[3-years results of endoprosthetic management of radiation-induced hip joint necrosis]

Radioosteonecrosis of the acetabulum is a rare side effect of radiotherapy. The latency period of 2 to 17 years is much longer than that reported for other bones (1-3 years). The reason for this is unknown. Plane radiograms show sclerosis, cysts and fractures of the acetabulum and, in most cases, a migration of the femoral head with flattening. The diagnosis of a radioosteonecrosis has to be made by exclusion of malignomas by scintigraphy and MRT or CT. This paper presents the follow-up of four patients treated by total hip replacement (THR) for radioosteonecrosis of the acetabulum. Within 9 months postoperatively the fractures of the acetabulum had healed with full weight bearing. 36 to 78 months after operation no signs of progression of the bone changes were detected. In this period the loosening of one spherical thread cup occurred, but a radiolucent gap above a cemented cup stayed unchanged. We conclude that irradiation damage of the acetabulum can be treated successfully by THR even in cases with fractures of the acetabulum as far as a stable implantation can be achieved and the remaining osteoblasts are preserved by the procedure.