Rheumatoid arthritis a condition of the immune system that can attack joints throughout the body, commonly affects the shoulder. Overtime, it can destroy cartilage and bone in the joint.

Approximately 2.1 million people in the US have rheumatoid arthritis. Anyone can be affected by the disease, including children (juvenile rheumatoid arthritis), but 70 percent of those affected are women. Symptoms usually begin between 30 and 50 years of age.

It’s not known exactly what causes rheumatoid arthritis. It may in fact be a combination of several similar diseases rather than a single disease. It is known, however, that the immune system is a key player in the disease process. In patients with rheumatoid arthritis, the immune system mistakes healthy  for a foreign invader and attacks it.

Another, less common, form of arthritis that can affect the shoulder is called Sceptic arthritis. This form of arthritis can result from infection from , viruses or other microorganisms. It also is associated with rheumatoid arthritis.

Causes

The causes of RA aren’t fully understood. It may be caused by inherited genetic factors, but environmental factors may also play a role in triggering the condition.

Symptoms can include pain, stiffness, a limited range of motion, swelling, and a sensation of grinding or popping in the joint. Symptoms don’t always progress steadily – they may worsen, improve, and then worsen again.