Is External Beam Radiation Therapy Really Associated With Low Rates of Heterotopic Ossification After Acetabular Surgery?

Objectives:Describe rate of postoperative heterotopic ossification (HO) after acetabular surgery in patients who received external beam radiation (XRT) as HO prophylaxis.Design:Retrospective.Setting:Level I trauma center.Patients/Participants:Consecutive series of patients who presented to a single, level I, academic trauma center over a 10-year period (2008-2018) for surgical fixation of an acetabular fracture. Patients eligible for inclusion were those who underwent surgical fixation of an acetabular fracture through a posterior (Kocher-Langenbeck), combined anterior and posterior, or extensile exposure. Patients were excluded if an isolated anterior approach was performed or if an acute total hip arthroplasty was performed at the time of index surgery.Intervention:XRT.Main Outcome:Severe HO (Brooker class III or IV).Results:The severe HO (Brooker class III or IV) rate for entire cohort was 12% (44 of 361 patients). Of these 44 patients, 30 patients were classified as Brooker III and 14 patients were classified as Brooker IV. The Brooker IV rate for the entire cohort was 4% (14 of 361 patients). Severe HO rates showed a declining trend over the period examined, with a risk reduction of -1.0% per year (95% confidence interval -2.1% to 0.2%; P = 0.10).Conclusion:To our knowledge, this is the largest single consecutive series on acetabular fracture patients who received XRT as HO prophylaxis. The overall severe HO rate was 12%, which is similar to other comparably large series data on patients who did not receive XRT after surgical fixation acetabular fractures. Although these data suggest that XRT may not be beneficial when used universally for all patients, comparative studies are required to rule out the benefits of XRT for preventing HO in this population.