Shoulder instability is a condition characterized by a loose shoulder joint that is able to move too much within the socket. Sometimes it becomes a chronic problem after a dislocation, which occurs when the ball of the upper arm bone comes out of the socket. The resulting instability may produce frequent slipping or partial dislocation known as subluxation, as well as full dislocation.
Shoulder instability can occur after an acute injury that stretches or tears the ligaments in the shoulder or be due to 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 are because it provides the arm with a tremendous range of motion. But 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.
People with unstable shoulders may experience pain and limited motion in the joint and feel that moving in the wrong way will cause their shoulder to dislocate. This may discourage participation in sports that require stretching the arm overhead. Younger patients who experience a traumatic dislocation are more likely to develop 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 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 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 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.
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. The length of time for a patient to achieve full recovery varies depending on how extensive the damage was, but typically takes several months.
As with any type of surgery, a procedure to repair shoulder instability does pose a risk of complications, although it is uncommon. The risks may include bleeding, infection, development of a blood clot, shoulder stiffness, failure of the repair to heal, shoulder weakness, failure to provide symptom relief and injury to a blood vessel or nerve.