Causes

One of the main causes of shoulder instability is a history of a previous dislocation resulting from a traumatic event. Following a shoulder dislocation a medical professional will perform a closed reduction consisting in the manual manipulation to place the humerus head into the correct position of the joint. However, despite its normal appearance, the shoulder may remain unstable due to the weakness of the ligaments and the labrum. This instability can lead to frequent shoulder subluxations. Shoulder instability can also occur in the absence of previous dislocations in those athletes performing repetitive throwing activities, which over time damage the ligaments. A disproportional distribution of the shoulder muscles may lead to shoulder instability. This condition is frequent in individuals with a congenital weakness of connective tissue, making all joint ligaments more elastic, e.g. Ehler Danlos Syndrome.