Osteoarthritis, or degenerative joint disease, is the most common type of arthritis. It is associated with the breakdown of a joint's cartilage. Cartilage is a firm, rubbery material that covers and cushions the ends of bones in normal joints. Its main function is to reduce friction in the joints and serve as a "shock absorber."
Osteoarthritis causes the cartilage in a joint to become stiff and lose its elasticity, making it more susceptible to damage. Over time, the cartilage may wear away in some areas, greatly decreasing its ability to act as a shock absorber. As the cartilage wears away, tendons and ligaments stretch, causing pain. If the condition worsens, the bones could rub against each other, causing even more pain and loss of movement.
OA is most common in middle-aged and older people, and its symptoms can range from very mild to very severe. The disorder most often affects hands and weight-bearing joints such as knees, hips, feet and the back, but can affect almost any joint in the body. Women are more commonly affected than men.
Symptoms of Osteoarthritis
Symptoms of osteoarthritis include:
- Joint aching and soreness, especially with movement
- Pain after overuse or after long periods of inactivity
- Bony enlargements in the middle and end joints of the fingers. These enlargements may or may not be painful.
What Causes Osteoarthritis?
There are many factors that can increase a person's chance of developing OA, including:
- Obesity. Maintaining an ideal weight or losing excess weight may help prevent osteoarthritis of the knees, hips, and back. Weight loss can also decrease the progression of OA.
- Injury. People with joint injuries due to sports, work-related activity, or accidents may be at increased risk of developing OA. For example, athletes with knee-related injuries may be at higher risk of developing osteoarthritis of the knee. In addition, people who have had a severe back injury may be predisposed to develop osteoarthritis of the spine. People who have had a broken bone near a joint are prone to develop osteoarthritis in that joint.
- Heredity. Some people have an inherited defect in one of the genes responsible for making cartilage. This can cause defective cartilage, which leads to more rapid deterioration of joints. People born with joint abnormalities are more likely to develop osteoarthritis, and those born with an abnormality of the spine (such as scoliosis, a curvature of the spine) are more likely to develop osteoarthritis of the spine.
- Joint Overuse. Overuse of certain joints increases the risk of developing OA. For example, people in jobs requiring repeated bending of the knee are at increased risk for developing OA of the knee.
- Age. Although age is a risk factor, research has shown that OA is not an inevitable part of aging.