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.

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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Total hip replacement in acute femoral neck fractures is done in salvage situations such as non-union and aseptic necrosis. Loosening of the prosthesis from the host bone has been recognised as a source of the most common post-operative complications. Therefore, continued follow up is necessary to identify early evidence of migration of the prosthesis. In current practice, clinicians assess loosening by visually inspecting a number of standard x-ray images of the patient's hip joint, taken over a period of time. This process is time-consuming and introduces inter-observer and intra-observer variability. The present thesis provides a new algorithm for computer-aided evaluation of prosthesis loosening in the form of an ???expert assistant???. / Computer-aided measurement of prosthesis migration involves finding a discrete mapping between features of the prosthesis model and features in the X-ray image. The orientation and the position of patient relative to the camera do not remain fixed in each radiograph taken over a long period. As a preliminary to this analysis, it is necessary to search for comparable radiographs in which the poses are similar. / This thesis introduces a robust geometrical matching algorithm to describe the pose of the prosthesis in a radiograph and the location of its key feature points relative to femur. An algorithm that uses the expectation maximisation (EM) approach has been designed and implemented to estimate the parameters of the rotation matrix and the translation vector for the 3D reference model of the prosthesis. This is achieved by matching selected control points on the reference model with corresponding set of control points extracted from X-ray image without the knowledge of their correspondence match. For matching purposes, feature points are extracted from X-ray images using novel and existing image processing techniques. Once they are located, the parameters of migration are measured. A Kalman filter-based bone edge detection algorithm is proposed and successfully implemented in this thesis. / Thesis (PhD)--University of South Australia, 2001.

Total hip replacement in acute femoral neck fractures is done in salvage situations such as non-union and aseptic necrosis. Loosening of the prosthesis from the host bone has been recognised as a source of the most common post-operative complications. Therefore, continued follow up is necessary to identify early evidence of migration of the prosthesis. In current practice, clinicians assess loosening by visually inspecting a number of standard x-ray images of the patient's hip joint, taken over a period of time. This process is time-consuming and introduces inter-observer and intra-observer variability. The present thesis provides a new algorithm for computer-aided evaluation of prosthesis loosening in the form of an ???expert assistant???. / Computer-aided measurement of prosthesis migration involves finding a discrete mapping between features of the prosthesis model and features in the X-ray image. The orientation and the position of patient relative to the camera do not remain fixed in each radiograph taken over a long period. As a preliminary to this analysis, it is necessary to search for comparable radiographs in which the poses are similar. / This thesis introduces a robust geometrical matching algorithm to describe the pose of the prosthesis in a radiograph and the location of its key feature points relative to femur. An algorithm that uses the expectation maximisation (EM) approach has been designed and implemented to estimate the parameters of the rotation matrix and the translation vector for the 3D reference model of the prosthesis. This is achieved by matching selected control points on the reference model with corresponding set of control points extracted from X-ray image without the knowledge of their correspondence match. For matching purposes, feature points are extracted from X-ray images using novel and existing image processing techniques. Once they are located, the parameters of migration are measured. A Kalman filter-based bone edge detection algorithm is proposed and successfully implemented in this thesis. / Thesis (PhD)--University of South Australia, 2001.

Thesis (D.PT.)--Sage Colleges, 2009. / "May 2009." "A Capstone project for PTY 768 presented to the Faculty of the Physical Therapy Department Sage Graduate School in partial fulfillment of the requirements for the degree of Doctor of Physical Therapy." Includes bibliographical references.

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).

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.