Heterotopic Ossification Prophylaxis Following Operative Fixation of Acetabular Fractures: A Systematic Review

Introduction: Heterotopic ossification (HO) is a well-recognized complication following operative fixation of acetabular fractures with a range of severity and clinical consequences. The purpose of this review was to: (1) report the incidence of heterotopic ossification (HO) formation following operative fixation of acetabular fractures; (2) determine the effectiveness of prophylactic treatments for HO; and (3) assess the radiographic severity of HO with and without prophylactic treatment. Materials and Methods: A literature search for peer-reviewed articles was conducted utilizing a variety of research databases. PRISMA guidelines were followed and included in this review were full-length, English language manuscripts published before September 2019, using the following search criteria: “heterotopic ossification AND acetabulum OR acetabular.” Studies that reported HO as one of the reported outcomes were included. Articles were excluded if radiographic HO was not reported and if it was evaluated in surgeries other than those involved in acetabular fractures. Extracted data included, but was not limited to: type of prophylaxis; incidence of HO; severity of HO based on the Brooker classification; and statistical significance. A methodologic quality appraisal of the included studies was also conducted. A total of 54 full-text studies with 5,890 patients with operatively fixed acetabular fractures met inclusion criteria. There were four level I studies, four level II study, 26 level III studies, and 20 level IV studies. Results: The overall incidence of HO after acetabular fracture surgery was 28.4%. The rate of HO formation was: 34.9% without prophylaxis, 28.3% with non-steroidal anti-inflammatory drugs (NSAID) prophylaxis, and 21.2% with radiation therapy (RT). Patients receiving a combination of both RT and NSAIDs developed HO 21.8% of the time. The rate of radiographic severe HO was 13.9% (range, 0–75%) in patients without prophylaxis, 9.4% (range, 0–50%) with NSAID prophylaxis, 5.7% (range, 0–12.8%) with RT prophylaxis, and 11.7% (range, 0–18.5%) with the combination of RT and NSAIDs. Conclusion: With the current literature collected in this systematic review, there was a lower incidence and severity of heterotopic bone formation following acetabular fracture fixation using radiation prophylaxis compared to NSAIDs or no treatment. The available literature is heterogeneous in fracture characteristics, surgical approaches, and prophylactic regimens with a general lack of randomized control trials. Further prospective studies are required to make definitive claims on the optimal prophylactic strategy to prevent heterotopic ossification.