Single dose 6 Gy prophylaxis for heterotopic ossification after total hip arthroplasty.

Forty-five patients (50 hips) at risk for heterotopic ossification after total hip arthroplasty who received a single dose of 6 Gy postoperative irradiation were compared with a historical control group of 42 patients (50 hips) with similar risk factors who did not receive radiation prophylaxis. All surgeries were done by the same surgeon using the same perioperative protocol. Radiation was delivered through anteroposterior/posteroanterior limited fields, avoiding areas of desired bony ingrowth. Of those hips that received radiation, Grade II or III heterotopic bone developed in 6% and Grade IV heterotopic bone developed in none. Of the control group, Grade II or III heterotopic bone developed in 34% of the hips and Grade IV heterotopic bone in 6%. The radiated hips had a significant net gain in abduction and adduction when compared with the nonradiated hips. No early complications were noted in association with the radiation treatment. A single dose of 6 Gy of radiation given within the first 3 postoperative days provides effective prophylaxis against heterotopic ossification developing after total hip arthroplasty in high risk patients.