WHAT CAUSES SHOULDER INSTABILITY?

The shoulder joint is extremely mobile, with a large range of motion; it is also the most frequently dislocated large joint. The shoulder can dislocate if the arm is pulled out to the side (arm tackle in football), as well as with a direct blow to the shoulder (fall onto the side). A traumatic dislocation typically results in an anterior labral tear, or Bankart lesion. The labrum is a bumper that deepens the socket and serves as an attachment site for the ligaments and joint capsule.  The torn anterior labrum displaces from the glenoid socket and leads to joint laxity; since the labrum doesn’t typically heal back in normal position, the disrupted anatomy and lax ligaments make it easier to redislocate the shoulder.

In some instances, the shoulder will “pop back in,” or reduce, spontaneously or with gentle manipulation; in other cases, the dislocated shoulder remains “out” until reduced in an emergency room setting with the aid of sedation. An appropriate evaluation includes a comprehensive history and physical exam; x-rays; and frequently an MRI.

An MRI can prove helpful in confirming the extent of the injury, including the presence of a labral tear. Anterior labral tears have been demonstrated to occur between 67-100% of the time with a traumatic shoulder dislocation, highest in contact athletes. Similarly, the presence of an anterior labral tear is associated with a high recurrence rate (approaching 100% in some series) of shoulder instability in young patients returning to collision sports.

Shoulder dislocations can be managed non-operatively. Initial treatment involves sling immobilization, pain control, and range of motion and strength recovery through home exercises and physical therapy. Rehabilitation and bracing in many cases can allow for a return-to-sport, depending on the sport and the athlete’s position. Harnesses restrict extension, abduction, and external rotation of the arm, effectively the “dislocation position”; thus, it is easier for an offensive lineman to play in a brace compared to a defensive back. A return to sport is permitted once range of motion and strength to protect oneself has returned, understanding the associated risks of continued participation. 

Surgery can be performed acutely for a labral tear, or immediately after the season to allow for suitable recovery time prior to the ensuing season.  Surgical intervention is typically arthroscopic, although in some instances an open surgical approach is preferable.  The rehabilitation period may range from 4 months in certain athletes up to 6 months for collision sports and 8 months or more if involving the dominant arm in the throwing athlete.