A computational model for the prediction of articular and backside polyethylene (PE) wear of total knee replacements (TKRs) could enable the optimization of TKRs for the reduction of polyethylene wear, thereby improving the long term success of TKRs. A finite element model was developed for the TKR and the results were implemented in a computational wear model to assess PE wear. The wear factors of Archard’s wear law were identified by implementing the finite element simulation results along with knee simulator wear test results. Archard’s wear law was found to have insufficient accuracy for the purpose of optimization. Therefore, a novel computational wear model was developed by the author based on a theoretical understanding of the molecular behavior of PE. The model predicted result fell within the standard deviation of the independent knee simulator wear test results, indicating a high level of accuracy for the novel computational wear model.

The purpose of this research study was to evaluate pain, strength, balance, and function in subjects before and after total knee arthroplasty. Thirteen subjects were tested prior to total knee arthroplasty. Seven of the original subjects returned to the laboratory and were tested one month after knee replacement surgery. At each testing session subjects completed questionnaires including a pain visual analog scale (VAS), Falls questionnaire, global rating of knee function, Western Ontario McMaster Universities (WOMAC) osteoarthritis index, and Knee Outcome Survey Activities of Daily Living Scale (KOS-ADLS). Strength was tested via unilateral, isometric squat. Knee range of motion was measured using a standard goniometer. Functional activities including walking, sit to stand transfers, and stepping on and off a curb were assessed using the Balance Master Force Plate system (Neurocom International). Balance activities including tandem walk, modified clinical test of sensory interaction on balance (mCTSIB), limits of stability (LOS), and sensory organization tests (SOT) were also assessed using the SMART Equitest (Neurocom International). There was a trend towards decreased pain on VAS post- surgery although the results were not significantly different (p = 0.0585). Subjective rating of function was improved on the composite WOMAC Osteoarthritis Index score (p = 0.0313). No differences were found after surgery for strength in the involved limb, balance tasks, or ability to perform functional activities. From this study we conclude that total knee arthroplasty does not have a deleterious effect on function or balance in the immediate post-operative period even through the knee is still in an acutely inflamed state. Further testing is needed to evaluate the effect of TKA on more strenuous functional activities and balance tasks and at larger post-operative intervals. / School of Physical Education, Sport, and Exercise Science

As a therapist within the multi-disciplinary setting, one is confronted with a wide array of pathology and diagnoses. Care is taken to optimize treatment outcomes and overall return of function to every patient admitted to the various rehabilitation facilities. Treatment is often standardized to ensure quality care benchmarked against outcome parameters. The aforementioned is also true for medical practitioners, pharmacists and other auxiliary service providers. Research is aimed at improving quality of care, finding and establishing the best practises through all hospitals and care facilities. Medical care has undergone a transformation over the past few decades with a strong emphasis being placed on protocols and procedures. Through applying standardized care, protocols and procedures, the researcher have come to realize that certain denominators within patient care have no prediction or outcome control. After more than a decade of treating patients in various rehabilitation settings the researcher have come to realize that one complaint exists with each and every patient under my care – pain. This was even more evident within the group of joint replacement patients. No two patients presented with the exact same pain profile or pain reports despite various commonalities such as anthropometric data (age, gender, length, mass), surgical procedure, attending physician, care facility, pathway exposure, diagnosis, radiographic findings and pharmaceutical intervention. If all the obvious factors were identical – what accounted for the different pain reports? This question is at the heart of the study – why do pain reports differ in the presence of so many similarities between patients? It soon became apparent that pain is recognized in the organic form. Organic pain can be measured and is expected with injury, illness or surgical intervention. The entire multi-disciplinary team is aware of organic pain and ready to intervene with medication, surgery and a pathway of care. All vigorously record organic pain and adapt treatment according to the pain levels as organic pain is real pain: real pain existing through exposure to real surgical intervention. Still the question remained: if all the factors prior to surgery, during surgery and after surgery were the same, why are patients experiencing and reporting very different pain levels? This question was the catalyst for the research and lead to keen focus during patient interviews. Every patient receiving an educational session prior to surgery had very vivid ideas about the pain they will experience post-operatively. The majority of patients formed pre-conceived notions about pain prior to undergoing surgery. They presented with a clear pain rating of what they expected to feel post-operatively. The pre-conceived pain rating was constructed in almost all the cases after some form of information obtained during consultation with their surgeon or a member of the multidisciplinary team. This pain notion existed as a tangible and measurable rating in the client’s mind prior to undergoing the knee replacement surgery. In select cases perceived pain was constructed as a result of information obtained from family or friends that underwent the same procedure while other clients constructed perceived pain due to a lack of information on the proposed surgery. It became evident that education or lack thereof on surgical interventions played a primary role in the construct of perceived pain. Patients were entering theatres for procedures and already experienced a form of perceived pain. If pain could be constructed prior to experiencing surgical intervention – can perceived pain then translate into actual organic pain and account for the variable pain reports post surgery? Against this backdrop, research was directed at understanding perceived pain and the factors that aid the construction of perceived pain. As education was found to be at the heart of every pain construct, the doctor-patient consultation was evaluated as a core component to ascertain the impact this relationship has on perceived pain. Measurement of perceived pain was also performed to conclude on the impact of this pain form on organic pain. The study is aimed at addressing the variant pain reports that no pathway or procedure can predict and provide for. It is an attempt to validate pain as constructed by the patient that impacts on their post-surgical pain ratings and behaviour. This research might contribute towards existing knowledge and understanding of the influence of doctor-patient interaction as well as the significance of this interaction on pain. As only scant research on perception of pain has been undertaken this research can prove insightful for further studies or as supplement to existing views and opinions. It can also serve as a foundation in developing practices that will manage pain by enhancing doctor-patient interaction in the health setting. / MA, Medical Sociology, North-West University, Vaal Triangle Campus, 2012

A computational model for the prediction of articular and backside polyethylene (PE) wear of total knee replacements (TKRs) could enable the optimization of TKRs for the reduction of polyethylene wear, thereby improving the long term success of TKRs. A finite element model was developed for the TKR and the results were implemented in a computational wear model to assess PE wear. The wear factors of Archard’s wear law were identified by implementing the finite element simulation results along with knee simulator wear test results. Archard’s wear law was found to have insufficient accuracy for the purpose of optimization. Therefore, a novel computational wear model was developed by the author based on a theoretical understanding of the molecular behavior of PE. The model predicted result fell within the standard deviation of the independent knee simulator wear test results, indicating a high level of accuracy for the novel computational wear model.

This research has investigated the influence of gait cycle, malalignment and overweight on total knee replacements using a finite element method. Dynamic and finite element models of fixed- and mobile-bearing implants have been created and solved; the fixed- and mobile-bearing implants demonstrated different performance on movement and contact pressure distribution in the tibio-femoral contact surfaces. More contact areas were found in the mobilebearing implant than in the fixed-bearing implant, but the maximum contact pressures were almost the same in both. The thickness of the tibial bearing component influenced the fixed- and mobile-bearing implants differently. A dynamic model of an implanted knee joint has been developed using MSC/ADAMS and MSC/MARC software. Stress shielding was found in the distal femur in the implanted knee joint. The stresses and strains in the distal femur were found to increase with body weight, especially during the stance phase. Serious stress shielding and more bone loss appear in condition of overweight. The increase of bone loss rate and stress in the distal femur with increase of body weight will result in a higher risk of migration of femoral component after total knee replacement. The peg size effect has been studied using this dynamic model; a longer peg with smaller diameter was found to be the best. Varus/valgus malalignment redistributed the tibio-femoral contact force and stress/strain distribution in the distal femur. The difference between contact forces on the medial and lateral condyle decreased in the valgus malalignment condition. Contact pressure increased in the varus/valgus malalignment condition in the dynamic models of both the fixed- and mobile-bearing implant. However, the mobile-bearing implant performed better in conditions of malalignment, especially malrotation. Body weight had less influence on the maximum contact pressure in the mobile-bearing implant.

Thesis (MHlthSc(OccTh))--University of South Australia, 1999

Thesis (MAppSc in Physiotherapy)--University of South Australia, 1996

Thesis (M.A.)--Northern Kentucky University, 2009. / Made available through ProQuest. Publication number: AAT 1462163. ProQuest document ID: 1686693671. Includes bibliographical references (p. 41-45)

Thesis (Ph.D.)--Duquesne University, 2004. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 90-97) and index.

Thesis (M.E.)--University of Canterbury, 2005. / Typescript (photocopy). "August 2005." Includes bibliographical references (p. 107-115). Also available via the World Wide Web.