What is Instability in the Shoulder?

As a joint, the shoulder supports the greatest movement in the body, allowing you to lift and rotate the arm, as well as move it in many different directions. While the shoulder offers great range of motion, this motion also increases the risk of shoulder instability. Shoulder instability results when the head of the upper arm bone (humerus) is expelled from the shoulder socket, an injury known as shoulder dislocation. This can occur from a sudden injury or overuse.


Once the shoulder experiences a dislocation, it increases the risk of future dislocations. Repeated dislocations is a condition known as shoulder instability.

The shoulder consists of three bones: the humerus (upper arm bone), scapula (shoulder blade), and clavicle (collarbone). The head (or ball) of the upper arm bone first into the shallow socket (glenoid) of your shoulder blade. The head of the upper arm bone is held in the socket by strong connective tissue (shoulder capsule). Your shoulder also depends on strong muscles and tendons to maximize the stability of your shoulder.

Shoulder dislocation can occur partially, with the ball of the humerus becoming partially dislocated from the shallow socket, a condition known as subluxation. A complete shoulder dislocation occurs when the ball becomes completely dislocated from the socket.

When the muscles, tendons, and ligaments surrounding the shoulder become torn or loose, dislocations can occur frequently. Shoulder instability is the inability of the strong connective tissue to keep the ball of the humerus in the shoulder socket.

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What Causes Shoulder Instability?

Shoulder instability can occur in three ways.

Shoulder Dislocation

Shoulder instability can occur from an initial shoulder dislocation, caused by severe trauma or injury. When the ball of the humerus dislocates from the shallow socket, it glenoid (socket bone) and shoulder ligaments often experience injury. In some cases, the cartilage around the edge of the glenoid, known as the labrum, may tear, an injury called a Bankart lesion. A severe initial dislocation can results in subsequent, repeated dislocations, creating instability.

Repeated Strain

While shoulder dislocations commonly lead to shoulder instability, some people develop the condition through repetitive overhead motion. In these cases, the ligaments in the shoulder may loosen naturally. Shoulder instability from repetitive strain may occur in athletes of swimming, tennis, and volleyball, where repetitive overhead motion is common and can stretch the shoulder ligaments. Yet shoulder instability can also occur from jobs that rely on repetitive overhead work.

Looser shoulder ligaments make it easier to experience shoulder instability.

Multi-directional Instability

Less common, shoulder instability can result when the ball of the humerus dislocates in multiple directions, such as the front, back, or bottom of the shoulder socket. In this case, the shoulder can become instable without history of major trauma resulting in a shoulder dislocation, or repetitive strain. Multidirectional instability can occur because patients naturally have loose ligaments in the body. Patients experiencing this condition may be “double-jointed.”

What are the Symptoms of Shoulder Instability?

  • Pain from shoulder injury
  • Repeated shoulder dislocations
  • Persistent feeling of the shoulder giving out, slipping, or hanging

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How is Shoulder Instability Evaluated?

To determine if your shoulder is unstable, your doctor will perform a physical examination and order specific tests to assist in the evaluation of your condition. This includes X-rays to show injuries to the bones that comprise the shoulder joint, as well as magnetic resonance imaging (MRIs) to see detailed pictures of the ligaments and tendons surrounding your shoulder joint.

How is Shoulder Instability Treated?

Based on this evaluation, your doctor may recommend non-surgical or surgical treatment options.

Non-surgical Treatment

Non-surgical treatments include one or more of the following:

  • Non-steroidal anti-inflammatory medication – Over-the-counter medications like ibuprofen and aspirin reduce pain and swelling.
  • Lifestyle changes – Your doctor may recommend making changes to your daily activities and lifestyle to prevent the recurrence of injury
  • Physical therapy – Exercises focused on strengthening shoulder muscles and controlling the shoulder can increase shoulder stability.

Surgical Treatment

Surgery is often needed to heal stretched or torn ligaments and ensure they can keep the head of the humerus in place.

  • Arthroscopy – A minimally-invasive procedure, arthroscopy relies on making small incisions and using pencil-thin instruments to repair the soft tissue in the shoulder joint.
  • Open surgery – In some cases, patients may need open surgery, in which a relatively larger incision is made and surgeons perform the procedure under direct visualization (open) rather than a tiny camera, as used in arthroscopy.


Upon completion of shoulder surgery, your doctor will prescribe the use of a sling to immobilize the shoulder as it heals. Once you can resume movement, your doctor will recommend physical therapy to improve your shoulder’s range of motion and strengthen the shoulder.

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Contact the Hand Center of Louisiana

If you recognize the signs and symptoms of shoulder instability, contact us today to get timely evaluation and treatment by one of our highly trained physicians. As the largest hand and upper extremity practice in the Gulf South, we specialize in treating shoulder instability.