Shoulder Injuries in the Throwing Athlete.

The throwing athlete with shoulder pain presents a diagnostic and treatment challenge to the orthopaedic surgeon. Because pitching a baseball requires the arm to accelerate at 7,000 degrees per second, tremendous forces are experienced at the shoulder joint. Electromyographic studies have shown that the larger scapular and trunk muscles are primarily responsible for arm acceleration. The smaller and more fragile rotator cuff muscles play a significant role in decelerating the arm. During the entire throwing mechanism, the rotator cuff and the capsulolabral complex act to stabilize the humeral head on the glenoid fossa. As a result, the labrum, the capsule, and the rotator cuff are frequently the site of shoulder injury in throwers. The diagnosis of injury to these structures is based on the findings from the history, physical examination, and imaging studies. The majority of throwing injuries respond well to a carefully designed rehabilitation program. Athletes who do not improve within 6 months are candidates for surgical repair. The procedure is planned so as to minimize the amount of surgical trauma and thereby to facilitate an early return to sport. Arthroscopy is a valuable first step to confirm the pathologic diagnosis. The arthroscope alone is used to perform subacromial debridement, labral repair, or debridement of undersurface partial-thickness rotator cuff tears. If the athlete has clinical evidence of shoulder instability and arthroscopic evidence of capsular stretch, an open stabilization procedure is performed.