[Polyethylene in total endoprosthetics--a dead end for permanent implants?].

Faced with a growing number of younger patients in need of total joint arthroplasty, orthopaedic surgeons are demanding long-term implants for total joint replacement. An assessment of the long-term mechanical behaviour is vivo of all biomaterials in common use in prostheses is in progress. In the present paper, we discuss the long-term reliability of polyethylene (UHMWPE) in joint replacement in terms of tribology and the different biomechanical situation in various human joints. Long-term failure mechanisms for polyethylene in total hip arthoplasty (THA) differ from those seen in total knee arthroplasty (TKA) although the same materials are used. It is thus questionable whether improvements in wear rates of polyethylene in THA would be helpful in TKA.