Diseases of the Joints

Abstract

Synonyms: Chronic polyarthritis, primary chronic polyarthritis.

Rheumatoid arthritis is a systemic rheumatic inflammatory disease primarily affecting the synovial membrane of small joints. It also involves the synovial sheaths and bursae and can be accompanied by pulmonary, cardiovascular, neurological, and haematological disorders in various degrees.

Rheumatoid arthritis is a fairly common disease with a prevalence of roughly 1%. The onset usually occurs during the third to fifth decade of life and women are far more affected than men (3:1 ratio).

Viral (or possibly bacterial) antigens induce an autoimmune response in genetically predisposed persons (HLA-DR 4 antigen) causing an inflammatory infiltration of the synovia. The key component of the immune response is the cytokine-induced stimulation of B cells, to produce autoantibodies against the Fc fragment of IgG (= rheumatoid factor). These decisively initiate synovitis through complement activation and release of inflammatory mediators resulting in destruction of cartilage.