Arthritis is a general term that means inflammation in joints. Osteoarthritis, also called degenerative joint disease, is the most common type of arthritis. It is associated with a breakdown of cartilage in joints and can occur in almost any joint in the body. It most commonly occurs in the weight bearing joints of the hips, knees and spine. It can also affect the fingers, thumb, neck, and large toe. It usually does not affect other joints unless previous injury or excessive stress is involved.

Cartilage is a firm, rubbery material that covers the ends of bones in normal joints. Its main function is to reduce friction in the joints and serve as a "shock absorber." The shock-absorbing quality of normal cartilage comes from its ability to change shape when compressed (flattened or pressed together).

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 deteriorates, tendons and ligaments stretch, causing pain. If the condition worsens, the bones could rub against each other.

Who Gets Osteoarthritis?

osteoarthritis

Osteoarthritis affects nearly 21 million Americans. The chance of developing the disease increases with age. Most people over age 60 have osteoarthritis to some degree, but its severity varies. Even people in their 20s and 30s can get osteoarthritis. In people over 50, more women than men get osteoarthritis.

What Are the Symptoms of Osteoarthritis?

Symptoms of osteoarthritis most often develop gradually and 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 (which may or may not be painful).
Joint swelling and joint fluid accumulation.

What Causes Osteoarthritis?

There are several factors that increase a person's chances of developing osteoarthritis. These include:

Heredity. Some people have an inherited defect in one of the genes responsible for making cartilage. This causes 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 or curvature of the spine) are more likely to develop osteoarthritis of the spine.
Obesity. Obesity increases the risk for osteoarthritis of the knee and hip. Maintaining ideal weight or losing excess weight may help prevent osteoarthritis of the knee and hip or decrease the rate of progression once osteoarthritis is established.
Injury. Injuries contribute to the development of osteoarthritis. For example, athletes who have 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.
Joint Overuse. Overuse of certain joints increases the risk of developing osteoarthritis. For example, people in jobs requiring repeated bending of the knee are at increased risk for developing osteoarthritis of the knee.