is inflammation of one or more joints. There are many types of arthritis. The two most common types of arthritis range from those related to wear and tear of cartilage causing osteoarthritis to those associated with inflammation resulting from an overactive immune system such as rheumatoid arthritis.
Osteoarthritis initially affects the smooth cartilage lining of the joint. This makes movement more difficult than usual, leading to pain and stiffness. The cartilage lining of the joint can then thin and tissues within the joint can become more active. This can then lead to swelling and the formation of bony spurs, called osteophytes.
In osteoarthritis, the cartilage (connective tissue) between the bones gradually erodes, causing bone in the joints to rub together. The joints that are most commonly affected are those in the hands, spine, knees and hips.
Rheumatoid osteoarthritis occurs when the body's immune system targets affected joints, which leads to pain and swelling. The outer covering (synovium) of the joint is the first place affected. This can then spread across the joint, leading to further swelling and a change in the joint's shape. This can cause the bone and cartilage to break down. People with rheumatoid arthritis can also develop problems with other tissues and organs in their body.
Symptoms of arthritis include pain and limited function of joints. Arthritis sufferers include men and women, children and adults. Earlier and accurate diagnosis can help to prevent irreversible damage and disability.
The causes of arthritis depend on the form of arthritis. Causes include injury leading to osteoarthritis, metabolic abnormalities like gout, hereditary factors, the direct and indirect effect of infections (bacterial and viral) and a misdirected immune system with autoimmunity such as in rheumatoid arthritis.