What is Shoulder Instability / Dislocation?

The shoulder is a ball-and-socket joint, and the socket is shallow, which gives the shoulder wide motion but also makes it prone to dislocation.

Instability means the ball moves too far within or out of the socket. A full dislocation is when the ball comes all the way out; a partial slip that goes back on its own is called a subluxation.

Instability often starts with a first dislocation from a fall or a sports collision. That first event can stretch or tear the soft tissues that normally hold the joint in place, which makes later slips more likely. Some people have naturally loose ligaments, the bands that connect bone to bone, and develop instability without a single injury.

Signs include the shoulder feeling loose or like it may give way, repeated slipping with certain arm positions, pain, and a sense of apprehension when the arm is raised and rotated outward.

How is Shoulder Instability / Dislocation diagnosed, and what does the visit involve?

Shoulder instability is diagnosed with a history, an exam, and imaging.

Dr. McMillan will ask how the shoulder first slipped and in what positions it happens now, then test how far the joint moves and check for apprehension when the arm is placed in the at-risk position. X-rays show the bones and reveal a dislocation or fracture. An MRI or a specialized MRI with contrast, called an MR arthrogram, shows tears in the labrum, the rim of cartilage that deepens the socket, and in the ligaments. A CT scan is used when bone loss needs to be measured. These findings guide whether therapy alone or a stabilization procedure fits.

What can I expect over time?

After a first dislocation, many shoulders settle and grow steadier as the muscles around the joint are strengthened through the therapy described above.

Some shoulders keep slipping, particularly in younger, active people, so the natural course varies from person to person. It helps to check back with Dr. McMillan if the shoulder keeps giving way, slips again, or feels unstable during everyday activities, since repeated slips may point toward a stabilization procedure.