Ulnar compression neuropathy secondary to the anconeus epitrochlearis muscle.

The treatment of the five arms of four patients with ulnar neuropathy at the elbow and an associated anconeus epitrochlearis muscle is presented. Two of these patients had unilateral involvement, one had bilateral neuropathy and bilateral anconeus epitrochlearis muscles, and one had bilateral symptoms, with an anconeus epitrochlearis muscle on the side that was treated by operation. All patients were treated with excision of the anconeus epitrochlearis muscle and cubital tunnel release without anterior transposition of the nerve. All five arms were clinically normal at follow-up 16 to 29 months after operation. Postoperative electrodiagnostic studies on four arms at an average of 9 months after operation showed marked improvement in conduction velocities across the elbow. We recommend simple excision of the anomalous anconeus epitrochlearis muscle when no other cause of ulnar nerve neuropathy at the elbow is identified. Anterior transposition of the nerve seems unnecessary.