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Ajemian, Stanley V. "Gait changes following total hip replacement." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq24641.pdf.
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Walter, William Lindsay School of Biomechanics UNSW. "Severe biomechanical conditions in total hip replacement." Awarded by:University of New South Wales. School of Biomechanics, 2006. http://handle.unsw.edu.au/1959.4/25968.
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Hip simulators are designed to reproduce the forces and motion patterns of normal walking. In vivo demands on total hip replacements, however, are varied and often more severe than normal walking conditions. It is these severe conditions that often lead to implant failure. This is clinically based research aimed at understanding some of the more severe conditions in hips and the effect that these have on the performance of the total hip replacement. The polyethylene liner can act as a pump in an acetabular component, forcing fluid and wear particles through the holes to the retroacetabular bone causing osteolysis. Ten patients were studied at revision surgery. Pressures were measured in retroacetabular osteolytic lesions while performing pumping manouvers with the hip. Two laboratory experiments were then designed to study pumping mechanisms in vitro. In patients with contained osteolytic lesions, fluid pressure fluctuations could be measured in the lesion in association with the pumping action. Patients with uncontained osteolytic lesions showed no such pressure fluctuations. In the laboratory we identified 3 distinct mechanisms whereby fluid can be pumped from the hip joint to the retroacetabular bone. These pumping effects could be mitigated by improved implant design. Loading of the femoral head against the edge of the acetabular component produces dramatically increased contact pressures particularly in hard-on-hard bearings. In an analysis of 16 retrieved ceramic-on-ceramic bearings we were able to characterise the mechanism of edge loading based on the pattern of edge loading wear on the bearing surface. Finally in a radiographic study of patients with squeaking ceramic-on-ceramic hips. Squeaking was found to be associated with acetabular component malposition. It seems that edge loading or impingement may be an associated factor in these cases.
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Warwick, David John. "Deep vein thrombosis after total hip replacement." Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283969.
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Torabi, Kachousangi Ehsanollah. "Edge loading effect on total hip replacement." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/90967/.
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The most important hip post-surgery problem is named Edge Loading (EL). This phenomenon significantly increases the contact pressure on the ball and the socket of the hip prosthesis hence decreasing the lifetime of the hip prosthesis drastically. Nowadays millions of patients cannot go under total hip replacement surgery due to the short lifetime of the hip prostheses. This research mainly focuses on finding solution for reducing the effect of this phenomenon. In this research, reasons of EL are investigated and important factors in designing of the prosthesis are studied. Furthermore, a novel hip prosthesis is proposed. The model has been successfully patented with PCT number: PCT/GB2015/052933 and published with International Publication Number: “WO2016/055783Al”. In this study the proposed design is analysed using three methods and the results are compared with the best available hip prosthesis in the market. The key results of the proposed design are outlined below: -Comparison of the features of the proposed design with those of the available hip prosthesis suggests a promising outcome. This is mostly due to eliminating of the EL causes, in the new design. -According to Hertzian Contact Theory, the proposed design reduces contact pressure during EL by 99.7% in comparison with the best available prosthesis in the market. This represents an upper limit. -Finite element method simulation demonstrates up to 63% reduction (lower limit) of contact pressure during EL and also Neck-Rim/Ring impingement by the proposed design in comparison with the best available prosthesis in the market. Although reduction of contact pressure by the novel design is noticeable, aforementioned methods show different results. This is due to the limitation of every method in this study. In this regard the novel design expecting to reduce contact pressure during EL / Microseparation more than 63% but less than 99.7%. The novel design may open a new path for the total hip replacement surgery, and solve the EL problem forever.
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Timperley, Andrew John. "Early complications relating to the acetabular component after total hip replacement." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670193.
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Malik, Khan Aamer. "Validation of computer navigation for total hip replacement." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/384238.
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Introducción: Está demostrado que incluso los cirujanos de cadera con una elevada experiencia, mal-posicionan los implantes durante la artroplastia total de cadera, pudiendo colocar los implantes fuera de la zona segura en casi un 50% de los casos. Las consecuencias de la mal-posición de implantes serían el impingement, la luxación, el aflojamiento aséptico, el desgaste, la osteolisis y dolor, pudiendo producir unas consecuencias dramáticas en la calidad de vida y funcionalidad de los pacientes. Este tesis describe la validación de un sistema de navegación sin imágenes primero con un fantoma y también clínicamente, para la precisa colocación del implante acetabular y femoral durante la artroplastia total de cadera. La información obtenida mediante esta reconstrucción numérica cambio nuestra técnica tradicional de colocar primero el cótilo hacia un número diana, a preparar primero el fémur y después la cadera con una anteversion combinada adecuada a unos números diana, técnica que validamos al final del estudio.
Materiales y Métodos: Primero, validamos nuestro sistema de navegación mediante un fantoma que diseñamos. Comparamos los resultados de la posición acetabular real del fantoma con las lecturas del sistema de navegación y de las imágenes de Tomografía Computarizada (TC) procesadas del fantoma. Esta información fue procesada mediante dos sistemas computarizadas de reconstrucción 3D de cadera independientes (HipNav® and Orthosoft®). Una vez la fiabilidad del sistema fue verificado, realizamos estudios clínicos sobre diferentes cohortes de pacientes sometidos a artroplastia total de cadera no-cementada con navegación. Comparamos la precisión del cirujano para colocación de implantes a la del sistema de navegación. Estos resultados fueron validados mediante TC postoperatorio.
Resultados: El fantoma confirmó que el Sistema de Navegación sin imágenes Navitrack, tenía una precisión de 1° y un sesgo de 0.02° para la inclinación y una precisión de 1.3° con un sesgo de 0° para medidas de anteversion. Clínicamente, la precisión del sistema de navegación del acetábulo fue de 4.4° con un sesgo de 0.03° para la inclinación y 4.1° con un sesgo de 0.73° para la anteversion. La precisión de los cirujanos con mucha experiencia fue de 11.5° para la inclinación y 12.3° para la anteversion, mientras que los cirujanos con menos experiencia tenían una precisión de 13.1° para la inclinación y 13.9° para la anteversion del cótilo. Para la versión del implante femoral, al comparar los valores del navegador a los TC postoperatorios, su precisión era de 4.8° con un sesgo de 0.2°. Al comparar las estimas del cirujano al navegador, su precisión fue de 16.8° con un sesgo de 0.2°. Confirmamos que el navegador tiene una precisión con error de < 5° y sesgo de < 1° para la colocación de implantes y siempre fue superior a los cirujanos. La anteversion combinada medida mediante TC postoperatorio fue de 37.6° ± 7° (rango 19°–50°). La anteversion combinada con navegación estaba dentro del rango deseado de 25° a 50° en 96% de caderas.
Conclusiones: Demostramos que el cirujano solo mediante su experiencia y intuición no puede colocar los implantes de una prótesis de cadera en la posición deseada. La artroplastia de cadera mediante la navegación es clínicamente precisa para la colocación del implante femoral y acetabular con un error de menos de 5°. La versión final del implante femoral no-cementado es muchísimo más variable de lo que se pensaba. Usando una herramienta precisa, previamente validada, para obtener información numérica intraoperatoria, llevamos a cabo una novedosa técnica de anteversion combinada para la reconstrucción de la artroplastia de cadera. Estudios a largo plazo que validen el coste efectividad y supervivencia de implantes con esta tecnología determinaran el papel de la navegación en nuestras cirugías de cadera de día a día.INTRODUCTION Even vastly experienced high-volume hip surgeons have been shown to be inaccurate with implant positioning during total hip replacement. Surgeons position the acetabular implants inclination and version, and femoral implants version out of the safe zone in almost 50% of cases. Consequences of implant mal-position are impingement, dislocation, aseptic loosening, wear, osteolysis and pain. These have dramatic effects on the patients’ functional outcome and quality of life. This thesis outlines the validation of an imageless navigation system with a phantom model, and posteriorly clinically, for accurate acetabular and femoral implant positioning during total hip replacement. The information obtained with this numerical reconstruction shifted our traditional surgical technique of placing the acetabulum first towards target numbers, to a femur first combined anteversion technique, which is validated at the end of the study. MATERIALS AND METHODS First, we validated our navigation system with a phantom model which we designed. We compared the readings of the imageless navigation system, and processed Computer Tomography (CT) scanned images of the phantom, with the true values of the phantom models acetabulum. This data was processed using two independent computer based hip reconstruction systems (HipNav® and Orthosoft®). Once robustness of the system was confirmed, clinical studies were undertaken in different cohorts of patients undergoing non-cemented total hip replacement with computer navigation between 2004 and 2009. The surgeon’s accuracy for implant positioning was compared to that of the navigation system. These results were validated by postoperative CT-scans (gold standard for postoperative implant position validation). RESULTS The phantom model confirmed that the Navitack Imageless Computer Navigation System had a precision of 1° and a bias of 0.02° for inclination and a precision of 1.3° and a bias of 0° for anteversion measurements. Clinically, the accuracy of the navigation system for the acetabulum was a precision of 4.4° with a bias of 0.03° for inclination and 4.1° with a bias of 0.73° for anteversion. The experienced surgeons’ precision was 11.5° for inclination and 12.3° for anteversion, whereas the less experienced surgeons’ precision was 13.1° for inclination and 13.9° for anteversion. For the femur implants version, on comparing the navigation systems values to postoperative CT-scans, its precision was 4.8° and bias was 0.2°. On comparing surgeon’s estimates to navigation, their precision was 16.8° with a bias of 0.2°. The distribution of femoral stem version had a wide variability (far from the assumed 15°) from complete retroversion to high anteversion. We confirmed that computer navigation had a precision of less than 5 degrees and bias of less than 1 degree for hip implant positioning, and was always better than that of surgeons. Combined anteversion by postoperative computed tomography scan was 37.6° ± 7° (range, 19°–50°). The combined anteversion with computer navigation was within the safe zone of 25° to 50° in 45 of 47 (96%) hips. CONCLUSIONS We demonstrated that the surgeon, through experience and intuition alone, cannot place implants within the desired positions. Hip replacement using computer navigation is clinically accurate to within 5° for acetabular and femoral implant positioning. There is far greater variability in femoral version of non-cemented implants than previously estimated. Using an accurate validated tool for numerical intraoperative information, we undertook a novel hip reconstruction method described as the combined anteversion technique. We believe it will reduce the risk for impingement and its complications. Long-term studies that validate improved implant survival and cost effectiveness with this expensive technology will help determine its future role in our day-to-day hip surgery
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Crawford, Ross William. "Focal femoral osteolysis in cemented total hip replacement." Thesis, University of Oxford, 2000. http://ora.ox.ac.uk/objects/uuid:67914dbd-6405-41a3-b4d6-6baeb8bbf0bf.
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As implant survival extends into the second and third decades focal osteolysis around cemented femoral components in total hip replacement is emerging as an important failure mechanism. Whilst the problem of focal osteolysis is well recognised, there are many aspects of its development which are poorly understood. The broad aim of this thesis is to try to provide some insights into how, why and where focal osteolysis develops around the cemented femoral component. There are broadly two sections to this thesis, chapters 2-5 present clinical and geometrical studies and chapters 6-10 a series of experimental studies. The aim of the first section was to establish what is observed in clinical practice, the aim of the second to try to explain these findings. A mid-term clinical study showed that focal osteolysis is more common with rough than polished stems that differed in no aspect other than their surface finish. Further studies established that focal osteolysis is probably always associated with defects in the cement mantle. These defects occur anteriorly at the mid-stem of the prosthesis and posteriorly at the component tip. The distribution of focal osteolysis and its strong association with cement mantle defects suggests the importance of the stemcement interface as a pathway for fluid and debris to reach the distal femur. However, at 15-25 years, osteolysis rarely develops with the polished Exeter stem even in the presence of confirmed defects in the cement mantle, suggesting that the stem seals the stem-cement interface against fluid and debris. In an attempt to explain the clinical findings a series of bench top experiments were undertaken. These studies showed that the behaviour of fluid and dye at the stemcement interface was significantly influenced by component surface finish. Bonded and debonded stem-cement interfaces of rough stems provided an incomplete barrier to fluid movement along this interface. In contrast, polished stems both bonded and debonded were able to provide a seal at the stem-cement interface. The seal at this interface was improved with component subsidence in the presence of rotational stability. It is believed that this thesis provides a rationale explanation for why focal osteolysis rarely develops around the Exeter stem in clinical practice. It also explains how, where, and why osteolysis develops around certain designs of cemented femoral components used in total hip replacement.
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Cook, Juliette Emma. "Fretting wear of total hip replacement femoral stems." Thesis, University of Exeter, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263286.
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Loughenbury, Faye Alexandra. "Minimising leg length inequality after total hip replacement." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/21329/.
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The total hip replacement is one of the most effective medical interventions undertaken, with high reported rates of pain relief and patient satisfaction 1,2. Leg length inequality (LLI) following total hip replacement was first recognised by Charnley when the operation was popularised but has only recently increased in prominence in the literature. The definition of an unacceptable value of LLI is controversial and is complicated not only by the lack of agreement of significance but also by the fact that for any given magnitude of LLI, only a proportion will be symptomatic. This thesis begins by exploring the opinions of British Hip Society (BHS) members to generate an expert opinion on acceptable values. Findings were in broad agreement with the literature, with 6784% of respondents stating they believed that LLI of less than 10mm would always be within the bounds of acceptable practice. A second survey of BHS members regarding methods of minimising LLI intra-operatively identified that 77% of surgeons use the Shuck technique during every total hip replacement, and that 11% use a commercial device. Chapter four evaluated five commonly used intra-operative tests and concluded that when used in combination these tests could produce acceptable values of LLI. Most reliance was placed on the Shuck technique during decision making. Results from this work identified scope for development of a novel device to be used as an adjunct to the Shuck test as an indirect measurement of leg length. A device was designed and manufactured and preliminary results from in vivo studies show a narrow range of both distraction distance and force applied during the Shuck test. These results indicate that the device could be developed further to standardise the Shuck test and use it as an adjunct to train junior surgeons how to assess leg length, minimising the requirement for subjective and invasive methods.
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Muller, Scott D. "The femoral cement mantle in total hip arthroplasty." Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273507.
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Kipping, Michael. "Wear and degradation of UHMWPE total hip replacement components." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/14468/.
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Long term (>2 years) failure of UHMWPE components in-vivo is predominantly caused by wear of the UHMWPE component. The surface properties of UHMWPE greatly influence the adhesive and abrasive mechanisms of wear that occur in the hip. However, there is not a clear understanding of how in-vivo wear mechanisms influence surface mechanical properties of UHMWPE. In addition, previous researchers have reported wear rates for Charnley UHMWPE acetabular components that vary considerably between patients. It is conceivable that these variations in wear are a result of variations in the surface mechanical properties of UHMWPE. This study used a combination of instrumented indentation testing and Ff-IR imaging to assess the depth dependent micromechanical and chemical properties of 32 retrieved UHMWPE acetabular components. Significant variations in the mechanical and chemical properties of samples taken from worn and unworn regions of retrieved UHMWPE acetabular components were found. In unworn regions, these variations were principally caused by post-irradiation ageing. However, in worn regions, the variation in properties was primarily caused by the wear process.
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Fogarty, Declan James. "Postoperative analgesia following spinal anaesthesia for total hip replacement." Thesis, Queen's University Belfast, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261938.
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Zant, Nikolaus Peter. "Fatigue integrity of reconstructed acetabula in total hip replacement." Thesis, University of Portsmouth, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438851.
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Isaac, Graham Hugh. "The tribology of bearings used in total hip replacement." Thesis, University of Leeds, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.713498.
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This thesis focusses on the dominant theme at my research activity, the triboiogy of bearings for use in Total Hip Replacement. This theme covers the majority of my research projects and hence publications to date. Restricting the research that is covered has the benefit of focusing the summary into a narrative which formed part of the worldwide research effort in this area. It does however mean that some of the more esoteric projects, such as the work on baby's dummies, were not included. . For those interested in this field or merely curious, the reference (6) has been included in the list of citations attached to this document.
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Okoro, Tosan. "Optimising patient function following elective total hip replacement surgery." Thesis, Bangor University, 2013. https://research.bangor.ac.uk/portal/en/theses/optimising-patient-function-following-elective-total-hip-replacement-surgery(11a74fb6-a659-42c1-9333-dbc5e42c3a89).html.
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Symptomatic hip osteoarthritis is associated with poor general health status and surgical intervention (total hip replacement; THR) is the most effective treatment for end stage disease. This procedure generally resolves pain, but function usually remains substantially sub-optimal. This protracted disability has detrimental economic, social and health consequences. 'Standard rehabilitation' (SR), (i.e. low intensity exercise, not involving progressive resistance training (PRT)), typically permits patients to regain basic levels of function but fails to resolve the significant muscle wasting and subsequent strength deficits associated with the condition. Supervised PRT following THR produces good results in terms of muscle strength and function. However, delivery of this type of program is expensive due to the high costs associated with supervision, facility provision, and transport of patients. A home-based program featuring relatively high intensity PRT but not requiring a high degree of supervision, would potentially overcome these problems. Before commencing this study, evidence was lacking regarding whether home-based PRT regimes with weekly supervision in the early postoperative period were effective in restoring muscle mass and physical function in THR patients.
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Gibson, Clare Naomi. "The effect of personality on recovery from total hip replacement and total knee replacement in patients with osteoarthritis." Thesis, University of Sheffield, 2007. http://etheses.whiterose.ac.uk/6097/.
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Background: Total hip replacement (THR) and total knee replacement (TKR) are increasingly common procedures to treat the pain and disability associated with osteoarthritis. There is a large variability in time to achieve functional milestones following these procedures and of success of surgery measured by pain and functional ability. Factors which affect outcome are poorly understood, but research in health psychology suggests psychological variables may play an important role. Objectives: To explore the relationships between selected psychological variables with pain and function pre-operatively in patients awaiting THR and TKR, on achievement of key functional milestones as an inpatient post-operatively, and of pain and function three-months post-operatively. Design: A correlational study of patients undergoing primary unilateral THR and TKR as a result of osteoarthritis. Subjects: 105 THR, 70 TKR. Psychological Measures: NEO-Five Factor Inventory, Multi-dimensional Health Locus of Control Questionnaire, Coping Strategies Questionnaire. Outcome Measures: Oxford Hip Score, Harris Hip Score, Oxford Knee Score, Knee Society Knee Score, key functional physiotherapy milestones. Results: Hip Study: Catastrophizing was a significant predictor of greater pain and worse function both pre-and post-operatively. Pain control efficacy was predictive of less pain and better function pre- and post-operatively. In addition, conscientiousness was a predictor of worse pre-operative function. Few psychological variables were predictive of physiotherapy outcome measures. Knee Study: Neuroticism was found to be a predictor of worse pain both pre- and post- operatively. Pre-operatively openness to experience was predictive of less pain and better function. Post-operatively, a chance locus of control was predictive of worse functioning. Few psychological variables were predictive of physiotherapy outcome measures. Conclusions: Psychological variables influence pain and function both pre- and post- operatively in THR and TKR. The psychological variables may exert their actions through pain control efficacy. There is scope to develop an intervention targeting negative psychological variables and improve outcome.
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Önsten, Ingemar. "Fixation of total hip components in rheumatoid arthritis and srthrosis a radiographic, roentgen stereophotogrammetric, densitometric and histomorphometric study /." Lund : Dept. of Orthopaedics, University of Lund, Malmö General Hospital, 1994. http://books.google.com/books?id=mGVsAAAAMAAJ.
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Neander, Gustaf. "Displaced femoral neck fractures : studies on osteosynthesis and total hip arthroplasty /." Stockholm, 2000. http://diss.kib.ki.se/2000/91-628-4167-X/.
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Pierrepont, James William. "Patient-Specific Component Alignment in Total Hip Arthroplasty." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17622.
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Appropriate component alignment is critical for improving stability, maximising bearing performance and restoring native biomechanics after total hip arthroplasty (THA). Due to the large variation in patient morphology and pelvic kinematics, current technologies lack definition of what constitutes the optimal target alignment for an individual. Analyses of large series of problematic THAs confirm that apparently well-orientated components on standard radiographs can still fail due to functional component malalignment. Evidently, previously defined “safe zones” are not appropriate for all patients as they do not consider the dynamic behaviour of the hip joint. The first goal of this thesis was to understand the variation in patients’ pelvic kinematics to demonstrate the clinical importance of functional cup orientation. Secondly, the variation in femoral morphology across the THA population was investigated in consideration of how that might affect femoral component positioning. From these findings, a commercially-scalable method of analysing each patient’s individual hip dynamics prior to THA was developed. This enabled an optimal component alignment to be chosen for each patient, accounting for their specific morphology and dynamics. Finally, we developed a simple intraoperative method to achieve the predetermined optimal alignment utilising 3D printed custom guides. The end result is the Optimized Positioning System™ (OPS™), comprising preoperative dynamic planning and patient-specific instrumentation for delivery of a patient’s optimal component alignment. The technology has been commercialised globally and used in over 5,000 primary total hip replacements to date.
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Otoum, Nesreen. "Medical image processing : applications in ophthalmology and total hip replacement." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/11848.
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Medical imaging tools technologically supported by the recent advances in the areas of computer vision can provide systems that aid medical professionals to carry out their expert diagnostics and investigations more effectively and efficiently. Two medical application domains that can benefit by such tools are ophthalmology and Total Hip Replacement (THR). Although a literature review conducted within the research context of this thesis revealed a number of existing solutions these are either very much limited by their application scope, robustness or scope of the extensiveness of the functionality made available. Therefore this thesis focuses on initially investigating a number of requirements defined by leading experts in the respective specialisms and providing practical solutions, well supported by the theoretical advances of computer vision and pattern recognition. This thesis provides three novel algorithms/systems for use within image analysis in the areas of Ophthalmology and THR. The first approach uses Contourlet Transform to analyse and quantify corneal neovascularization. Experimental results are provided to prove that the proposed approach provides improved robustness in the presence of noise, non-uniform illumination and reflections, common problems that exist in captured corneal images. The second approach uses a colour based segmentation approach to segment, measure and analyse corneal ulcers using the HVS colour space. Literature review conducted within the research context of this thesis revealed that there is no such system available for analysis and measurement of corneal ulcers. Finally the thesis provides a robust approach towards detecting and analysing possible dislocations and misalignments in THR X-ray images. The algorithm uses localised histogram equalisation to enhance the quality of X-ray images first prior to using Hough Transforms and filtered back projections to locate and recognise key points of the THR x-ray images. These key points are then used to measure the possible presence of dislocations and misalignments. The thesis further highlights possible extensions and improvements to the proposed algorithms and systems.
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Techamahamaneerat, S. "Psychological factors and experience of patients undergoing total hip replacement." Thesis, Liverpool John Moores University, 2016. http://researchonline.ljmu.ac.uk/4572/.
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This study aimed to comprehensively explore the relationship between psychological factors and pain, function and quality of life. A mixed method approach comprising two longitudinal and one cross-sectional elements, was conducted, with results being triangulated to give a multi-perspective view of the relationships. In the longitudinal elements, the questionnaire used in the quantitative phase was developed from validated tools, with cognitive interviews incorporating a think-aloud technique, used to validate the questionnaire package. Diary and interview schedules for the qualitative phase were developed from the existing literatures in this field. Additionally, a cross-sectional review of the pre-operative education programme in five centres was examined through participant observation. One-hundred and five patients scheduled for initial assessment were recruited into the quantitative phase. Of these, thirty-nine were successfully recruited to the quantitative phase and sixteen were followed up at six months post-operative. Twelve of the participants in the quantitative phase also participated in the qualitative phase, with five being successfully followed up at six months post-operative. Results indicated that pain, function and quality of life were highly associated with self-efficacy, pain catastrophising, functional expectations, pre-operative depression, post-operative anxiety and post-operative negative affect. The qualitative element identified five themes: physical symptoms; management and awareness; support; well-being; and cognitive aspects of the self-regulatory model. Evaluation of the content of the education programme identified that all information provided to the patients was in line with the guidelines. Triangulation of the mixed methods identified the congruence of major relationships between pain, function and quality of life with self-efficacy and expectations in the longitudinal elements. Self-efficacy and expectations should be considered throughout the hip surgery journey. Interventions, such as use of a reflective diary and talking to former patients who have undergone hip replacement, will enhance self-efficacy and adjustment of expectations, thus promoting better pain control, functional recovery and helping to tackle negative emotions.
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Dopico, Gonzalez Carolina. "Probabilistic finite element analysis of the uncemented total hip replacement." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/68694/.
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There are many interacting factors aecting the performance of a total hip replacement (THR), such as prosthesis design and material properties, applied loads, surgical approach, femur size and quality, interface conditions etc. All these factors are subject to variation and therefore uncertainties have to be taken into account when designing and analysing the performance of these systems. To address this problem, probabilistic design methods have been developed. A computational probabilistic tool to analyse the performance of an uncemented THR has been developed. Monte Carlo Simulation (MCS) was applied to various models with increasing complexity. In the pilot models, MCS was applied to a simplied nite element model (FE) of an uncemented total hip replacement (UTHR). The implant and bone stiness, load magnitude and geometry, and implant version angle were included as random variables and a reliable strain based performance indicator was adopted. The sensitivity results highlighted the bone stiness, implant version and load magnitude as the most sensitive parameters. The FE model was developed further to include the main muscle forces, and to consider fully bonded and frictional interface conditions. Three proximal femurs and two implants (one with a short and another with a long stem) were analysed. Dierent boundary conditions were compared, and convergence was improved when the distal portion of the implant was constrained and a frictional interface was employed. This was particularly true when looking at the maximum nodal micromotion. The micromotion results compared well with previous studies, conrming the reliability and accuracy of the probabilistic nite element model (PFEM). Results were often in uenced by the bone, suggesting that variability in bone features should be included in any probabilistic analysis of the implanted construct. This study achieved the aim of developing a probabilistic nite element tool for the analysis of nite element models of uncemented hip replacements and forms a good basis for probabilistic models of constructs subject to implant position related variability.
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Watters, Eamon Patrick John. "Wear properties of artificial hip joint materials." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321968.
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Khaw, Fu-Meng. "Osseointegration of hydroxyapatite coated femoral prostheses : a clinicopathological and biomechanical study of human autopsy retrieved implants." Thesis, University of Newcastle upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289162.
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Good, Victoria Diane. "The tribological significance of the joint fluid analog in a hip joint simulator." Thesis, University of Strathclyde, 2001. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21422.
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Wear is the number one concern with regards to the longevity of THR (total hip replacement). Therefore, reliable in-vitro prediction of wear is necessary. Thus, the laboratory should first validate their hip simulators with known clinical materials. The limiting factor in hip wear simulation has been the joint fluid analog. Using 100% bovine serum as the joint fluid analog, UHMWPE (ultra-high molecular weight polyethylene) wear-rates have been continually underestimated and PTFE (polytetrafluoroethylene) wear has been overestimated. Therefore, this work investigated the effect of protein concentration in bovine serum on the wear of PTFE and UHMWPE in a biaxial hip joint simulator. Validation criteria were developed based on the clinical findings of: ball size effect of increased wear with increased head size, 6% increase in wear for each millimeter of increased head diameter, clinical wear magnitudes, PTFE/UHWMPE wear-rate ratio and debris morphology. Both materials duplicated the clinical criteria using bovine serum with 10mg/ml of protein concentration. As protein concentration went from 0 to 10mg/ml, wear of both materials increased, however with greater than 10mg/ml protein; a) the rate of increase for PTFE was reduced by 80% and b) the wear of UHMWPE reversed, thus, showing that proteins cause wear. Additionally as the volume of fluid was increased, wear increased. This change in wear with protein concentration and volume was due to a protection of protein precipitate. As protein concentration increased protein precipitation increased and wear was decreased due to a protective layer of precipitates. Furthermore, wear protection was dependent on the amount of protein precipitation which was in turn, dependent on the initial concentration, volume of fluid and time. Therefore, wear in-vitro was dependent on the joint fluid analog. This work proved that the laboratory could duplicate clinical findings using bovine serum with 10mg/ml of protein concentration as the joint fluid analog and thus increase confidence in wear evaluation; taking the first steps to showing reliability of in-vitro THR wear studies.
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Yung, Kai-cheong, and 翁啟昌. "A retrospective study of changes in sexual behavior after total hip arthroplasty in individuals under 55 years old." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48334431.
Full textAbstract:
Introduction
Total hip arthroplasty is one of the most effective interventions to treat patients with end-stage hip arthritis. Although the outcomes of total hip arthroplasty have already been widely studied and most of the published results are positive, the dominant outcomes measures are focused on implant survivorship, patient mortality and complication rates. Quality of life assessment is regarded as a gold standard for outcomes measurement nowadays and was more frequently adopted in researches. However, in most of the study assessing the quality of life of patients undergoing total hip arthroplasty ignored the importance of quality of sexual life. Moreover, none of them are studying the Chinese population. In order to assess the quality of life of patients holistically, a study that focused on the quality of sexual life among Chinese population undergoing total hip arthroplasty is recommended. The aim of the present study is to investigate the changes in quality of sexual life in young Chinese patients undergoing primary total hip arthroplasty.
Methodology
The present study is a descriptive survey adopted a retrospective design and was conducted either as a phone interview or interview in person. 118 Patients who have undergone total hip arthroplasty at the Queen Mary Hospital are recruited from March 2012 to June 2012. Questionnaires assessing the pre-operation and post-operation sexual life and quality are administered. 118 subjects participated in the study finally.
Results
118 subjects participated in the present study. 35 of them reported to have no sexual life due to reasons other than the condition of their hip and were analyzed separately. 83 of the subjects were included in the analysis of changes in sexual life. Preoperatively 50.6% of subjects reported having severe to extreme sexual difficulty. 64 (78.0%) and 16 (19.5%) subjects reported the cause of sexual difficulty to be joint pain and joint stiffness respectively. 61 (73.5%) subjects believed the condition of their hip caused some degree of distress in the relationship with their partner preoperatively. 83.2% of subjects rated their level of sexual difficulty from minimal to mild after having total hip arthroplasty. 23 (28%) and 47 (57.3%) of subjects reported their post-operation sexual life experience to be better and much better respectively.
It is shown that greater joint pain (p<0.001) and stiffness (p=0.003) and lower Harris hip score (p=0.001) are significantly correlate with greater pre-total hip arthroplasty sexual difficulty, while only the range of motion of hip remained to be negatively correlated with sexual difficulty post-operatively (p=0.022). Subjects with ankylosing spondylitis are having significantly greater sexual difficulty than participants with other diagnosis post-operatively (p<0.001).
None of the subjects have discussed post-total hip arthroplasty sexual life issue with the health care professional. 24 (28.9%) subjects reported their need of more sexual life related information and the most wanted information is safe position for sexual intercourse (75%).
Conclusion
Total hip arthroplasty can significantly improve the quality of sexual life experience of Chinese patients. Further studies are necessary to be done in order to obtain more relevant information and modify the current patient routine assessment and education.published_or_final_version
Orthopaedics and Traumatology
Master
Master of Medical Sciences
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Hailey, Jacquolyn Lesley. "The influence of storage environment on the fracture behaviour of acrylic bone cement." Thesis, University of Bath, 1993. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336074.
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Elfick, Alistair Philip David. "A tribological assessment of the porous coated anatomic total hip replacement." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4574/.
Full textAbstract:
The tribological performance of internal joint prostheses is a fundamental influence on their longevity. The aim of this study is to characterise the tribological performance of the Porous Coated Anatomic total hip replacement by the analysis of 119 explanted prostheses. Investigations of the friction, wear, surface topography and wear debris were made and related to the joint's clinical performance. The friction of the joints at explant was similar to that of new prostheses. The median total wear volume (419mm(^3)) was found to agree with previous wear studies suggesting the existence of a threshold wear volume which promotes osteolysis. Clinical wear factor for the whole cohort matched that of alternative joint designs. The femoral head finish was shown to degrade but not in proportion to implant duration. The roughness of the UHMWPE liner was shown to fall but no relationship with any head roughness, or temporal, parameter could be distinguished. Simulator studies confirmed that the wear factor of a joint is likely to change over its lifespan. Wear models published previously describing the influence of femoral head roughness on wear could not predict the performance of explanted prostheses. An alternative relationship was observed indicating that head roughness is not as powerful a predictor of wear as previously held. A novel technique for the characterisation of the size distribution of ex vivo and in vitro wear debris was developed. A Low-Angle Laser Light Scattering Particle Analyser was used to size particles continuously over a range from 0.5 to 1000μm. This technique offers considerable unprovement over existing microscope-based methods in terms of the detail of the information and does so with less experimental effort. It was shown to be highly accurate and repeatable in preliminary investigations. Case studies of five tissue samples revealed the potential of this method.
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Liu, Chaozong. "In vitro dynamic simulation of interface failure in total hip replacement." Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397544.
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McWilliams, Anthony Bernard. "Leg length inequality following total hip replacement : a little understood complication." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/17048/.
Full textAbstract:
Total hip replacement (THR) is one of the most effective medical interventions undertaken. Leg length inequality (LLI) following total hip replacement is a recognised complication and although recognized when the operation was pioneered, has only more recently come to prominence in the literature. Understanding of LLI following THR is impeded by there being little consensus regarding definition, incidence, measurement, symptoms, treatment or even clinical significance. The thesis begins by outlining the extent of LLI using an analysis of litigation data for orthopaedic operations covered by the National Health Service Litigation Authority. The data found that LLI following THR was cited in 100 claims, 44 of which were successful and at a total cost of nearly £3.9 million. During the same time period, nearly 800,000 THRs were performed. The thesis then studies techniques to measure LLI following THR on plain radiograph. The four techniques studied were comparable in terms of inter and intra reader reliability as well as for the image acquisition protocol. The CFH-TD-LT method, has an advantage of providing information regarding the contribution of any LLI due to the components of the joint replacement. The final part of this work employs a computational model and a radiographic experiment to study the effect of femoral malposition has on the measurement of LLI using the CFH-TD-LT technique. Results indicate that errors associated with flexion and abduction are small when in isolation. However, when the malpositions are combined there is an additive effect this is not predicted by the malpositions in isolation. Extension and adduction result in a greater error of interpretation both in isolation and when combined with internal rotation, and while clinically less common, should be viewed with caution when being interpreted on plain radiograph. Perhaps just as significantly, it is only in the extremes of malposition that there is any major difference in the contribution that the cup measurement makes to the limb length. In summary, this thesis presents data regarding the validation for measurement on plain radiographs. It provides evidence to suggest that should a patient present with an LLI following THR, then a plain x-ray will give all the necessary information, even in the presence of larger angles of the clinically relevant deformities of flexion and abduction.
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Balck, Friedrich, Maike Lippmann, Csilla Jeszenszky, Klaus-Peter Günther, and Stephan Kirschner. "The influence of optimism on functionality after total hip replacement surgery." Sage, 2016. https://tud.qucosa.de/id/qucosa%3A35605.
Full textAbstract:
Among other factors, optimism has been shown to significantly influence the course of some diseases (cancer, HIV, coronary heart disease). This study investigated whether optimism of a patient before a total hip replacement can predict the functionality of the lower limbs 3 and 6 months after surgery. A total of 325 patients took part in the study (age: 58.7 years; w: 55%). The functionality was measured with the Western Ontario and McMaster Universities arthrosis index, and optimism with the Life Orientation Test. To analyse the influences of age, gender and optimism, general linear models were calculated. In optimistic patients, functionality improved significantly over time. The study showed a clear influence of dispositional optimism on the recovery after total hip replacement in the first 3 months after surgery.
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Eisler, Thomas. "On loosening and revision in total hip arthroplasty /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-545-x/.
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Apatsidis, Dimitrios P. "The hip joint capsule : mechanical properties and contribution to joint stability in total hip replacement." Thesis, University of Strathclyde, 2002. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21186.
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The hip joint capsule is a complex soft tissue structure that comprises a number of ligaments with different thickness and strength respectively, as well as a thinner membrane-like part that provides the structural integrity for the capsule. The role of the capsule is twofold, forming a closed environment around the joint surfaces, in which the synovial fluids are retained, but also providing a passive joint resistance that acts in addition to the surrounding muscles and mainly in extreme limb positions and in unexpected limb loading. Despite its important role, the capsule is commonly removed in Total Hip Replacement (THR), either fully or partially, to clear the view to the joint. The little existing knowledge on the mechanical properties of the capsule and its performance in situ during various walking activities makes it difficult to argue for its preservation and repair following THR, especially due to the additional efforts that this brings along for the surgical team. This project is an attempt to provide this required information and to highlight any changes in joint resistance that occur as a result of a complete or partial removal of the hip joint capsule. A cadaveric approach was used at first, in which complete human hip joints with intact capsules were tested. A sequential removal of the capsular ligaments was carried out, in order to reveal the total contribution to joint resistive moments of the individual ligaments. Anterior ligaments were distinguished from posterior ones and the tests were carried out in those limb positions in which the joint would be least stable under absence of the respective ligaments. Partial damage of the posterior aspects of the capsule showed increased risk for posterior joint dislocation when the limb was in flexion and internal rotation compared to the effects of an anteriorly damaged capsule. A 3-D computer model of the hip joint with its capsular ligaments was created, in order to confirm the findings from the cadaveric study, but also for the purpose of simulating effects in post-operative anatomies. Different methods of creating the geometric model were attempted and it was achieved to create a model that would be used to simulate the resistive moments produced by the individual ligaments. For simplicity, the ligament action was simulated by linear spring elements. The findings of the cadaveric experiments could not be reproduced, because of the way the ligament forces were modelled, which does not consider the viscoelastic properties of soft biological tissues. However, it was still possible to draw valuable conclusions on the effect that various prosthetic component attributes have on the total joint moments. Recommendations were made for the optimal approach to the capsule in THR.
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Keisu, Kjell. "The femoral component in total hip arthroplasty : results of uncemented and cemented fixation /." Stockholm, 2001. http://diss.kib.ki.se/2001/91-628-4750-3/.
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Sandell, Claire-Louise. "A study of self-reported surgical site infection post total hip or total knee replacement." Thesis, University of Portsmouth, 2012. https://researchportal.port.ac.uk/portal/en/theses/a-study-of-selfreported-surgical-site-infection-post-total-hip-or-total-knee-replacement(ff96dda8-7c00-4e3a-8de2-ade5c54bfd02).html.
Full textAbstract:
Background: Currently there is little published evidence exploring the experience of post discharge surgical patients who have developed infection following hip and knes joint surgery. This mixed methods syudy used both quantitative (Phase One) and qualitative (Phase Two)methodologies to explore the experience of patients with self-reported surgical site infection Methods: Phase One - Used a researcher developed postal questionnaire to identify the incidence of self-reported surgical site infection at six weeks post surgery as well as investigating the patients' experience of diagnosis, treatment and outcome following surgical site infection. Phase Two - Recruited from Phase One, twenty three patients were recruited from Phase One and invited to participate in one to one unstructured, audio taped qualitative interviews. Guided by Husserlian phenomenological approach to data collection and analysis informed by Colaizzi's method of data analysis, nine patients shared their lived experience of developing an infection post surgery. Findings: Phase One - A total of 523 patients were identified at one NHS trust and after exclusions questionnaires and stamped addressed envelopes were posted 505 patients six weeks following either total hip or total knee replacement surgery. A reponse rate 88.5% led to a final analysis of 447 questionnaires to reveal that 23 (or 5.1%)patients developed a surgical site infection, 7 in total hip replacement and 16 in total knee replacement patients. Ten infections were identified prior to discharge and 13 post discharge. Only 6 of the 23 patients were first seen by a hospital practitioner after suspecting a surgical site infection. 4 patients sought review by their general practitioner, who then referred them on to a hospital pratitioner. The remaining 13 patients utilised a combination of different management pathways. In Phase Two analysis of the nine verbatim transcriptions revealed 5 main themes of (1) Vulnerability, (2) Perception of infection, (3) Significant event, (4) Yo yoing and (5) Pendulum of care. Dicussion: Comparisons between current surveillance methods and those utilised in the study identified that current surveillance methos are likely to under represent the total number of self-reported surgical site inf
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Coutts, Fiona Jane. "Analysis of hip and lumbar spine movement during functional activity two years after total hip replacement." Thesis, University of Strathclyde, 2008. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21984.
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Total Hip Replacement (THR) is considered one of the commonest, mechanically effective and cost effective orthopaedic procedures performed. Routinely patients are discharged from follow-up at 1-year after surgery and little is known about hip and lumbar spine movement during function after this time. Twenty four participants, two years after uncomplicated primary THR were compared with 24 matched healthy adults during 4 functional activities and clinical assessment of hip and lumbar spine movement. The clinical tests and hip, pelvis and lumbar spine motion during gait are presented. A6 camera, Kinemetrix Motion Analysis system(50Hz) (MIE Ltd., UK) and a single 0.4 x 0.6m Bertec force platform (300Hz) (MIE Ltd., UK) were used. Reliability testing of dynamic and clinical measures was undertaken and all data were tested for normality. Mean range and peak data were tested using Analysis of variance and post hoc t-tests. Data were analysed in three groups: Those after THR both the operated (THR op) and non-operated sides (THR non op) were investigated and compared to healthy individuals (THN). Alpha was set at p<0.05. All physiological hip movements were greater in the THN group but only lumbar spine flexion and lateral flexion were significantly larger with extension being less. During gait, the THR op side had significantly decreased mean hip range compared to the THR non op side and THN groups, whilst the THN side had significantly less mean range of lumbar spine motion in the sagittal plane. Sagittal plane peak hip moments were significantly larger in the THN group compared to the THR op. Considerable difference were identified in timing and range of the movement patterns in angle-time and angle-angle diagrams for the THN and THR groups. These findings highlight possible longer term spinal complications through abnormal mechanical use and question the effectiveness of current rehabilitation after THR.
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Brown, Christopher U. "Time-dependent circumferential deformation of cortical bone subjected to internal radial loading." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1861.
Full textAbstract:
Thesis (Ph. D.)--West Virginia University, 2001.Title from document title page. Document formatted into pages; contains xv. 191 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 166-183).
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Thompson, Mark S. "The design of a novel hip resurfacing prosthesis." Thesis, Queen Mary, University of London, 2001. http://qmro.qmul.ac.uk/xmlui/handle/123456789/28944.
Full textAbstract:
Total hip replacement (THR) is one of the most successful and most frequently performed operations. For most implants the published rate of revision at 10 years is less than 10%. However the revision rates are higher for younger and more active patients who are likely to outlive their implants. The most frequent cause of THR failure is aseptic loosening, commonly accompanied by bone loss at the implant site. THR revisions give worse functional results and fail sooner than primary THR and are complicated by this loss of bone stock. A resurfacing hip prosthesis replaces the diseased surface layer of bone and cartilage and retains the majority of the femoral head. The stress distribution in the proximal femur is closer to that in an intact hip. A conservative resurfacing prosthesis will present the surgeon with no greater problems at revision than encountered at primary conventional 11-JR. Early designs of resurfacing prosthesis conserved femoral bone stock at the expense of acetabular bone. Revision rates were high and while some failures were caused by avascular necrosis and femoral neck fracture the predominant cause was acetabular loosening. The design of a bone conserving prosthesis requires knowledge of the shape of the bony surfaces of the hip joint. A survey of the morphology of the acetabulum showed a wide variation in shape. While early resurfacing designs had hemispherical acetabular cups the bony surface is less than hemispherical. The morphology and desired range of hip motion constrain prosthesis thickness and shape. A novel resurfacing design using a polyacetal femoral component and an UHMWPE acetabular component is proposed. This bearing combination has a lower volumetric wear rate than an equivalent Co-Cr on UHWMPE bearing. Computer modelling of the resurfacing concept showed that lower moduli materials reduced stress shielding and distributed implant-bone interface stresses more evenly. Mechanical testing of polyacetal following immersion in Ringer's solution showed substantial decreases in Young's modulus while strength was unaffected.
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Ebreo, Darren. "The role of metal ions in metal-on-metal total hip replacement." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/59343/.
Full textAbstract:
Metal-on-metal (MoM) total hip replacement (THR) offered theoretical advantages of decreased wear and increased functional outcomes. MoM bearings have been associated with sterile inflammatory masses and significant soft tissue destruction with poorer outcomes following revision surgery. The natural history of adverse reactions to metal debris (ARMD) is unknown, but may represent contributions from bearing surface wear, taper junction wear, and corrosion. Immunological and genetic factors may influence susceptibility to development of ARMD. Between 1997 and 2004, 652 Ultima TPS THRs (DePuy) were implanted in 545 patients who went on to experience a high rate of early implant failure (13.8%). Management of these patients has evolved beyond regular clinical follow up with plain radiographs to include surveillance monitoring of trends in levels of blood metal ions and staging of disease using metal artefact reduction (MAR) MRI. This study investigated: • The natural history of ARMD in 28mm MoM THR using MAR MRI. • The possibility of diurnal variation of cobalt (Co) and chromium (Cr). • Differences in gene expression profiles of patients undergoing revision of a metal-on-polyethylene (MoP) THR for aseptic loosening and those with ARMD arising from MoM THR. In patients whose MARS MRI staging on initial scan is normal or where mild evidence of disease is demonstrated, further deterioration is unlikely. Where it does occur, the rate of deterioration is slow and there may be a latent period of many years. There is no diurnal variation in levels of cobalt (Co) in plasma or urine. There is diurnal variation in levels of plasma chromium, but this is not clinically significant. Patterns of gene expression in patients with aseptic loosening of a metal-onpolyethylene (MoP) THR, and patients with ARMD from a MoM THR investigated by a microarray experiment were found to be similar on a genome-wide level suggesting that they may share common factors in their aetiologies. These studies have helped to describe the natural history of ARMD on a cellular and radiological level, and have provided a contribution to the evidence base that will inform as to the optimum strategy for monitoring these patients before they develop catastrophic complications.
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Revie, Ian Crawford. "The manufacture and evaluation of custom acetabular components for total hip replacement." Thesis, Queen's University Belfast, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286851.
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Mburu, Gathuru. "Cement keyhole fixation of the acetabular component of a total hip replacement." Thesis, University of Aberdeen, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342193.
Full textAbstract:
Loosening of the cemented acetabular component of a total hip replacement is 2-3 times more common than femora stem failure. Cement keyholes drilled into the acetabulum have been recommended to improve this fixation but little is known of the optimum sizes and locations of these holes. This study investigated the diameter, depth and number of keyholes to be drilled to maximise the failure torque in a model system. A two-pronged approach was used; mechanical testing and finite element (FE) analysis. A Taguchi experimental design was used to identify the most significant factors and to predict the best configuration of keyholes within the constraints of the acetabular dimensions. One hole at each of the pubic, iliac and ischial sites, of 12 mm diameter and 6 mm depth, was found to be the optimum configuration. The failure torque was most strongly dependent on the hole diameter in the pubic region, decreased with increasing hole depth and was not sensitive to the number of holes. Both two dimensional and three dimensional FE analyses of a single cement keyhole showed that the lowest von Mises stress and the best distribution of shear stress was for the hole of 12 mm diameter and 6 mm depth. The results of the two approaches used here are in excellent agreement. The final stage of this study investigated the optimisation of the keyhole shape and the design of a suitable drill bit for surgical use.
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Hussain, Azad. "Characterisation of wear particles genarated during accelerated testing of total hip replacement." Thesis, Queen Mary, University of London, 2004. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1783.
Full textAbstract:
Total hip replacements have been in use for over 30 years, and have shown great improvement from design to surgery since the first generation of implants were introduced. The greater need for hip replacements has led to the development of test methods that can be applied in the lab, which can predict the lifetime of a particular implant. To achieve this aim this study has sought to investigate key parameters, which may affect wear and its subsequent effect upon the production of particles for various material combinations and bearing geometries, under high (jogging) and low (walking) loads, with concurrent assessment of wear reduction, particle size and morphology. The clinical use of cross-linked polyethylene (XLPE) has been shown to reduce wear and thereby the onset of osteolysis in total hip arthroplasty. Hip simulator studies have suggested that while XLPE generates low wear under smooth counterface bearing surfaces, there appears to be an increased sensitivity to scratched femoral head conditions which can occur in the patient. However, these simulator studies have not combined damaged articular surfaces with a severe gait model, representing the worst-case scenario for high-risk, active patients. This hip simulator study has shown that the size distribution of wear particles generated in tests on 5 MRads crosslinked polyethylene can be influenced by the degree of patient activity. Fast jogging showed a greater influence on the number of sub-micron-sized wear particles (5-fold increase compared to walking) than on volumetric wear rate (26 mm3/106 cycles compared to 29 mm3/106 cycles). Fast jogging also did not generate the largest wear particles (>I 0p m) produced by normal walking. Roughening of the Co-Cr-Mo femoral heads created a 1700-fold increase in the numbers of sub-micron PE particles under fast jogging. The clinical significance of this result suggests that highly active patients will generate high numbers of bioactive PE wear particles within the accepted bioactive range, 0.2-10μm. Metal-on-metal (MOM) hip arthroplasty has also seen rapid growth worldwide. However, there remains concern over their long-term biocompatibility due to systemic ion release. Therefore, the aim of this current investigation was to test the hypothesis that larger diameter MOM bearings (greater than 40 mm) will generate smaller Co-Cr-Mo wear particles compared to a 28 mm size bearing, and reduce the total wear particle surface area, and to test the hypothesis that `severe' gait conditions will greatly increase the size of Co- Cr-Mo wear particles, thereby causing a sizable increase in wear particle surface area. Walking with a 28 mm bearing produced the largest wear rate of at 0.92 mm3/106 cycles, whereas the 40 mm and 56 mm bearings, generated lower wear rates of 0.39 mm3/106 cycles and 0.32 mm3/106 cycles respectively. Simulated fast jogging created a 3-fold increase in the number of elongated (needle) wear particles compared to normal walking, and generated a 20-fold increase in total wear particle surface area per year of use compared to normal walking. The clinical significance of this result suggests that highly active patients with MoM implants will exhibit greater ion release, although this may be minimised by using larger diameter bearings for active or younger patients.
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Partridge, Susan. "Wear and rim damage of UHMWPE acetabular cups in total hip replacement." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/17574/.
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Wear and fatigue of polyethylene acetabular cups have been reported to play a role in the failure of total hip replacements. Edge loading of hip replacements can occur where there is sub-optimal component positioning and/or joint laxity. Wear resistance can be improved by crosslinking but the manufacturing process of these materials involves post-irradiation thermal treatments to recombine free radicals and to stabilise the materials. Stabilisation can also be achieved by adding antioxidants. Material degradation due to oxidation and manufacturing process can result in rim cracking and/or fracture due to a reduction in mechanical properties and this has been observed in vivo. A requirement for pre-clinical hip simulator testing under edge loading conditions for all of these materials has therefore been identified. This thesis describes the development and evaluation of a hip simulator edge loading protocol using accelerated aged conventional UHMWPE acetabular liners as positive controls and commercially available crosslinked UHMWPE acetabular liners as negative controls. The edge loading protocol was then used to evaluate antioxidant stabilised liners in hip simulator tests. Explanted UHMWPE acetabular liners were evaluated for wear and damage mechanisms and compared with the damage observed on the hip simulator tested liners and new methodologies were developed to measure and analyse these explanted liners. The edge loading protocol produced cracking and subsurface damage in the aged UHMWPE liners but not in the non-aged crosslinked liners. Rim deformation was observed on all liners and the volume change produced was reduced under edge loading conditions for both types of UHMWPE liner. The antioxidant liners performed as well as the commercially available crosslinked liner in hip simulator tests and the rim deformation that was observed on explanted liners was replicated under edge loading conditions in the hip simulator tests. The edge loading protocol can be used in the future to test a range of UHMWPE materials, including aged materials, and explant analysis using the methodologies developed in this study can be used to inform the design of future simulator tests.
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Huebner, Blake James. "Comparing Total Hip Replacement Drug Treatments for Cost and Length of Stay." Thesis, North Dakota State University, 2015. https://hdl.handle.net/10365/27859.
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The objective of this study is to identify the potential effect anticoagulants, spinal blocks, and antifibrinolytics have on overall cost, length of stay, and re-admission rates for total hip replacement patients. We use ordinary least squares regression, multiple comparison testing, logistic regression, and chi square tests to fulfill this objective. The combination of warfarin and enoxaparin is associated with the highest cost and length of stay out of the anticoagulants studied. There is no clear combination of spinal blocks associated with the highest cost and length of stay. Tranexamic acid is associated with a reduction in length of stay and likelihood of receiving a blood transfusion, while not increasing overall cost. No drug combination in any category is associated with a change in re-admission rates.
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Al-Zadjali, Najiba. "Computer-aided diagnosis of complications of total hip replacement X-ray images." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/33729.
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Hip replacement surgery has experienced a dramatic evolution in recent years supported by the latest developments in many areas of technology and surgical procedures. Unfortunately complications that follow hip replacement surgery remains the most challenging dilemma faced both by the patients and medical experts. The thesis presents a novel approach to segment the prosthesis of a THR surgical process by using an Active Contour Model (ACM) that is initiated via an automatically detected seed point within the enarthrosis region of the prosthesis. The circular area is detected via the use of a Fast, Randomized Circle Detection Algorithm. Experimental results are provided to compare the performance of the proposed ACM based approach to popular thresholding based approaches. Further an approach to automatically detect the Obturator Foramen using an ACM approach is also presented. Based on analysis of how medical experts carry out the detection of loosening and subsidence of a prosthesis and the presence of infections around the prosthesis area, this thesis presents novel computational analysis concepts to identify the key feature points of the prosthesis that are required to detect all of the above three types of complications. Initially key points along the prosthesis boundary are determined by measuring the curvature on the surface of the prosthesis. By traversing the edge pixels, starting from one end of the boundary of a detected prosthesis, the curvature values are determined and effectively used to determine key points of the prosthesis surface and their relative positioning. After the key-points are detected, pixel value gradients across the boundary of the prosthesis are determined along the boundary of the prosthesis to determine the presence of subsidence, loosening and infections. Experimental results and analysis are presented to show that the presence of subsidence is determined by the identification of dark pixels around the convex bend closest to the stem area of the prosthesis and away from it. The presence of loosening is determined by the additional presence of dark regions just outside the two straight line edges of the stem area of the prosthesis. The presence of infections is represented by the determination of dark areas around the tip of the stem of the prosthesis. All three complications are thus determined by a single process where the detailed analysis defer. The experimental results presented show the effectiveness of all proposed approaches which are also compared and validated against the ground truth recorded manually with expert user input.
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Varini, Elena <1977>. "Primary stability in cementless total hip replacement: measurement techniques and aided-surgery." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/404/1/Varini_Elena_-_Tesi_dottorato_BIOINGEGNERIA.pdf.
Full textAbstract:
Primary stability of stems in cementless total hip replacements is recognized to play a critical
role for long-term survival and thus for the success of the overall surgical procedure. In
Literature, several studies addressed this important issue. Different approaches have been
explored aiming to evaluate the extent of stability achieved during surgery. Some of these are
in-vitro protocols while other tools are coinceived for the post-operative assessment of
prosthesis migration relative to the host bone. In vitro protocols reported in the literature are
not exportable to the operating room. Anyway most of them show a good overall accuracy. The
RSA, EBRA and the radiographic analysis are currently used to check the healing process of
the implanted femur at different follow-ups, evaluating implant migration, occurance of bone
resorption or osteolysis at the interface. These methods are important for follow up and clinical
study but do not assist the surgeon during implantation.
At the time I started my Ph.D Study in Bioengineering, only one study had been undertaken to
measure stability intra-operatively. No follow-up was presented to describe further results
obtained with that device.
In this scenario, it was believed that an instrument that could measure intra-operatively the
stability achieved by an implanted stem would consistently improve the rate of success. This
instrument should be accurate and should give to the surgeon during implantation a quick
answer concerning the stability of the implanted stem. With this aim, an intra-operative device
was designed, developed and validated. The device is meant to help the surgeon to decide how
much to press-fit the implant. It is essentially made of a torsional load cell, able to measure the
extent of torque applied by the surgeon to test primary stability, an angular sensor that measure
the relative angular displacement between stem and femur, a rigid connector that enable
connecting the device to the stem, and all the electronics for signals conditioning. The device
was successfully validated in-vitro, showing a good overall accuracy in discriminating stable
from unstable implants. Repeatability tests showed that the device was reliable. A calibration
procedure was then performed in order to convert the angular readout into a linear
displacement measurement, which is an information clinically relevant and simple to read in
real-time by the surgeon.
The second study reported in my thesis, concerns the evaluation of the possibility to have
predictive information regarding the primary stability of a cementless stem, by measuring the
micromotion of the last rasp used by the surgeon to prepare the femoral canal. This information
would be really useful to the surgeon, who could check prior to the implantation process if the
planned stem size can achieve a sufficient degree of primary stability, under optimal press
fitting conditions. An intra-operative tool was developed to this aim. It was derived from a
previously validated device, which was adapted for the specific purpose. The device is able to
measure the relative micromotion between the femur and the rasp, when a torsional load is
applied. An in-vitro protocol was developed and validated on both composite and cadaveric
specimens. High correlation was observed between one of the parameters extracted form the
acquisitions made on the rasp and the stability of the corresponding stem, when optimally
press-fitted by the surgeon. After tuning in-vitro the protocol as in a closed loop, verification
was made on two hip patients, confirming the results obtained in-vitro and highlighting the
independence of the rasp indicator from the bone quality, anatomy and preserving conditions
of the tested specimens, and from the sharpening of the rasp blades.
The third study is related to an approach that have been recently explored in the orthopaedic
community, but that was already in use in other scientific fields. It is based on the vibration
analysis technique. This method has been successfully used to investigate the mechanical
properties of the bone and its application to evaluate the extent of fixation of dental implants
has been explored, even if its validity in this field is still under discussion. Several studies have
been published recently on the stability assessment of hip implants by vibration analysis.
The aim of the reported study was to develop and validate a prototype device based on the
vibration analysis technique to measure intra-operatively the extent of implant stability. The
expected advantages of a vibration-based device are easier clinical use, smaller dimensions and
minor overall cost with respect to other devices based on direct micromotion measurement.
The prototype developed consists of a piezoelectric exciter connected to the stem and an
accelerometer attached to the femur. Preliminary tests were performed on four composite
femurs implanted with a conventional stem. The results showed that the input signal was
repeatable and the output could be recorded accurately.
The fourth study concerns the application of the device based on the vibration analysis
technique to several cases, considering both composite and cadaveric specimens. Different
degrees of bone quality were tested, as well as different femur anatomies and several levels of
press-fitting were considered. The aim of the study was to verify if it is possible to discriminate
between stable and quasi-stable implants, because this is the most challenging detection for the
surgeon in the operation room. Moreover, it was possible to validate the measurement protocol
by comparing the results of the acquisitions made with the vibration-based tool to two
reference measurements made by means of a validated technique, and a validated device. The
results highlighted that the most sensitive parameter to stability is the shift in resonance
frequency of the stem-bone system, showing high correlation with residual micromotion on all
the tested specimens. Thus, it seems possible to discriminate between many levels of stability,
from the grossly loosened implant, through the quasi-stable implants, to the definitely stable
one.
Finally, an additional study was performed on a different type of hip prosthesis, which has
recently gained great interest thus becoming fairly popular in some countries in the last few
years: the hip resurfacing prosthesis.
The study was motivated by the following rationale: although bone-prosthesis micromotion is
known to influence the stability of total hip replacement, its effect on the outcome of
resurfacing implants has not been investigated in-vitro yet, but only clinically. Thus the work
was aimed at verifying if it was possible to apply to the resurfacing prosthesis one of the intraoperative
devices just validated for the measurement of the micromotion in the resurfacing
implants. To do that, a preliminary study was performed in order to evaluate the extent of
migration and the typical elastic movement for an epiphyseal prosthesis. An in-vitro procedure
was developed to measure micromotions of resurfacing implants. This included a set of in-vitro
loading scenarios that covers the range of directions covered by hip resultant forces in the most
typical motor-tasks. The applicability of the protocol was assessed on two different commercial
designs and on different head sizes. The repeatability and reproducibility were excellent
(comparable to the best previously published protocols for standard cemented hip stems).
Results showed that the procedure is accurate enough to detect micromotions of the order of
few microns. The protocol proposed was thus completely validated. The results of the study
demonstrated that the application of an intra-operative device to the resurfacing implants is not
necessary, as the typical micromovement associated to this type of prosthesis could be
considered negligible and thus not critical for the stabilization process.
Concluding, four intra-operative tools have been developed and fully validated during these
three years of research activity. The use in the clinical setting was tested for one of the devices,
which could be used right now by the surgeon to evaluate the degree of stability achieved
through the press-fitting procedure. The tool adapted to be used on the rasp was a good
predictor of the stability of the stem. Thus it could be useful for the surgeon while checking if
the pre-operative planning was correct. The device based on the vibration technique showed
great accuracy, small dimensions, and thus has a great potential to become an instrument
appreciated by the surgeon. It still need a clinical evaluation, and must be industrialized as
well. The in-vitro tool worked very well, and can be applied for assessing resurfacing implants
pre-clinically.
47
Varini, Elena <1977>. "Primary stability in cementless total hip replacement: measurement techniques and aided-surgery." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/404/.
Full textAbstract:
Primary stability of stems in cementless total hip replacements is recognized to play a critical
role for long-term survival and thus for the success of the overall surgical procedure. In
Literature, several studies addressed this important issue. Different approaches have been
explored aiming to evaluate the extent of stability achieved during surgery. Some of these are
in-vitro protocols while other tools are coinceived for the post-operative assessment of
prosthesis migration relative to the host bone. In vitro protocols reported in the literature are
not exportable to the operating room. Anyway most of them show a good overall accuracy. The
RSA, EBRA and the radiographic analysis are currently used to check the healing process of
the implanted femur at different follow-ups, evaluating implant migration, occurance of bone
resorption or osteolysis at the interface. These methods are important for follow up and clinical
study but do not assist the surgeon during implantation.
At the time I started my Ph.D Study in Bioengineering, only one study had been undertaken to
measure stability intra-operatively. No follow-up was presented to describe further results
obtained with that device.
In this scenario, it was believed that an instrument that could measure intra-operatively the
stability achieved by an implanted stem would consistently improve the rate of success. This
instrument should be accurate and should give to the surgeon during implantation a quick
answer concerning the stability of the implanted stem. With this aim, an intra-operative device
was designed, developed and validated. The device is meant to help the surgeon to decide how
much to press-fit the implant. It is essentially made of a torsional load cell, able to measure the
extent of torque applied by the surgeon to test primary stability, an angular sensor that measure
the relative angular displacement between stem and femur, a rigid connector that enable
connecting the device to the stem, and all the electronics for signals conditioning. The device
was successfully validated in-vitro, showing a good overall accuracy in discriminating stable
from unstable implants. Repeatability tests showed that the device was reliable. A calibration
procedure was then performed in order to convert the angular readout into a linear
displacement measurement, which is an information clinically relevant and simple to read in
real-time by the surgeon.
The second study reported in my thesis, concerns the evaluation of the possibility to have
predictive information regarding the primary stability of a cementless stem, by measuring the
micromotion of the last rasp used by the surgeon to prepare the femoral canal. This information
would be really useful to the surgeon, who could check prior to the implantation process if the
planned stem size can achieve a sufficient degree of primary stability, under optimal press
fitting conditions. An intra-operative tool was developed to this aim. It was derived from a
previously validated device, which was adapted for the specific purpose. The device is able to
measure the relative micromotion between the femur and the rasp, when a torsional load is
applied. An in-vitro protocol was developed and validated on both composite and cadaveric
specimens. High correlation was observed between one of the parameters extracted form the
acquisitions made on the rasp and the stability of the corresponding stem, when optimally
press-fitted by the surgeon. After tuning in-vitro the protocol as in a closed loop, verification
was made on two hip patients, confirming the results obtained in-vitro and highlighting the
independence of the rasp indicator from the bone quality, anatomy and preserving conditions
of the tested specimens, and from the sharpening of the rasp blades.
The third study is related to an approach that have been recently explored in the orthopaedic
community, but that was already in use in other scientific fields. It is based on the vibration
analysis technique. This method has been successfully used to investigate the mechanical
properties of the bone and its application to evaluate the extent of fixation of dental implants
has been explored, even if its validity in this field is still under discussion. Several studies have
been published recently on the stability assessment of hip implants by vibration analysis.
The aim of the reported study was to develop and validate a prototype device based on the
vibration analysis technique to measure intra-operatively the extent of implant stability. The
expected advantages of a vibration-based device are easier clinical use, smaller dimensions and
minor overall cost with respect to other devices based on direct micromotion measurement.
The prototype developed consists of a piezoelectric exciter connected to the stem and an
accelerometer attached to the femur. Preliminary tests were performed on four composite
femurs implanted with a conventional stem. The results showed that the input signal was
repeatable and the output could be recorded accurately.
The fourth study concerns the application of the device based on the vibration analysis
technique to several cases, considering both composite and cadaveric specimens. Different
degrees of bone quality were tested, as well as different femur anatomies and several levels of
press-fitting were considered. The aim of the study was to verify if it is possible to discriminate
between stable and quasi-stable implants, because this is the most challenging detection for the
surgeon in the operation room. Moreover, it was possible to validate the measurement protocol
by comparing the results of the acquisitions made with the vibration-based tool to two
reference measurements made by means of a validated technique, and a validated device. The
results highlighted that the most sensitive parameter to stability is the shift in resonance
frequency of the stem-bone system, showing high correlation with residual micromotion on all
the tested specimens. Thus, it seems possible to discriminate between many levels of stability,
from the grossly loosened implant, through the quasi-stable implants, to the definitely stable
one.
Finally, an additional study was performed on a different type of hip prosthesis, which has
recently gained great interest thus becoming fairly popular in some countries in the last few
years: the hip resurfacing prosthesis.
The study was motivated by the following rationale: although bone-prosthesis micromotion is
known to influence the stability of total hip replacement, its effect on the outcome of
resurfacing implants has not been investigated in-vitro yet, but only clinically. Thus the work
was aimed at verifying if it was possible to apply to the resurfacing prosthesis one of the intraoperative
devices just validated for the measurement of the micromotion in the resurfacing
implants. To do that, a preliminary study was performed in order to evaluate the extent of
migration and the typical elastic movement for an epiphyseal prosthesis. An in-vitro procedure
was developed to measure micromotions of resurfacing implants. This included a set of in-vitro
loading scenarios that covers the range of directions covered by hip resultant forces in the most
typical motor-tasks. The applicability of the protocol was assessed on two different commercial
designs and on different head sizes. The repeatability and reproducibility were excellent
(comparable to the best previously published protocols for standard cemented hip stems).
Results showed that the procedure is accurate enough to detect micromotions of the order of
few microns. The protocol proposed was thus completely validated. The results of the study
demonstrated that the application of an intra-operative device to the resurfacing implants is not
necessary, as the typical micromovement associated to this type of prosthesis could be
considered negligible and thus not critical for the stabilization process.
Concluding, four intra-operative tools have been developed and fully validated during these
three years of research activity. The use in the clinical setting was tested for one of the devices,
which could be used right now by the surgeon to evaluate the degree of stability achieved
through the press-fitting procedure. The tool adapted to be used on the rasp was a good
predictor of the stability of the stem. Thus it could be useful for the surgeon while checking if
the pre-operative planning was correct. The device based on the vibration technique showed
great accuracy, small dimensions, and thus has a great potential to become an instrument
appreciated by the surgeon. It still need a clinical evaluation, and must be industrialized as
well. The in-vitro tool worked very well, and can be applied for assessing resurfacing implants
pre-clinically.
48
Fisher, Emily Kay. "SYSTEMATIC REVIEW OF OUTCOMES OF TOTAL JOINT REPLACEMENT CLASS PARTICIPATION." Kent State University Honors College / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1367924351.
Full text
49
Bastidos, Amanda Marie. "Failure analysis and materials characterization of hip implants." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
Full text
50
Hustosky, Keith T. "Experimental characterization of the mechanical consequences of a debonded total hip stem with an unsupported distal tip." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2510.
Full textAbstract:
Thesis (Ph. D.)--West Virginia University, 2002.Title from document title page. Document formatted into pages; contains xi, 95 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 85-92).