The effect of late radiotherapy on the progression of heterotopic ossification following total hip arthroplasty.

ABSTRACT

INTRODUCTION: Heterotopic ossification (HO) is a known complication after total hip arthroplasty (THA). Radiotherapy is an effective prophylactic treatment for high-risk patients. However, there is no treatment for patients who did not receive prophylactic treatment and subsequently develop HO postoperatively. This study was to determine whether late radiotherapy treatment can prevent the progression of HO following THA. METHODS: A chart review was performed to identify patients who developed HO following THA and were treated with late radiotherapy. All these patients received radiotherapy after their 6- or 12-week postoperative follow-up. Patients were evaluated radiographically pre- and 2 years post-radiotherapy using ImageJ software to measure the difference in the area of HO that formed. RESULTS: Nine patients with a mean age of 64.5 years were identified. All patients developed HO within 6- or 12-week postsurgery and received later radiotherapy. Eight of the nine hips (89%) treated with late radiotherapy demonstrated no further progression in the amount of bone formed. Overall, there was an increase in the mean total area of HO by 19 mm2 (2%), (p = 0.12). CONCLUSION: Late, low-dose radiotherapy is effective in preventing the progression of HO in patients who unexpectedly develop significant HO following THA.