Prevention of heterotopic ossification about the hip: final results of two randomized trials in 410 patients using either preoperative or postoperative radiation therapy. - Seegenschmidt,M.HK.; Keilholz,L.; Martus,P.; Goldmann,A.; Wolfl,R.; Henning,F.; Sauer,R. (Int J Radiat Oncol Biol Phys, 1997)