Indomethacin prophylaxis for heterotopic ossification after acetabular fracture surgery increases the risk for nonunion of the posterior wall.

OBJECTIVES

To determine if indomethacin has a positive clinical effect for the prophylaxis of heterotopic ossification (HO) after acetabular fracture surgery. To determine whether indomethacin affects the union rate of acetabular fractures.

DESIGN

Prospective randomized double-blinded trial.

SETTING

Level 1 regional trauma center.

PATIENTS: Skeletally mature patients treated operatively for an acute acetabular fracture through a Kocher-Langenbeck approach.

INTERVENTION: Patients were randomly allocated to 1 of 4 groups comparing placebo (group 1) to 3 days (group 2), 1 week (group 3), and 6 weeks (group 4) of indomethacin treatment.

MAIN OUTCOME MEASUREMENTS: Factors analyzed included the overall incidence, Brooker class and volume of HO, radiographic union of the acetabular fracture, and pain. Patients were followed clinically and radiographically at 6 weeks, 3 months, 6 months, and 1 year. Serum levels of indomethacin were drawn at 1 month to assess compliance. Computed tomographic scans were performed at 6 months to assess healing and volume of HO.

RESULTS

Ninety-eight patients were enrolled into this study, 68 completed the follow-up and had the 6-month computed tomographic scan, and there was a 63% compliance rate with the treatment regimen. Overall incidence of HO was 67% for group 1, 29% for group 2 (P = 0.04), 29% for group 3 (P = 0.019), and 67% for group 4. The volume of HO formation was 17,900 mm for group 1, 33,800 mm for group 2, 6300 mm for group 3 (P = 0.005), and 11,100 mm for group 4. The incidence of radiographic nonunion was 19% for group 1, 35% for group 2, 24% for group 3, and 62% for group 4 (P = 0.012). Seventy-seven percent of the nonunions involved the posterior wall segment. Pain visual analog scores (VASs) were significantly higher for patients with radiographic nonunion (VAS 4 vs. VAS 1, P = 0.002).

CONCLUSIONS

Treatment with 6 weeks of indomethacin does not appear to have a therapeutic effect for decreasing HO formation after acetabular fracture surgery and appears to increase the incidence of nonunion. Treatment with 1 week of indomethacin may be beneficial for decreasing the volume of HO formation without increasing the incidence of nonunion.

LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.