Shoulder Instability

Anatomy / Pathophysiology – Shoulder Instability

Shoulder instability can be a common problem following a shoulder dislocation. After the first violent injury that causes the shoulder to dislocate, the joint may remain unstable. This can result in repeated episodes of dislocation, even during normal activities.

Sometimes the shoulder does not come completely out of the socket but slips partially out and then returns to its normal position. This is called subluxation. In some cases, instability may be present without an initial dislocation. The initial injury may not have been severe enough to cause a dislocation or all the joints may be hyper-lax due to a genetic problem with the connective tissue of the body.

97 out of 100 dislocations are anterior, meaning that the humerus slips out of the front of the shoulder socket. Only 3 out of 100 dislocate posteriorly, or out the back.

Symptoms -Shoulder Instability

Shoulder dislocation

A shoulder dislocation is usually very obvious. The injury is usually very painful and the shoulder looks abnormal. A dislocated shoulder may cause damage to the nerves around the shoulder joint. This is usually temporary. Subluxation of the shoulder usually causes a quick feeling of pain, like something is slipping, or pinching, in the shoulder.


Diagnosis – Shoulder Instability

The diagnosis of shoulder instability relies on the history and physical examination. For the dislocated shoulder, xray-shoulder-jointxrays are necessary to rule out a fracture of the shoulder as well. Xrays are usually done after the shoulder is relocated as well, to check and make sure it is back in place and no fractures are present.

In some cases where the diagnosis is in question, special tests such as examining the shoulder while you are under general anesthesia, and arthroscopy may be suggested. This will allow your doctor to test the ligaments of the shoulder while you are asleep and the muscles around the shoulder are paralyzed. Remember that the muscles play an important role in the stability of the shoulder and it is sometimes difficult to test the ligaments alone if you are awake and reflexively tightening these muscles during the exam.

Treatment – Shoulder Instability

The treatment of shoulder instability begins with a well designed physical therapy program. The two major parts to stability of the shoulder are the muscles and the ligaments about the shoulder. If the ligaments have been weakened by injury, the muscles can be strengthened to replace them to some extent.

If rehabilitation fails to stabilize your shoulder, surgery may be suggested. There are many different types of shoulder operations designed to stabilize the shoulder. Nearly all of these operations attempt to tighten the ligaments that are loose, usually the ligaments at the front of the shoulder.

Probably the most popular method for surgically stabilizing the shoulder that dislocates anteriorly (out the front) is a procedure known as a Bankart repair.

Shoulder Joint, joint capsule


This procedure was developed based on the idea that the primary reason the  shoulder is dislocating is that the ligamentsin the front of the joint have been torn from their attachment on the front end of the socket(glenoid) of the shoulder joint. In this type of operation the ligaments are sewn or stapled back into their original position, and allowed to heal so that the shoulder is once again stable.

Typically this operation is done through an incision on the front of the shoulder, but some physicians prefer to perform a similar operation with the aid of the arthroscope. This is a new technique and not widely
practiced yet.


Speak Your Mind