Although there are many types of arthritis that can effect the shoulder joint, the most common ones are Osteoarthritis, Rheumatoid Arthritis, and Arthritis of Dislocation.

Osteoarthritis occurs when the surfaces of the joint wear out and the soft and smooth surfaces become worn down to hard bone. The true cause of osteoarthritis is unknown and although the process is progressive, the rate of progression varies from patient to patient. The destruction of the bone is however, typical in osteoarthritis. While the head of the humerus can flatten and lose it’s covering of smooth articular cartilage, the glenoid (socket) tends to lose it’s cartilaginous covering and wear down to bone mostly on the back side of the socket.

Rheumatoid Arthritis is a systemic disease that effects soft tissues, organs and the joints of the body. The damage to the joint surfaces is mediated by the joint’s own lining. The joint is lined by a thin layer of cells called synovial cells. The joint surfaces are attacked by aggressive synovial proliferation. The surfaces soften and can collapse after progressive involvement. Rheumatoid arthritis is usually managed by a primary care physician or rheumatologist, in order to decrease the inflammation and the aggressive nature of the synovial proliferation.

Arthritis of Dislocation is the result of damage to the shoulder joint from instability. When the shoulder dislocates, the relationship of the ball and socket of the humerus and scapula is changed. The ligaments that keep the humeral head (ball) in the socket are damaged when the shoulder dislocates. Continued use of the shoulder when the moving surface is unbalanced can cause uneven wear and progressive arthritis. The unstable shoulder continues to damage itself with each dislocation until the restraints to instability are totally destroyed. At the point of destruction of the ligamentous restraints in the shoulder, the movement of the ball can occur anywhere on the socket, or even beyond the socket. Instability of the shoulder is therefore best addressed early.

How is arthritis diagnosed?
Orthopedic surgeons can diagnose shoulder arthritis with a combination of a physical exam and x-rays. Blood tests may be required to diagnose Rheumatoid Arthritis, and most rheumatologists use the results of the blood tests to guide treatment.

Physical examination of the arthritic shoulder usually demonstrates limited motion in all directions with pain. Crepitus (the crunching sensation inside a joint) is frequently found in shoulder arthritis.

X-ray evaluation of the arthritic shoulder will demonstrate different things depending on the type of arthritis there is in the shoulder.

Osteoarthritis and rheumatoid arthritis, although similar usually have different x-ray appearances, and can be differentiated on x-ray appearance most of the time. Occasionally there are questions regarding the soft tissues in addition to the bony changes and an MRI is useful to view the rotator cuff, or other soft tissues around the shoulder.

How is arthritis treated?
Once the process of osteoarthritis begins in the shoulder, it is important to maintain as much flexibility and strength in the shoulder to prevent stiffness, which can cause more pain. Treatment is usually with anti-inflammatory medication and therapy to minimize symptoms. In the earliest stages of arthritis, arthroscopy may be beneficial to remove loose bodies or inflammatory tissue in the joint and to provide temporary relief. Long lasting relief from the pain of shoulder arthritis can be provided by Shoulder Replacement surgery, which involves removing the diseased bone and replacing it with a prosthetic implant.