RESUMEN
BACKGROUND AND PURPOSE: :Heterotopic ossification (HO) is a frequent complication following total hip arthroplasty. The aim of this study was to evaluate the efficacy of combined radiotherapy and indomethacin as compared to indomethacin alone for the prevention of HO after hip arthroplasty. PATIENTS AND METHODS: 96 patients were prospectively enrolled to receive either a single dose of postoperative radiotherapy of 7.0 Gy and indomethacin for the first 15 postoperative days or indomethacin alone for the same period. A historical group of 50 patients that received indomethacin alone served as control. Primary endpoint was the radiographic evidence of HO at 6 months. Secondary endpoints were the evaluation of factors related to HO development, side effects from each treatment, and group differences in the clinical assessment with the Merle d'Aubigné Score. RESULTS: Four patients in the combined-therapy group developed HO compared to 13 patients in the indomethacin group (p < 0.05) and 13 patients in the historical group (p < 0.05). One patient each in the combined group and the historical group developed Brooker III HO (nonsignificant difference). Duration of surgery and congenital hip disease were associated with HO development in the indomethacin groups, while age and congenital hip disease showed such an association in the combined-therapy group. The side effects and mean Merle d'Aubigné Score did not differ significantly between the three groups. CONCLUSION: Combined radiotherapy and indomethacin was more efficacious in preventing HO after total hip arthroplasty compared to indomethacin alone and should be considered for future investigation.