Anatomic relation between the medial collateral ligament of the elbow and the humero-ulnar joint axis

The anatomic relation between the proximal attachment of the medial collateral ligament of the elbow joint and the humero-ulnar joint axis has not been clearly shown in a published study. We examined cadaveric specimens to find the exact relation between them. The medial collateral ligament was microscopically dissected to isolate specific fiber bundles. The length of each bundle was measured with a charge-coupled device camera system that faced the medial side of the elbow joint. The measurements indicated that the projected length of the deep middle bundle of the anterior oblique ligament, which is the strong cord-like part of the medial collateral ligament, is isometric during elbow flexion. The proximal end of the deep middle bundle was thus considered to be located almost on the humero-ulnar joint axis.