Baseball Players and their Shoulder Injuries
Shoulder pain is a common complaint among baseball players, especially pitchers, regardless of age or level of play. Pain experienced during the throwing motion results in an inability to throw with velocity, causing what is commonly referred to as "dead arm" syndrome. The cause of pain is most often injury to either the bones or the soft-tissue structures of the shoulder joint.
The 4 phases of throwing
The shoulder, like the hip, is a ball-and-socket joint (Fig. 2). However, unlike the hip where the ball fits tightly into the socket and is restricted, the shoulder ball (humeral head) fits loosely in the socket (glenoid) and is unrestricted, much like a golf ball on a tee. The farther one is able to bring the arm back into abduction (raised away from the side of the body) and external rotation, the faster the ball will go when released. This lack of restriction is a double-edged sword: it allows tremendous range of motion in the shoulder, making it possible to cock the arm back farther and throw with tremendous velocity. However, it also forces a reliance on relatively weak soft-tissue structures to maintain shoulder stability. These soft-tissue stabilizers feel the greatest stress during the throwing motion and are, therefore, the most frequently injured structures when this stress is applied repetitively. The shoulder's soft-tissue stabilizers can be divided into two categories: static and dynamic (Fig. 3). The static stabilizers are the ligaments of the shoulder capsule and the labrum (the cartilage ring that surrounds the socket). The labrum is an important part of the thrower's shoulder anatomy because it serves as the attachment site for the capsular ligaments at the glenoid and it also deepens the socket to provide extra stability. The dynamic stabilizers, which include the rotator cuff muscles, are the muscle groups that surround the shoulder. These muscles contract at different times during the various stages of throwing. The static and dynamic stabilizers work together in a delicate balance to stabilize the humeral head in the glenoid during the act of throwing. When the soft tissue stabilizers become too loose or too tight, the delicate balance of humeral head stability is thrown off, resulting in abnormal movement of the humeral head during throwing. This abnormal movement of the humeral head puts increased stress on the labrum and can lead to a tearing away of the labrum from the glenoid, the so-called SLAP (Superior Labrum Anterior to Posterior) lesion, which is thought to be one of the major causes of pain in the thrower's shoulder (Fig. 4).
The ultimate goal of treatment for shoulder pain is to return the player to the field in a safe and timely manner, with a restored ability to throw with speed and accuracy. Initial treatment consists of resting the arm, thereby avoiding the activity that causes or increases the pain. In the case of Little Leaguer's shoulder, an average of 3 months of rest with a gradual return to throwing is recommended, provided the athlete has no shoulder symptoms.2 If the problem is thought to be with the soft tissue stabilizers, a physical therapy program that focuses on stretching and strengthening the ligaments and muscles of the shoulder is undertaken as the mainstay of treatment. Most shoulder problems in throwers can be treated effectively with physical therapy. Achieving and maintaining range of motion in the shoulder, especially internal and external rotation, while strengthening the muscles around the shoulder at the same time is the mark of a good physical therapy program.
The diagnosis and treatment of shoulder pain in baseball players can be a challenging undertaking. Early recognition of a problem is an important responsibility of coaches and parents. Once a problem is recognized, diagnosis and treatment should be sought from a physician. Beginning with the history, physical examination, and findings from imaging studies, a working diagnosis can often be made and a treatment plan determined. Rest and physical therapy are the mainstays of treatment, with surgery reserved for those who do not improve with nonoperative treatment. Surgery is directed at repairing the injury and restoring the normal shoulder anatomy.
Champ L. Baker, Jr., MD, and