Re-irradiation for prophylaxis of heterotopic ossification after hip surgery.

Heterotopic ossification (HO) may occur after total hip arthroplasty, but fortunately most patients are asymptomatic. Rick factors for HO include previous HO, hypertrophic osteoarthritis, diffuse idiopathic skeletal hyperostosis, ankylosing spondylitis, Paget's disease and post-traumatic arthritis. Both pre-operative and post-operative radiotherapy are effective in the prevention of HO in 85-95% of high-risk patients treated. In the few patients who needed re-operation for a variety of reasons, we found that re-irradiation is possible and safe. These case reports present our experience with single dose re-irradiation of the hip in an attempt to prevent post-operative HO.