Rheumatoid arthritis is another form of arthritis. The body’s own immune system attacks a joint’s synovial membrane, which secretes fluid and lines the joint. The synovium becomes inflamed, produces excess fluid, and the cartilage becomes rough and pitted.
Review Date 5/21/2017
Updated by: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.