OBJECTIVES: To determine the effect of external beam radiation (XRT) on preventing severe heterotopic ossification (HO) after acetabular surgery. METHODS: Design : Randomized controlled trial. Setting: Two level I academic trauma centers. Patient Selection Criteria: Patients with an acetabular fracture (OTA/AO type 62) surgically treated through a posterior or combined anterior and posterior approach. Outcome Measures and Comparisons : Radiographic HO was determined using Brooker Classification at the last follow-up. The primary outcome was severe HO (Brooker class III-IV). The secondary outcome was any HO (Brooker class I-IV). The incidence of radiographic HO was compared between patients that did and did not undergo postoperative XRT. The results were analyzed in both an intention-to-treat (randomized to XRT) and as-treated (received XRT) basis. RESULTS: Severe HO occurred in 3 of 54 (6%) patients randomized to XRT and 9 of 50 (18%) patients randomized to no XRT (odds ratio (OR) 0.24, 95% confidence interval (CI) 0.05 to 0.94; p=0.05). Any HO occurred in 10 (19%) patients assigned to XRT and 17 (34%) patients in the no XRT control group (OR 0.39; 95% CI 0.13 to 1.05; p =0.07). CONCLUSIONS: The findings of this dual-center randomized controlled trial suggest that XRT after acetabular surgery significantly reduced the odds of severe HO compared to patients that did not receive XRT. These results can help guide shared decision-making between surgeons and patients regarding the use of XRT for HO prophylaxis. LEVEL OF EVIDENCE: Level I, therapeutic

The Use Of External Beam Radiation Therapy For Heterotopic Ossification Prophylaxis After Surgical Fixation Of Acetabular Fractures: A Randomized Controlled Trial