Shoulder Dislocation & Instability
What Is a Shoulder Dislocation?
The shoulder is a ball-and-socket joint, with the ball (the head of the humerus, or upper arm bone) sitting in a shallow socket on the shoulder blade called the glenoid. This shallow socket is what gives the shoulder its remarkable range of motion — but it also makes the shoulder the most frequently dislocated joint in the body. A dislocation occurs when the ball is forced completely out of the socket. When the ball only partially slips out and returns on its own, it’s called a subluxation. Shoulder instability refers to a shoulder that dislocates or subluxates repeatedly, often after an initial dislocation stretches or tears the tissues that normally hold the joint in place.
What Causes a Shoulder Dislocation?
- A fall onto an outstretched arm
- A direct blow to the shoulder, common in contact sports
- Forcefully raising and rotating the arm overhead, such as during an awkward throwing or reaching motion
- Repetitive overhead activity in patients with naturally looser ligaments, which can lead to instability without a single traumatic event
The vast majority of shoulder dislocations occur toward the front of the joint (anterior dislocation), though dislocations toward the back (posterior) or in multiple directions are also possible.
What Are the Symptoms of a Shoulder Dislocation?
- Visible deformity, with the shoulder appearing out of its normal rounded shape
- Severe pain at the moment of injury
- Inability to move the arm
- Swelling and bruising
- Numbness or tingling down the arm, since nerves running near the joint can be stretched during a dislocation
- After the joint is relocated, a lingering sense that the shoulder feels loose or “unstable”
Why Do Shoulders Dislocate More Than Once?
The first dislocation often tears or stretches the labrum — a ring of cartilage that deepens the socket and helps hold the ball in place — along with the surrounding ligaments. Once these structures are damaged, the socket no longer holds the ball as securely, making repeat dislocations more likely, especially in younger patients. Each subsequent dislocation can cause further damage to the labrum, ligaments, and even the bone at the edge of the socket, which is why recurrent instability is taken seriously rather than treated as “just” a repeat of the same minor injury.
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Treatment Options for Shoulder Dislocation & Instability
Nonsurgical treatment is often appropriate after a first-time dislocation, especially in older patients with a lower risk of recurrence:
- A brief period of immobilization in a sling
- Physical therapy focused on restoring motion and strengthening the muscles that support the shoulder
- Activity modification during the initial healing phase
Surgery is more often considered for younger, active patients after a first dislocation (who carry a higher risk of recurrence), for anyone with recurrent instability, or when imaging shows significant damage to the labrum or bone. The most common surgical treatment is an arthroscopic Bankart repair, which reattaches the torn labrum; more complex or bone-deficient cases may require a Latarjet procedure. Learn more on our Bankart Repair and Latarjet Procedure pages.
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Dr. Palsis specializes in the treatment of knee, shoulder, and sports injuries.