Surgical management of bony encasement of the ulnar nerve secondary to heterotopic ossification of the elbow

Heterotopic ossification (HO) is the most common extrinsic cause of elbow contracture. However, associated ulnar neuropathy at the elbow due to HO is uncommon. The purpose of the study is to describe the surgical management and investigate the effect of operative treatment of HO about the ulnar nerve on neuropathic symptoms. A retrospective review of all patients treated with bony encasement of the ulnar nerve secondary to HO over a 13-year period was performed. All patients underwent surgery for clinically symptomatic or debilitating HO of the elbow. Each patient received HO prophylaxis postoperatively. Subjects underwent regimented physical therapy and utilized a continuous passive motion machine in the postoperative period. Eighteen elbows with complete bony encasement of the ulnar nerve were identified (13 burns, 4 trauma, 1 closed head injury). There was a statistically significant decrease in ulnar neuropathy symptoms, as evidenced by a reduction of mean McGowan grade (1.5 to 1, P<0.02). Twenty-five percent of symptomatic patients (4/16) had complete resolution of their neuropathy symptoms. The mean arc of motion improved from 14 to 98 degrees following surgery and rehabilitation. Comparison of preoperative and postoperative motion demonstrated a statistically significant improvement in elbow extension, flexion, and total arc of motion (P<0.01). Average time from initial visit until surgery was 266 days (range, 76 to 797 d), while mean postoperative follow-up was 16 months (range, 1 to 51 mo). Surgical management combined with postoperative HO prophylaxis may be an effective treatment for treating patients with HO of the elbow with bony encasement of the ulnar nerve, resulting in superior range of motion and improved or resolved ulnar neuropathy.