The prevention of heterotopic bone formation following total hip arthroplasty using 600 rad in a single dose.

While postoperative irradiation has been shown to lower the incidence of heterotopic ossification effectively in high-risk patients following total hip arthroplasty, patients in multiple-dose protocols continue to develop some heterotopic ossification despite therapy. Sixteen patients (17 hips) received single-dose exposure to 600 rad delivered within 3 days of total hip arthroplasty. The patients were considered at high risk for development of heterotopic ossification because of hypertrophic osteoarthritis, posttraumatic arthritis, or the presence of previously formed ectopic bone. Thirty-five percent of the patients underwent excision of preexisting ectopic bone at the time of arthroplasty. The average follow-up period was 11.8 months (range, 6-24 months). At follow-up study, all hips were classified as Brooker class O or I, compared to a 17% incidence of Brooker class II and III for previously reported multiple-dose protocols. All patients were asymptomatic at last follow-up study, and no component demonstrated subsidence or radiolucent lines indicative of loosening. The authors conclude that low-dose, single-fraction radiotherapy is more cost-effective and convenient and as efficacious as current multiple-dose regimens.