Shoulder instability is a condition characterized by a loose shoulder joint, caused by weakened and stretched surrounding muscles and ligaments. This may become a chronic condition after a dislocation, which occurs when the ball of the upper arm bone comes out of the socket. Chronic instability may produce frequent slipping, or partial dislocation, known as subluxation.

Shoulder instability may occur after an acute injury that stretches or tears the ligaments in the shoulder, or it may be a result of overuse. In other cases, a naturally loose joint capsule simply does not hold the ball of the humerus tightly in its socket. Athletes whose sports involve repetitive overhead motions, such as tennis and volleyball players and swimmers, have a higher instance of developing instability. The shoulder is more susceptible to this type of condition than other joints because it provides the arm with a tremendous range of motion. If a dislocation takes place, the muscles, tendons and ligaments of the shoulder may tear or loosen, resulting in the persistent slippage associated with instability.

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Symptoms of Shoulder Instability

People with unstable shoulders may experience pain and limited motion in the joint and additional symptoms may include:

  • Soreness
  • Weakness
  • Numbness in the arm

Symptoms of shoulder instability may discourage participation in sports that require stretching the arm overhead.

Diagnosis of Shoulder Instability

Shoulder instability can be diagnosed after a medical history has been taken and a physical examination performed. The exam may include certain tests of movement in order to evaluate potential shoulder instability. Additionally, imaging tests such as X-rays or MRI scans may be necessary to provide clear visualization of the bones and tissues around the shoulder.

Treatment of Shoulder Instability

Treatment for shoulder instability usually begins with conservative measures including resting the affected arm, physical therapy and use of non-steroidal anti-inflammatory medications. However, for some people these approaches may fail to provide relief. At that point, surgical treatment may be recommended. Instability surgery varies depending on the cause of the condition, but usually aims to tighten the loose ligaments of the shoulder. The two most common types of instability surgery include Bankart repair and capsular shift procedures, which may be performed in combination.

Bankart Repair

Bankart repair is used for shoulders prone to dislocation and it involves the surgeon removing torn or degenerated tissue and any bone spurs that rub on the tendons of the shoulder. The torn ligaments are then reattached to the bone with suture anchors.

Capsular Shift

Capsular shift is used to decrease and tighten the joint capsule, which is the lining of the joint, when it is too large. This is accomplished by folding the affected ligaments over on themselves and suturing them in this more layered position.
Both of these outpatient surgeries can often be performed through arthroscopy, which allows for minimally invasive procedures with smaller incisions and shorter recovery times.

Risks of Shoulder Instability Surgery

As with any type of surgery, shoulder repair surgery may pose a risk of complications. Although uncommon, risks may include:

  • Bleeding
  • Infection
  • Blood clot
  • Shoulder stiffness
  • Shoulder weakness
  • Nerve or blood vessel damage

In some cases, the shoulder may fail to heal after surgery.

Recovery from Shoulder Instability Surgery

Patients are required to wear a sling or another immobilization device for several weeks after surgery to correct shoulder instability in order to properly support and protect the arm. Pain medication and applications of ice may be necessary for at least a few days following the procedure. Physical therapy can be very effective in restoring the flexibility and strength to the shoulder. Recovery periods vary depending on the extent of the shoulder damage, but full recovery typically takes several months.