Unstable / Dislocating Shoulder

What is it?

The shoulder is the most moveable joint in your body. It helps you to lift your arm, to rotate it, and to reach up over your head. It is able to turn in many directions. This greater range of motion, however, can cause instability.

Shoulder instability occurs when the head of the upper arm bone is forced out of the shoulder socket. This typically happens as a result of a sudden injury, such as a fall or accident.


Once a shoulder has dislocated, it is vulnerable to repeat episodes. When the shoulder is loose and slips out of place repeatedly, it is called chronic shoulder instability.

When the ball of the upper arm comes partially out of the socket, this is called a subluxation. A complete dislocation means the ball comes all the way out of the socket.


Once the ligaments, tendons, and muscles around the shoulder become loose or torn, dislocations can occur repeatedly. Chronic shoulder instability is the persistent inability of these tissues to keep the arm centered in the shoulder socket.


Common symptoms of chronic shoulder instability include:

Mechanism of Injury

There are two common ways that a shoulder can become unstable:

Shoulder Dislocation

Severe injury, or trauma, is often the cause of an initial shoulder dislocation. When the head of the humerus dislocates, the socket bone (glenoid) and the ligaments in the front of the shoulder are often injured. The labrum — the cartilage rim around the edge of the glenoid — may also tear. This is commonly called a Bankart lesion. A first dislocation can lead to continued dislocations, giving out, or a feeling of instability.


Some people with shoulder instability have never had a dislocation. Most of these patients have looser ligaments in their shoulders. When this increased looseness is just your normal anatomy, it is called hyperlaxity.

Sometimes, the looseness is the result of repetitive overhead motion. Swimming, tennis, and volleyball are among the sports requiring repetitive overhead motion that can stretch out the shoulder ligaments. Many jobs also require repetitive overhead work.

Looser ligaments can make it hard to maintain shoulder stability. Repetitive or stressful activities can challenge a weakened shoulder. This can result in a painful, unstable shoulder.

In a small minority of patients, the shoulder can become unstable without a history of injury or repetitive strain. In such patients, the shoulder may feel loose or dislocate in multiple directions, meaning the ball may dislocate out the front, out the back, or out the bottom of the shoulder. This is called multidirectional instability. These patients have naturally loose ligaments throughout the body and may be “double-jointed”.

Common Management Techniques


Recovery will depend on age, the severity of the subluxation/dislocation, necessity for surgery, and the patient’s response to treatments. These injuries are slow to heal with recovery time ranging from 6 weeks to 12 months. 


To avoid recurrence a home exercise program, to build adequate strength, is an essential component of your rehabilitation. For more information feel free to ask your physiotherapist.