Overhead throwing motions cause the humerus to rotate, flex and extend, which rotate the glenohumeral joint. Greater supination of the forearm and shoulder is necessary to generate superior rotation, and there is a maximum extension required to generate external rotation and a minimum flexion requirement to generate internal rotation. Some overhead throwing movements, such as pitching, also involve extremes of abduction and adduction. Although all these movements may occur in consistent dynamic patterns during a period of training, excessive supination or extension or extreme adduction or abduction may lead to injury.
A chronic tear occurs when the tendon detaches from the bone and the cuff muscles and tendons cannot sufficiently stabilize the shoulder, leaving it susceptible to dislocation. Particularly difficult to diagnose is a partial tear, because unlike a complete tear, a 10 to 30% tear of the rotator cuff remains clinically intact, showing no swelling or friction rub, and limited movement resembling a strained tendon
A complete tear, on the other hand, does not have any fibers remaining attached to the humeral head and needs to be surgically repaired with the goal ofregaining shoulder stiffness, motion, and strength. d2c66b5586