We studied the effect of indomethacin on the prevention of formation of
heterotopic bone after total hip replacement. In a randomized, double-blind
clinical trial involving 201 patients, 102 patients received twenty-five
milligrams of indomethacin three times daily for the first six
postoperative weeks, and the other ninety-nine patients received a placebo.
One year after the operation, eighty-nine of those who had received
indomethacin had no sign of heterotopic ossification, and the remaining
thirteen had a grade-I lesion. In the group that had received a placebo,
twenty-seven had no heterotopic ossification; twenty-four, a grade-I
lesion; thirty, a grade-II lesion; and eighteen, a grade-III lesion.
Significantly fewer patients who had received indomethacin had formation of
heterotopic bone compared with those who had been given a placebo
(chi-square test, p less than 0.0005). Only patients who had grade-III
formation of heterotopic bone had a significant reduction in movement of
the hip.