A group of diseases affecting joints or their component tissues. Several types of arthritis are recognized, and these can be divided into groups by their clinical course and pathologic appearance. There are four basic types of arthritis: inflammatory arthritis, degenerative joint disease, nonarticular rheumatism, and miscellaneous arthritis.
Inflammatory arthritis is characterized by inflammation of tissues associated with joints. Connective tissue diseases, crystal deposition diseases, infectious arthritis, and spondyloarthropathies are examples of inflammatory arthritis. Connective tissue diseases are a group of acute and chronic diseases characterized by involvement of joints, connective tissue, serosal membranes, and small blood vessels. These diseases are divided into acquired disorders (for example, rheumatoid arthritis, systemic lupus erythematosus, scleroderma, polymyositis, vasculitis) and rare hereditary diseases (for example, Ehlers-Danlos syndrome). Rheumatoid arthritis is the most common variety of inflammatory arthritis. It occurs in younger and middle-aged persons and is characterized by noninfectious inflammation of the synovium (joint-lining membrane) frequently associated with extraarticular manifestations other than in the joints. The etiology is unknown, but genetic, immunologic, infectious, and psychologic disturbances have all been suggested. The systemic disease follows a variable but slowly progressive course, marked by spontaneous flares and remissions. There are three groups of crystal deposition disease classified according to type of crystal involvement: gout (monosodium urate), pseudogout (calcium pyrophosphate), and calcific tendonitis (hydroxyapatite). Infectious arthritis is an inflammatory joint disease caused by the invasion of the synovial joint by living microorganisms such as gonorrheal, streptococcal, and staphylococcal bacteria. Such arthritis usually results from a generalized infection but may appear following local spread or after trauma. The spondyloarthropathies are types of inflammatory arthritis characterized by involvement of the axial (central) skeleton (for example, the spine rather than the limbs). Ankylosing spondylitis and Reiter's syndrome are examples of the spondyloarthropathies. See also Connective tissue disease; Gonorrhea; Gout; Staphylococcus; Streptococcus; Uric acid.
Degenerative joint disease (osteoarthritis) is a ubiquitous joint disease characterized pathologically by deterioration of cartilage lining the joints and new bone formation beneath the cartilage. The disease is very common in older persons and is thought to be inherent in the aging process. Degenerative joint disease is marked by a progressive stiffness, loss of function, and destruction of the larger, weight-bearing joints of the body. With advancing age, the continued slow damage causes increasing disability. See also Aging.
Nonarticular rheumatism is a group of diseases, also called soft-tissue rheumatisms, that includes tendonitis, bursitis, tenosynovitis, and fibrositis. The etiology is unclear, but the disorder may relate to psychobiologic or sleep disturbances or muscular and soft-tissue abnormalities. See also Bursitis; Rheumatism.
Systemic diseases of other or unknown etiology may produce arthritis or joint destruction. There are neurologic, blood, and endocrine examples of these unusual rheumatic diseases.
Disability can often result from arthritis but can be curtailed by general health maintenance, rest, and rehabilitation. Occupational and physical therapies can be helpful. Diagnosis of the particular type of arthritis is extremely important in choosing drug therapy. Rheumatoid arthritis can be treated with nonsteroidal anti-inflammatory drugs such as aspirin. Disease-modifying antirheumatic drugs and immunosuppressive drugs are also frequently used. Osteoarthritis is treated with anti-inflammatory and analgesic drugs. Cortisone compounds are also used to treat arthritis, but the dosage and duration of treatment must be carefully monitored because of significant side effects. Surgical treatment includes arthroscopic surgery and joint replacement. See also Autoimmunity.