THE MEDIAL COLLATERAL LIGAMENT OF THE ELBOW JOINT - ANATOMY AND KINEMATICS

Eighteen osteoligamentous elbow joint specimens were included in a stu dy of the medial collateral ligament complex (MCL). The morphologic ch aracteristics of the MCL were examined, and three-dimensional kinemati c measurements were taken after selective ligament dissections were pe rformed. On morphologic evaluation the MCL is divided into the anterio r bundle and the posterior bundle. The anterior bundle can be divided into anterior and posterior bands. The maximum valgus and internal rot atory instability after transection of the anterior band, 11.7 degrees and 11.2 degrees respectively, were found at elbow flexions of 30 deg rees and 40 degrees. Severance of the entire anterior bundle produced major valgus and internal rotatory laxity through the complete flexion are of maximal 14.2 degrees and 18.5 degrees, respectively, at 70 deg rees and 60 degrees of elbow flexion. Cutting both the posterior band and the posterior bundle resulted in only internal rotatory laxity of maximal 7.2 degrees at 130 degrees of elbow flexion. This study define s the anterior band as the primary constraint to valgus and internal r otatory forces, the posterior band as the secondary, and the posterior bundle as the tertiary constraint. The MCL was observed to be a compl ex of ligamentous fibers rather than individual bands that stabilizes the joint against valgus and internal rotatory forces.