Prophylactic indomethacin for the prevention of heterotopic bone formation following total hip arthroplasty.

In July 1977, prophylactic indomethacin for "high-risk" total hip arthroplasty candidates was adopted for the prevention of heterotopic bone formation. A total of 1053 patients were included in this retrospective study. Five hundred twenty-five patients were operated on before July 1977, whereas 528 patients had a total hip arthroplasty after July 1977, when the indomethacin program was initiated. Eighty-one of the 528 patients operated on after July 1977 were identified as high-risk surgical candidates and therefore received prophylactic coverage. None of the 81 patients treated with indomethacin developed the functionally disabling Grade II or III ectopic ossification. Statistical analysis revealed a marked different (p less than .001) between the overall incidence of heterotopic bone formation in patients operated on before July 1977 and that of patients who had hip procedures after July 1977, when the indomethacin program began. Surprisingly, the action of indomethacin on bone metabolism did not seem to retard fusion of the greater trochanter with the femur or alter the frequency of nonunion.