Shoulder Dislocation & Instability | Mathew Mazoch, MD

Bone & Joint Clinic of Baton Rouge | Sports Medicine


  Contact : (225) 766-0050

Shoulder Dislocation & Instability

Introduction to Shoulder Dislocation and Instability

The shoulder joint consists of the rounded top of the bone in the upper arm (humerus), which fits into the socket (glenoid) — the cup-shaped outer part of the shoulder blade.  When the top of the humerus moves out of its usual location in the shoulder joint, the shoulder is said to be dislocated.

Shoulder dislocations can occur after a traumatic event or can be atraumatic in people who are loose jointed.  In a dislocation event sometimes the structures around the shoulder can be damaged and can cause labral tears or rotator cuff tears.  Proper treatment is necessary to prevent recurrent instability of the shoulder joint which can cause continued dislocations and progressive damage if not treated appropriately.

shoulder surgery shoulder specialist shoulder pain shoulder instability shoulder doctor shoulder dislocation rotator cuff tear labral tear bankart

This image shows a normal shoulder relationship of the humerus to the glenoid as well as an anterior dislocation and a posterior dislocation.

Types of Shoulder Dislocation and Instability

In some cases, a shoulder is dislocated when the arm is pulled or twisted with extreme force in an outward, upward or backward direction. This extreme force literally pops the top of the humerus out of its socket. In other cases, a shoulder dislocation is the result of a fall on an outstretched arm, a direct forceful blow to the shoulder, a seizure or a severe electric shock.  Seizures and shock can cause shoulder dislocations because they produce extreme, unbalanced muscle contractions that can wrench the humerus out of place.

In general, doctors classify shoulder dislocations into three types, depending on the direction of the dislocation:

Anterior dislocation

In anterior dislocations, the top of the humerus is displaced forward, toward the front of the body. This is the most common type of shoulder dislocation, accounting for more than 95% of cases. In young people, the cause is typically sports-related and involve a tear of the labrum. In older people, it usually is caused by a fall on an outstretched arm and are often accompanied by a rotator cuff tear.

shoulder surgery shoulder specialist shoulder pain shoulder instability shoulder doctor shoulder dislocation rotator cuff tear labral tear bankart

The images show x-rays of an anterior shoulder dislocation

Posterior dislocation

In posterior dislocations, the top of the humerus is displaced toward the back of the body. Posterior dislocations account for 2% to 4% of all shoulder dislocations and are the type most likely to be related to seizures and electric shock. Posterior dislocations also can happen because of a fall on an outstretched arm or a blow to the front of the shoulder.

shoulder surgery shoulder specialist shoulder pain shoulder instability shoulder doctor shoulder dislocation rotator cuff tear labral tear bankart

The images show x-rays of a posterior shoulder dislocation

Inferior dislocation

In inferior dislocations, the top of the humerus is displaced downward.  This type of shoulder dislocation is the rarest, occurring in only one out of every 200 cases. It can be caused by various types of trauma in which the arm is pushed violently downward.

shoulder surgery shoulder specialist shoulder pain shoulder instability shoulder doctor shoulder dislocation rotator cuff tear labral tear bankart

The image shows an x-ray of an inferior shoulder dislocation

Symptoms of Shoulder Dislocation and Instability

Symptoms of a dislocated shoulder include:

  • Severe shoulder pain
  • Limited motion of the shoulder especially rotation and elevation
  • An abnormal external appearance of the shoulder’s contour compared to the opposite side.
  • A hard circular knob under the skin near the shoulder
  • Shoulder bruising or abrasions if an impact has caused your injury
shoulder surgery shoulder specialist shoulder pain shoulder instability shoulder doctor shoulder dislocation rotator cuff tear labral tear bankart

Notice the abnormal shoulder contour on the patients right shoulder

 

Treatment of Shoulder Dislocations and Instability

Shoulder dislocations need to be reduced in a timely manner.  If not immediately reduced, a first time dislocator will often have to be given relaxation medication to reduce it.  Many different reduction maneuvers exist for shoulder dislocations.  A gentle reduction is key to help avoid further damage to the soft tissue structures and bone around the shoulder.

Management of shoulder dislocations after reduction is based on the patients individual characteristics and demands they will place on the shoulder in the future.

Non-operative management of shoulder dislocations

Non-operative management of shoulder dislocations consists of a period of relative rest followed by a rehab program.

In general, the prognosis of non-operative management depends on many factors, including the severity of your shoulder injury, your age and your participation in athletic activity. For example, young athletes that play contact sports, such as football or hockey, that have a shoulder dislocation, have an overall risk of having  a second shoulder dislocation of greater than 90%. Repeat injury may make your shoulder unstable enough that it needs to be repaired with surgery. Surgery usually restores the shoulder’s stability and reduces the risk of future dislocation.

If you are an adult and have an uncomplicated shoulder dislocation, your risk of a second dislocation is low, with repeat dislocations occurring only about 25% of the time for people in their 30s and even less often for older age groups.

Operative management of shoulder dislocations

If you continue to have severe shoulder pain after closed reduction or if your injured shoulder is loose and unstable in spite of physical therapy, you may need surgery to repair the fibrous tissues that support your shoulder joint.  Depending on what is injured the capsule or labrum may need to be repaired (Bankart repair),  the rotator cuff may need to be repaired, or occasionally a fracture or bone loss will need to be addressed.

shoulder surgery shoulder specialist shoulder pain shoulder instability shoulder doctor shoulder dislocation rotator cuff tear labral tear bankart

The image shows a procedure used for bone loss in patients with recurrent shoulder dislocations

Final thoughts on Shoulder Dislocation and Instability

Shoulder dislocation can lead to recurrent instability and pain in the shoulder.  If treated appropriately people can experience a significant increase in quality of life and function of the shoulder.

Surgery of the shoulder is not to be undertaken lightly; however, if performed for the right reasons it can result in significant pain relief and an increased quality of life.  If you have any further questions please don’t hesitate to schedule an appointment with Dr. Mazoch.