Common Shoulder Instability Problems

The second most common shoulder problem after Rotator Cuff tears is shoulder instability, which ranges from subluxation to dislocation. Shoulder instability problems often result from rigorous contact and overhead sports, or activities. The shoulder joint is a ball and socket joint similar to the hip, though it is extremely shallow and inherently unstable.  Fibrocartilage tissue called the labrum, lip in Latin, helps compensate for the shallow nature of the joint by forming a type of suction cup for the end of the arm bone (humerus) – facilitating stability and movement.  Ligaments course from the labrum to the humerus providing static stability.  Many muscle groups, primarily the rotator cuff and the muscles that position the scapula provide dynamic stability to the shoulder.   Not only can the ligaments tear resultant from acute trauma, they can attenuate secondary to chronic  overloading.  When a shoulder dislocation occurs, the passage of the humeral head over the front or back of the glenoid (socket) can and will cause acute fracture, or gradual grinding away of the bones, leaving the shoulder even more unstable.  These problems are call instability.

An unstable shoulder is often tender to palpation, and upon examination, patients appear to have difficulty moving their arm comfortably. The patient also experiences “apprehension” when asked to reach over and behind their head.  When this happens, the patient becomes fearful that the arm will go out of socket.  Not only will the patient not allow the examiner to position the arm in that way, but the fear is seen in the patient’s eyes.   It is also reported that the arm seems to “go dead” in the middle of an activity such as pitching a baseball.

A lesser amount of instability in shoulder ligaments can permit the shoulder to slip slightly out of its socket, which is called subluxation. A more severe case of instability can cause the shoulder to come completely out its socket and is known as a dislocation.

Typically in cases of dislocation, the ball at the upper end of the arm bone (humerus) slips out of the socket of the shoulder blade (scapula). The socket, which is composed of the “bony” socket and the Labrum cartilage tissue, is compromised when a shoulder has dislocated or subluxed – often times resulting in the Labrum tearing away from the bone.

Another type of problem associated with a dislocation is a SLAP lesion (Superior Labrum, anterior-posterior), which occurs when the arm is forcefully bent inward at the shoulder and tears the biceps tendon and Labrum cartilage from the glenoid cavity in a front-to-back (anterior-posterior) direction. A tear to the anterior-inferior, or less commonly the posterior-inferior part of the Labrum accompanying an anterior or posterior dislocation is called a Bankart lesion and is the typical lesion seen in recurrent dislocation. These are the primary types of Labrum problems.

Shoulder dislocation and instability affects people differently at different ages. In young patients who are active in competitive sports, a shoulder dislocation almost always results in future dislocations and ultimately surgery. For patients in their 30s, the likelihood of future dislocations is low after a first-time episode. In patients over 40, a dislocation usually results in a Rotator Cuff tear as well. In these cases, the rotator cuff tear is the primary lesion.

Addressing a Dislocation or Subluxation
Preventing shoulder instability conditions are the best way to avoid more serious damage and invasive treatment. When shoulder sensitivity is first felt, individuals are encouraged to keep their arms out in front of them and avoid overhead and behind placement, as well as excessive overhead activities.

A series of Reconditioning exercises developed to strengthen the Rotator Cuff, the Deltoid and the Scapula Rotators is also recommended. These exercises are part of the Reconditioning Program, which helps athletes avoid serious injury by strengthening overstressed limbs, recover non-surgically when injuries do occur, as well as prepare for and recover from surgery when a serious injury does not respond to conservative treatment.

This series of shoulder exercises with a Thera-Band®, which is a latex resistive exercise band, is designed to strengthen the shoulder by providing both positive and negative force on the muscles, as well as improve range of motion and cooperation of muscle groups. Thera-Band® exercises help strengthen the shoulder in Flexion, Abduction, Internal rotation and External rotation. They also help stretch the shoulder into internal rotation, as well as strengthen the Scapula Rotators. Three sets of 12 repetitions of each exercise are necessary each day.

For patients in their mid-20s and older, these exercises are a very effective non-surgical way to avoid serious Shoulder Instability and Rotator Cuff problems. They are not, though, as effective for teenagers and those in their early twenties, because such instability usually results in a labral tear and its associated loss of bone either on the glenoid (socket), humeral head, or not infrequently both sides of the joint.  These problems typically require surgical treatment.

The basis of surgical treatment has been to repair the Labrum down to the bone, using metal or plastic anchors embedded into the bone – with sutures that sew the Labrum and the capsule back to the bone.  Following six weeks of immobilization, a slow rehabilitation process is necessary and return to sports is usually delayed between six months and one year. These procedures performed arthroscopically are very commonly done, and in the best of circumstances leads to an 80% success rate.  Unfortunately, this means that 20% of patients will continue to experience instability and if they are unwilling to give up most sports, they face further surgical procedures.

Patients aged less than twenty years, involved in contact or competitive sports, with X-ray, MRI, or CT scan evidence of bone loss are particularly at risk for failure of arthroscopic labral repair.  This group typically includes those with multiple dislocations, and those whose shoulder easily dislocates with the arm below the horizontal.  A particularly prone group is those awaken from sleep with their shoulder dislocated.

It has been well demonstrated that simple arthroscopic surgery is not the solution for this problem, with failure rates in this group approaching 60%.  At our Clinic we have found an excellent solution, first developed in France in the 1950s and is known as the Latarjet Procedure.  This procedure involves transplanting the coracoid process of the scapula to the front of the glenoid socket, and holding it, typically, with two strong screws.  This restores and extends the shape of the socket, and also will allow for transfer of two strong muscles to the front of the shoulder to block dislocation.   The stability of this procedure will generally allow an accelerated rehabilitation to be performed such that these athletes can discard the sling after a week, use the arm for ordinary activities, and return to sports by three months.  Most importantly, the redislocation rate of this outpatient procedure is considerably under 5%.