Tardy ulnar nerve palsy caused by cubitus varus deformity.

Fifteen patients with tardy ulnar nerve palsy caused by cubitus varus deformity were studied. All patients had a history of previous fracture of the humerus during childhood. The mean interval between fracture and onset of symptoms was 15 years. The severity of the palsy was classified as McGowan's grade I in 12 patients, grade II in 2 patients, and grade III in 1 patient. The mean carrying angle was -2 degrees before surgery. X-ray films showed a shallow ulnar nerve groove, a dysplastic humeral trochlea, medial shift of the ulna, and deformity of the medial epicondyle. The ulnar nerve was explored in all but one patient. Operative findings suggested that the main cause of the palsy was compression by a fibrous band running between the two heads of flexor carpi ulnaris. Surgical steps included release of the fibrous band in 14 patients with anterior subcutaneous transposition of the ulnar nerve in 5 of those patients. A corrective osteotomy was done in 11 patients who requested correction of the varus deformity. Traumatic cubitus varus deformity should be recognized as another cause of cubital tunnel syndrome.