[Postoperative, conventional fractionated radiotherapy for prevention of heterotopic ossification after total endoprosthesis of the hip joint].

: Radiotherapy is the only local means of treatment in the prevention of heterotopic bone formation. It is possible to reduce the incidence of HO following total hip arthroplasty from an average of 50% without further treatment to an average of 8% using different doses and fractionation schemes. In this retrospective clinical study 22 hips of 20 patients were treated with a conventional fractionated radiotherapy. Total doses of 12.0-20.0 Gy in daily fractionation of 200 cGy single doses were applied 18 hips were postoperatively irradiated as secondary prophylaxis against recurrence of HO. 4 hips were high-risk cases with contralateral HO after previous hip surgery. After 6-30 months observation periods the roentgenogramms were analyzed with a modified Brooker-Score. Patients with a score > II were classified as nonresponders. 95.5% of the treated hips showed satisfactory results, only one hip (4.5%) achieved a score IIIA. In this case radiotherapy was interrupted after 3 x 200 cGy. The high therapeutic efficiency of local irradiation in the prevention of heterotopic bone formation following total hip replacement could be proved. No considerable side effects were observed. Further prospective clinical investigations are necessary to optimize the doses and fractionation schemes.