What is frozen shoulder?
Frozen shoulder results from the gradual loss of movement in the shoulder (glenohumeral) joint. This joint consists of a ball (the humeral head) and socket (the glenoid). Normally it is one of the most mobile joints in the body. When the shoulder is frozen, the joint has become stuck and its movement is limited.
What causes frozen shoulder?
Although many shoulder diseases involve pain and loss of motion, frozen shoulder is most often caused by inflammation (swelling, pain and irritation) of the tissues surrounding the joint. The tissue that envelops the joint and holds it together is called the capsule. Normally the capsule has folds that can expand and contract as the arm moves into various positions. In a frozen shoulder, the capsule has become inflamed and scarring develops. The scar formations are called adhesions. As the capsule’s folds become scarred and tightened, shoulder movement becomes restricted and moving the joint becomes painful. This condition is called adhesive (scarring) capsulitis (inflammation of the capsule).