Functional anatomy of the ligaments of the elbow.

Dissections of 10 fresh cadaver specimens revealed an important insertion of the posterior portion of the lateral collateral ligament to the ulna at the crista supinatoris. The humeral origin of the medial ligament attachments was found to lie posterior to the axis of elbow flexion; in this position a cam effect is created so that ligament tension varies with elbow flexion. The three-dimensional distance between the origin and the insertion of the anterior portion of the medial collateral ligament was found to increase slightly from extension to approximately 60 degrees of flexion; thereafter, it remained nearly constant. The distance of the posterior portion increased by about 9 mm from 60 degrees to 120 degrees of flexion. The flexion axis was shown to pass through the origin of the lateral collateral ligament, so the length of this structure was not changed during elbow flexion.