A Multicenter, Modern Cohort, Study of Radiation Therapy Versus Usual Care for Heterotopic Ossification Prophylaxis After Fixation of Acetabular Fractures Through a Posterior Approach.

Abstract

Controversy remains regarding the optimal prophylactic treatment method to prevent heterotopic ossification (HO) formation after acetabular fracture fixation. The purpose of this study was to determine the effect of postoperative radiation therapy (XRT) on HO incidence and severity after acetabular fracture fixation through a posterior approach. This was a multicenter study of two level 1 trauma centers. From 2017 to 2021, 177 (N = 177) patients underwent acetabular fracture fixation through a posterior approach and achieved at least 3 months of follow-up. Trauma Center 1 (TC1, N = 116) offered all patients prophylactic postoperative XRT. Trauma Center 2 (TC2, N = 61) offered no specific postoperative HO prophylaxis. The primary outcome measure was the radiographic prevalence and severity of HO formation. At TC1, 53 patients (45.7%) received XRT. Comparing centers, rates of HO incidence (TC1 vs. TC2: 19.8% vs. 31.1%, P = 0.10) and Brooker III/IV HO severity (6.0% vs. 13.1%, P = 0.10) did not differ statistically. Comparing treatment groups (XRT: 53, no XRT: 124), XRT reduced HO incidence (11.3% vs. 29.0%, P = 0.003) and severity (1.0 vs. 2.2, P < 0.001), with differing rates of Brooker III/IV (0% vs. 12.1%, P = 0.006). Multivariable analysis further supported this result (XRT HO incidence: OR: 0.30, confidence interval, 0.11 to 0.77, P = 0.01). Complication and HO excision rates did not differ between groups (deep infection: XRT: 1.9%, no XRT: 4%, P = 0.67). Multivariable analysis identified higher Injury Severity Score as an independent risk factor for HO incidence and Brooker III/IV severity. Radiation therapy (XRT) reduced the incidence and severity of HO after acetabular fixation conducted through a posterior approach. However, its effect on functional outcomes remains unclear because surgery to perform HO excision remains exceedingly rare. III.