3-YEAR FOLLOW-UP AFTER TOTAL HIP-REPLACEM ENT FOR RADIOOSTEONECROSIS OF THE ACETABULUM

Radioosteonecrosis of the acetabulum is a rare side effect of radiothe rapy. The latency period of 2 to 17 years is much longer than that rep orted for other bones (1-3 years). The reason for this is unknown. Pla ne radiograms show sclerosis, cysts and fractures of the acetabulum an d, in most cases, a migration of the femoral head with flattening. The diagnosis of a radioosteonecrosis has to be made by exclusion of mali gnomas by scintigraphy and MRT or CT. This paper presents the follow-u p of four patients treated by total hip replacement (THR) for radioost eonecrosis of the acetabulum. Within 9 months postoperatively the frac tures of the acetabulum had healed with full weight bearing. 36 to 78 months after operation no signs of progression of the bone changes wer e detected. In this period the loosening of one spherical thread cup o ccurred, but a radiolucent gap above a cemented cup stayed unchanged. We conclude that irradiation damage of the acetabulum can be treated s uccessfully by THR even in cases with fractures of the acetabulum as f ar as a stable implantation can be achieved and the remaining osteobla sts are preserved by the procedure.