Radiation treatment of heterotopic bone formation in the temporomandibular joint articulation

Purpose: The efficacy and toxicity of radiation therapy used for preventing re-formation of heterotopic bone involving the temporomandibular joint are assessed. Methods and Materials: Ten patients (15 TMJs) with bony ankylosis of the TMJ were referred after reconstruction with costochondral graft, gap arthroplasty, or debridement of heterotopic bone. Treatment consisting of 10 Gy was delivered early postoperatively to a field encompassing the TMJ with adequate margin. Response to therapy was assessed by comparison of routine roentgenograms obtained preoperatively, immediately postoperatively, and at last follow-up; the Turlington-burr grading system was used. Median duration of postoperative follow-up was 19 months. Results: Radiation therapy prevented ectopic bone re-formation in 10 (69%) of 15 TMJs with prior bony ankylosis. Of the 15 TMJs, 13 (87%) had improvement in their Turlington-Durr scores compared with the preoperative scores. Development of ectopic bone formation was prevented in 9 (90%) of 10 TMJs rendered Turlington-burr grade 0 postoperatively. Eight of the 10 patients have remained asymptomatic. Treatment was well tolerated. The only complication experienced was parotitis in three patients. Conclusion: Radiation therapy is useful for prevention of heterotopic bone redevelopment after TMJ operation. We recommend 10 Gy in 5 fractions beginning early postoperatively for high-risk patients. This strategy appears beneficial in this young patient population, who suffer significant pain and functional impairment in the TMJ articulation.