Kinematics of the lateral ligamentous constraints of the elbow joint.

Thirty osteoligamentous elbow joint specimens were included in a study of the lateral collateral ligament complex (LCLC). The morphologic characteristics of the LCLC were examined, and then three-dimensional kinematic measurements were undertaken after selective ligament dissections were performed. Isolated sectioning of the annular ligament (AL) or the lateral ulnar collateral ligament (LUCL) induced only minor laxity to the elbow joint with a maximum of 2.2 degrees and 4.4 degrees during forced varus and external rotation (supination), respectively. Transsection of the lateral collateral ligament (LCL) caused a maximal laxity of 15.4 degrees and 22.8 degrees during forced varus and external rotation (supination), respectively. Combined ligament dissections showed that total transection of the LCLC at the ulnar or the humeral insertion was important for joint laxity. Total transection of the LCLC at the humeral or the ulnar insertion induced a maximal laxity of 24.5 degrees and 37 degrees during forced varus and external rotation (supination), respectively. This study suggests the AL and the LUCL are of minor importance as constraints when cut separately, whereas the LCL is a significant preventer of elbow joint laxity. The LCLC was observed to be a complex structure of ligamentous fibers rather than discreet bands. The LCLC forms a ligamentous constraint between the lateral humeral epicondyle and the ulna, stabilizing the elbow joint and forming a base for radial head stability and rotation.