Context

Total hip replacement surgery (THR) is a highly successful procedure for relieving painful degenerative conditions of the hip and restoring function. The articulating surfaces of the prosthetic joint can be manufactured from a number of different materials. Traditionally, metal (cobalt-chromium-molybdenum alloys) has been employed for the femoral head bearing surface and polyethylene for the acetabular bearing surface. Polyethylene wear particles have been implicated in loosening of the components and the need for revision surgery. More recently, the focus is on alternative bearing couples (combinations of materials) in an attempt to improve the longevity of THR and reduce the rate with which revision surgery is required. To this end, metal on metal, ceramic on ceramic and ceramic on metal bearings have been employed. Possible advantages include improved longevity and the ability to use a larger diameter articulation, thus reducing risk of dislocation. Possible disadvantages include exposure …