Materials for internal prostheses: the present position and possible future developments.

In this paper we consider solid phase forming as a method of manufacturing acetabular cups. Static and cyclic creep tests have been carried out on Charnley cups and indicate that creep, rather than wear, plays the major role in the penetration of the socket by the femoral ball, at least in the first few years. We have investigated a new type of cross-linked polyethylene and found it to be extremely good from both a wear and creep viewpoint, particularly under high loads and at high sliding velocities.