The athlete's shoulder.

Throughout the ages, instability has been noted to be the underlying problem in shoulder dysfunction of the young, overhand-throwing athlete. Impingement and rotator cuff tears are progressive symptoms of this instability. The classic theory of impingement describes a mechanism for "outside impingement," which is most often seen in the older, nonathletic population. The mechanism for "inside impingement" in the younger, athletic population is a pinching of the cuff undersurface on the posterosuperior glenoid labrum. In this younger group, the first treatment of choice is rehabilitation. If that fails, the surgical procedure with successful outcome is the ACLR coupled with a progressive rehabilitation program.