Osteoarthritis Patient Information Fact Sheet

What is osteoarthritis?
Osteoarthritis is the most common type of arthritis. In people affected by this disease the cartilage, or shiny coating that covers the ends of the bones inside the joints, becomes thinned and roughened. The end of each affected bone gradually becomes thicker and grows out sideways, causing the joint to change shape. Fluid may collect inside the joint, causing swelling. The joints most commonly affected are the small joints at the ends of the fingers, the base of the thumb, hips, knees, neck and lower back. Sometimes only the finger joints are involved, or one or two big joints such as the knees or hips.

What causes osteoarthritis?
No one knows for certain. Osteoarthritis becomes more common with age, but it is not just due to normal wear and tear. Some types of osteoarthritis, such as those affecting the finger joints, tend to run in families. Some people, especially younger people, get osteoarthritis in a joint that has been damaged previously by an injury or operation. Obesity and weak muscles have also been linked to developing osteoarthritis.

How common is osteoarthritis?
Today, an estimated 27 million Americans live with osteoarthritis. Many of these people have only mild symptoms, in some cases so mild that they don’t even know they have the disease. It is estimated that treatment is requested in about one-eighth of cases . Osteoarthritis is slightly more common in women than in than men, particularly affecting their knees and hands.

How will osteoarthritis affect me?
Most people continue living a normal life with their osteoarthritis and do not become disabled by it. But in some people it can be very painful and disabling. The most common symptoms are pain and stiffness in and around the affected joints. The pain is usually worse after exercising or walking, and at the end of the day. Your symptoms will usually change from day to day, so even if your joints are painful today, it does not mean they will stay painful in the future. You may notice that the affected joints are swollen or out of shape and tender when you knock or touch them.

What tests confirm a diagnosis of osteoarthritis?
Your doctor will examine your joints and may send you for an x-ray. However, the amount of damage seen on the x-ray does not always match the amount of pain and stiffness you are feeling. Most doctors will not perform an x-ray unless you are likely to need an operation. There is no blood test for osteoarthritis, but a blood test can be used to rule our some other types of arthritis.