[Experiences with Wagner's cup prosthesis].
Surface replacement is an alternative procedure especially in younger patients who absolutely need hip replacement. Accurate diagnosis is imperative and the range of indications is naturally small. A follow up study of 44 patients (range, 10 months to 4 years) showed 2 loosenings (5%); other severe complications were not seen. In 39 (89%) hips was no more pain after operation and there was a distinct improvement of motility in 39 (89%) cases. Avascular necrosis should not be treated by surface replacement. Primary inflammatory diseases (rheumatoid arthritis) seem to have a higher incidence of complications, especially when long time treated with large doses of steroids. Cortisone medication promotes avascular necrosis of the hip and lytic enzymes coming from the pannus might be another reason for loosening. According to our experience the position of the cup according to varus or valgus has no influence on the result of the operation. The Watson-Jones approach seems to be better than the approach recommended by Wagner, because paraarticular calcifications are seldom seen.