Heterotopic ossification after total hip arthroplasty: risk factors and prevention.

A retrospective review of 168 consecutive total hip arthroplasty procedures done in 1983 at the Cochin Teaching Hospital, Paris, France, was conducted to determine the rate of occurrence of heterotopic paraarticular ossification and to look for risk factors for this complication. None of the patients received preventive therapy for heterotopic ossification. Mean age was 66.2 years. The reason for arthroplasty was hip osteoarthritis in every case. The index operation was the first arthroplasty procedure. Heterotopic ossification was noted in 61.3% of patients and was high-grade in 8.3%. The rate of occurrence of heterotopic ossification was not influenced by age, gender, joint destruction, preoperative osteophytosis, duration of the arthroplasty or the occurrence of complications during or after the arthroplasty. However, severe ossification was more common in men that in women (12.7% men versus 5.7% women had grade III ossification) and in patients operated on by relatively inexperienced surgeons (28/8% grade II and III ossifications, versus 14.7% in patients operated on by experienced surgeons). The rate of occurrence of heterotopic ossification in the patients who had no risk factors (60.9%) was not significantly different from that in the overall study population. These data suggest that preventive strategies targeted to specific patient subgroups would probably be ineffective, and that routine preventive therapy of all total hip arthroplasty patients is warranted.