Arthritis (from Greek arthro-, joint + -itis, inflammation) is a group of conditions that affect the health of the bone joints in the body. One in three adult Americans suffer from some form of arthritis and the disease affects about twice as many women as men.

Arthritic diseases include rheumatoid arthritis and psoriatic arthritis, which are autoimmune diseases; septic arthritis, caused by joint infection; and the more common  osteoarthritis, or degenerative joint disease. Arthritis can be caused from strains and injuries caused by repetitive motion, sports, overexertion, and falls. Unlike the autoimmune diseases, osteoarthritis largely affects older people and results from the degeneration of joint cartilage. Other forms are discussed below.

Arthritic joints can be sensitive to weather changes. The increased sensitivity is thought to be caused by the affected joints developing extra nerve endings in an attempt to protect the joint from further damage.

Signs and symptoms

All arthritides feature pain, which is generally worse in the morning and on initiating movement, and resolves in the cause of time. In elderly people and children, the pain may not be the main feature, and the patient simply moves less (elderly) or refuse to use the affected limb (children).

When faced with joint pain, a doctor will generally ask about several other medical symptoms (such as fever, skin symptoms, breathlessness, Raynaud's phenomenon) that may narrow down the differential diagnosis to a few items, for which testing can be done.

Arthritis and fever together are pointers towards septic arthritis. This is a medical emergency, and requires urgent referral to a rheumatologist.

Treatment

Treatment options vary depending on the precise condition, but include surgery, and drug treatment, reduction of joint stress, physical and occupational therapy, and  pain management. There are also numerous herbal remedies that purportedly treat arthritis, including Harpagophytum procumbens. For specifics, see the articles on the individual conditions listed below.

Primary forms of arthritis:

• Septic arthritis
• Rheumatoid arthritis
• Osteoarthritis
• Gout and pseudogout
• Juvenile arthritis
• Still's disease
• Ankylosing spondylitis

Secondary to other diseases:

• Systemic lupus erythematosus (SLE)
• Henoch-Schönlein purpura
• Psoriatic arthritis
• Reiter's syndrome
• Reactive arthritis
• Hemochromatosis
• Hepatitis
• Wegener's granulomatosis (and many other vasculitis syndromes)
• Familial Mediterranean fever (FMF), HIDS and TRAPS.

Diseases that can mimic arthritis:

• Pierre Marie-Bamberger syndrom e (hypertrophic pulmonary osteoarthropathy, a paraneoplastic phenomenon of lung cancer)
• multiple myeloma
• osteoporosis
• others