Use of the uncemented bipolar endoprosthesis for the treatment of steroid-induced osteonecrosis of the hip in renal transplantation patients.

Osteonecrosis of the hip is a well known complication in renal transplantation patients who are treated with corticosteroids for immunosuppression. In a consecutive series of 10 patients with osteonecrosis of the hip, 16 primary uncemented bipolar endoprostheses were inserted between April 1984, and February 1986. The average follow-up period after surgery was 40 months, (range, 24-48 months). All patients developed osteonecrosis of their hips and were operated on within 2 years of their renal transplant. At the time of surgery, all patients were still taking corticosteroids as well as other immunosuppressants. The average age at surgery was 34.6 years (range, 21-48 years). All hips were classified as stage 3 or 4 before operation. The average Harris score at follow-up examination was 94.2 (range, 74-101), with 13 hips rated excellent, 1 hip rated good, and 1 hip rated fair. One patient's hip prosthesis was removed after 17 months secondary to a septic arthritis. This was the only major complication in this series. Pain was improved in all patients. However, postoperative limp and abductor weakness still presented a significant problem. An extensive radiographic evaluation was made on all hips. Eleven observations and measurements were made using radiographs of the pelvis and hip. Vertical subsidence was present in 33% of the hips and averaged 2.2 mm (range, 1-4 mm). No significant radiographic loosening was evident in any hip. Acetabular protrusio was evaluated in all patients, and was found to be less than 4 mm in either the superior or axial direction. Heterotopic ossification was present in 80% of hips, but resulted in loss of motion in only one hip.(ABSTRACT TRUNCATED AT 250 WORDS)