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In the project a method to calculate the displacement of hip prostheses inside a hip socket is made. The project, performed as a bachelor thesis project is a cooperation between Karolinska Institute and Uppsala University. Hip replacements are expensive surgeries. Loosening is a large problem for orthopedists and patients, and costs both time and expenses. If dislocations of hip prostheses are detected in an early stage, preventions to reduce the loosening can be done. The method is programmed in Matlab code utilizing Computational Tomographic Images (CT). The CT images are built up by putting 0.5 [mm] wide X-ray slices after each other. In the project a model of a human hip made of plastic is used with two real hip prostheses, one for each hip, and small balls, around some [mm] in diameter, made of tantalum are located inside the plastic bone. The purpose of the tantalum balls are to mark the bones’ position and makes it easier toget exact coordinates from the X-ray images of the bone structure.

Corrosion at the head-neck junction of total hip replacements is a poorly understood phenomenon with an incidence of 1 - 2 %. Concerns around taper junction corrosion have focused on design factors including changes in taper surface topography and geometry as well as operating conditions such as high bearing surface friction and fluid ingress-egress at the taper junction. Hence, this thesis considered 3 aspects of the head taper junction namely: (1) frictional torque at the bearing surface and below the taper junction for varying head sizes and bearing material combinations, (2) Cobalt and Chromium ion release from CoCr/Ti taper junctions, (3) FE analysis of tapers utilising variables including taper length, material, angle, and clearance under loading conditions representative of walking, hip simulator profiles and stair climb. Bearing friction and the torque about the taper axis beneath the taper junction were positively correlated with the head size (R2 = 0.57 bearing friction, R2 = 0.88 torque) and average surface roughness (Ra) (R2 = 0.66 bearing friction, R2=0.79 torque) of the femoral head. Torque generated on large MoP bearings (0.93 ± 0.2 Nm) was found to be comparable to MoM (0.81 Nm). The median cumulative Cr release rate was at least 2 times greater than that of Co (0.0220 ppb/cycle Cr relative to 0.0109 ppb/cycle Co) due to the acidic environment utilised in the accelerated tests. No statistically significant difference in ion release was found, between the trunnions of different surface finishes. Finite element analyses showed that the largest gaps generated at the mouth of the taper, were associated with smaller taper contact areas. Clearances within ±0.1° enabled the tapers to engage over comparable lengths and therefore did not show differences in taper opening, showing this was influenced by the taper engagement length rather than location (proximal or distal) of contact. Stair climb loading generated the largest taper gaps (80 m) and surface stresses on the head taper (1200 MPa); these were greatest on the shortest trunnion. Although the stair climb loading condition is not currently mandated in testing THR devices, its use could provide a more accurate prediction of taper performance in vivo and may be beneficial to 'beyond compliance' initiatives to improve implant performance.

Made available in DSpace on 2014-06-11T19:31:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-29Bitstream added on 2014-06-13T19:01:31Z : No. of bitstreams: 1 minto_bw_dr_botfmvz.pdf: 1369635 bytes, checksum: 072ba26b6934c744d4aadd30423153ae (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A artroplastia total da articulação coxofemoral é a técnica cirúrgica mais comumente realizada para o tratamento da displasia coxofemoral canina grave. Diversos modelos e sistemas protéticos são descritos; desde os sistemas cimentados de cabeça femoral fixa que foram amplamente utilizados no passado, até os mais recentes, munidos de sistema osteointegravel e cabeça femoral intercambiável. A presente pesquisa teve como objetivo avaliar a aplicação de uma prótese total modular híbrida da articulação coxofemoral confeccionada no Brasil, em cães sadios, até 360 dias de pós-operatório. Foram utilizados 10 animais da espécie canina esqueleticamente maduros, sem raça definida, machos e fêmeas, com peso variando entre 19 e 27 kg, sem alterações no aparelho locomotor. Constituiu-se um único grupo experimental de animais submetidos ao procedimento de artroplastia total, utilizando-se componente femoral cimentado de cabeça intercambiável e componente acetabular não cimentado. Os cães foram submetidos ao exame clínico e radiográfico às 24 horas, e aos 30, 60, 90, 120, 180 e 360 dias após a cirurgia. A artroplastia total coxofemoral foi exequível. Sete dos 10 animais apresentaram escore excelente na locomoção, no período de avaliação final; dois apresentaram luxação protética com subsequente afrouxamento do componente femoral, sendo tratados por excisão artroplástica; um cão apresentou fratura completa do fêmur no pós-operatório imediato, e foi submetido à remoção dos componentes protéticos e osteossíntese. A artroplastia total modular híbrida da articulação coxofemoral canina proporcionou excelente resultado funcional do membro operado. / Total hip arthroplasty is the most accepted treatment for severe canine hip dysplasia. Several prosthetic devices and systems are available, from the old fixed head cemented prostheses to the modern uncemented modular ones. The aim of this study is to evaluate the surgical procedure and results of hybrid modular total hip prosthesis, developed in Brazil. Ten mature healthy mongrel dogs were used, their weight varied between 19 and 27kg. They did not have any orthopaedic problems. Hybrid modular total hip arthroplasty was performed in all 10 dogs. Cemented modular femoral stems and uncemented porous coated acetabular cups were used. Clinical and radiographic evaluations were performed before surgery and again at 30, 60, 90, 120, 180 and 360 days postoperatively. The technique of total hip arthroplasty was performed without complications or difficulties. Excellent weight bearing was noticed on the operated limb in seven dogs. Luxation followed by loosening, was noticed in two dogs and they were properly treated with an femoral head osteotomy. A femoral fracture occured in one dog, which was properly treated with full implant removal and femoral ostheosynthesis. The canine hybrid modular total hip arthroplasty provided excellent function of the operated limb.

Orientador: Cláudia Valéria Seullner Brandão / Banca: Luiz Carlos Vulcano / Banca: Paulo Iamaguti / Banca: Gilberto José Cação Pereira / Banca: Fernando De Biasi / Resumo: A artroplastia total da articulação coxofemoral é a técnica cirúrgica mais comumente realizada para o tratamento da displasia coxofemoral canina grave. Diversos modelos e sistemas protéticos são descritos; desde os sistemas cimentados de cabeça femoral fixa que foram amplamente utilizados no passado, até os mais recentes, munidos de sistema osteointegravel e cabeça femoral intercambiável. A presente pesquisa teve como objetivo avaliar a aplicação de uma prótese total modular híbrida da articulação coxofemoral confeccionada no Brasil, em cães sadios, até 360 dias de pós-operatório. Foram utilizados 10 animais da espécie canina esqueleticamente maduros, sem raça definida, machos e fêmeas, com peso variando entre 19 e 27 kg, sem alterações no aparelho locomotor. Constituiu-se um único grupo experimental de animais submetidos ao procedimento de artroplastia total, utilizando-se componente femoral cimentado de cabeça intercambiável e componente acetabular não cimentado. Os cães foram submetidos ao exame clínico e radiográfico às 24 horas, e aos 30, 60, 90, 120, 180 e 360 dias após a cirurgia. A artroplastia total coxofemoral foi exequível. Sete dos 10 animais apresentaram escore excelente na locomoção, no período de avaliação final; dois apresentaram luxação protética com subsequente afrouxamento do componente femoral, sendo tratados por excisão artroplástica; um cão apresentou fratura completa do fêmur no pós-operatório imediato, e foi submetido à remoção dos componentes protéticos e osteossíntese. A artroplastia total modular híbrida da articulação coxofemoral canina proporcionou excelente resultado funcional do membro operado. / Abstract: Total hip arthroplasty is the most accepted treatment for severe canine hip dysplasia. Several prosthetic devices and systems are available, from the old fixed head cemented prostheses to the modern uncemented modular ones. The aim of this study is to evaluate the surgical procedure and results of hybrid modular total hip prosthesis, developed in Brazil. Ten mature healthy mongrel dogs were used, their weight varied between 19 and 27kg. They did not have any orthopaedic problems. Hybrid modular total hip arthroplasty was performed in all 10 dogs. Cemented modular femoral stems and uncemented porous coated acetabular cups were used. Clinical and radiographic evaluations were performed before surgery and again at 30, 60, 90, 120, 180 and 360 days postoperatively. The technique of total hip arthroplasty was performed without complications or difficulties. Excellent weight bearing was noticed on the operated limb in seven dogs. Luxation followed by loosening, was noticed in two dogs and they were properly treated with an femoral head osteotomy. A femoral fracture occured in one dog, which was properly treated with full implant removal and femoral ostheosynthesis. The canine hybrid modular total hip arthroplasty provided excellent function of the operated limb. / Doutor

Orientador: Cecilia A. C. Zavaglia / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-25T02:10:22Z (GMT). No. of bitstreams: 1 Fernandes_BeatrizLuci_D.pdf: 8612737 bytes, checksum: 5b82e95884b98b376d5146b5ea2586e9 (MD5) Previous issue date: 1999 / Resumo: Apesar dos 30 anos de história, engenheiros e pesquisadores continuam procurando soluções para problemas que persistem até os dias de hoje, em relação à resistência ao desgaste de superfícies articuladas e à fixação aos tecidos ósseos de implantes ortopédicos de quadril. Esses problemas estão interligados, desde que a formação de grandes partículas nas articulações é o principal fator responsável pela perda da prótese e a qualidade da fixação do implante determina a produção dessas partículas. O material das amostras, analisadas neste trabalho, foi um dos empregados atualmente em próteses totais de quadril não cimentadas, ou seja, liga Ti6Al-7Nb revestida de hidroxiapatita (HA), aplicada através da técnica de aspersão por plasma. O principal objetivo deste trabalho foi apresentar uma alternativa para a avaliação da resistência da interface, utilizando-se uma nova técnica, rápida e confiável. As informações contidas estão relacionadas à técnica de deposição de materiais em forma de pó através de aspersão por plasma; ao estudo da resistência à adesão da HA sobre a liga de titânio através de ensaio de nanorisco e à caracterização superficial das amostras por determinação da rugosidade superficial, difração de raio-X e imagens do Microscópio Eletrônico de Varredura / Abstract: In spite of 30 years of history, engineers and researchers in general, are still trying to find solutions for the problems related to wear resistance of sliding surfaces and related to biological attachment of hip prostheses. These two questions are connected since the debris released in the joints are the main factor for loosing the prostheses and the fixation quality determines the production of those debris. The samples analyzed on this work were made of materials presently applied on hip prostheses like Ti-6Al-7Nb alloy with hydroxyapatite coating applied by plasma spray method. The main purpose of this work was to present an alternative to analyze the adhesion strength between the HA and the Ti-6Al-7Nb alloy using a new technique, fast and reliable. The information presented are related to the plasma spray' s deposition technique using powdered materials, to the evaluation of the interface between the two materials through the nanoscratch test and to the surface characterization using a mechanical profiler (profilometer), an X-Ray Diffract meter and a Scanning Electron Microscope / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica

This thesis, comprising 5 separate studies, is concerned with fixation of prosthetic components in total hip arthroplasty. The results and conclusions of the studies fol-low; The initial stability of femoral revision components, the long cementless PCA stem and the Exeter standard stem cemented in a bed of impacted bone graft, was com-pared in an experimental study. The PCA stem was more stable than the Exeter stem. However, for both stems initial stability may not be sufficient to allow bone ingrowth. Initial fixation is especially vulnerable to torsion. Identical femoral stems with or without HA-coating were compared in a prospec-tive randomized clinical trial. The long-term stable fixation of a cementless Link RS femoral component was improved by application of hydroxyapatite coating to the femoral stem. In a clinical study the method of extensive impaction of morsellized bone allograft and a hydroxyapatite-coated cementless Mallory-Head acetabular component was found to be advantageous for acetabular revision in the presence of contained or acetabular wall defects. The limited contact between the HA-coated implant and living host bone did not seem to compromise long-term stable fixation. Two different cup designs were compared in a prospective randomized RSA study. At 3 years after implantation the cemented low profile Lubinus FAL cup performed as well as the cemented Lubinus Standard cup in terms of migration and polyethyl-ene wear. In a study of the relationship between radiolucent lines and migration the Lubinus FAL cup displayed more radiolucent lines in the cement bone interface than the Lubinus Standard cup but no difference in migration was found. Early appearance of such radiolucent lines represents an unspecific finding without reliable correla-tion to 3-year migration of the acetabular component.

Over one million hip prostheses are implanted in patients worldwide each year and the need is increasing as the patient group of younger and more active patients is increasing. Many parameters affect the longevity of the implant, where aseptic loosening caused by wear debris is the most common reason for revision. To be able to monitor wear in vivo and also to predict the longevity of new materials for hip prostheses are therefore important issues in this interdisciplinary research area. This thesis comprise a true non-invasive 3D method for determination of acetabular cup wear using Computed Tomography (CT) intended for clinical routine use in order to plan for a revision. It also comprises investigations of the influence of surface roughness and sterilization method in wear testing of materials for hip prostheses. Mainly wear of ultra high molecular weight polyethylene (UHMWPE) was investigated since it is the most common soft bearing in hip prostheses. The 3D-CT method was found to be easy to use and showed an accuracy and repeatability at a clinical relevant level for acetabular cup wear. It should lend itself well to semi-automation. The influence of surface roughness was investigated with both a multidirectional pin-on-disk machine and with a hip simulator. A new low friction coating, Micronite, was also evaluated with the pin-on-disk machine. This coating showed potential for use in artificial joints, but further investigations are needed. In the hip simulator test, it was found that not only a rougher counter surface increased wear, but also sterilization by γ-irradiation increased wear of UHMWPE cups. / QC 20101117

<p>Over one million hip prostheses are implanted in patients worldwide each year and the need is increasing as the patient group of younger and more active patients is increasing. Many parameters affect the longevity of the implant, where aseptic loosening caused by wear debris is the most common reason for revision. To be able to monitor wear in vivo and also to predict the longevity of new materials for hip prostheses are therefore important issues in this interdisciplinary research area. This thesis comprise a true non-invasive 3D method for determination of acetabular cup wear using Computed Tomography (CT) intended for clinical routine use in order to plan for a revision. It also comprises investigations of the influence of surface roughness and sterilization method in wear testing of materials for hip prostheses. Mainly wear of ultra high molecular weight polyethylene (UHMWPE) was investigated since it is the most common soft bearing in hip prostheses. The 3D-CT method was found to be easy to use and showed an accuracy and repeatability at a clinical relevant level for acetabular cup wear. It should lend itself well to semi-automation. The influence of surface roughness was investigated with both a multidirectional pin-on-disk machine and with a hip simulator. A new low friction coating, Micronite, was also evaluated with the pin-on-disk machine. This coating showed potential for use in artificial joints, but further investigations are needed. In the hip simulator test, it was found that not only a rougher counter surface increased wear, but also sterilization by γ-irradiation increased wear of UHMWPE cups.</p>