PREVENTION OF HETEROTOPIC OSSIFICATION AFTER TOTAL HIP-REPLACEMENT - A PROSPECTIVE, RANDOMIZED STUDY USING ACETYLSALICYLIC-ACID, INDOMETHACIN AND FRACTIONAL OR SINGLE-DOSE IRRADIATION

We have carried out a prospective, randomised study of prophylaxis for heterotopic ossification (HO) comparing indomethacin for 7 and 14 day s, acetylsalicylic acid, and fractional (4 x 3 Gy) or single exposure of 5 or 7 Gy irradiation after operation. We initially had 723 patient s (733 hip replacements), but after withdrawals there were 685 hips of which 18.4% developed HO; 14% were grade I, 2.9% grade II and 1.5% gr ade III of the Brooker classification. We compared the results between these groups with those of a matched control series and found that in domethacin, 2 x 50 mg for 7 and 14 days, and postoperative irradiation of 4 x 3 Gy or 1 x 7 Gy, significantly reduced the development of HO compared with the control group, Patients in the acetylsalicylic acid group and those with a single irradiation of 5 Gy after operation deve loped significantly more ossification than those in the indomethacin a nd other irradiation groups. We suggest the use of 2 x 50 mg of indome thacin with mucoprotection for seven days as prophylaxis against HO af ter total hip replacement for all patients, A single irradiation of 7 Gy is recommended for patients who have developed HO after previous op erations or to whom administration of indomethacin is contraindicated.