Definition of Arthritis:

Arthritis is inflammation of one or more joints, which results in pain, swelling, stiffness, and limited movement. There are over 100 different types of arthritis.

See also: Joint pain

Causes, incidence, and risk factors:

Arthritis involves the breakdown of cartilage. Cartilage normally protects the joint, allowing for smooth movement. Cartilage also absorbs shock when pressure is placed on the joint, like when you walk. Without the usual amount of cartilage, the bones rub together, causing pain, swelling (inflammation), and stiffness.

You may have joint inflammation for a variety of reasons, including:

• An autoimmune disease (the body attacks itself because the immune system believes a body part is foreign)
• Broken bone
• General "wear and tear" on joints
• Infection (usually caused by bacteria or viruses)

Often, the inflammation goes away after the injury has healed, the disease is treated, or the infection has been cleared.

With some injuries and diseases, the inflammation does not go away or destruction results in long-term pain and deformity. When this happens, you have chronic arthritis. Osteoarthritis is the most common type and is more likely to occur as you age. You may feel it in any of your joints, but most commonly in your hips, knees or fingers. Risk factors for osteoarthritis include:

• Being overweight
• Previously injuring the affected joint
• Using the affected joint in a repetitive action that puts stress on the joint (baseball players, ballet dancers, and construction workers are all at risk)

Arthritis can occur in men and women of all ages. About 37 million people in America have arthritis of some kind, which is almost 1 out of every 7 people.

Other types or cause of arthritis include:

• Adult Still's disease
• Ankylosing spondylitis
• Fungal infections such as blastomycosis
• Gonococcal arthritis
• Gout
• Juvenile rheumatoid arthritis (in children)
• Other bacterial infections (nongonococcal bacterial arthritis)
• Psoriatic arthritis
• Reactive arthritis (Reiter syndrome)
• Rheumatoid arthritis (in adults)
• Scleroderma
• Systemic lupus erythematosus (SLE)
• Tertiary Lyme disease
• Tuberculous arthritis
• Viral arthritis