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What is an Unstable Shoulder

The shoulder is the most mobile joint in the human body. This also makes the shoulder the most often dislocated joint in the human body. Shoulder instability or an unstable shoulder is a general term representing many different types of problems. As the bony socket of the shoulder provides very little inherent stability, the shoulder relies on the tissues surrounding it for stability – labrum, capsule, ligaments, rotator cuff, and the shoulder girdle and core muscles that help position the shoulder blade. Tearing, stretching, or injury of any or all of these tissues can result in an unstable shoulder.

While an unstable shoulder can occur at any age, the most common are less than 30 years of age and 50 to 70 years of age. However, multiple episodes of instability are more common in younger patients. Older patients who suffer a dislocation also have a higher risk of tearing the rotator cuff.

It is important to consider all the potential sites and causes of injury in developing a treatment plan that can address each in a highly successful manner. The decision and plan for treatment is recommended keeping each patient’s goals and desires in mind.

Next, it is important to take the risk of continued shoulder instability into account. As the chart below demonstrates, a patient suffering a shoulder dislocation at age 20 has a much higher risk of the shoulder continuing to be unstable than a patient that suffers a dislocation at age 40.

Studies have also shown that with a greater number of dislocations, the risk of developing shoulder arthritis at an earlier age increases.


Utilizing advanced arthroscopic techniques, we are able to address the entire spectrum of soft tissue injuries responsible for shoulder instability in a highly successful manner. Our advanced arthroscopic technique has an approximately 95% rate of success.

As the shoulder joint is circular, a tear on one side requires stretching or tearing of tissue on the opposite side. This “circle concept” of shoulder instability has helped greatly improve the results of treatment for shoulder instability by recognizing that any method of treatment must address all potential causes of instability.

Injury can result in tearing or stretching in more than one zone at the same time and we typically find that successful treatment requires treating pathology in all three zones.


The following video will open in a new window and shows sutures being used to tighten the capsule in all three zones for a patient with an unstable shoulder:

Zone A: Superior


Zone B: Anterior
HAGL/Capsular Tear


Anterior Tear in a patient with Posterior Dislocation


Zone C: Posterior
Posterior Tear in the same patient as above

Global Repair Completed for Successful Treatment