Arthritic shoulder. Coloured X-ray of the right shoulder of a patient with periarthritis. The upper arm bone (humerus, centre left) articulates with the shoulder blade (scapula, centre right) at the shoulder. Periarthritis, also called frozen shoulder, is the inflammation of tissues around the shoulder joint. It causes pain and limits the movement of the shoulder. Periarthritis may be associated with other forms of arthritis such as rheumatoid or osteoarthritis. It may also be associated with diabetes mellitus, or may develop following a fractured or dislocated shoulder. Treatment is with analgesic and anti-inflammatory drugs and controlled exercise.