Disorders of the rotator cuff represent one of the most common reasons for shoulder pain. Although many causative factors have been implicated, the true pathogenesis remains controversial. The most common and central factors include age-related degeneration of the tendons, mechanical impingement, and changes in the vascularity of the rotator cuff tendon. The natural history of rotator cuff disease has been recognized as a continuum, progressing from simple tendinitis to partial-and full-thickness rotator cuff tears.