[Loosening of hip prostheses].

Charnley's low-friction total hip prosthesis is now considered one of the most effective treatment methods available in the discipline of orthopaedic medicine; it must be mentioned that it is also one of the most demanding. The treatment does not end with implantation of the total hip prosthesis: this step is only the beginning of a long period of meticulous patient care. This requires regular monitoring of the clinical and roentgenological findings over many years. The results of the initial implantation depend very heavily both on a correct surgical technique and a reliable asepsis. The sterile "greenhouse", with air changes at least 300 times per hour, has proved impressively worthwhile. The proximal support of the stem is an important factor in the durability of the femoral component. The durability of the socket component is obviously influenced more by attrition of the polyethylene than by the method of socket fixation. The controversy about whether fixation with or without cement is better is relatively unimportant. If a prosthesis does loosen, replacement must be considered under the essential aspects of subjective symptoms and progressive bone resorption. Delay in replacement of a prosthesis when this is indicated can jeopardize the ultimate result of treatment because of the progressive bone loss.