What Goes Wrong With Joints
Age, stress, and disease can make joints stiffen in much the same way as wear, weather, and a lack of lubrication can cause stiffness and squeaking in door hinges.
Causes of Joint Disorders
One of the most common causes of joint pain is arthritis, which afflicts nearly 20% of the American population. The most common types of arthritis are:
- Osteoarthritis (OA)—Sometimes called degenerative arthritis because it is a “wearing out” condition involving the breakdown of cartilage in the joints. When cartilage wears away, the bones rub against each other, causing pain and stiffness. OA usually occurs in people aged 50 years and older, and frequently in individuals with a family history of osteoarthritis.
- Rheumatoid arthritis (RA)—Produces chemical changes in the synovium that cause it to become thickened and inflamed. In turn, the synovial fluid destroys cartilage. The end result is cartilage loss, pain, and stiffness. RA affects women about 3 times more often than men, and may affect other organs of the body.
- Post-traumatic arthritis—May develop after an injury to the joint in which the bone and cartilage do not heal properly. The joint is no longer smooth and these irregularities lead to more wear on the joint surfaces.
- Avascular necrosis—Can result when bone is deprived of its normal blood supply. Without proper nutrition from the blood, the bone’s structure weakens and may collapse and damage the cartilage. The condition often occurs after long-term treatment with cortisone or after organ transplantation.
In patients with arthritis, the joint’s cartilage lining wears away, allowing the bones to rub against each other, resulting in friction, swelling, stiffness, instability, and sometimes deformity. Severe arthritis can cause crippling pain when sufferers bend, walk, climb stairs, or even sit.
Joint pain can also be caused by a deformity or by direct injury to the joint, as in the case of trauma or a sports injury. Sometimes, joint pain is made worse by avoiding use of a painful joint, which weakens the muscles and makes the joint even more difficult to move.