Increased risk of heterotopic ossification following revision hip arthroplasty for periprosthetic joint infection

Background: To investigate whether surgery for Periprosthetic Joint Infection (PJI) of the hip, the number of procedures and their duration contribute to risk of Heterotopic Ossification formation. Methods: 56 patients with hip PJI undergoing one-stage (10) or two-stage (46) exchange arthroplasty were matched to 112 patients undergoing revision arthroplasty for aseptic failure based on age, gender, body mass index (BMI), surgical approach (all direct lateral) and date of surgery (2006-2013). Patients with Paget's disease and ankylosing spondylitis, or preoperative HO were excluded. Perioperative pain management included use of the anti-inflammatory medications in all patients without prophylactic radiotherapy. Six-month postoperative radiographs were reviewed based on Brooker classification. Results: The incidence of overall HO in PJI and aseptic groups was 84% (47/56) and 11% (12/112), respectively. High grade HO (grades 3 and 4) in PJI and aseptic groups were 25% (24/56) and 4% (4/112), respectively. PJI was an independent risk factor for HO in the multivariate analysis (odds ratio of 9.3, 95% CI: 2.9-29.9, P<0.001). Conclusion: Patients undergoing surgical treatment of hip PJI seem to be at increased risk of developing HO compared to aseptic failure. HO prophylaxis regimens may be recommendable in eligible patients undergoing surgical intervention for PJI of the hip.