Arthritis can be caused by several factors, depending on the form it takes and what area within the shoulder is affected. Three main types of arthritis generally affect the shoulder:

• Osteoarthritis — Wear-and-tear arthritis
• Rheumatoid arthritis — Inflammation of the joints
• Posttraumatic arthritis — Arthritis resulting from an injury

The shoulder joints most commonly affected are:

• The glenohumeral (ball and socket) joint
• The acromioclavicular joint (where the shoulder blade and collarbone meet)

To provide you with effective treatment, your physician will determine what type of arthritis you have, and which joint is affected.