[Ceramic acetabulum cup inserts for hip endoprostheses]

The articulating components of a total hip prosthesis are the spherical femoral head and the acetabular cup. Particularly high rates of wear are seen with cups made of polyethylene, and the abrasion particles cause osteolysis, which often makes surgical revision necessary. Despite considerable progress in the development of total hip replacement systems over the last 20 years, there is still a need to eliminate or further minimize the problem of osteolysis, which is also referred to as polyethylene disease. Clinical experience over the last 20 years has shown that by using Biolox (medical grade alumina) femoral heads and acetabular cups it is possible to achieve very low wear rates, which histological studies have shown to be readily tolerated. The secondary conditions needed to develop modern modular ceramic acetabular cup inserts are discussed. For the fixation of cup inserts, the well known taper fixation concept has proved to be of value. A concept taking into account the needs of the surgeon and the manufacturing constraints applying to ceramic materials is proposed.