Heterotopic ossification after Primary Total Hip Replacement

Abstract

Introduction: Heterotopic ossification (HO) is a well-recognised complication of total hip replacement (THR). Reported incidence ranged from 8 to 90% in the western literature, but the incidence in Chinese is largely unknown. This study aimed at reviewing the incidence and clinical symptoms of HO. Materials and Methods: All consecutive THRs performed between 2008 and 2012 in our centre were reviewed. All were performed in posterior approach without perioperative HO prophylaxis. Patient’s gender, age, diagnosis, and types of prosthesis were recorded. Serial postoperative X-rays were reviewed for HO and were graded according to Brooker classification if present. Results: A total of 289 primary THRs were performed on 245 patients in the study period, and all had clinical and radiological follow-up for at least 2 years. In all, 5 all-cementless THRs (3 male and 2 female, all were Chinese) were found to have HO, and the calculated incidence was 1.7%. The HO was graded as class I in 2 hips, class II in 1 hip, and class III in 2 hips. Also, 3 had underlying diagnosis of primary osteoarthritis with the remaining being rheumatoid arthritis and ankylosis spondylitis. Among the patients with HO, 3 had no pain and 2 only reported occasional ache. They had a mean postoperative Harris Hip Score of 77.5. Discussion and Conclusion: The incidence of HO in our study was low compared with that in the western literature. The patients reported minimal clinical symptoms even when complicated by HO.