4.06 Osteoarthritis vs Rheumatoid Arthritis Rheumatology review for the USMLE Step 1 exam Rheumatoid arthritis and osteoarthritis both cause joint inflammation, joint pain, and can limit joint range of motion Osteoarthritis is a degenerative joint disease that occurs when the articular cartilage that covers the ends of bones begins to degrade and erode The most common joints affected by osteoarthritis are the hips and knees, and the distal interphalangeals of the hands are also commonly affected Osteoarthritis tends to be more asymmetric and localized, presenting as a single degenerated joint Rheumatoid arthritis is an inflammatory autoimmune disease that affects the joints and other parts of the body RA typically develops in patients who are genetically predisposed and triggered by environmental factors, such as smoking The two autoantibodies present in RA are rheumatoid factors and anti-cyclic citrullinated peptide (anti-CCP) antibodies Rheumatoid factors activate the complement system and stimulate the inflammatory response in the body. Anti-CCP antibodies bind citrullinated peptides and stimulate inflammation in the synovium of joints Rhematoid arthritis has extra-articular manifestations, the most common of which are rheumatoid nodules