[Pre- and postoperative radiotherapy to prevent heterotopic ossification of the hip joint]

In-vivo experimental data indicate that both pre- and postoperative radiotherapy can prevent heterotopic ossification after hip surgery. This comparison was clinically tested in a randomized study.

From June 1992 to September 1993, 84 patients with high risk for the development of heterotopic ossification were randomized. The treatment concept consisted either of preoperative radiotherapy within four hours prior to surgery (arm A) or postoperative radiotherapy within 72 hours following hip surgery (arm B). Preoperative radiotherapy was given in one fraction of 7 Gy, while the postoperative radiotherapy was delivered in five fractions of each 3.5 Gy (total 17.5 Gy). All patient variables (age, sex, prior surgery) and predisposing risk factors were comparable in both treatment arms. For the radiological assessment of heterotopic ossification according to (Brooker-Score) X-rays of the pelvis or hip were evaluated which had been taken immediately pre- and postoperatively as well as at least six months following surgery and prophylactic irradiation. The functional hip status was evaluated pre- and postoperatively using the Harris-Score. Cases in which the Brooker- and/or Harris-Score worsened during the postoperative follow-up as compared to the pre- and immediate postoperative situations were considered as treatment failures.

Of 44 patients with at least six months follow-up 41 (93%) experienced a successful prophylaxis. Two failures were observed in the preoperative and one in the postoperative group. The prophylactic efficacy was not influenced if the pre- or postoperative interval was longer than prescribed. All intra- and postoperative complications were comparable for both treatment groups. The mean interval to partial strain (50% body weight) of the operated hip was longer in the preoperative group (mean 19 +/- 27 days) as compared to the postoperative group (mean 8 +/- 13 days). With respect to full strain (100% body weight), the results were equal in both groups. The functional hip status decreased in two patients. Again the mean overall improvement in the postoperative group was larger (mean 42.7 +/- 17.1 points) as compared to the preoperative group (mean 34.3 +/- 13.7 points).

Preoperative and postoperative radiotherapy have equal prophylactic efficacy to prevent heterotopic ossification following hip surgery. The main advantage of preoperative radiotherapy are the simple management of the patient, the reduction of possible complications associated with transport and positioning of the patient in the postoperative period as well as excellent acceptance of this treatment concept by patients, nurses and staff.