Three forms of arthritis can affect the two joints of the shoulder: osteoarthritis, rheumatoid arthritis and post-traumatic arthritis. In all cases, the main symptom is pain, which often is brought on by activity. To diagnose these conditions, doctors relay on a physical examination and X-rays. If arthritis is in an early stage, your physician may recommend physical therapy, rest, applying moist heat and icing any inflamed or painful areas. Surgical options depend on the type, stage and severity of the arthritis. However, surgery often is highly effective in reducing the discomfort associated with arthritis.