Indomethacin for 3 days is not effective as prophylaxis for heterotopic ossification after primary total hip...

Although indomethacin is effective in preventing heterotopic ossification (HO) after total hip arthroplasty (THA) when used for 8 to 14 days, side effects are frequently observed. We conducted a prospective, nonrandomized pilot study of prophylaxis for HO in THA using indomethacin for 3 days. We used a 2-stage design for phase 2 clinical data, based on earlier studies in our department. Our study group consisted of 19 patients, of whom 14 (74%) developed HO; 7 (37%) showed grade 1, 4 (21%) grade II, and 3 (15.8%) grade III according to the Brooker classification. We compared these results with 2 historic control groups; one group received indomethacin for 7 days, and the other group received no prophylaxis. We did not see any reduction of the ossification relative to the group that received no prophylaxis. Indomethacin for 3 days seems not to be sufficient to prevent HO.