The shoulder is a ball- and-socket joint, but with a special socket. When the ball comes out of the socket, this is called a dislocation.
The socket is made of muscle, tendon, and ligaments. The ball can only come out of the socket if something tears in the socket and lets the ball dislocate. The something that tears is usually the labrum and a key ligament in the front of the shoulder, an area called the Bankart Region. The labrum is tissue that rims the bony floor of the socket (glenoid). It is a soft type of cartilage deepens the socket. This helps keep the shoulder ball in the socket. This increased stability is very important for normal function of the shoulder.
Why do shoulders dislocate or become loose?
The most common reason for a dislocation is a trauma to the shoulder from a fall. Some shoulders will become loose from repetitive motions performed as part of a sport or a job. Swimmers and gymnasts are good examples of people who can develop loose shoulders from repetitive stress on the socket. A loose shoulder is called an unstable shoulder.
Loose shoulders do not usually come all the way out of the joint. Typically, they move around in the socket, and the patient can feel that the ball is on the verge of coming out of the joint.
A very small number of patients have structural problems with the socket associ- ated with how the bones formed prior to birth (called a congenital problem). These congenital problems set them up to have problems with a loose or dislocating shoulder.
In general, the younger you are when you have a dislocation, the higher the chance that the shoulder will keep coming out of the socket. In fact, if you are under thirty, very active, the chance of re-dislocating the shoulder is greater than 70 percent. If you are under twenty-five, the chance of re-dislocating is 98 percent. Because of the risk of re-dislocation in patients under thirty, it is often best to fix the torn ligament right after the first dislocation to prevent any further problems.
In patients over forty years old, the rate of re-dislocation is much lower, so often these patients can be treated without surgical repair of the ligament. However, these patients have an increased chance of tearing the rotator cuff tendons with a dislocation or a repeat dislocation. If the rotator cuff is torn from a dislocation, this is best treated with a surgical repair.
No matter what your age, each dislocation has a small, but very real, risk of injuring the shoulder. First, nerves can be stretched, resulting in loss of sensation or weakness. Next, the bone of the glenoid and humerus can be fractured. Finally, the cartilageon the glenoid and the humeral head can be damaged. All of these injuries canhave a serious long-term effect on how the shoulder can function.
What are the treatment choices for a loose or dislocated shoulder?
In patients who have developed a loose (unstable) shoulder from sports or work, we try to tighten the shoulder with physical therapy. If this is not successful, then surgical tightening is often necessary.
In patients who have a dislocated shoulder from a trauma, often I will surgically repair the ligament. This is best for a patient who is young enough to have a high chance of re-dislocating the shoulder or for an older patient who has not returned to full function after physical therapy.
What type of surgery is performed to treat a dislocated shoulder?
In general, the surgery must reattach the ligament in the front of the shoulder back to the bone in its normal position. This will restore the stability of the shoulder. This can be achieved either using the arthroscope or through the traditional open surgery.
I perform most of these as arthroscopic repairs, with very good results. However, there are certain patients and types of problems that are more successfully treated with the traditional open surgery.