Shoulder arthritis is the degeneration of cartilage in the glenohumeral joint (shoulder socket) and acromioclavicular joint. There are several causes for arthritis in the shoulder. Osteoarthritis is the primary cause of shoulder arthritis. Osteoarthritis is common in older patients and is rarely seen in younger athletes. Osteoarthritis results from wearing down the smooth articular cartilage surrounding the bone. The articular cartilage is located on the surface of the glenoid (bone of the shoulder socket) and humeral head (the ball of the upper arm bone). Osteoarthritis causes more bone to bone contact, which produces pain and stiffness in the shoulder. This bone to bone contact instigates the formation of bone spurs (osteophytes) that will also contribute to the pain and reduce mobility. Rheumatoid arthritis is an inflammatory disease of the synovium (a specialized membrane) in the shoulder joint, and it also causes pain and decreased range of motion.

Post-traumatic arthritis can arise after injuries occur in the shoulder. Injuries such as rotator cuff tears and dislocations can lead to the humeral head rubbing against other bones in the shoulder. This bone to bone contact can damage the cartilage covering the surfaces of the bone and develop arthritis. Dislocations can also form tears in the articular cartilage and make the bones in the shoulder more susceptible to developing arthritis. Arthritis in the glenohumeral joint is indicated by a deep, aching pain that is located toward the center and back of the shoulder. Arthritis in the acromioclavicular joint causes pain on top of the shoulder that frequently radiates up the neck. Arthritis in the shoulder can limit the range of motion of the arm and movement can produce a grinding sound. Non-surgical treatment plans are recommended to reduce the pain and restore mobility of the joint. If non-surgical treatment does not provide relief, minimally invasive arthroscopic surgery may be recommended to remove debris from the shoulder and relieve the pain depending on the degree of arthritis and patient age. Alternatively, a total shoulder replacement is recommended when the arthritis becomes advanced with severe symptoms.