What is rheumatoid arthritis?

Arthritis means inflammation of the joints. Unlike osteoarthritis (OA), the most common form of arthritis that is caused by general wear and tear, RA is caused by an autoimmune reaction where the immune system attacks the tissue that protects joints, leading to the characteristic pain, swelling, inflammation and eventual joint destruction. RA tends to affect the joints in a different way than OA. RA joints have a distinct, more 'squishy' type of joint swelling in contrast to the type of hard, bony enlargement of joints that is often seen in the fingers of people with OA.