Osteoarthritis is a deterioration of cartilage and overgrowth of bone often due to "wear and tear". Rheumatoid arthritis is the inflammation of a joint's connective tissues, such as the synovial membranes, which leads to the destruction of the articular cartilage.
Update Date 10/18/2015
Updated by: Gordon A. Starkebaum, MD, Professor of Medicine, Division of Rheumatology, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.