Arthritis affects more than 50 million Americans. Shoulder arthritis is one type of arthritis that when left untreated can make it hard to do simple everyday tasks. Here are a few common forms of shoulder arthritis. If you think you may be suffering with arthritis of the shoulder, you should discuss treatment options with your physician.

Osteoarthritis (OA)
The damage from Osteoarthritis is known to be from wear and tear over time. The cartilage which covers the bone begins to wear away and bones begin to rub against one another, which causes pain. This condition most commonly affects people over 50, and progressively gets worse.

Rheumatoid Arthritis (RA)
RA is an autoimmune disorder in which the body mistakenly attacks the shoulder joints. The joints begin to feel stiff and painful. What makes RA different from other types of arthritis is that is often occurs in both shoulders at once instead of just one.

Rotator Cuff Arthropathy
This condition occurs when there is a tear in the rotator cuff. The arm bone, the humerus, becomes difficult to hold and it can move out of place, rubbing against other bones. This rubbings against bone is what eventually leads to pain and arthritis.

Sources:
http://www.painmanagementdr.com/blog/2015/march/types-of-shoulder-arthritis.aspx