[Technical problems in reoperation of hip joint prostheses].

At the Orthopaedic Clinic of the Institute for Postgraduate Medical Training in the course of 10 years (1979-1989) 2340 primary implantations of total endoprostheses of the hip joint were performed. During the same period 168 total endoprostheses of the hip joint and 20 cervico-occipital prostheses were reoperated. The most frequent reason for reoperation was aseptic loosening of the acetabular component. The mean period between operation and reoperation in these patients was 98 months. In the group with loosening of the socket associated with mechanical destruction of the component the mean period which had elapsed since the primary operation was 43 months. In 87% small size sockets were involved. The most serious problem of reoperation of total endoprostheses of the hip joint is replacement of bone defects. During reoperation of acetabular components an isolated defect on the floor of the acetabulum was found in 26%, a defect of the margins in 38% and a combined defect of the margins in 26% of the patients. For treatment of the defects the authors used bone grafts in the majority allogenic grafts were involved which were used to reconstruct the margins and floor of the acetabulum. Metal implants should hold the bone grafts in the desired position and should not serve as a skeleton. Reoperation of the acetabular part of total endoprostheses of the hip joint is easier from the technical aspect; in defects of the upper portion of the femur it is essential to use a very careful procedure and to preserve the skeleton to a maximal extent.(ABSTRACT TRUNCATED AT 250 WORDS)