Thesis (M.S.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references.

The objective of this thesis was to develop a concept and methodologies for designing a total knee replacement (TKR) with normal kinematics and a high range of motion. The design philosophy was that a TKR can function similar to the normal knee, provided that after TKR the inherent passive characteristics of the joint are restored to normal with minimum disruption in the functions of the remaining structures of the joint. As the first step prior to design, cadaver experiments were conducted and biomechanical models of the passive knee were developed to study the mechanics of the normal knee. The guiding roles of the tibial articular surface including the menisci, the combined effects of the cruciates and contact forces, and the elongation patterns of the cruciates were investigated. Based on the results obtained from these studies and the relevant information in the literature, design requirements for a TKR with normal kinematics were identified, and an innovative design concept was introduced. On the medial compartment of this design the shape of the articular surfaces resembled a ball-and-socket joint, and on the lateral side a pair of guiding bearing surfaces mimicked the guiding roles of the cruciate ligaments. The novelty in the design concept lies in the design of the shape of the lateral articular surfaces. The progressive variations of the curvature of the medial and lateral aspects of the lateral condyle generate the desired guiding effect for the full cycle of extension and flexion. The bearing spacing defined as the distance between the medial and lateral contact points was kept constant throughout the motion, as this was proved to be necessary to ensure compatibility between the geometry of the bearing surfaces and the desired pattern of motion. Appropriate methodologies were developed to generate the complete shapes of the bearing surfaces and to build the prototypes based on the constraints of the bone geometries and kinematics of a sample cadaver knee. The kinematic test of the prototype proved the viability of the design concept and methodologies. The novel design philosophy, concept and methodologies developed in this thesis provide a foundation for a new generation of TKR with normal kinematics. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2008-09-18 16:56:02.502

Thesis (M. Med. Sc.)--University of Hong Kong, 2004. / Also available in print.

Thesis (M. Med. Sc.)--University of Hong Kong, 2005. / Also available in print.

published_or_final_version / Orthopaedic Surgery / Master / Master of Philosophy

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

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Total knee joint replacements (TKRs) are a commonly used treatment when joint pain becomes a major issue and the function of activities of daily living is impaired. TKRs may last for up to 20 years; however, younger and physically more active patients are receiving TKRs, necessitating increased prosthesis life-time. There has been considerable interest in more cartilage-like materials for the tibial inlay of a TKR. Compliant, rubbery polymers may be a first step towards such a material. In this thesis, finite element analysis (FEA) was utilized to assess the feasibility of polycarbonate urethane (PCU) in a TKR application. Mechanical characterisation of PCU55D and PCU80A was performed in order to better understand the deformation behaviour of these materials. Mechanical test data was then used to tune and validate a hyperelastic material model. In a last step, the material model was applied to a static FE knee model which was used to simulate five discrete loading cases: three gait cycle events, stair climbing and squatting. Contact pressure, contact area and von Mises stress of the PCU inlay were compared to literature and to a standard ultra-high molecular weight polyethylene (UHMWPE) inlay. The contact area of the articulating implant surfaces was on average 345% greater in PCU than in UHMWPE and contact pressure was on average 77% lower in PCU than in UHMWPE. The difference between TKRs simulated with a PCU tibial inlay and those simulated with a UHMWPE inlay increased with increasing flexion angle. The contact pressures measured in TKRs simulated with a PCU tibial inlay were well below values that are expected to cause damage to the polymer, possibly reducing the risk of wear. The contact areas found in TKRs simulated with a PCU tibial inlay were close to what has been reported for the natural knee. Considering the low contact pressures even at high flexion angles, where initial congruency is limited, it may be feasible to design less conforming knee prostheses that still exhibit low contact pressures, allowing for a greater range of motion. The reported results strongly indicate that compliant polymers may offer an opportunity to improve current TKRs. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-08-11 14:59:50.801