What is anterior dislocation of the shoulder?

When the glenohumeral joint of the shoulder (the ball and socket joint) is twisted apart so that the ball slips out the front of the socket, this is called an anterior dislocation. If the ball only partly slips out, and then slips back in on it's own, this is called a subluxation.

Who is at risk for dislocation?

Most commonly, shoulder dislocations occur in young, active individuals under the age of 30. When dislocation occurs in individuals over 30, it is often associated with other types of injury, such as fractures of the shoulder or tears in the rotator cuff tendon. Also, there is a small group of patients who are born with loose shoulders and consequently experience subluxations of the shoulder without significant trauma.

How does dislocation occur?

Usually the injury causing dislocation occurs when the arm is elevated overhead as in a throwing position and a force is applied to the arm, causing it to be pushed backwards. Sometimes people dislocate their shoulder when they fall directly on the shoulder.

What is injured with a dislocation?

When the shoulder is forced out of the socket anteriorly (in front), the ligamentous attachment to the bone usually fails in people under the age of 25. The anchor of this ligament to the bone is called the labrum. When the labrum is torn from the bone, it seldom heals back to it's proper location. This makes the chance of a second dislocation relatively high in people under 25 who dislocate their shoulders. When an individual over 30 dislocates, the tear usually occurs in the substance of the ligament instead of the labrum. These older individuals usually do heal without much difficulty, using conservative, nonoperative measures. In addition, during a dislocation, the force applied often causes the humeral head to impact against the front of the shoulder socket, causing an indention fracture in the humeral head (called a Hill-Sachs lesion). The front edge of the glenoid socket can be fractured as well. Usually this is a small fracture, but it can be a large piece, particularly if the bone is soft.

Are any tests needed?

A series of plain radiographs of the shoulder is always obtained to look for any fractures or other associated injuries. Additionally, an MRI scan can more clearly define the injury to the ligaments around the shoulder, as well as reveal any unsuspected injury. The introduction of dilute contrast dye into the shoulder joint allows for better accuracy when evaluating an MRI scan and may be requested by your surgeon.

What is the treatment of shoulder dislocation?

When the shoulder first dislocates, it should be put back in joint as soon as possible because of potential damage to nerves and the joint structures. Each time the joint dislocates, there is another chance for further damage to the cartilage surface of the bone and more damage to the ligaments. The corrective treatment of shoulders with recurrent instability is an operative procedure to reattach the torn ligament back to the bone. This surgery is almost always necessary in people under 25 because without repair chance of recurrence is as high as 90%. In people over 40, it is probably better to allow the joint to heal with a period of rest followed by physical therapy. A second dislocation is usually an indication for surgical repair, even in the older age group.

How is the shoulder joint repaired surgically?

Surgical repair of the torn ligaments can usually be done using arthroscopic techniques. The arthroscope is a small telescope that is inserted into the shoulder to allow visualization of the joint structures. While observing the torn ligament arthroscopically, the surgeon can use small instruments to reattach the ligament to the bone with mini suture anchors implanted in the rim of the glenoid (the socket). All arthroscopic surgery is videotaped for the medical record and patient education. Patients are encouraged to review their videotapes to better understand their surgery.

If there is a large fracture of the glenoid or a severe injury to the humeral head, then open surgery may be necessary to completely stabilize the shoulder.

What is the benefit or risk of the arthroscopic repair?

Many publications studies show there is a slightly greater chance of the dislocation with arthroscopic repair versus open surgery. Ongoing refinement of arthroscopic techniques has lowered the recurrence rate to within 3-5% of the recurrence rate with open surgery. The benefits of arthroscopic surgery include:

• Almost no scar
• Very little pain
• Outpatient surgery (home same day)
• Better post-op range of motion (good for throwing and overhead athletes)
• Very small infection risk
• Less surgical morbidity

What is the postoperative treatment?

In either case, arthroscopic or open, the early postoperative treatment is the same. That is, use of a shoulder sling for three weeks. Elbow, writs, and hand motions are started immediately in the postoperative period. At about 3 weeks post-op, the sling is removed and pendulum exercises are started. The sling is continued for daytime support. At approximately 4 to 5 weeks, forward evaluation exercises are started with a pulley. Swimming pool therapy exercises can also begin at 5 to 6 weeks. Active range of motion exercises are begun at 6 weeks, along with gentle progressive resistance muscle strengthening exercises. By 3 months, most weight lifting exercises are allowed, and throwing exercises can start if the patient is an athlete. By 6 months any desired activity can be pursued.

What happens if the shoulder becomes unstable again?

If the reconstructed tissues stretch out and the shoulder becomes loose again, then it will be necessary to do an open procedure with shortening of the muscles, tendons, and ligaments. By doing this, the rotation and elevation of the shoulder may be decreased to ensure better stability.

Is there anything else I need to know about anterior shoulder instability?

This can be very disabling condition, particularly in young people, and may sometimes lead to joint deformity and arthritis. In addition, the nerves that supply the hand can also be injured, sometimes, although not frequently, this damage can be permanent. Most patients do extremely well after this type of surgery, although the surgical risks should be carefully considered.

Who can I call for more information?

Please feel free to contact us and ask one of our physicians for a referral. We will be happy to answer your questions and evaluate your shoulder in the Clinic.

Don Buford, M.D. © 2010