LAUSR

Abstract Throwers, particularly baseball players, are dependent on a delicate balance of shoulder mobilty and stability to excel at their sport. Disruptions to this balance can lead to a number of different types of anterior shoulder instability: microinstability, acute atraumatic instability and traumatic instability. Pathologic microinstability can develop over time in a pitcher, as repetative throwing (ie extreme external rotation in abduction) causes stretch to the joint capsule anteriorly and impingement posteriorly. The resultant anterior or posterior shoulder pain can affect pitch velocity and control. Over time, the anterior capsule and ligaments can also become attenuated. They can tear abruptly during routine pitching, resulting in actue atraumatic instability. While microinstability and acute atraumatic instability typically occur in pitchers, position players are at a higher risk of traumatic shoulder instability. Diving for a ball or sliding into a base with an arm outstretched can cause the shoulder to sublux or frankly dislocate. These traumatic instability events often lead to injury of the anterior labrum and can result in recurrent instability. Treatment of instability in these throwing athletes includes physical therapy to restore the strength and coordination of the periscapular muscles, rotator cuff, deltoid and biceps. When non-operative treatments fail, a number of arthroscopic and open procedures are available, with the type of procedure depending on the type of instability. While these techniques can adequately restore stability to the shoulder and many throwers do return to play, throwers do so at lower rates and often at lower levels than athletes of other sports.