Thesis (M.S.)--New Jersey Institute of Technology, Dept. of Biomedical Engineering, 2003. / HFT20030804. Includes bibliographical references (p. 75-76). Also available via the World Wide Web.

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As the number of total knee arthroplasty (TKA) procedures increases annually, the patient demographic is shifting to include younger patients with higher expectations for post-operative function. The aim of this study was to compare movement patterns during activities of daily living among TKA patients and a healthy, age-matched group using 3D motion analysis. Specifically, this analysis looked at walking on level and inclined surfaces, as well as sitting up and down from a chair. It was predicted that (1) TKA patients would exhibit reduced knee extension moments at the operated limb and increased adduction moments at the contralateral limb during gait, (2) walking downhill would result in greater differences between TKA and control groups, compared to level walking, and (3) TKA participants would have greater flexion angles, moments and power values at the hip, compared to controls, during the sit-stand tasks. Seventeen participants (age=62±6 years, BMI=30±3 kg/m2, time after surgery=11±5 months) were recruited from the Ottawa Hospital, having undergone unilateral TKA by the same surgeon. An age-matched control group was composed of 17 individuals (age=63±8 years, BMI=27±4 kg/m2) who were recruited from the local community. Three dimensional (3D) biomechanical assessment was conducted with all participants performing five trials of walking on level and inclined surfaces, stair ascent and descent as well as sit-stand tasks. Results from this study were focused on gait and sit-stand transitions, showing that TKA participants exhibited altered gait patterns on both walking surfaces, with significantly smaller knee flexion angles and moments, as well as reduced peak power at the knee. The TKA group also experienced reduced knee extension moments; however, this was only significant for downhill walking. Consistent with our hypothesis, downhill walking resulted in greater discrepancies between the groups compared to level walking. Contrary to our third hypothesis, TKA participants exhibited significantly smaller peak hip flexion angles and moments during the sit-stand task, along with reduced hip abduction angles and knee abduction moments. The reduced knee flexion kinematics and kinetics observed during gait tasks, combined with the differences in frontal plane mechanics observed during the sit-stand task suggest that altered loading patterns persist six to twelve months after surgery. This may be a result of continued pre-operative movement patterns as well as the surgery itself, and should be kept in mind when developing rehabilitation programs for this patient population.

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 (Ph. D.)--University of Adelaide, 1987. / Includes bibliographical references (leaves 196-251).

Thesis (M.D.S.)--University of Adelaide, 1987. / Typescript. Includes bibliographical references (leaves 131-167).