X Close

Request An Appointment

All fields are mandatory.
Any Questions? Call Us: (203) 268-2882

What Causes Shoulder Instability?

The shoulder is a ball and socket joint made up of the head of the humerus (arm bone) and the glenoid cavity of the scapula (shoulder blade). Because the shoulder joint is the most mobile joint in the body, it’s also the joint that is the most unstable. The following are the three most common causes of shoulder instability:

Rotator Cuff Injuries 

The rotator cuff muscles and tendons hold the shoulder in place and help move it. The rotator cuff is the major dynamic stabilizer of the shoulder joint. Age and/or injury can partially or completely tear the rotator cuff tendons and cause shoulder instability. When the rotator cuff tendons are torn, the head of the humerus loosely fits in the glenoid cavity. Movement can cause a partial dislocation (subluxation) or complete dislocation. In many cases, physical therapy can be used to strengthen an injured rotator cuff and improve shoulder instability. A rotator cuff that is completely torn may require surgical intervention in the form of a rotator cuff repair.

Illustration 1- The muscles and tendons of the rotator cuff

Labrum Injuries

An outer rim of cartilage known as the labrum surrounds the glenoid cavity (shoulder socket). A healthy labrum allows the head of the humerus to sit perfectly in the glenoid cavity. It is considered one of the primary static shoulder stabilizing structures. A partially or completely torn labrum allows the head of the humerus to move in and out of the cavity. Like rotator cuff tears, labral tears are caused by age and/or injury. The degree of shoulder instability corresponds to the severity of the tear. Small tears may be treated non-surgically. Large, complete tears may require surgical intervention. The most common labral injuries that require surgical intervention are a superior labral anterior to posterior (SLAP) tears and a Bankart tears.

Illustration 2- A partially torn labrum

Repetitive Strain

Many patients are born with loose shoulder ligaments. When overhead sports and/or activities are performed, the ligaments are stretched and shoulder instability may develop. The best way to treat shoulder instability caused by loose ligaments and repetitive strain is by using physical therapy to strengthen the surrounding structures, including the shoulder muscles, tendons, and ligaments.

Seeking Treatment

If shoulder instability is affecting the way you live your life, please don’t hesitate to contact one of our 5 Fairfield County offices to arrange an appointment with one of our orthopedic shoulder specialists. Regardless of the cause of your shoulder instability, we’ll have a treatment option that’s right for you. You can expect results when you choose our experts.