Incidence and risk factors for development of postoperative heterotopic ossification in a high-volume hip arthroscopy practice: A case series

Abstract

Background and objective: Heterotopic ossification (HO) is a known complication of hip arthroscopy and may significantly affect the outcomes of patients undergoing hip arthroscopy. Its incidence in the literature varies from 0–44% following hip arthroscopy without prophylaxis. Our primary goal was to find the local rate of HO after hip arthroscopy as determined by the Brooker Classification. Secondary outcomes included determining risk factors for development of HO by sex, age, body mass index, hip pathology and effects on outcome scores. Subjects and methods: Patients who underwent hip arthroscopy by a local high-volume surgeon from July 2012 to June 2015 were reviewed for the presence of pre- and postoperative HO retrospectively. Patients required at least 12 months of postoperative radiographic follow-up with anteroposterior pelvis radiographs. Patients were excluded if they had any other procedure performed at the time of hip arthroscopy or if medical records were not accessible. Radiographs were reviewed for HO according to the Brooker Classification. Demographic data including sex, age, body mass index, presence of labral tear and repair and outcome score were obtained. The incidence of HO and demographic averages were calculated and compared. This study received approval from the Nova Scotia Health Authority (NSHA) Research Ethics Board (REB) (approval No. 1021503) on August 8, 2016. Results: A total of 307 hips met inclusion criteria, 152 females and 155 males. The overall incidence of HO was 23.45% (72 hips). Fifty-six hips (78%) had Brooker class I HO, 13 (18%) hips had Brooker class II HO, and 3 (4%) hips had Brooker class III HO. No specific demographic variables or the pathology were seen to be associated significantly with development of HO. Outcome score differences were not significantly different between the HO and non-HO groups (P = 0.94). Conclusion: The incidence of HO in our series matched the range found in other studies of HO incidence in the literature. The incidence of HO dose not appear to be influenced by demographic variables including sex, age, and body mass index in our study. This data will add to the developing base of literature on HO incidence in hip arthroscopy and will serve as a comparison and benchmark for future study on HO prophylaxis.