Postoperative Low Dose Single Fraction Irradiation for Prevention of Heterotopic Bone Formation after Hip Surgery

Abstract

Purpose: To investigate retrospectively the effects of postoperative low-dose single fraction irradiation in prevention of ectopic bone formation after hip surgery in high-risk patients. Materials and Methods: From 1989 to 1994 fifteen patients (18 hips) were treated with single-dose irradiation to hip joints after hip surgery in an attempt to prevent heterotopic bone formation. Of these patients, there were 12 patients with ankylosing spondilitis, 1 patient with osteoarthritis, 2 patients with bony fractures, 3 patients post multiple surgical procedures, and 1 patient with past history of ectopic bone formation. These patients received surgical procedures of primary total-hip arthroplasty (14 hips), revision of arthroplasty (3 hips), or open reduction of acetabular fracture (1 hip). Radiotherapy was delivered with either Cobalt-60 gamma ray (4 patients) or 10 MV X-ray (11 patients) at midplane doses of 5 or 7 Gy several hours to 6 days after operation. Results: New ectopic bone formation was found in 2 patients (2 hips), while 1 patient (1 hip) has stable disease, with a follow-up time from 4 to 66 months (median=31 months). Neither functional disability nor complication related to heterotopic ossification and irradiation developed. Conclusion: Postoperative low-dose single fraction irradiation with 5 or 7 Gy is an effective and safe procedure to prevent heterotopic bone formation in high-risk patients after hip surgery.