The effect of indomethacin on para-articular ectopic ossification following total hip arthroplasty.

Three patients exhibiting Grade III para-articular ectopic ossification following bilateral hip arthroplasty were successfully treated by excision of the bone and small-dose, short-term indomethacin therapy. Based on these results, a preliminary study was performed to determine the effect of indomethacin used prophylactically in patients who were predisposed to ectopic ossification and were undergoing total hip arthroplasty. Of a retrospective control group of 24 hips with extensive bilateral osteoarthritis, 63% were found to develop ectopic ossification following arthroplasty compared to 17% of a similar group treated with indomethacin (p less than 0.001). The ectopic ossification in the indomethacin-treated group possibly was of lesser severity (Grade I) than that encountered in the control group.