Shoulder problems are common in overhead throwing athletes, especially baseball pitchers. In this article, posterior capsular contracture of the shoulder is reviewed in detail. The posterior capsule is a band of tissue across the back of the shoulder. It blends with fibers from the tendons of the rotator cuff, the four muscles that support and hold the shoulder in place.
The posterior cuff tightens up as the arm is lifted forward and rotates inwardly. It keeps the head of the humerus (round bone at the top of the upper arm) from moving too far in one direction.
Too much tension in the posterior capsule changes the way the shoulder moves. The head of the humerus can’t stay in the center of the socket like it should. There’s a loss of internal rotation, cross-body movement, and shoulder flexion. For a baseball pitcher, the loss of these three motions affects his or her throwing ability.
Two movements in the shoulder during the throwing motion are important for pitchers. One is called the glenohumeral internal rotation deficit or GIRD. The other is the external rotation gain or ERG. GIRD is the loss of internal rotation of the throwing arm. ERG is the amount of external rotation in the shoulder during the throwing motion.
The authors point out that whenever GIRD is greater than the ERG, the risk of shoulder injury goes up. They suggest that screening before and during each baseball season can help prevent shoulder problems for pitchers and other overhead throwing athletes. Tests of motion for this problem are reviewed in detail. Some simple stretches may be able to help prevent the need for surgery. The authors also review surgical techniques used for this problem and the rehab program following.