Shoulder Instability and Weakness

Shoulder instability may follow a traumatic injury, or it can result from repetitive motions that weaken the shoulder joint.

What is shoulder instability?

The shoulder is the connection of three bones: the arm bone (humerus), the shoulder blade (scapula) and the collarbone (clavicle). The head of the humerus is a ball that fits into a socket, and it is held in place by muscles, ligaments and tendons. Weakness in the joint increases the risk that the ball will pop completely out of the socket (dislocation) or come partway out (subluxation).

A fall may cause the initial dislocation or subluxation, and the injury weakens the shoulder’s supporting structures. The joint then becomes susceptible to subsequent dislocations or subluxations. Repetitive motions involving the shoulder can also cause weakness and instability. Sports such as football, basketball, baseball and soccer increase the risk for injuries that lead to shoulder instability.

Treating shoulder instability with physical therapy

While surgery is sometimes necessary, most cases of shoulder instability and weakness can be treated with physical therapy. Strengthening exercises, heat, cold, massage, ultrasound and electrical stimulation are some of the treatments that may be helpful.