Anatomy, biomechanics, and pathophysiology of instability of the glenohumeral joint

The stability of the shoulder is dependent on both static and dynamic anatomic restraints. In most cases, there must be insufficiency of more than one restraint for the shoulder joint to become instable. Although the role of these restraints is largely known in maintaining shoulder stability, our information on their interactions is insufficient. This article reviews the anatomy and biomechanics of the shoulder, and conditions causing instability of the glenohumeral joint.