cause of rheumatoid arthritis
A. A. A. Unlike osteoarthritis, a condition caused by wear and tear on joints, rheumatoid arthritis happens when your immune system targets your joint linings. Itâs a long-term condition that also affects other tissue, but the joints are usually the most severely affected.Doctors donât know exactly what causes RA.. A. Unlike osteoarthritis, a condition caused by wear and tear on joints, rheumatoid arthritis happens when your immune system targets your joint linings. Itâs a long-term condition that also affects other tissue, but the joints are usually the most severely affected. Doctors donât know exactly what causes RA.