Conditions that involve disorders of movement, associated with pain and limitation of movement, usually caused by inflammation processes in and around a joint. A large number of such inflammations are caused by disturbances of the body’s defence system, so-called autoimmune diseases, in which the body produces antibodies against its own cell structures and proteins. This group includes disorders such as rheumatoid arthritis, polymyositis and dermatomyositis, scleroderma, lupus erythematosus, Bechterew’s disease and Reiter’s syndrome. Autoimmune diseases primarily affecting other organs (such as ulcerative colitis and Crohn’s disease) are often associated with arthritis. In rheumatic fever the inflammation is caused as reaction to infection with certain bacteria (streptococci, after tonsillitis or scarlet fever). Arthrosis is caused by wear and tear on cartilage in joints, and the reaction of the bones to this. It is thus not an inflammation reaction of the kind characteristic of the above rheumatic disorders. In gout, uric acid crystals are deposited in the tissue of the joints, causing irritation and consequential inflammation. Polymyalgia rheumatica is associated with restricted movement not caused by inflamed joints but by as yet not understood disease processes in the muscles.