Geometric Variances in Hip Osteoarthritis and Tribology of the Natural Hip

Osteoarthritis (OA) of the hip joint is a common form of arthritis that often requires surgical intervention using total hip replacement (THR), as treatment using early interventional techniques is still poorly understood. It is hoped that gaining a better understanding of hip geometry, and that using this information in future in-vitro simulations, will contribute to the evidence base regarding the aetiology of OA and the use of early surgical interventions to prevent or delay the onset of hip OA. This thesis aimed to investigate geometric variations in patients with known hip OA and compare them to asymptomatic participants of the same age. The thesis also aimed to develop a novel in-vitro simulation model for the tribological testing of complete natural hip joints. Twenty nine participants were recruited into the study (n=15 control and n=14 hip OA), and the geometry of their hip joints was explored and compared using high resolution (3.0 T) MRI and 3D shape matching software (EndPoint), which in the main, had previously been used for investigating the knee joint. In the study group, obvious shape differences such as superior flattening of the femoral head, differences in the sphericity of the head and acetabulum, and a significantly smaller degree of acetabular anteversion were observed when compared to the asymptomatic group. Experimental work began by validating a new pendulum friction simulator (Mk B) using THR bearings and hemiarthroplasties. One major modification and several minor modifications were required before the simulator could be used to develop the novel complete natural hip joint in-vitro simulation model, which was done successfully using porcine tissue. This model and the novel sample potting methodology developed alongside it can be used in future in-vitro tribological studies of the natural hip joint, and information gained from the MRI study can be used as geometric parameters for future in-vitro simulations