The Efficacy of 500 CentiGray Radiation in the Prevention of Heterotopic Ossification After Total Hip Arthroplasty: A Prospective, Randomized, Pilot Study Douglas E. Padgett, MD,* Keith G. Holley, MD,* Marilyn Cummings, RN,† Aaron G. Rosenberg, MD,† Dale R. Sumner, PhD,† Dean Conterato, MD,† and Jorge O. Galante, MD† Abstract: A prospective, randomized, pilot study comparing 500 cGy (group A) versus 1,000 cGy (group B) radiation treatment for the prevention of heterotopic bone in a consecutive group of high-risk patients undergoing total hip arthroplasty was performed. Treatment was initiated within ninety-six hours and given in equal, divided doses: 2 doses for group A and 5 doses for group B. No statistically significant difference was found in the demographics between the 2 groups. At follow-up evaluation, the distribution of heterotopic bone according to the Brooker classifica- tion was: group A, 9 class 0, 17 class 1, one class 2, and 2 class 3. Group B: 17 class 0, 10 class 1, 2 class 2, and one class 3. This difference was not statistically significant (P=.086). Only 3 cases were considered treatment failures, for a success rate of 93% in group A and 97% in group B. As a result of this pilot study, 500 cGy radiation treatment appears to be effective in the prevention of clinically significant hetero- topic ossification after total hip arthroplasty. Key words: heterotopic bone radiation, total hip arthroplasty. © 2003 Elsevier Inc. All rights reserved. Heterotopic ossification after total hip arthroplasty is a relatively common complication [1– 6]. The clinical manifestations of heterotopic ossification can be pain or a reduction in function of an other- wise functional arthroplasty [3,7]. Once formed, the only known treatment for heterotopic bone is excision [8]. Therefore, prophylaxis against forma- tion appears rational. Although the incidence of heterotopic ossification for all patients undergoing hip arthroplasty without prophylaxis varies greatly, with ranges from 3% to 85% [2,3,9], several stud- ies have identified specific high-risk groups in whom the incidence of heterotopic ossification is consistently much higher, ranging from 65% to 81% [1,10,11]. It is in this subgroup of patients that prophylaxis may be indicated. Prophylactic options have included the use of diphosphonates [12,13], the use of nonsteroidal anti-inflammatory medications [4,14,15], or the From the *Hip and Knee Service, The Hospital For Special Surgery, New York, New York; and †the Departments of Orthopaedic Surgery and Radiation Oncology, Rush-Presbyterian-St. Luke’s Medical Center, Chicago, Illinois. Submitted January 30, 2003; accepted May 2, 2003. No benefits or funds were received in support of this study. This article was written in part by LCDR Keith G. Holley, MC, USNR while a Fellow at The Hospital For Special Surgery train- ing in Adult Reconstructive surgery. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, nor the U.S. Government. Reprint requests: Douglas E. Padgett, MD, The Hospital for Special Surgery, 535 East 70 Street, New York, NY 10021. © 2003 Elsevier Inc. All rights reserved. 0883-5403/03/1806-0001$30.00/0 doi:10.1054/S0883-5403(03)00265-1 The Journal of Arthroplasty Vol. 18 No. 6 2003 677