Shoulder Dislocation

Normal shoulder x-ray with ball and socket aligned
Figure 1. A normal shoulder with the ball and socket aligned.

The human shoulder has the greatest range of motion of any joint in the body. It allows overhead activities, throwing, lifting, and many daily tasks. A shoulder dislocation is a painful injury in which the ball of the shoulder joint comes out of the socket.

Normal Anatomy of the Shoulder

When most people think of the shoulder joint, the “ball and socket” comes to mind. The shoulder is actually made up of three separate joints:

  1. Glenohumeral joint: where the ball of the humerus meets the socket of the glenoid.
  2. Acromioclavicular joint: the AC joint, where the collar bone meets the shoulder blade.
  3. Scapulothoracic joint: where the shoulder blade meets the rib cage.

The scapulothoracic and glenohumeral joints provide most shoulder motion, while the AC joint provides a stable connection between the arm and the rest of the skeleton. In this guide, “shoulder joint” and “shoulder dislocation” refer to the glenohumeral joint.

The shoulder is unique because much of its stability comes from the soft tissues around the joint rather than from the shape of the bones. These stabilizing layers include:

  1. Outer layer: large powerful muscles including the deltoid, trapezius, and pectoralis.
  2. Middle layer: the rotator cuff, a group of four small muscles that help keep the ball centered in the socket.
  3. Inner layer: strong ligaments and the labrum, which help prevent the joint from dislocating.

Causes

The normal shoulder joint can be compared to a golf ball balancing on a tee. If a large enough force is applied in the right direction, the ball can dislocate from the socket. This causes pain, and the shoulder may look or feel abnormal. It may be difficult to move the shoulder and arm.

Sometimes the shoulder goes back into place on its own. When it does not, a reduction is required. This usually involves a trip to the emergency room or another health care professional.

Diagnosis

The first step in treating a painful shoulder injury is reaching the correct diagnosis. The shoulder can dislocate out the front, out the back, or toward the armpit. X-rays help determine the direction of the dislocation and whether there is an associated fracture.

X-ray of a dislocated shoulder where the ball is not aligned with the socket
Figure 2. A dislocated shoulder in which the ball is not aligned with the socket.

Non-Surgical Treatment

A dislocated joint is usually painful. Relaxation of the shoulder muscles is often needed to put the shoulder back in place. Sedation or an injection of anesthetic medication into the shoulder joint may be used.

Putting the joint back in place is called a reduction. It is performed by pulling the arm in a specific direction based on the type of dislocation. Once the joint is back in place, comfort usually improves. A sling is often used for comfort.

Recovery

Occasionally there will be numbness over the shoulder for several days to weeks. This is common and usually temporary, but it should be mentioned to a health care professional. Once the shoulder is back in place, there is still a risk of redislocation, so precautions are important.

Shoulder dislocations can also be associated with tendon tears or fractures. Follow-up with an orthopaedic surgeon or other musculoskeletal specialist is often recommended.

After a dislocated shoulder is reduced, a sling may be used for 4-6 weeks. During this time, it is important to occasionally come out of the sling for elbow, wrist, and finger range of motion because these joints can become stiff. Physical therapy may help restore shoulder motion while protecting healing ligaments.

Careful shoulder motion often begins 4-6 weeks after injury under the supervision of a physical therapist. Many people can use the shoulder for most normal activities a few months after injury. Contact sports or activities with a high risk of redislocation are usually not resumed for 4-6 months.

Risks of Re-Dislocation

Research shows that younger and more active patients have a higher risk of redislocation. For example, an 18-year-old athlete or military member is generally more likely to redislocate than a 45-year-old with lower physical demands.

Surgical Treatment

Most first-time shoulder dislocations can be treated without surgery. Surgery may be considered when the risk of redislocation is high or when there are associated injuries to the rotator cuff, shoulder bones, or labrum.

Repeated shoulder dislocations can lead to cartilage damage, bone loss, pain, weakness, chronic instability, and osteoarthritis. If the risk of redislocation is higher than the risks of surgery, stabilization surgery may be recommended.

The main goal of stabilization surgery is to keep the shoulder in place while preserving as much motion as possible. This is usually done by repairing structures damaged during the dislocation. This may include repair of the torn labrum and surrounding tissues, sometimes called a Bankart tear. Repair may use bone anchors and strong sutures, and it may be performed through an open incision or arthroscopically through small incisions.

Recovery After Surgery

A sling is usually used for 4-6 weeks after surgery and may need to be worn at night. Restrictions should be confirmed with the surgeon. Some people find it easier to sleep in a recliner during this period.

Surgery for shoulder instability is usually followed by some discomfort and stiffness. Pain control varies by patient. If opioid pain medication is prescribed, it is important to discuss safe use and the expected pain-control plan with the surgeon.

Physical therapy often starts within a few weeks of surgery. A licensed therapist helps restore and maintain range of motion while protecting the repair during the early healing period. Most patients regain improved range of motion and pain control by three or four months after surgery. Shoulder conditioning often continues for four to six months, and many people return to sports around six months after surgery.

Conclusion

Shoulder dislocations are painful injuries that can happen to anyone. Fortunately, most can be treated without surgery. Younger and more active people are at higher risk for redislocation. Recurrent dislocations can lead to chronic instability, additional shoulder injuries, and shoulder arthritis. A consultation with an orthopaedic surgeon or other qualified musculoskeletal care professional can help guide treatment.

This mobile-friendly version is adapted from patient education content originally provided by the American Society for Surgery of the Hand.