Radiation prophylaxis of heterotopic bone formation following total hip arthroplasty: current status.

Differentiation of pluripotential stem cells into osteogenic precursors is exquisitely sensitive to ionizing radiation. Radiation prophylaxis effectively prevents ectopic ossification if delivered to the operative site within 5 days following total hip arthroplasty. Continued efforts at dose reduction over the last decade have demonstrated efficacy with as little as 6,000 to 8,000 rad; no soft tissue sarcomas have been reported in this low dose range following treatment of malignant disease. Precise limitation of the treatment field is necessary for application of this modality to cementless implants dependent on bony ingrowth for stable fixation. Trochanteric nonunion is reported in 25% of hips following radiation prophylaxis, but this is as likely related to the high proportion of revision surgery in these series as it is a direct consequence of the radiation.