Session VII Pelvis and Acetabulum

Indomethacin Versus Radiation Therapy for Prophylaxis against Heterotopic Ossification in Acetabular Fractures. A Randomized, Prospective Study

K. David Moore, MD, Katy Goss, RN, Jeffrey O. Anglen, MD

University of Missouri Hospital & Clinics, Columbia, Missouri

The purpose of this study was to prospectively compare the efficacy of indomethacin and radiation therapy in prevention of heterotopic ossification in operatively treated acetabular fractures.

Sixty-six patients who underwent open reduction and internal fixation of acetabular fractures through a Kocher-Langenbeck, combined ilio-inguinal and Kocher-Langenbeck, or extended iliofemoral approach were prospectively randomized to receive either indomethacin (25 mg tid for six weeks) or radiation therapy (800 cGy delivered within three days of surgery). The operative procedures were performed by a single orthopaedic traumatologist. Plain radiographs were reviewed and given Brooker classification scores by three independent observers who were unaware of the method of prophylaxis.

One patient died of causes unrelated to his surgery less than six weeks after his operation. One patient had no post-discharge follow-up and three had only a single set of radiographs six weeks after the procedure. Sixty-one patients were available for evaluation at an average follow-up period of ten months.

Twenty-eight of twenty-nine patients were randomized to treatment with radiation therapy and were available for follow-up. There were 20 men and 9 women in the group. Thirty-six of thirty-seven patients in the indomethacin group were available for evaluation. There were 25 men and 12 women in the group. There was no significant difference in the two groups in terms of sex (p = .9), age (p = .24), ISS score (p = .31), EBL (p = .14), delay to surgery (p = .95), head injury (p = .1), presence of femoral head dislocation (p=.96), or operative time (p=.32). There were no complications referable to either of the treatment modalities. The final extent of HO was present by 6 weeks postoperatively in all patients who had follow-up beyond that point.

There were two patients with Brooker III HO in each group and three patients with Brooker IV HO in the indomethacin group. Two of the patients with Brooker IV HO had failed to receive the indomethacin according to protocol. Pearson's Chi-Square analysis showed no significant difference in the two treatment groups with regard to formation of HO (p= 0.25).

The authors conclude that indomethacin 25 mg tid for six weeks and single dose radiation therapy delivered at 800 cGy within three days of the surgery are both safe and efficacious in the prevention of heterotopic ossification in operatively treated acetabular fractures. However, non-compliance with prophylactic therapy occurred only in the indomethacin group.

HO Grade	0	I	II	III	IV
Indomethacin	18	6	7	3	2
Radiation	13	5	1	2	0