Naproxen in the prevention of heterotopic ossification after total hip replacement

The effectiveness of naproxen, indomethacin, and a placebo were compared for the prevention of heterotopic ossification after total hip arthroplasty. Eighty-four men at high risk of experiencing heterotopic ossification received randomly either naproxen 750 mg per day, indomethacin 75 mg per day, or a placebo for 6 consecutive weeks after surgery. Efficacy analysis showed that in 70% of patients treated with naproxen, in 34.8% of those treated with indomethacin, and in 15% of those treated with a placebo, no heterotopic ossification appeared on radiographs taken at 6 months. Naproxen was significantly more effective than the placebo or indomethacin in preventing the development of heterotopic ossification. Stratification into five categories, according to Brooker's classification at 6 months, showed that both drugs were equally superior to the placebo. Class III heterotopic ossification occurred only in patients who were given the placebo. The improvement in clinical criteria was comparable in the three groups, although at 6 months there was an improvement in abduction in patients treated with indomethacin compared with those treated with naproxen and the placebo. The overall tolerance was rated good by 87% of patients and 86% of physicians, with no difference between the groups. The results show that naproxen, given daily for 6 weeks, is an effective and safe medication for the prevention of heterotopic ossification after total hip replacement.