Posterosuperior and anterosuperior impingement in overhead athletes

The throwing athlete puts enormous stress on both the dynamic and the static stabilizers of the shoulder during the throwing motion. These repetitive forces cause adaptive soft tissue and bone changes that initially improve the performance but ultimately may lead to shoulder pathologies, especially during the motion of throwing. Although a range of theories have been suggested for the pathophysiologic development of internal impingement, the causes are obviously of multifactorial nature. The cardinal lesions of internal impingement, articular-sided rotator cuff tears, and posterosuperior labral lesions, have been shown to occur not only in association with a number of other findings, most importantly GIRD and SICK scapula syndrome, but also with posterior humeral head lesions, posterior glenoid bony injury, and rather rarely with Bankart and IGHL lesions. Extensive biomechanical and clinical research is necessary before a complete understanding and reconciliation of the varying theories of the pathomechanics of injury can be developed.