The Role of Glenohumeral Capsular Ligaments in Internal and External Rotation of the Humerus

Abstract

The purpose of this study was to define the relationship between internal and external rotation of the humerus and the lengths of the anterior and posterior compo nents of the glenohumeral capsuloligamentous com plex. Six cadaveric shoulders (with intact ligaments and humeri) were stripped of all muscles. Each shoulder was mounted in its correct anatomic position. The ex tent of internal and external rotation of the humerus was then measured 36 times (at 10° intervals in a 360° hu meral cone of motion). One component of the gleno humeral capsuloligamentous complex was lengthened, and the humeral rotation was again measured 36 times. The process of lengthening was done by cutting the ligament and replacing it with a beaded chain and catches sutured across the joint. The process of length ening each component was repeated in 12 combina tions, each with a different anterior and posterior com ponent length. Humeral rotation was measured 36 times using a specially designed goniometer. The length of the anterior component of the glenohumeral capsuloligamentous complex most affected external humeral rotation, and the length of the posterior com ponent most affected internal humeral rotation. How ever, the lengths of both the anterior and posterior com ponents shared in limiting rotation at a number of positions.