Heterotopic ossification (HO) is thought to occur in 30 to 40% of patients undergoing primary total hip arthroplasty (THA). Prophylaxis often includes nonsteroidal anti- inflammatory and/or low-dose irradiation. As COX-II blockers have a lower rate of GI-complications than do non-selective NSAIDs, this study compared the efficacy of etoricoxib (ETO) and diclofenac (DIC) for the prevention of HO.

This prospective, double-blind, randomized trial included 100 patients scheduled for THA, with 50 randomized to receive etoricoxib, 90 mg/day, and 50 to receive diclofenac, 75 mg/day for nine days post-surgery. During this time, only opioids and acetaminophen were permitted for pain control. The patients were evaluated at six months post-surgery, with radiographs of the pelvis obtained to evaluate for HO.

Eighty-nine patients were examined at six months, with HO found in 38.6% in the DIC group and 37.8% in the ETO group (P＝0.871). While only Brooker grades 1 and 2 HO were found, there was a significant negative correlation between ossification and hip abduction and internal rotation. Two patients of each group complained of nausea, and one patient of the ETO group experienced elevated blood pressure.

This study of patients undergoing total hip arthroplasty found that heterotopic ossification prophylaxis with etoricoxib a Cox II blocker and diclofenac were equally effective.