Rheumatoid arthritis is a systemic autoimmune disease which initially attacks the synovium, a connective tissue membrane that lines the cavity between joints and secretes a lubricating fluid.
Review Date 4/8/2019
Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.