Shoulder Instability

Shoulder instability refers to a broad spectrum of disorders of the shoulder that can include subtle abnormal amounts of motion that can generate pain, to complete dislocations of the shoulder. The motion and stability of the shoulder joint is controlled by a number of factors including the strength and integrity of several muscles around the shoulder and shoulder blade (scapula), the ball and socket configuration itself, the cartilage rim around the socket (the labrum) and the capsule and ligaments surrounding the shoulder joint itself. Any one of these items can be damaged or function incorrectly and instability can occur.

Subtle instability patterns typically will present with pain in the shoulder area that may be confused for shoulder impingement syndromes or rotator cuff injury. This is a common mis-diagnosis for younger patients, where the pain complaints and even some of the physical exam findings may suggest one of these problems, however the underlying cause is actually instability. More significant levels of instability may feel as though the shoulder joint is slipping out of place with certain motions or activities or even present with complete dislocations. Shoulder instability can be described as unidirectional (only excessive motion in 1 direction) or multidirectional instability (too much motion in 2 or more directions). This is an important distinction to make as they are commonly treated differently and have a different prognosis.

The diagnosis is made based on a complete history of pain and motion complaints as well as a very careful physical exam that will be performed by an orthopaedic surgeon. This is typically accompanied by a series of X-rays and an MRI. These imaging studies help to determine if the instability has lead to any changes in the bone structure, small fractures that may associated with it, and any damage to ligaments, capsule, labrum, or muscles.

The treatment for instability of the shoulder is typically started with a focused course of physical therapy to stabilize the muscular support for the shoulder. If this does not provide enough stability to perform activities that are required for employment or sporting activities of interest, then surgery is indicated.  This traditionally had been performed with an "open" surgical approach to the shoulder. However, currently this is often performed via arthroscopy which is a minimally invasive surgery and has demonstrated similar results with less risk involved (see shoulder arthroscopy). This may include repairs of damaged tissue such as the labrum and moving areas of tissue to tighten the capsule and ligament structures to provide the necessary support.