What is atraumatic shoulder instability?
Atraumatic shoulder instability develops in patients who have increased looseness of the supporting ligaments that surround the shoulder’s glenohumeral joint. The laxity can be a natural condition (present from birth) or a condition that has developed over time. Many patients with MDI are active in overhead sports (such as gymnastics, swimming, or throwing) that repetitively stretch the shoulder capsule to extreme ranges of motion. The glenoid (the socket of the shoulder joint) is a relatively flat surface that is deepened slightly by the labrum, a cartilage cup that surrounds part of the head of the humerus. The labrum acts as a bumper to keep the humeral head firmly in place in the glenoid. It is also the attachment point for important ligaments that stabilize the shoulder. These ligaments often become stretched out with MDI, allowing dislocation or subluxation (an incomplete or partial dislocation) to occur. The increased motion of the joint can lead to repetitive microtrauma (small
