A frozen shoulder, or adhesive capsulitis, causes pain and difficulty of movement in the shoulder area due to inflammation of the connective tissue around the shoulder joint. Pain from a frozen shoulder is a dull ache around the outer shoulder and upper arm that worsens with movement. Over time, the shoulder goes through a period where pain slowly increases until the shoulder is completely "frozen," and then "thaws" as movement returns.
The cause of frozen shoulder is not yet known, though it is more common in people with diabetes, thyroid disorders, and other diseases. It also occurs after a period in which a person has been unable to move their shoulder due to surgery or injury. Treatment includes NSAIDs to reduce pain, physical therapy, or surgery.