'

Thesis (M.S.)--University of Missouri-Columbia, 2006.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 30, 1981) Includes bibliographical references.

Introduction:Internal fixation of fractures in the presence of osteopenia has been associated with a failure rate as high as 25%. Enhancing bone formation and osseointegration of orthopaedic hardware is a priority when treating patients with impaired bone regenerative capacity. Fibroblast Growth Factor (FGF) 18 regulates skeletal development and could therefore have applications in implant integration. This study was designed to determine if FGF 18 promotes bone formation and osseointegration in the osteopenic FGFR3-/- mouse and to examine its effect on bone marrow derived mesenchymal stem cells (MSCs).Methods: In Vivo: Intramedullary implants were fabricated from 0.4 x 10mm nylon rods coated with 300nm of titanium by physical vapour deposition. Skeletally mature, age matched female FGFR3-/- and wild type mice received bilateral intramedullary femoral implants. Left femurs received an intramedullary injection of 0.1μg of FGF 18 (courtesy Merck Serono), and right femurs received saline only. Six weeks later, femurs were harvested, radiographed, scanned by micro CT, and processed for undecalcified for histology.In Vitro: MSCs were harvested from femurs and tibiae of skeletally mature age matched FGFR3-/- and wild type mice. Cells were cultured in Alpha Modified Eagle's Medium (αMEM) to monitor proliferation or αMEM supplemented with ascorbic acid and sodium beta-glycerophosphate to monitor differentiation. Proliferation was assessed through cell counts and metabolic activity at days 3, 6 and 9. Differentiation was assessed through staining for osteoblasts and mineral deposition at days 6, 9 and 12.Results: Wild type mice exhibited more peri-implant bone formation compared to FGFR3-/- mice. Peri-implant bone formation at the proximal metaphyseal-diaphyseal junction was increased in FGF18 treated femurs compared with contralateral control femurs in wild type (p = NS) and FGFR3-/- (p = 0.04) mice. Histological analysis corroborated micro CT findings, with FGF 18 treated FGFR3-/- femurs forming peri-implant bone instead of the fibrous response seen in controls. In vitro studies showed that FGF18 significantly increased MSC proliferation and metabolism in a dose dependent manner in wild type and FGFR3-/- mice. Osteoblast differentiation was inhibited by FGF18 in wild type MSCs, while no significant effect was observed in cells harvested from FGFR3-/- mice.Conclusion: FGF 18 increases bone formation and osseointegration of intramedullary implants in osteopenic mice and increases MSC proliferation in both the presence and absence of FGFR3. FGF18 also inhibits early osteoblast differentiation in the presence of FGFR3. FGF 18 mediated MSC proliferation and osteogenesis is likely due to signalling through an alternate FGFR, likely FGFR1 or 2. Additional work is needed to confirm the identity of the alternate FGFR and to evaluate its capacity to improve osseous healing in unfavourable in-vivo environments.
Introduction: La fixation interne de fractures dans la présence de l'ostéopénie a été associée à un taux d'échec aussi élevé que 25%. Amélioration de la formation osseuse et l'ostéo-intégration de matériel orthopédique est une priorité pour le traitement de patients. Facteur de croissance des fibroblastes (FGF) 18 régit le développement squelettique et pourrait donc avoir des applications dans intégration de l'implant. Cette étude a été conçue pour déterminer si le FGF 18 favorise la formation osseuse et l'ostéo-intégration dans le ostéopénique FGFR3-/- souris et d'examiner son effet sur la moelle osseuse provenant de cellules souches mésenchymateuses (CSM).Méthodes: Implants intramédullaires ont été fabriqués à partir de tiges de nylon 10mm x 0,4 revêtus de 300nm de titane par dépôt de vapeur physique. Les souris de type FGFR3-/- et souris de type sauvage a reçu des implants intramédullaires au femurs. Les fémurs gauche ont reçu une injection intra-médullaire de 0.1μg de FGF 18 (Merck Serono), et les fémurs droit ont reçu une solution saline seule. Après six semaines, les fémurs ont été récoltés, analysé par les micro CT, et préparé pour l'histologie. Les CSM ont été récoltées à partir de fémurs et les tibias de souris de type FGFR3-/ - et de type sauvage. Les cellules ont été cultivées dans 'Alpha Modified Eagle's Medium' (aMEM) pour surveiller la proliferation, ou cultivées dans un milieu 'aMEM' complété avec de l'acide ascorbique et de sodium bêta-glycérophosphate pour surveiller la différenciation. La prolifération a été évaluée par dénombrement des cellules et l'activité métabolique aux jours 3, 6 et 9. Différenciation a été évaluée par coloration pour les ostéoblastes et les dépôts minéraux aux jours 6, 9 et 12.Résultats: Les souris de type sauvage ont produit plus d'os péri-implantaire par rapport à FGFR3-/ - souris. La formation osseuse péri-implantaire à la jonction proximale métaphysodiaphysaire a été augmenté en fémurs traités avec FGF18 par rapport aux fémurs de contrôle controlatéraux dans de type sauvage (p > 0.05) et FGFR3-/ - (p = 0.04). L'analyse histologique a corroboré les conclusions micro CT. Les femurs FGFR3-/ - qui ont recus FGF 18 traités fémurs ont formé l'os autour de l'implant au lieu de la réponse fibreuse vu dans les contrôles. Des études in vitro ont montré que la proliferation du MSC ont été augmenté avec FGF18 d'une manière dose-dépendante pour les type sauvage et les type FGFR3-/ -. La différenciation des ostéoblastes a été inhibée par FGF18 pour les CSM du type sauvage. Aucun effet significatif sur la différenciation a été observé dans les cellules récoltées à partir de souris FGFR3-/ -.Conclusion: FGF 18 augmente la formation osseuse et l'ostéo-intégration des implants intramédullaires chez la souris ostéopéniques. FGF 18 augmente la prolifération des CSM à la présence et l'absence de FGFR3. FGF18 inhibe également la différenciation ostéoblastique a la présence de FGFR3. Les effets de FGF 18 sur le prolifération des CSM et l'ostéogenèse est probablement dû à la signalisation grâce à un FGFR alternative, probablement FGFR1 ou 2. Des travaux in vivo supplémentaires sont nécessaires pour confirmer l'identité de l'autre FGFR et d'évaluer sa capacité à améliorer la cicatrisation de l'os en environnements défavorable

Bone mechanics and traditional implant materials produce a recurring problem for patients of total hip arthroplasty (THA): the bone is "shielded" from the loading it has become accustomed to over many years of development. Bone adheres to what is called "Wolff's Law", meaning it is an adaptive structure which adjusts its geometry based on the loads experienced over its life (Pearson; Goldstein). As the new femoral hip implant transmits reduced stresses to the remaining bone, bone tissue atrophies at the interface, permitting loosening of the implant, pain, and thereby obliging additional surgery to correct the issue (Meade). In the present work, a methodology is endeavored for creating an innovative design for femoral hip implants. The approach uncouples the finite element implant model from the bone model, in order to focus solely on expected behavior within the implant while considering the varying material behavior in unique directions and locations. The implant's internal geometry is optimized in order to better match typical, intact bone conditions. The eventual design reduces extreme changes in stresses within remnant bone such that the implant will remain implanted for greater periods of time without additional surgical attention.
ID: 030423147; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 86-91).
Ph.D.
Doctorate
Mechanical, Materials, and Aerospace Engineering
Engineering and Computer Science

In the pool of women over the age of 50, the likeliness of an atypical fracture increase drastically, partly due to osteoporosis. With a pre-existing implant in the femur bone, inserted due to a prior atypical fracture, treating a later femoral neck fracture is complex and risky. Currently, a fractured femoral diaphysis is treated using an intermedullary nail which is fixed to the femur bone either through the femoral neck (Recon locking method)or through the lesser trochanter (Antegrade locking method). In a study conducted by Bögl et.al. JBJS102.17 (2020), pp. 1486-1494, it is found that the fixation of the intermedullary nail through the femoral neck reduces the risk of future femoral neck fractures. The study also states that more than 50% of the patients with atypical femoral fractures related to bisphosphonate treatment for osteoporosis (within the study sub population) were treated with the Antegrade locking implant. There does not exist much literature that reasons as to how one locking method is showing lesser risk of re-operation as compared to the other. The purpose of this study is to look into the effects these two implants have on the femur bone using the Finite Element Analysis (FEA). The study presented is aimed at comparing the results of the finite element analysis for the Recon implant model (Recon model) and Antegrade implant model (Antegrade model). The femur model without the implants (native bone model) is used to verify material behavior, while the other two are used for the comparison to study the stress-strain distribution, primarily in the neck region. This is a patient specific study, hence the femur bone model is generated using patient Computed Tomography (CT) scans. The bone model was assigned a heterogeneous isotropic material property derived from patient CT data. The finite element (FE) model of the bone was meshed using Hypermesh. The peak loading condition including the muscle forces were applied on the native bone model along with the Recon and the Antegrademodel. While the loading conditions during normal walking cycle were only applied to theRecon and the Antegrade model to compare the impacts of the two implant types. Both loading conditions were simulated by fixing the distal condyle region of the bone. The analysis results show that the Antegrade implant experiences much higher stresses and strains in the neck region as compared to Recon implant. Also, the presence of the intermedullary nail through the femur diaphysis helps to distribute the stresses and strains in the anterior distal diaphysis region of the bone. For the case of no implants, the model showed strains and stresses in the lateral distal region of femoral diaphysis.

Thesis (M.S.)--West Virginia University, 2002.
Title from document title page. Document formatted into pages; contains vii, 79 p. : ill. Includes abstract. Includes bibliographical references (p. 71-79).

Removal of well-fixed femoral components during revision of hip arthroplasty is generally challenging for the surgeon. It can be associated with an increase in the length of procedure and operative complications. The easier extraction of femoral components and expansion of the proximal femur using episiotomy as a single posterior longitudinal split osteotomy was therefore described. In this research, we designed an in vitro protocol to simulate the extraction of press fit implants using an episiotomy in the long axis of the femur analogue to remove the implant. The mean extraction force after performing the episiotomy was significantly lower compared with similar constructs without performing the episiotomy. This paper presents an artificial model for the simulation of implant-bone interface and investigates episiotomy as a method for the extraction of well-fixed implants. It can provide information that may help in subsequent orthopedic techniques in revision surgery.

Total Hip Arthroplasty (THA) is an orthopaedic procedure that is performed to reduce pain and restore the functionality of hip joints that are affected by degenerative diseases. The outcomes of THA are generally good. However, the stress shielding of the periprosthetic femur is a factor that can contribute towards the premature loosening of the femoral stem. In order to improve the stress shielding characteristics of metallic femoral stems, stiffness configurations that offer more flexibility should be considered. This research has investigated the potential of more flexible and lightweight cobalt chromium molybdenum (CoCrMo) femoral stems that can be manufactured using Selective Laser Melting (SLM). Square pore cellular structures with compressive properties that are similar to human bone have been presented and incorporated into femoral stems by utilising fully porous and functionally graded designs. A three dimensional finite element model has been developed to investigate and compare the load transfer to the periprosthetic femur when implanted with femoral stems offering different stiffness configurations. It was shown that the load transfer was improved when the properties of the square pore cellular structures were incorporated into the femoral stem designs. Factors affecting the manufacturability and production of laser melted femoral stems have been investigated. A femoral stem design has been proposed for cemented or cementless fixation. Physical testing has shown that a functionally graded stem can be repeatedly manufactured using SLM, which was 48% lighter and 60% more flexible than a traditional CoCrMo prosthesis. The research presented in this thesis has provided an early indication of utilising SLM to manufacture lightweight CoCrMo femoral stems with levels of flexibility that have the potential to reduce stress shielding in the periprosthetic femur.

Thesis (PhD)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: The knee is the largest, most complicated and incongruent joint in the human body. It sustains very high forces and is susceptible to injury and disease. Osteoarthritis is a common disease prevalent among the elderly and causes softening or degradation of the cartilage and subcondral bone in the joint, which leads to a loss of function and pain. This problem can be alleviated through a surgical intervention commonly termed a “knee replacement”. The aim of a knee replacement procedure is to relieve pain and restore normal function. Ideally, the knee replacement prosthesis should have an articulating geometry similar to that of the patient’s healthy knee, and must allow for normal motion. Unfortunately, this is often problematic since knee prostheses are supplied in standard sizes from a variety of manufacturers and each one has a slightly different design. Furthermore, commercial prostheses are not always able to restore the complex geometry of an individual patient’s original articulating surfaces. This dissertation shows that there is a significant variation between knee geometries, regardless of gender and race. This research aims to resolve the problem in two parts: Firstly by presenting a method for preoperatively selecting the optimal knee prosthesis type and size for a specific patient, and secondly by presenting a design procedure for designing and manufacturing patient-specific unicompartmental knee replacements. The design procedure uses mathematical modelling and an artificial neural network to estimate the original and healthy articulating surfaces of a patient’s knee. The models are combined with medical images from the patient to create a knee prosthesis that is patient-specific. These patient-specific implants are then compared to conventional implants with respect to contact stresses and kinematics. The dissertation concludes that patient-specific implants can have characteristics that are comparable to or better than conventional prostheses. The unique design methodology presented in this dissertation introduces a significant advancement in knee replacement technology, with the potential to dramatically improve clinical outcomes of knee replacement surgery.
AFRIKAANSE OPSOMMING: Die knie is die grootste, mees komplekse en mees ongelyksoortige gewrig in die liggaam. Osteoarthritis is ’n siekte wat algemeen by bejaardes voorkom en die versagting of agteruitgang van die kraakbeen en subchondrale bene in die gewrig tot gevolg het, wat tot ’n verlies van funksionering en pyn lei. Hierdie probleem kan verlig word deur ’n chirurgiese ingryping wat algemeen as ’n “knievervanging” bekend staan. Die doel van ’n knievervangingsprosedure is om pyn te verlig en normale funksionering te herstel. Ideaal gesproke behoort die knievervangingsprostese ’n gewrigsgeometrie te hê wat soortgelyk aan die pasiënt se gesonde knie is, en normale beweging moontlik maak. Ongelukkig is dit dikwels problematies aangesien knieprosteses in standaardgroottes en deur ’n verskeidenheid vervaardigers verskaf word, wat elkeen se ontwerp effens anders maak. Verder kan kommersiële prosteses nie altyd die komplekse geometrie van ’n individuele pasiënt se oorspronklike gewrigsoppervlakke vervang nie. Hierdie proefskrif wys dat daar ’n betekenisvolle variasie tussen knieafmetings is, afgesien van geslag en ras. Hierdie navorsing is daarop gemik om die problem op tweërlei wyse te benader: Eerstens deur ’n metode aan te bied om die optimal knieprostesetipe en -grootte vir ’n spesifieke pasiënt voor die operasie uit te soek, en tweedens om ’n ontwerpprosedure aan te bied vir die ontwerp en vervaardiging van pasiëntspesifieke unikompartementele knievervangings. Die ontwerpprosedure gebruik wiskundige modellering en ’n kunsmatige neurale netwerk om die oorspronklike en gesonde gewrigsoppervlakke van ’n pasiënt se knie te bepaal. Die modelle word met mediese beelde van die pasiënt gekombineer om ’n knieprostese te skep wat pasiëntspesifiek is. Hierdie pasiëntspesifieke inplantings word dan met konvensionele inplantings vergelyk wat kontakstres en kinematika betref. Daar word tot die slotsom gekom dat die pasiëntspesifieke inplantings oor eienskappe kan beskik wat vergelykbaar is met of selfs beter is as dié van konvensionele prosteses. Die unieke ontwerpmetodologie wat in hierdie proefskrif aangebied word, stel beduidende vordering in knievervangingstegnologie bekend, met die potensiaal om die kliniese uitkomste van knievervangingsoperasies dramaties te verbeter.

Mestrado em Engenharia Mecânica
O joelho é uma das articulações mais importantes do corpo humano, permite a mobilidade e a estabilidade em simultâneo. Algumas patologias como a síndrome patelo-femoral podem conduzir à necessidade da realização da artroplastia patelo-femoral. Vários efeitos comprometem a longevidade desta artroplastia, sendo os mais frequentes o efeito de stress shielding, responsável pela reabsorção óssea localizada, o efeito de fadiga por sobrecarga associado à geração de microfissuras e colapso do osso de suporte, e a osteólise provocada pela fratura e libertação de micropartículas do cimento-ósseo. Os parâmetros biomecânicos associados a estes efeitos foram estudados em três implantes comerciais; Journey PFJ (Smith & Nephew Inc), Vanguard PFR (Biomet Inc) e Zimmer PFJ (Zimmer Inc). Adicionalmente foram ainda propostos seis novos modelos de implante por forma a tentar melhorar o desempenho destes, tendo sido este o principal objetivo deste trabalho. Para a análise dos parâmetros biomecânicos (deformações no osso e tensões no cimento ósseo) foram utilizados modelos de elementos finitos desenvolvidos a partir de imagens médicas de TAC de um paciente saudável. Foram simuladas as condições de carga para três atividades fisiológicas distintas; ciclo de marcha, subir escadas e agachamento profundo. Estas análises foram realizadas por forma a serem representativas de duas situações clínicas distintas, uma representativa do curto termo, em que o cimento-ósseo foi considerado rigidamente ligado ao osso e outra representativa do longo termo, em que o cimento-ósseo foi considerado apenas em contacto com atrito com o osso, ou seja uma situação de descolamento desta interface. Após a análise comparativa dos diferentes modelos implantados relativamente aos modelos intactos, verificou-se que nas regiões de bordo dos implantes comerciais os níveis de deformação no osso esponjoso são bastante elevados tendo todos os modelos apresentando um risco de falência por fadiga, devido a sobrecarga localizada, sendo o risco mais elevado associado à atividade de agachamento. O efeito stress shielding foi observado com diferentes graus, em todos os modelos na zona central do implante. O cimento ósseo apresentou várias zonas com tensões de von Mises superiores à tensão limite de fadiga para os casos da atividade de subir escadas e agachamento. Os novos modelos de implante patelo femoral propostos apresentam comportamentos comparáveis aos observados nos implantes comerciais, no entanto uma das novas propostas de implante sugere um melhor compromisso de entre todos os implantes analisados.
The knee joint is one of the most important articulations of the human body, allowing simultaneous mobility and stability. Some pathologies such as patellofemoral syndrome can lead to patellofemoral arthroplasty. The longevity of arthroplasty is compromised by various effects, being the most frequent the effect of stress shielding, responsible for the located bone reabsorption, the effect of fatigue by overcharge associated to the generation of microfissures and the collapse of the supporting bone, and the osteolysis provoked by the fracture and release of microparticle of bone cement. The biomechanical parameters associated with these effects were studied in three commercialized implants; Journey PFJ (Smith & Nephew Inc.), Vanguard PFR (Biomet Inc.) and Zimmer PFJ (Zimmer Inc). Additionally there were also proposed six new models of implants in order to try to improve their performance, being this the main goal of this work. To analyze the biomechanical parameters (bone strain and bone cement stress) there were used the finite element models developed from CT medical images of a healthy patient. Three different loading conditions for three distinct physiological activities were simulated: gait cycle, climb stairs and deep squat. These analyzes were performed to represent two distinct clinical situations, a representative of the short term, were the bone cement was considered rigidly connected to the bone and another representative of the long term, were the bone cement was found only in frictional contact with the bone, in other words, a state of detachment of this interface. After comparative analysis of the different models implanted with the intact models, it was found that in the edge regions of the commercialized implants the levels of deformation in the cancellous bone are quite high with all models presenting a risk of fatigue failure due to localized overload, and the higher risk is associated with the squatting. The stress shielding effect was observed with varying degrees, in all models in the central area of the implant. The bone cement showed several areas with von Mises stresses above the fatigue limit stress for cases climbing stairs and squatting. The new models of patellofemoral implant proposed exhibit behaviors similar to those seen in commercial implants, however one of the new proposed implants suggests a best compromise amongst all implants analyzed.

The intervertebral discs of the lumbar spine can be damaged as a result of trauma, disease or deformity. If an intervertebral disc becomes too compromised the current surgical solution is to fuse the vertebra at the affected spinal level. Spinal fusion presents its own complications which can limit its short and long term success. One of the key limiting factors is the loss of mobility at the affected level, this causes additional loading and accelerated degradation of the adjacent intervertebral discs. Therefore, the aim of this project was to develop an intervertebral disc implant which allowed natural motion at the affected level. The implant developed consists of a fluid filled welded bellows assembly. This arrangement is similar to a healthy intervertebral disc in which the fluid nucleus pulpous is contained by the annulus fibrosus. The proposed implant also incorporates overload and motion-restricting features to prevent the implant and spinal column being damaged. Artificial disc implants have been developed by other researchers. The implant developed in this project is unique as it does not generate any wear debris. This is significant as wear debris can cause a macrophage response and osteolysis, thus ultimately limiting the long term viability of implants which do produce wear debris. This thesis also details the development of BioModelling methodology for producing graphical reconstructions from medical scan data. These reconstructions can be used to produce plastic and metallic models for pre-operative planning purposes and implants for in-vivo use. While originally intended for the spinal implant work, it was ultimately used for other tasks. A case study illustrates its use in producing a maxilla implant. The final component of this project was to design and produce a femoral endoprosthesis for a patient with Osteogenesis Imperfecta. The patient's existing implants had failed and as a result an implant was required which could fully support all the applied loads whilst still allowing the patient's healthy hip and knee joints to be retained.

Total hip arthroplasty (THA) has a proven clinical record for providing pain relief and return of function to patients with disabling arthritis. There are many successful options for femoral implant design and fixation. Cemented, polished, tapered femoral implants have been shown to have excellent results in national joint registries and long-term clinical series. These implants are usually 150mm long at their lateral aspect. Due to their length, these implants cannot always be offered to patients due to variations in femoral anatomy. Polished, tapered implants as short as 95mm exist, however their small proximal geometry (neck offset and body size) limit their use to smaller stature patients. There is a group of patients in which a shorter implant with a maintained proximal body size would be advantageous. There are also potential benefits to a shorter implant in standard patient populations such as reduced bone removal due to reduced reaming, favourable loading of the proximal femur, and the ability to revise into good proximal bone stock if required. These factors potentially make a shorter implant an option for all patient populations. The role of implant length in determining the stability of a cemented, polished, tapered femoral implant is not well defined by the literature. Before changes in implant design can be made, a better understanding of the role of each region in determining performance is required. The aim of the thesis was to describe how implant length affects the stability of a cemented, polished, tapered femoral implant. This has been determined through an extensive body of laboratory testing. The major findings are that for a given proximal body size, a reduction in implant length has no effect on the torsional stability of a polished, tapered design, while a small reduction in axial stability should be expected. These findings are important because the literature suggests that torsional stability is the major determinant of long-term clinical performance of a THA system. Furthermore, a polished, tapered design is known to be forgiving of cement-implant interface micromotion due to the favourable wear characteristics. Together these findings suggest that a shorter polished, tapered implant may be well tolerated. The effect of a change in implant length on the geometric characteristics of polished, tapered design were also determined and applied to the mechanical testing. Importantly, interface area does play a role in stability of the system; however it is the distribution of the interface and not the magnitude of the area that defines stability. Taper angle (at least in the range of angles seen in this work) was shown not to be a determinant of axial or torsional stability. A range of implants were tested, comparing variations in length, neck offset and indication (primary versus cement-in-cement revision). At their manufactured length, the 125mm implants were similar to their longer 150mm counterparts suggesting that they may be similarly well tolerated in the clinical environment. However, the slimmer cement-in-cement revision implant was shown to have a poorer mechanical performance, suggesting their use in higher demand patients may be hazardous. An implant length of 125mm has been shown to be quite stable and the results suggest that a further reduction to 100mm may be tolerated. However, further work is required. A shorter implant with maintained proximal body size would be useful for the group of patients who are unable to access the current standard length implants due to variations in femoral anatomy. Extending the findings further, the similar function with potential benefits of a shorter implant make their application to all patients appealing.

Neste trabalho propõe-se o projeto e a análise estrutural de uma haste femoral de implante de quadril em material compósito polimérico. No trabalho, realizaram-se algumas etapas com a finalidade de obter parâmetros confiáveis de comportamento do material, visando à consistência dos resultados numéricos e experimentais. Primeiramente, faz-se um levantamento bibliográfico sobre o comportamento mecânico dos materiais compósitos poliméricos reforçados, como também dos critérios de falha existentes para este tipo de material. Em seguida, apresentam-se as etapas experimentais com a descrição dos procedimentos de fabricação dos corpos-de-prova e os resultados obtidos a partir dos ensaios quase-estáticos de tração do poliuretano derivado de óleo de mamona. A etapa seguinte foi desenvolver um dispositivo de ensaio monotônico quase-estático para a haste femoral em poliuretano com o objetivo de levantar a curva força-deslocamento seguindo as especificações das normas ISO 7206-3 e ISO 7206-4. Com base nos resultados experimentais obtidos, foi possível propor um reforço estrutural, na forma de tubo, na haste femoral em poliuretano e adotar uma análise de falha progressiva para determinar o seu comportamento mecânico. Para esta finalidade foi implementado um modelo de material em sub-rotina FORTRAN, compilada em conjunto com um programa de elementos finitos (ABAQUS). Concluiu-se, que o modelo de material implementado e o reforço estrutural proposto para a haste femoral traz contribuições inovadoras, visto que se pode prever com mais precisão o comportamento mecânico da haste femoral reforçada com o tubo em material compósito polimérico.
A design and structural analysis of a femoral stem using a polymeric composite material is proposed in this work. The work had some steps in order to achieve trusty parameters for the material behavior aiming the consistence of numerical and experimental results. In the first step, a bibliographic review of mechanical behavior of reinforced polymeric composite materials as well as failure criterion was done. Following experimental steps are presented with specimen manufacturing procedure description and the results obtained from quasi-statics tension tests of polyurethane derivated from castor oil. The next step was the development of a monotonic quasistatic test device for the polyurethane femoral stem aiming to determine the forcedisplacement curve according to ISO 7206-3 and ISO 7206-4 standards. Considering the experimental results obtained it was possible to propose a structural reinforcement, which consists on a tube, in the polyurethane femoral stem and to adopt a progressive failure analysis in order to determine its mechanical behavior. A material model using FORTRAN sub-routine was developed and compiled joint with a finite element program (ABAQUS). The conclusion is that the model developed and the structural proposed reinforcement for the femoral stem bring innovation for this contribution once it is possible to preview accurately the mechanical behavior of the reinforced femoral stem with tube in polymeric composite material.

Introducción La amputación de una extremidad inferior es un procedimiento quirúrgico permanente que tiene importantes secuelas funcionales, psicológicas y sociales que pueden influir en la calidad de vida de la persona con amputación. El porcentaje de amputaciones femorales se sitúa en Europa alrededor de un 20-35% del total de amputaciones de la extremidad inferior. El 75% de todas las amputaciones de la extremidad inferior ocurren en pacientes mayores de 65 años al igual que ocurre en Estados Unidos. Diversos estudios han demostrado que los pacientes desarticulados de rodilla consumen menos oxígeno en la marcha y la osteoporosis del muñón es inferior que los de nivel femoral. Objetivo del estudio El objetivo de este estudio es la evaluación de la funcionalidad de pacientes amputados de nivel femoral con un implante que permite el apoyo distal del muñón y la mejora de los parámetros de dolor, calidad de vida, control y estabilidad del muñón, aumentar la densidad mineral ósea y disminuir el gasto energético respecto al uso del encaje convencional, en personas que han sufrido una amputación del miembro inferior por encima de la rodilla. Material y métodos Se ha llevado a cabo un estudio experimental prospectivo no aleatorizado de tipo antes - después realizado en el Hospital de Mataró en 10 pacientes amputados femorales tras la colocación de un implante de titanio entre 1 de marzo de 2011 a 1 de marzo de 2013. Se obtuvo el informe favorable del Comité de Ética del Hospital de Mataró para este estudio y todos los pacientes firmaron un consentimiento informado previo al inicio del estudio. Resultados La media de la edad fue de 50,3 ±16,3 años, con una mayor proporción de hombres participantes 6 (60%). La media de evolución de la amputación fue de 96,9 ± 96,3 meses, amputándose más la extremidad derecha 6 (60%). La etiología más frecuente de la amputación fue la traumática en 6 pacientes (40%). Todos los pacientes habían sido amputados en el tercio medio del fémur. Tras los 14 meses de seguimiento del procedimiento quirúrgico los pacientes incrementaron de forma significativa los metros recorridos en la prueba de 2 MWT obteniendo una media de 122,5 metros (p=0,008) y de la velocidad, pasando de 49,2 m/s previa a la intervención a 61,3 m/s a los 14 meses (p=0,008).También hubo una mejora del dolor en el muñón tras la cirugía (2,9 vs 0,4 p=0,04) y en la utilización de la prótesis en número de horas al día (10,1h vs 12,9 h p=0,01). Conclusiones Los resultados de nuestro estudio muestran una mejora de la capacidad funcional valorado en el total de metros recorridos y velocidad de marcha evaluados mediante la prueba de los 2 MWT, en pacientes amputados, principalmente de causa vascular a los 14 meses de ser intervenidos quirúrgicamente realizándose un implante femoral.
Introduction Lower-limb amputation is a permanent surgical procedure that leads to a series of physical, psychological and social consequences that may affect the quality of life of the amputee.The percentage of transfemoral amputations in Europe is estimated in 20-35% of all lower limb amputations. Around 75% of the individuals who require an amputation of the lower limb are over 65 years old. Several studies have shown that individuals with a knee disarticulation have less oxygen consumption during gait performing and have less residual limb osteoporosis than individuals with a transfemoral lower limb amputation. Objective of the study The objective of this study was to investigate the functional level of individuals with a transfemoral amputation and an implant that allows distal support to the residual limb, as well as to investigate the clinical improvement in terms of pain, quality of life, residual limb control and stability, improvement of the bone mineral density and decrease of the energy expenditure when comparing with the use of a conventional socket in individuals with an above knee amputation. Materials and methods This is an experimental prospective non randomized study before-and-after intervention type developed at the Hospital de Mataró in 10 individuals with transfemoral amputation after a titanium implant placement between March 1st,2011 and March 1st, 2013. The local Ethics Committee of Hospital de Mataró approved the study and patients gave informed consent before being enrolled as participants. Results The average age was 50,3 ±16,3 years, with a higher proportion of men participating 6 (60%). The average of time since lower limb amputation was 96,9 ± 96,3 months, most of them, amputation of the right lower limb 6 (60%). The most prevalent aetiology of amputation was traumatic in 6 participants (60%). All participants had been amputated in the middle third of the femur. At the end of the 14 months of follow-up, participants significantly improved the total of meters walked in the 2 MWT, the mean was 122,5 meters (p=0,008) and they also improved the speed of gait, from 49,2 m/s before intervention to 61,3 m/s 14 months after (p=0,008). An improvement in pain was observed too after surgery (2,9 vs 0,4 p=0,04) and the number of hours using the prosthesis also improved after intervention (10,1h vs 12,9 h p=0,01). Conclusions The results of our study show an improvement in the functional capability in terms of number of meters walked and speed of gait using the 2MWT, in individuals with a lower limb amputation mainly secondary to peripheral vascular disease, 14 months after surgery for a femoral implant placement.

A bilateral, canine uncemented total hip arthroplasty model was used to assess the effect of widely ranging stem stiffness on femoral stem fixation and peri-implant remodeling. A porous coated titanium stem, with stiffness properties similar to those of the canine femur was compared, with a porous coated composite stem that was more flexible than the canine femur. The femora were analyzed for the extent of bone ingrowth, the extent of radiopaque line formation, peri-implant cortical area, intracortical porosity, and bone remodeling.
Despite the marked increase in stem flexibility with the composite stem, there was no statistically significant difference in the overall degree of femoral stress shielding, cortical area, or cortical porosity when compared with the stiffer titanium stem at either time period. Overall, the tissue response to the more flexible composite stem resulted in less bone ingrowth and more radiopaque line formation at the bone-implant interface than with the titanium stem. (Abstract shortened by UMI.)

This work describes advanced fabrication of custom orthopaedic implants using unconventional additive manufacturing technology - Selective Laser Melting (SLM). There was a main focus on custom knee replacement and certainly on its femoral component. The study investigated three general issues within the domain of the usage of additive manufacturing technology in medical application. First, there was an evaluation of process parameters influences of SLM fabrication method on surface and mechanical properties of titanium Ti6Al4V ELI specimens. This material was used because of its biocompatibility and its wide use within implant fabrication. Then, a proposal of the manufacturing strategy was carried out and the fabrication of customized knee femoral component prototype by SLM technology was done. The elaboration of the numerical chain prior the SLM implant fabrication, from patient's CT knee scan to final femoral replacement model, was also done. Then, a proposal of different 3-axis and 5-axis strategies of machining of the fitting femoral surface of bone prototype (3D printed from the powder) using CNC machines FV 25 CNC and TAJMAC ZPS MCV 1210 was projected and also, the 3-axis spiral machining was realised. The individual machining tool paths were generated by software Power Mill from Delcam group. Finally, these machining strategies were generated as a prior step before a machining of real patient’s bone, therefore the machining tests of cartilage and bone were done.

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O objetivo deste estudo foi comparar as propriedades biomecânicas de dois modelos de hastes femorais da prótese total de quadril, não cimentada, modular e nacional. A haste A, possui uma extensão na base do colo do implante, denominado “colar”, já o implante B, possui a sua porção proximal abaulada. Buscou-se determinar qual dos dois modelos de hastes femorais tem melhor desempenho ao evitar, ou impedir, o afundamento (subsidence). Para tal, utilizou-se 8 pares de fêmures de cães adultos, machos e fêmeas, de diferentes raças e massa corporal de ±25 kg. Em cada fêmur, uma ostectomia da cabeça e do colo femoral foi realizada e inserido um dos implantes selecionados. As construções foram submetidas, previamente, à radiografia e densitometria óssea, a fim de determinar a homogeneidade da amostra. Logo em seguida, divididos em dois grupos, Haste A (8 fêmures) e Haste B (8 fêmures), aplicou-se carga de flexo-compressão, no eixo axial de cada amostra, em máquina universal de ensaios. A força máxima, a deflexão, a resistência à compressão e a energia foram as variáveis analisadas nos dois sistemas, assim, o Grupo B exibiu valores significativamente maiores (p≤0,05) para as variáveis resultantes deste estudo, com exceção da rigidez que, estatisticamente, considerou-se similar entre os dois grupos (p=0,2031). A média da força máxima no teste de compressão axial para o Grupo A foi de 1347±357 N e, para o Grupo B, de 1805±123 N (p≤0,0069). A média da deflexão para o Grupo A foi de 5547±2639 mm e, para o Grupo B, de 10033±3998 mm (p≤0,0056). Para a variável energia, a média da força máxima para o Grupo A foi de 6203±3488 N.mm, já para o Grupo B, foi de 12885±5056 N.mm (p≤0,0054). A média do módulo de deformação elástica, expresso em rigidez, no Grupo A foi de 860±160 N/mm, já no Grupo B, de 1011±305 N/mm (p≤0,0054). Os dados obtidos apresentavam distribuição normal e foram submetidos ao teste t pareado (p≤0,05). Constatou-se que a Haste B possui maior força máxima, deflexão e energia. Todavia, quanto a rigidez, ambas são eficientes em amortizar o impacto das forças axiais de flexo-compressão em fêmures cadavéricos de cães.
The goal of this study was to compare the biomechanical properties of two models of femoral stems of the total hip, uncemented, modular, and national (Brazil) prosthesis. The stem A has an extension at the base of the implant, called the "collar", and the implant B, has its convex proximal portion. We sought to determine which of the two models of femoral rods perform best by avoiding, or preventing, subsidence. To this end, we used eight pairs of femurs of adult dogs, male and female, of different races and body weight ± 25 kg. In each femur, an ostectomy of the head and femoral neck was performed and inserted one of the selected implants. The constructs were previously submitted to radiography and bone densitometry, in order to determine the homogeneity of the sample. Then, divided into two groups, Stem A (8 femurs) and Stem B (8 femurs), a flexo-compression load was applied on the axial axis of each sample in a universal testing machine. Maximum strength, deflection, compressive strength and energy were the variables analyzed in both systems, thus, Group B showed significantly higher values (p≤0.05) for the variables resulting from this study, except for the rigidity that, statistically, it was considered similar between the two groups (p=0.2031). The mean maximal force in the axial compression test for Group A was 1347±357 N and, for Group B, 1805 ± 123 N (p≤0.0069). The mean deflection for Group A was 5547 ± 2639 mm and, for Group B, 10033±3998 mm (p≤0.0056). For the energy variable, the mean of the maximum force for Group A was 6203±3488 N.mm, for Group B, it was 12885±5056 N.mm (p≤0.0054). The mean elastic strain modulus, expressed as rigidity, in Group A was 860±160 N/mm, in Group B, of 1011±305 N/mm (p≤0.0054). The obtained data presented normal distribution and were submitted to paired t test (p≤0.05). It was verified that Haste B has greater maximum strength, deflection and energy. However, for stiffness, both are efficient in amortizing the impact of axial flexion-compression forces on cadaverous femurs of dogs.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Bone defects due to trauma, postoperative and mutilating surgery complications, associated to removal of neoplasia, are part of the routine of hospitals and veterinary clinics. Bone grafts, within all their variants, represent the main viable alternative in the structural correction of great bone losses. Currently, the search for alternatives to correct these problems and the great potential of cellular therapy, have led numerous researchers to ingress into this line of study. The present work aimed to evaluate the influence of the hydration of bone implants conserved in glycerin 98% over their biomechanical resistance; the viability of a bone marrow harvesting protocol, for application in the clinical surgical routine; and the effect of intralesional application of bone marrow mononuclear cell fraction, over the consolidation of graft-host interface of dogs submitted to segmental bone grafting, with bone implants conserved in glycerin 98%. This research was developed in two phases. The first, ex-vivo, in which 108 bone fragments conserved in glycerin 98% were separated in six different groups, according to hydration period, and later were submitted to axial load test for biomechanical resistance evaluation. The second phase, in-vivo, in which 20 mongrel dogs, with mean weight of 13kg, were divided in four different groups according to the type of graft employed and with or without application of bone marrow mononuclear cell fraction. All animals were submitted to a bone marrow harvesting protocol, obtaining a final volume of 5ml kg-1 of body weight. The collected bone marrow was analyzed by means of myelogram and later submitted to isolation of the mononuclear cell fraction by a technique already affirmed in the literature. A diaphyseal femoral bone defect was created and repaired with the same removed segment (groups I and III) or with a bone segment conserved in glycerin 98% (groups II and IV). The bone marrow mononuclear cell fraction, after isolation, was injected via intralesional route in dogs of the treated groups (I and II), whereas the control group (III and IV) received an injection of the same volume, however, of 0.9% sodium chloride solution. The bone consolidation progress of the graft-host interfaces was followed by serial radiographic exams up to 90 days after surgical intervention, whereas the presence of mononuclear cells was followed up to seven days after implantation, by detection of Qtracker-665 nanocrystal fluorescence, used as cell marker. According to the results obtained, it can be concluded that: hydration of bone implant conserved in glycerin 98% does not produce statistically significant alterations in the biomechanical resistance of cortical bone for the different evaluated times. However, the bone mineral density has a close relationship with this property; bone marrow harvesting protocol with reduced volume of 5ml kg-1 of body weight, obtained from different long bones, proved to be adequate for isolation of mononuclear cell fraction and for obtaining a cell button with adequate number of cells and high viability, essential for the success of its therapeutic application; the consolidation of proximal and distal graft-host interfaces at 90 days after surgery no showed clinical and radiographic difference in the groups control and treated with bone marrow mononuclear cell fraction. Nevertheless, it cannot be confirmed that the cellular therapy used in this study is not an effective bone healing adjuvant, as it is believed that the restriction of load deposition on the focus of the fracture, achieved by reduced postoperative exercise, has influenced directly on the result of the consolidation.
As falhas ósseas decorrentes de trauma, complicações pós-operatórias e cirurgias mutilantes, associadas à remoção de neoplasias, fazem parte da rotina dos hospitais e clínicas veterinárias. Os enxertos ósseos, dentre todas as suas variantes, representam a principal alternativa viável na correção estrutural de grandes perdas ósseas. Na atualidade, a busca por alternativas para corrigir estes problemas e o grande potencial da terapia celular, tem levado inúmeros pesquisadores a ingressar nesta linha de estudo. No presente trabalho, buscou-se avaliar a influência da hidratação de implantes ósseos conservados em glicerina 98% sobre a resistência biomecânica dos mesmos; a viabilidade de um protocolo de colheita de medula óssea, para aplicação na rotina clínico-cirúrgica; e o efeito da aplicação intralesional da fração de células mononucleares da medula óssea, sobre a consolidação da interface enxerto-hospedeiro de cães submetidos à enxertia óssea segmentar, com implantes ósseos conservados em glicerina 98%. Esta pesquisa foi desenvolvida em duas fases. A primeira, ex-vivo, onde 108 fragmentos ósseos conservados em glicerina 98% foram separados em seis diferentes grupos, de acordo com o período de hidratação, sendo posteriormente submetidos a teste de compressão axial para avaliação de sua resistência biomecânica. A segunda fase, in-vivo, onde 20 cães sem raça definida e peso médio de 13kg, foram separados em quatro diferentes grupos de acordo com o tipo de enxerto empregado e com a aplicação ou não da fração de células mononucleares da medula óssea. Todos os animais foram submetidos a um protocolo de colheita de medula óssea, obtendo-se um volume final de 5ml kg-1 de peso corporal. A medula óssea colhida foi analisada por meio de mielograma e posteriormente submetida ao isolamento da fração de células mononucleares por técnica já consagrada na literatura. Um defeito ósseo femoral diafisário foi criado e reparado com o próprio segmento removido (grupos I e III) ou com um segmento ósseo conservado em glicerina 98% (grupos II e IV). A fração de células mononucleares da medula óssea, após isolamento, foi injetada por via intralesional nos cães dos grupos tratados (I e II), enquanto os grupos controle (III e IV) receberam a injeção do mesmo volume, porém, de solução de cloreto de sódio a 0,9%. A progressão da consolidação óssea das interfaces enxerto-hospedeiro foi acompanhada por exames radiográficos seriados até os 90 dias após a intervenção cirúrgica, enquanto a presença das células mononucleares, até os primeiros sete dias após a implantação, foi acompanhada pela detecção da fluorescência do nanocristal Qtracker-665, utilizado como marcador celular. De acordo com os resultado obtidos, pode-se concluir que: a hidratação do implante ósseo conservado em glicerina 98%, não produz alteração estatisticamente significativa na resistência biomecânica do osso cortical para os diferentes tempos avaliados. Contudo, a densidade mineral óssea possui estreita relação com esta propriedade; O protocolo de colheita de medula óssea em volume reduzido a 5ml kg-1 de peso corporal, obtidos de diferentes ossos longos, demonstrou-se adequado para isolamento da fração de células mononucleares e obtenção de um botão celular com adequado número de células e alta viabilidade, essenciais ao sucesso de sua aplicação terapêutica; a consolidação das interfaces enxerto-hospedeiro proximal e distal aos 90 dias após a cirurgia não apresentou diferença clínica e radiográfica entre os grupos controle e tratados com a fração de células mononucleares da medula óssea. Porém, não se pode afirmar que a terapia celular empregada neste estudo, não seja bom adjuvante da cicatrização óssea, pois se acredita, que a restrição na deposição de carga no foco de fratura, proveniente do reduzido exercício pós-operatório, tenha influenciado diretamente no resultado da consolidação.

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Objetivo: O objetivo deste estudo foi avaliar a utilização da membrana de biopolímero de cana-de-açúcar como remendo em arterioplastias femorais em cães. Material e método: Oito cães adultos mestiços foram anestesiados por via endovenosa com cloridrato de cetamina na dose de 2,5 mg / Kg e brometo de pancurônio na dose de 0,2 mg / Kg, após indução com tiopental sódico na dose de 12,5 mg / Kg. Foi realizada tricotomia das regiões inguinais e a seguir procedeu-se a velocimetria Doppler percutânea das artérias femorais direita e esquerda para controle pré-operatório. Sob condições de assepsia e anti-sepsia os cães foram submetidos à dissecção das artérias femorais seguida da medida do diâmetro arterial e de uma arteriotomia longitudinal com retirada de um fragmento elíptico da parede arterial medindo 1,5 cm por um terço do diâmetro da artéria. Para a correção do defeito da parede arterial, os animais foram submetidos à arterioplastia femoral bilateral com remendos da membrana de biopolímero de cana-de-açúcar no lado esquerdo (grupo experimental) e de PTFE expandido (grupo controle) no lado direito. As suturas foram contínuas com fio de prolene ® 7.0. As membranas utilizadas como remendos são constituídas de um biopolímero obtido por síntese bacteriana a partir do melaço de cana-de-açúcar, produzidas na Estação Experimental de Cana-de-Açúcar de Carpina da Universidade Federal Rural de Pernambuco e processadas para aplicação como prótese cirúrgica no Núcleo de Cirurgia Experimental do Centro de Ciências da Saúde da Universidade Federal de Pernambuco. Na primeira semana pós-operatória os cães foram submetidos a avaliação clínica diária e semanal a partir do oitavo dia. A avaliação clínica consistiu no exame dos pulsos femorais, na avaliação da marcha e na observação da presença de tumor pulsátil, hematoma ou hemorragia e infecção da ferida operatória. Após 180 dias das arterioplastias, sob anestesia geral, foi realizada tricotomia das regiões inguinais e abdominal e procedeu-se nova fluxometria Doppler percutânea das artérias femorais . Os animais foram submetidos à dissecção das artérias femorais, medido o diâmetro arterial e realizada velocimetria Doppler trans-operatória em pontos proximal e distal à arterioplastia. A seguir foi realizada laparotomia e exposição da aorta abdominal para acesso arteriográfico. Através da velocimetria Doppler e da arteriografia foi pesquisada a ocorrência de trombose, aneurisma e falso-aneurisma. Os segmentos das artérias femorais com os remendos foram retirados para estudo histopatológico e os animais foram mortos com dose tóxica de anestésico. Resultados: No período de avaliação de 180 dias, nos dois grupos, não foram observados casos de infecção da ferida operatória , dilatação, ruptura, falso-aneurisma ou trombose. Nos dois grupos foi encontrada uma resposta inflamatória crônica com neutrófilos e linfócitos. Nas superfícies externa e interna dos remendos foi encontrada fibrose. No grupo controle ocorreu invasão dos remendos de e-PTFE por fibroblastos. Conclusões: Com base nos resultados obtidos com o modelo experimental utilizado, conclui-se que a membrana de biopolímero de cana-de-açúcar pode ser utilizada como remendo em arterioplastias femorais em cães

INTRODUÇÃO: A implantação de stent auto-expansível de nitinol para o tratamento das lesões oclusivas femoro-poplíteas tem sido associado com maus resultados a longo prazo. O everolimus administrado via oral para inibir reestenoses do stent foi investigado recentemente em animais com bons resultados, porém sua segurança e eficácia não têm sido estudada em seres humanos. O propósito deste estudo piloto foi avaliar o impacto da terapia antiproliferativa com everolimus administrado via oral por 28 dias na diminuição de reestenose após implante de stent auto-expansível de nitinol para tratamento de lesões oclusivas da artéria femoral superficial. MÉTODOS E RESULTADOS: Trinta e quatro pacientes foram recrutados para este estudo randomizado, prospectivo. O grupo que recebeu everolimus via oral foi constituído por 15 pacientes e o grupo que não recebeu medicação composto por 19 pacientes. As características basais e do procedimento foram similares entre os dois grupos. Todos os pacientes tinham isquemia crônica do membro inferior e oclusão da artéria femoral superficial (média da lesão de 83,14 mm no grupo sem medicação e 105 mm no grupo everolimus). O objetivo primário do estudo foi a redução da porcentagem média do diâmetro da reestenose intra-stent após seis meses da angioplastia avaliada por angiografia quantitativa. A porcentagem média do diâmetro das reestenoses foi 46,9% no grupo tratado com everolimus e 44,5% no grupo que não recebeu a medicação (p=0,81). Não foram observados efeitos colaterais graves nos grupos. No acompanhamento clínico aos 24 meses não houve diferenças significativas entre os grupos em relação a eventos clínicos. A patência primária, primária assistida e secundária em 24 meses, foi 42%, 74% e 79% no grupo sem medicação e 27%, 73% e 73% no grupo tratado com everolimus. CONCLUSÃO: O everolimus via oral por 28 dias em doses altas é seguro e bem tolerado, com baixo índice de efeitos colaterais, porém não é eficaz na redução da porcentagem média do diâmetro da reestenose intra-stent em pacientes com implante de stents auto-expansíveis de nitinol nas lesões oclusivas complexas da artéria femoral superficial.
INTRODUCTION: The implantation of a self-expanding of nitinol stent in the treatment of femoropopliteal occlusive lesions has been associated with a poor outcome in a long term setting. Everolimus administered orally to inhibit restenosis of the stent was investigated recently in animals with good results, but its safety and efficacy has not been studied in humans. The purpose of this pilot study was to evaluate the impact of antiproliferative therapy with everolimus administered orally for 28 days in the reduction of restenosis after implantation of self-expandable nitinol stent for treatment of occlusive lesions of the superficial femoral artery. METHODS AND RESULTS: Thirty-four patients were recruited for this randomized, prospective study. The group that received oral Everolimus was consisted of 15 patients and the group that received no medication was 19 patients. The baseline characteristics and procedure were similar in both groups. All the patients had chronic lower limb ischemia and occlusion of the superficial femoral artery (mean of the lesion of 83.14 mm in the group without medication and 105 mm in the everolimus group). The primary objective of the study was to evaluate the reduction of the average percentage of the diameter of in-stent restenosis six months after angioplasty assessed by quantitative angiography. The in-stent mean percent diameter stenosis was 46.9% in the group treated with everolimus and 44.5% in the group that received no medication (p = 0.81). There were no serious side effects seen in either group in the clinical follow up at 24 months. There was no significant difference between groups in relation to clinical events. The primary patency, assisted primary and secondary in 24 months was 42%, 74% and 79% in the group without medication and 27%, 73% and 73% in the group treated with Everolimus. CONCLUSION: Everolimus administered orally for 28 consecutive days to stent implantation in high doses proves to be safe and well tolerated, with low rate of side effects, but it is not effective in reducing the average percentage of diameter of in-stent restenosis in patients with implantation of self-expandable nitinol stent in complex occlusive lesions of the superficial femoral artery.

The greatest orthopedical operations are characterized by the hard post operative pain control. Thus, the femoral block (FB) has been used in several cases around the world, effectively promoting the inferior member analgesia, safety and few side effects. Based upon it, the present study evaluated the quality of analgesia in 90 patients undertaken to surgeries of anterior cruciate ligament repair and of total knee prosthesis implant, having been randomily distributed in three groups: ropivacaine group, composed of 32 patients undertaken to FB with ropivacaine at 0,25%, bupivacaine group, composed of 30 patients undertaken to FB with bupivacaine at 0,25% and control group, composed of 28 patients who received continuous oral and vein analgesia with non esteroids anti-inflammatory and opioids without FB. According to the verbal scale of pain, evaluated at rest, the incidence of moderate or intense pain was higher in the control group than in the ropivacaine and bupivacaine groups, in the times T1 (until 6 hours after the FB; p = 0,002) and T2 (between 6 and 10 hours after FB; p = 0,001). Not only at rest, but also in motion was moderate or intense pain higher in the control group than in the ropivacaine or bupivacaine, in times T1 (p = 0,001) and T2 (p = 0,000). In relation to the satisfaction with postoperative analgesia, the control group mentioned lower satisfaction when compared to the ropivacaine or bupivacaine in times T2 (p = 0,001) and T3 (after 10 hours and until 24 hours after FB; p = 0,047). Concerning the necessity for opioids, the control group patients presented in time T2 higher consume of opioids than the patients undertaken to FB (p = 0,03). So, concluded by unique bupivacaine injection at 0,25% or ropivacaine at 0,25% in the FB presented better quality of analgesia and higher satisfaction, when compared to the patients of the control group, after the surgeries of reconstruction of the crossed anterior ligament and of the total knee prosthesis implant. Between the ropivacaine and bupivacaine groups there has been no difference in relation to the quality and satisfaction with postoperative analgesia. So, FB with bupivacaine is longer than FB with ropivacaine (p< 0,05).
As operações ortopédicas de grande porte têm como característica o difícil controle da dor pós-operatória. Nesse sentido, o bloqueio femoral (BF) tem sido utilizado, em diversos serviços no mundo, promovendo analgesia do membro inferior com eficiência, segurança e poucos efeitos colaterais. Baseando-se nisso, o presente estudo avaliou a qualidade da analgesia em 90 pacientes submetidos às operações de reconstrução do ligamento cruzado anterior (RLCA) e de implante de prótese total do joelho (IPTJ), sendo distribuídos, aleatoriamente, em três grupos: grupo ropivacaína, composto por 32 pacientes submetidos ao BF com ropivacaína a 0,25%; grupo bupivacaína, composto por 30 pacientes submetidos ao BF com bupivacaína a 0,25% e grupo-controle, composto por 28 pacientes que receberam analgesia oral e venosa intermitente com antiinflamatórios não esteróides e opióides, sem BF. De acordo com a escala verbal de dor, dor moderada ou intensa, avaliada em repouso, foi mais freqüente no grupo-controle do que nos grupos ropivacaína e bupivacaína, nos tempos T1 (até 6h após o BF; p = 0,002) e T2 (entre 6h e 10h após o BF; p = 0,001). Também durante o movimento, dor moderada ou intensa foi mais freqüente no grupo-controle do que nos grupos ropivacaína e bupivacaína, nos tempos T1 (p = 0,001) e T2 (p = 0,000). Já em relação à satisfação com a analgesia pós-operatória, o grupo-controle referiu menor satisfação comparando com os grupos ropivacaína e bupivacaína, nos tempos T2 (p = 0,001) e T3 (após 10h e até 24h após o BF; p = 0,047). No que diz respeito à necessidade de opióides, os pacientes do grupo- controle apresentaram, no tempo T2, maior consumo de opióides do que os pacientes dos grupos submetidos ao BF (p = 0,03). Conclui-se, portanto, que os pacientes submetidos ao BF por injeção única com bupivacaína a 0,25% ou ropivacaína a 0,25% apresentam melhor qualidade de analgesia e maior satisfação, comparando aos pacientes do grupo-controle, após as operações de RLCA e IPTJ. Entre os grupos ropivacaína e bupivacaína não se observa diferença em relação à qualidade e satisfação com a analgesia pósoperatória. Além disso, há maior duração do BF com bupivacaína em relação à ropivacaína (p < 0,05).

Mestrado em Materiais e Dispositivos Biomédicos
Zircónia e alumina são biocerâmicos bastante conhecidos, e são usados principalmente em aplicações ortopédicas. Estes materiais têm sido aplicados em implantes de anca e joelho graças à reduzida taxa de desgaste e à excelente biocompatibilidade que apresentam. No entanto, estes cerâmicos apresentam também algumas limitações: a fragilidade da alumina ao impacto e a sensibilidade da zircónia ao envelhecimento. Devido a estas limitações, o objectivo passou por desenvolver implantes mais resistentes e com uma resposta inflamatória menos intensa. Surgiram, então, estudos de compósitos de zircónia e alumina. Neste estudo, foram desenvolvidas três diferentes composições de Alumina reforçada com Zircónia (ZTA) com 80 wt% a 90 wt% de alumina, e três composições de Zircónia reforçada com Alumina (ATZ) com 80 wt% a 90 wt% de zircónia. Foram usados dois tipos diferentes de zircónia estabilizada: zircónia estabilizada com 3 mol% de yttria (3YSZ) que foi usada nos compósitos ATZ, e zircónia estabilizada com 2 mol% de yttria (2YSZ) aplicada nos compósitos ZTA. A composição ATZ com o melhor conjunto de propriedades foi também testada com a zircónia 2YSZ, de forma a produzir um compósito com melhores propriedades mecânicas e uma resistência à degradação semelhante à apresentada pelo compósito ATZ, com a zircónia 3YSZ. Foram seleccionados dois aditivos, óxido de lântanio e pentóxido de tântalo, que foram depois adicionados aos compósitos ATZ e ZTA com o melhor conjunto de propriedades (composição 80:20), com o objectivo de melhorar a resistência ao envelhecimento e as propriedades mecânicas dos materiais produzidos. Após uma etapa de moagem, os pós compósitos foram obtidos por atomização, a partir de suspensões estabilizadas, com uma distribuição de tamanho de partícula nanométrica controlada. Estes pós foram caracterizados através de várias técnicas tais como microscopia electrónica de varrimento, difracção de raios-X, fluorescência de raios-X, densidade real, e área superficial específica. De forma a aumentar a densidade dos corpos em verde, foram efectuadas duas diferentes prensagens, prensagem uniaxial e prensagem isostática a frio (CIP). Foram obtidos cerâmicos com uma elevada densidade (com densidade relativa entre 97% e 99%) a uma baixa temperatura de sinterização (1400ºC). O tamanho de grão das amostras sinterizadas foi observado por SEM e, de forma a verificar as fases cristalográficas presentes, foi realizada difracção de raios-X. Em todos os compósitos foi obtida uma microestrutura dispersa, com um tamanho de grão nanométrico (abaixo dos 500 nm). Este conjunto de etapas de produção aplicado levou à obtenção de compósitos com propriedades mecânicas melhoradas. Foram estudadas a dureza de Vickers, a tenacidade à fratura e resistência à flexão das amostras sinterizadas. Os compósitos ATZ atingiram os melhores valores de tenacidade à fractura e resistência à flexão (acima de 5 MPa.m1/2 e 1394 MPa respetivamente), enquanto os compósitos ZTA apresentaram os melhores valores de dureza (acima de 1846 HV). Como era esperado, o compósito ATZ com zircónia 2YSZ apresentou melhores propriedades mecânicas, tendo sido obtidos 7.94 MPa.m1/2 de tenacidade à fratura e 1498 MPa para a resistência à flexão. A aplicação dos dopantes nos compósitos ZTA e ATZ induziram alterações nas suas propriedades. A adição de Ta2O5 melhorou, com sucesso, as propriedades mecânicas dos dois tipos de compósitos. Foi verificado um aumento dos valores de dureza, tenacidade à fratura e resistência à flexão em relação às amostras sem dopantes. A adição de La2O3 não levou a melhorias nas propriedades mecânicas mas, no entanto, também não teve um efeito prejudicial, o que levou à sua preservação. Foram realizados testes de envelhecimento de acordo com a norma ISO13356 (2008) em todos os compósitos produzidos. A quantidade de zircónia monoclínica, indicador de degradação, foi determinada por difracção de raios-X após 5,12,24,48 e 96 horas de testes de envelhecimento. Foi determinado que os compósitos ZTA não dopados, não apresentaram zircónia monoclínica após 96 horas em ambiente agressivo. Para os compósitos ATZ, apesar de a quantidade de zircónia monoclínica aumentar proporcionalmente ao conteúdo de zircónia presente no compósito, foi verificado que a extensão da degradação foi mínima, e relegada apenas para a superfície do material. Esta evidência permitiu que as propriedades mecânicas se mantivessem durante todo o período dos testes de degradação. Como era esperado, o compósito com a zircónia menos estável, o ATZ com a zircónia 2YSZ, apresentou o conteúdo mais elevado de zircónia monoclínica. No entanto, o facto de as propriedades mecânicas se manterem ao longo dos testes de degradação, confirmou que a degradação, mais uma vez, não se expandiu para o interior do material. A adição dos dois dopantes levou a melhorias na resistência à degradação dos compósitos ATZ, que apresentaram um conteúdo de zircónica monoclínica menor em comparação com as amostras não dopadas, após 96 horas de testes de degradação. No entanto, a adição de Ta2O5 teve um efeito desestabilizador na zircónia 2YSZ presente no compósito ZTA, sendo que foi detectada 10% de zircónia monoclínica após as 96 horas de testes de degradação. De novo, foi confirmado que esta degradação esteve presente apenas à superfície do material, visto que as propriedades mecânicas se mantiveram após estes testes. Foi também testada a biocompatibilidade destes compósitos. Células MG63 foram cultivadas nas amostras sinterizadas e foram realizados ensaios MTT e ensaios de atividade da fosfatase alcalina. Para todos os compósitos produzidos foi verificado que a viabilidade/proliferação celular aumentou significativamente desde o dia 1 para o dia 4. Os compósitos ZTA, que possuíam um maior número de locais de adesão, apresentaram uma maior adesão e proliferação celular, em comparação com os compósitos ATZ. A adição de La2O3 e Ta2O5 não induziu diferenças significativas na viabilidade celular dos compósitos ATZ. No entanto, no compósito ZTA, a adição de Ta2O5 levou a um pior desempenho devido à sua verificada hidrofobicidade. O presente estudo mostra que podem ser obtidas composições óptimas destes compósitos, com excelentes propriedades mecânicas, resistência à degradação e biocompatibilidade satisfatória.
Zirconia and alumina are well known bioceramics, used in the field of orthopedics. These materials have been used as hip and knee bearings thanks to their reduced wear rate and excellent biocompatibility. However, these ceramics presented some limitations: the brittleness of alumina and the aging sensitivity of zirconia. The aim became to develop long-lasting hip implants, with less inflammatory response and better designs. Zirconia alumina composites were then studied. In this study, three different grades of alumina toughened zirconia composites (ATZ) from 80 wt% to 90 wt% of zirconia, and three grades of zirconia toughened alumina (ZTA) from 80 wt% to 90 wt% of alumina were developed. Two different types of stabilized zirconia were used: 3 mol% yttria stabilized zirconia (3YSZ) was applied on the ATZ samples, and a 2 mol% yttria stabilized zirconia (2YSZ) on the ZTA samples. The ATZ with the best set of properties (80Z20A) was also tested with the 2YSZ, in order to produce a composite with improved mechanical properties and similar aging resistance to the ATZ with 3YSZ. Two selected additives, lanthanum oxide and tantalum pentoxide were added to the best ATZ and ZTA composite (80:20 composition) with the aim of enhance the aging resistance and mechanical properties of the produced materials. After a wet milling stage, the composite powders were achieved by spray-drying, from stabilized suspensions with a controlled nanometric particle distribution. The obtained composite powders were characterized through several techniques, such as scanning electron microscopy, X-ray diffraction, X-ray fluorescence, true density and specific surface area. Two stages of pressing, uniaxial pressing and cold isostatic pressing, were performed in order to improve the density of the green pieces. High density ceramics (with a relative density between 97% and 99%) were achieved with a low sintering temperature (1400ºC). The grain size of the sintered pieces was determined by SEM, and X-ray diffraction was performed in order to verify the present crystallographic phases. A disperse microstructure was obtained for all composites, with a nanometric grain size (under 500 nm). This set of producing stages, lead to the obtention of composites with enhanced mechanical properties. The Vickers Hardness, fracture toughness and flexural strength of the sintered samples were evaluated. Higher values of fracture toughness and flexural strength were achieved for the ATZ samples (up to 5 MPa.m1/2 and 1394 MPa respectively), while ZTA samples presented higher values of hardness (up to 1846 HV). As expected, the ATZ with 2YSZ presented enhanced mechanical properties, with an outstanding fracture toughness of 7.94 MPa.m1/2, and 1498 MPa of flexural strength. The addition of the two dopants to both ZTA and ATZ composites induced changes in their properties. The addition of Ta2O5 successfully improved the mechanical properties of both composites. In comparison with the undoped ATZ and ZTA composites, improvements of the hardness, fracture toughness and flexural strength were verified. The addition of La2O3 did not lead to an enhancement of the mechanical properties; however, it did not led to a deleterious effect either, and these properties were maintained. Accelerated aging tests were made on all produced composites, accordingly to ISO13356 (2008). The amount of monoclinic zirconia, which is an indicator of degradation on these composites, was quantified by X-ray diffraction analysis for 5,12,24,48 and 96 hours of aging tests. It was determined that, the undoped ZTA samples did not present monoclinic zirconia after 96 hours on an aggressive environment. Regarding the ATZ composites, even though the monoclinic zirconia content increased proportionally to the zirconia content present in the composite, it was found that the extent of degradation was minimal, since it was relegated to the material surface. This fact allowed the maintaining of the mechanical properties of the material throughout all the duration of the aging tests. As expected, the less stable composite, the ATZ with 2YSZ, presented the highest content of monoclinic zirconia. Nonetheless, the mechanical properties tested on the aged composite confirmed that the degradation did not expand to the material bulk. The addition of both dopants, successfully improved the aging resistance of the ATZ composite, presenting a lower amount of monoclinic zirconia after 96 hours of aging tests in comparison with the undoped ones. However, the addition of Ta2O5 destabilized the 2YSZ present on the ZTA composites, and 10% of monoclinic zirconia was detected after 96 hours of aging tests. Still, the mechanical properties were maintained on all the doped composites, which again confirmed the presence of degradation only at the material surface. The biocompatibility of these composites was also tested. MG63 cells were seeded on the sintered samples and MTT and alkaline phosphatase activity (ALP) assays were performed. The cell viability/proliferation increased significantly from day 1 to day 4 for all the produced composites. The ZTA composites, with more anchorage sites, presented higher cell adhesion and proliferation in comparison with the ATZ composites. The addition of La2O3 and Ta2O5 did not induced significant changes on the cell viability of the ATZ composites. However, the addition of Ta2O5 on the ZTA composite led to a poor performance, due to its verified hydrophobicity. The present study shows that optimal compositions of these composites can be achieved, with improved mechanical properties, hydrothermal degradation resistance and satisfactory biocompatibility.

Introduction : Le titane, à la fois utilisé comme moyen de fixation d’un implant devant ses propriétés biomécaniques proches de l’os et comme moyen d’ostéointégration a pris une place prépondérante en orthopédie. L’ostéointégration d’un implant titane (IT) essentielle pour la pérennité de ce dernier, dépend de 2 phases : une phase primaire MECANIQUE correspondant à l’impaction ou tenue primaire de l’IT et une phase secondaire BIOLOGIQUE correspondant à la colonisation de l’IT par le tissu osseux.L’objectif de ce travail fut d’évaluer et d’améliorer lors de ces deux phases la stabilité et l’ostéointégration de l’implant titane :(1) Évaluer la tenue primaire des tiges fémorales en titane non cimentées par l’analyse de l’impact correspondant à la mesure de l’impact au cours du temps.(2) Évaluer si la quantité de CSM contenues dans l’aile iliaque est corrélée à la survie sans reprise de des implants acétabulaires impactés dans le cadre de l’ostéonécrose aseptique de la tête fémorale.(3) Améliorer l’ostéointégration des IT par les méthodes de thérapie cellulaire en étudiant in vitro la survie et la division des cellules stromales mésenchymateuses humaines (CSM) osseuses au contact de cages lombaires inter-somatiques recouvertes d’alliage titane rugueux.Matériels et Méthodes: L’évaluation de la tenue primaire des tiges fémorales en titane sans ciment selon l’analyse de l’impact a été réalisée à l’aide d’un marteau muni d’un capteur de force piézo-électrique sur 20 sujets anatomiques soit 40 hanches. On a comparé le nombre de coups de marteau pour obtenir l’impaction idéale de la prothèse selon 3 méthodes d’évaluation différentes : le nombre de coups nécessaires pour le chirurgien (Nchir), le nombre de coups nécessaires par l’analyse vidéo de l’enfoncement de la tige dans le fémur (Nvid) et le nombre de coups nécessaires par l’analyse de l’impact (NI).Pour savoir si la quantité de CSMs dans la crête iliaque pouvait refléter l’ostéointégration des implants acétabulaires impactées et le risque de reprise chirurgicale, on a comparé le taux de CSMs mesuré lors de la réalisation d’une ponction concentration et réinjection dans la zone d’ostéonécrose et l’évolution clinico-radiographique des implants acétabulaires mis en place par la suite pour ces même patients (n=90) qui ont eu une arthroplastie totale de hanche in fine. Le recul moyen était de 15 ans.La survie cellulaire des CSM osseuses humaines a été évaluée sur des cages intersomatiques lombaires recouvertes de titane. Trois groupes (n=5) furent constitués : un groupe contrôle, un groupe cages avec surface titane, un groupe cage sans titane. Sur chaque implant, 1 microlitre contenant 106 CSM osseuses humaines a été mis en culture. L’analyse de la survie cellulaire, de la prolifération cellulaire et de l’expression de gènes de différenciation ostéoblastique ont été réalisés et comparés.Résultats : Concernant la première étude sur l’intérêt de l’analyse de l’impact pour la tenue de la tige fémorale, la différence entre NI, Nchir et Nvid était inférieure ou égale à 3 pour plus de 85% des configurations réalisées. Concernant la deuxième étude, il a été mis en évidence qu’un faible nombre de CSM dans la crête iliaque était un facteur de risque de révision chirurgicale chez les patients traités par un implant acétabulaire sans ciment. La troisième étude a montré que les CSMs pouvaient survivre, se développer pendant 96 heures et exprimer des gènes de différenciation ostéoblastique de manière identique sur les cages avec ou sans titane.Conclusion : L’analyse de l’impact permet de donner une information objective sur la tenue primaire de la tige fémorale en titane et impactée. Le titane est aussi un milieu favorisé de survie et de prolifération des CSM osseuses prédestinées à devenir des cellules ostéoformatrices surtout qu’un faible nombre de CSM semble être un risque d’échec d’ostéointégration des implants acétabulaires sans ciment
Introduction: Titanium, both used as a mean of fixing an implant to its biomechanical properties close to the bone and as a mean of osseointegration has taken a prominent place. The implant stability is essential for the durability of a titanium implant (TI); it depends on 2 phases: a primary phase, MECHANICAL, corresponding to the impaction or primary holding of the TI and a secondary phase, BIOLOGICAL, corresponding to the colonization of TI by bone tissue.The objective of this work was to evaluate and improve during these two phases the osseointegration of the titanium implant:(1) To evaluate the primary stability of uncemented titanium femoral stems by impact analysis corresponding to the measurement of impact over time.(2) To evaluate whether the amount of mesenchymal stromal cells (MSCs) contained in the iliac crest is correlated with the non-recovery survival of acetabular implants impacted in a context of aseptic osteonecrosis of the femoral head.(3) To improve the osseointegration of TI by cell therapy methods in vitro by studying the survival and division of human MSCs in contact with interbody lumbar cages coated with rough titanium alloy.Methods: The evaluation of the primary stability of cementless titanium femoral stems according to the impact analysis was carried out using a hammer equipped with a piezoelectric force sensor on 20 anatomical subjects, i.e. 40 hips. The number of hammer strokes was compared to obtain the ideal impaction of the prosthesis according to 3 different evaluation methods: number of impacts required by the surgeon (Nsurg), number of impacts required by the video analysis of the depression of the stem in the femur (Nvid), numbers of impacts needed by the impact analysis (Ni).To determine whether the amount of MSCs in the iliac crest could reflect the osseointegration of impacted acetabular implants and the risk of surgical revision. The rate of MSCs measured when performing a surgical cell therapy for aseptic osteonecrosis of the femoral head and the clinical and radiographic outcome of acetabular implants subsequently established for these same patients (n = 90), who had total hip arthroplasty in fine were compared. The mean follow-up was 15 years.The cell survival of bone marrow-derived MSCs was evaluated on lumbar interbody cages coated with titanium. Three groups (n = 5) were formed: a control group, a cage group with titanium surface, a cage group without titanium. On each implant, 1 microliter containing 106 human bone MSCs was cultured. The analysis of cell survival, cell proliferation and expression of osteoblastic genes were performed and compared.Results: Regarding the impact analysis of the cementless femoral stem impaction, the difference between NI, Nchir and Nvid was lower than 3 for more than 85% of the configurations performed.For the second study, a small number of MSCs in the iliac crest was a risk factor for surgical revision in patients treated with a cementless acetabular implant.The third study showed that MSCs could grow until 96 hours and could express osteoblastics genes 21 days after cell seed. No difference between PEEK cage and Titanium-coated PEEK has been found.Conclusion: The impact analysis provides objective data on the primary holding of the titanium impacted femoral stem. Titanium is also a favored biomaterial for the survival and proliferation of bone marrow-derived MSC predestined to become osteforming cells, especially since a small number of MSCs seems to be a risk of failure of osseointegration of cementless acetabular implants

碩士
國立臺灣科技大學
機械工程系
99
There are two main methods of the operative treatment of proximal femoral fractures, one is intramedullary, and the other one is extramedullary. Gamma nail (GN) is the standard treatment of intramedullary fixation, and the Dynamic hip screw (DHS) is the standard treatment of extramedullary fixation. These two fracture fixation devices are widely used in the treatment of proximal femoral fractures, but clinical failures of those implants are still to be found. So there were many studies to propose the improved designs to reduce the risk of implant failure for the DHS and GN. The purpose of this study is to develop three-dimensional finite element models to investigate and improve the biomechanical performances of GN and DHS. The FEM was used to evaluate the improvement of DHS and GN in the biomechanical performances under three types of the proximal femoral fractures (neck fracture, subtrochanteric fracture, and subtrochanteric fracture with gap).Improvement of the DHS is increasing length of bone plate, using the locking or non-locking bone plates, and increasing diameter of distal screw. Improvement of GN is increasing length of nail, and increasing length of nail tip. The maximum distortion energy criterion and the maximum deflection criterion were used to discuss the merits of their biomechanical implant performance. Finally, this study will also compare optimum improvement of DHS and GN with DSN. The results showed that DHS with longest length, will increase the risk of the implant failure, but the fracture fixation stability will enhance. However, maximal von Mises stress was found in the distal screw. So the diameter of the distal locking screw was increased to reduce the stress. The above improvement (ILDHS) could increase the stability of fracture fixation and reduce the risk of implant failure. The isthmus can protect the Gamma Nail as the long Gamma nail (LGN) was designed. So the risk of implant failure and the fracture fixation stability can be improved simultaneously. This study showed that the improved designs have greater biomechanical performance in the neck fracture and subtrochanteric fracture. However, in subtrochanteric fracture with gap fracture the risk of implant failure and the fixation stability of ILDHS were inferior to that of the LGN and DSN. It can be speculated that for unstable fractures intramedullary implants are superior than extramedullary implants.

Bibliography: leaves 198-219.
xii, 219 leaves : ill. (chiefly col.) ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Examines the effect of implant design on the femoral bone remodelling response in a sheep cemented hip arthroplasty model. The clinical section of the thesis also indicates the importance of biological factors in the femoral bone remodelling response.
Thesis (Ph.D.)--University of Adelaide, Dept. of Orthopaedics and Trauma, 1998

Bibliography: leaves 198-219.
xii, 219 leaves : ill. (chiefly col.) ; 30 cm.
Examines the effect of implant design on the femoral bone remodelling response in a sheep cemented hip arthroplasty model. The clinical section of the thesis also indicates the importance of biological factors in the femoral bone remodelling response.
Thesis (Ph.D.)--University of Adelaide, Dept. of Orthopaedics and Trauma, 1998

Bibliography: leaves 193-206.
xiii, 206 leaves : ill. (chiefly col.) ; 30 cm.
This thesis investigates the effect of femoral stem surface roughness and a collar on the fixation of cemented hip hemi-arthroplasty femoral stems in an in vivo sheep model up to nine months following implantation. Plain radiography, micromotion between prosthesis and bone during mechanical testing and histology are used.
Thesis (Ph.D.)--University of Adelaide, Dept. of Orthopaedics and Trauma, 1997?

Hip resurfacing is an alternative to total hip arthroplasty for the young and active patient likely to outlive traditional means of hip joint replacement. The acetabular cup is implanted in much the same fashion as an uncemented total hip arthroplasty, however, implantation of the femoral component is unique to hip resurfacing, presenting both distinct benefits and limitations. Hip resurfacing spares much of the proximal femur including the femoral neck and portions of the femoral head. This may be advantageous if the patient requires revision surgery; however, preservation of the femoral neck bears with it the risk of femoral neck fracture. The exact mechanism of neck fracture is not fully understood. Avoiding potential fracture risks is vital to ensuring optimal patient outcomes. The current work investigated mechanical femoral head preparatory factors that may predispose to femoral neck fracture. Intra-operative computer navigation is emerging as the gold-standard in orthopaedic care. In hip resurfacing, navigation may improve the surgeon’s ability to optimally implant the resurfacing prosthesis; however, much of this technology is still in its infancy and requires investigation into the accuracy and repeatability of this peri-operative tool. Pre-operative planning can assist the surgeon in optimally determining the size and position of the resurfacing components, specifically in reference to the patient’s unique anatomy, prior to performing the operation. This may aid in correct implant selection and provide a basis on which to conduct intra-operative navigation. However, the accuracy and repeatability of pre-operative planning for hip resurfacing has not yet been established. Thus, this body of work looked to establish a clear methodology for pre-operative planning, intra-operative computer navigation and surgical technique in order to optimize preparation of the femoral head, ultimately reducing the risk of femoral neck fracture in hip resurfacing.