Indomethacin compared with localized irradiation for the prevention of heterotopic ossification following surgical treatment of acetabular fractures

Background: There is controversy surrounding the relative effectiveness of local irradiation and oral indomethacin for prophylaxis against heterotopic ossification following surgical treatment of acetabular fractures. The purpose of this study was to compare the efficacy of these two commonly used methods in a prospective, randomized trial. Methods: From July 1992 to June 1999, 166 patients in whom a fracture of the acetabulum was treated surgically through a posterior, extensile, or combination approach were randomized to receive either indomethacin or radiation therapy postoperatively. Seventy-eight patients received 800 cGy of local radiation therapy within seventy-two hours after surgery, and seventy-two patients received a six-week course of indomethacin (25 mg three times a day) beginning within twenty-four hours after surgery Sixteen additional patients were randomized but did not receive treatment with either prophylactic regimen. At an average of fourteen months, the extent of heterotopic ossification was assessed on plain radiographs with use of the classification of Brooker et al. The grade of ossification was correlated with hip motion. Results: There was no significant difference between treatment groups with regard to patient age, gender, Glasgow Coma Scale, operative time, estimated operative blood loss, duration of follow-up, or presence of closed head injury. The Injury Severity Score appeared to be the only covariate that was significantly different between the groups (p = 0.019). Grade-III or IV ossification developed in eight (11%) of the patients in the indomethacin group and three (4%) in the radiation therapy group. The difference was not significant (p = 0.22; 95% confidence interval, -1.1%, +15.7%). No complications related to the prophylaxis were noted in either group. Heterotopic ossification developed in all sixteen patients who did not receive prophylaxis, with six demonstrating grade-III or IV changes. The overall prevalence of grade-III or IV heterotopic ossification was 7% (eleven of 150) in the treated groups and 38% (six of sixteen) in the untreated group. We did not find any association between the prevalence of heterotopic ossification and fracture type (p = 0.296) or posterior hip dislocation (p = 0.306). Grade-I, II, and III heterotopic ossification did not decrease the range of motion of the hip except in flexion. Conclusions: Both local radiation therapy and indomethacin were found to provide effective prophylaxis against heterotopic ossification following surgical treatment of acetabular fractures through a posterior or extensile approach. We detected no significant difference in efficacy between the two prophylactic regimens.