Prophylactic radiation therapy for prevention of heterotopic ossification after hip arthroplasty: results in 141 high-risk hips.

In a 4 1/2-year, prospectively randomized study, 137 patients with 141 hips at high risk for heterotopic ossification (HO) received prophylactic radiation therapy (RT). Patients were randomly assigned to a low-dose regimen of five fractions of 2 Gy each (n = 73) or a high-dose regimen of either 10 fractions of 2 Gy each (n = 7) or five fractions of 3.5 Gy each (n = 61). Treatment failure was assessed by comparing immediately postoperative radiographs with radiographs obtained at least 6 months after hip surgery (Brooker grading score). Positive responses (ie, effective prophylaxis of HO) were seen in 129 (91.5%) hips. Treatment failures were observed in 12 (8.5%). Use of a nonsteroidal antiinflammatory drug (NSAID) lowered the failure rate in both RT groups. High RT dose with a short duration (< or = 9 days) and use of an NSAID was significantly (P = .009) correlated with treatment success. RT delivered within a few days after hip surgery is effective in preventing HO, even in high-risk patients, and provides an excellent alternative for patients with contraindications to long-term medication with either NSAIDs or corticosteroids.