The impact of heterotopic ossification prophylaxis after surgical fixation of acetabular fractures: national treatment patterns and related outcomes

Background Heterotopic ossification (HO) is a common complication after surgical fixation of acetabular fractures. Numerous strategies have been employed to prevent HO formation, but results are mixed and optimal treatment strategy remains controversial. The purpose of the study was to describe current national heterotopic ossification (HO) prophylaxis patterns among academic trauma centers, determine the association between prophylaxis type and radiographic HO, and identify if heterogeneity in treatment effects exist based on outcome risk strata. Methods We used data from a subset of participants enrolled in the Pragmatic Randomized Trial Evaluating Pre-Operative Alcohol Skin Solutions in Fractured Extremities (PREPARE) trial. We included only patients with closed AO-type 62 acetabular fractures that were surgically treated via a posterior (Kocher-Langenbeck), combined anterior and posterior, or extensile exposure. PREPARE Clinical Trial Registration Number: NCT03523962 Patient population This cohort study was nested within the Pragmatic Randomized Trial Evaluating Pre-Operative Alcohol Skin Solutions in Fractured Extremities (PREPARE) trial. The PREPARE trial is a multicenter cluster-randomized crossover trial evaluating the effectiveness of two alcohol-based pre-operative antiseptic skin solutions. All PREPARE trial clinical centers that enrolled at least one patient with a closed AO-type 62 acetabular fracture were invited to participate in the nested study. Results 277 patients from 20 level 1 and level 2 trauma centers in the U.S. and Canada were included in this study. 32 patients (12%) received indomethacin prophylaxis, 100 patients (36%) received XRT prophylaxis, and 145 patients (52%) received no prophylaxis. Administration of XRT was associated with a 68% reduction in the adjusted odds of overall HO (OR 0.32, 95% CI, 0.14 – 0.69, p = 0.005). The overall severe HO (Brooker classes III or IV) rate was 8% for the entire cohort; XRT reduced the rate of severe HO in high-risk patients only (p=0.03). Conclusion HO prophylaxis patterns after surgical fixation of acetabular fractures have changed dramatically over the last two decades. Most centers included in this study did not administer HO prophylaxis. XRT was associated with a marked reduction in the rate of overall HO and the rate of severe HO in high-risk patients. Randomized trials are needed to fully elucidate the potential benefit of XRT. PREPARE Clinical Trial Registration Number: NCT03523962.