what is synovitis within the AC joint.
Acromioclavicular Joint Pain. Common causes are arthritis and synovitis, also called osteolysis. There is a small joint between the bones of the clavicle and the acromion, which is covered with articular cartilage and surrounded by a synovial membrane which makes fluid.
Joint Degeneration. The acromio-clavicular joint is the anatomical part of the shoulder where the collarbone joins the shoulder. It is commonly called the A/C joint or ACJ. Pain and inflammation may occur as part of a sudden (acute) injury, or a recurrent overload (overuse) injury.