A joint is where the ends of two or more bones in the body meet. Most joints are movable and allow the body parts to engage in activity. Healthy joint anatomy maintains stability while allowing the bones to glide over each other through a full range of motion without discomfort. Damage to joints caused by injury or disease can hamper smooth movement, interfere with activity, and cause pain.
Arthritis refers to joint disease affecting one or more joints. The word itself means joint inflammation, which can be a symptom of the disorder along with pain, stiffness, and a decreased range of motion. Arthritis is one of the leading causes of disability. Although it more commonly occurs with aging and is more frequently seen in women, arthritis can affect can any individual at any stage of life.
Arthritis is not a single disease; rather it is a term that applies to the more than 100 rheumatic diseases and conditions that affect joints, the tissues that surround the joint, and other connective tissues. In general these conditions share the characteristic symptoms of pain and stiffness around a single or multiple joints. However, depending on the exact type of arthritic condition present, additional and more widespread effects can occur. Some types of arthritis that are associated with a degenerative process involving cartilage wear and tear are often confined to the joint. While other types of arthritis, such as those related to an inflammatory process and the immune system, may affect outside connective tissues and organs including the skin.
Risk factors for developing arthritis may include injury, aging, metabolic abnormalities, hereditary factors, infections, and immune system disorders. Symptoms of an arthritic condition can develop gradually over time or appear suddenly. Sometimes arthritic joint changes may be visually apparent, as in the case of knobby fingers. However, much of the time joint damage associated with arthritis is only detected with imaging tests.
There are several categories of arthritis including degenerative arthritis, inflammatory arthritis, infectious arthritis and metabolic arthritis. The two most common types of arthritis are osteoarthritis and rheumatoid arthritis.
- Osteoarthritis - Osteoarthritis is most common form of arthritis. It is a degenerative condition that is related to the aging process and to joint wear and tear. Osteoarthritis develops when the cartilage covering the surfaces of the bone within the joint is worn away by repeated overuse or repeated impact. As cartilage deterioration progresses the bone ends within the joint rub directly against each other. This bone on bone contact produces symptoms of pain, swelling and stiffness. The flexibility of the joint is reduced, bony spurs develop and the joint swells.
Osteoarthritis often involves the hips, knees, neck, lower back, or small joints of the hands. It typically occurs in individuals over the age of 50 and often in those with a family history of the condition. In some cases it may be caused or accelerated by a previous injury, excess weight, or the presence of subtle joint irregularities.
- Rheumatoid arthritis - Rheumatoid arthritis is classified as an autoimmune disease. In an autoimmune disease the body releases enzymes that mistakenly attack its own healthy tissue. In the case of rheumatoid arthritis, the tissue under attack is the synovial membrane. This membrane is important as it functions to line and seal the joint cavity as well as secrete a fluid, which helps to lubricate the joint. When rheumatoid arthritis is present the synovial membrane becomes inflamed and thickened. This chronic inflammation can damage the cartilage and cause pain, stiffness, deformity, and reduce function. Rheumatoid arthritis usually involves various joints in the fingers, thumbs, wrists, elbows, shoulders, knees, feet, and ankles. Individuals with rheumatoid arthritis may also have systemic problems including fatigue, fever, weight loss, eye inflammation, anemia, subcutaneous nodules (bumps under the skin), or pleurisy (a lung inflammation).
Early and accurate diagnosis of arthritis can help prevent irreversible damage, slow the progression, reduce disability, as well as increase the chances for successful treatment. The prognosis for individuals with arthritis depends on its severity, complications, and whether there are associated non-joint manifestations of the disease. Although the exact treatment regimen will depend upon which type of arthritis is present, shared goals include preserving joint function, mobility and quality of life.