Abstract

7 patients were diagnosed with an undersurface tear of the deep capsular layer of the anterior bundle of the ulnar collateral ligament. Preoperatively, all patients had tenderness over the anterior bundle of the ulnar coll. ligament and pain with valgus stressing of the elbow. 6 of 7 patients had a normal magnetic resonance imaging scan, 1 magnetic resonance imaging scan showing degeneration within the ligament. All patients had a negative computed tomography arthrogram for extracapsular contrast extravasation. A consistent finding in 5 of 7 patients was a leak of contrast around the edge of the humerus or ulna, although the contrast was contained within the joint. At arthroscopic evaluation, all patients demonstrated medial elbow instability as valgus stress was applied across the elbow joint in 70 degrees of flexion. All patients underwent open medial elbow surgery, where the ulnar coll. ligament was visualized and found to be intact externally. But when the anterior bundle was incised, there was a detachment of the undersurface of the ligament at the ulna or the humerus. Cadaveric dissections were performed to define the anatomy of the insertion sites and to confirm that this lesion was not an anatomic variant. A tear of the deep layer of the ulnar coll. ligament can result in symptomatic instability that is difficult to diagnose with conventional preoperative testing. This lesion of the anterior bundle of the ulnar collateral ligament has not been previously reported, but is associated with persistent medial elbow pain. Verf.-Ref.