What is osteoarthritis?

Last Updated: July 1, 2003

Osteoarthritis is the most common type of arthritis, especially among older people. Sometimes it is called degenerative joint disease.

Osteoarthritis is a joint disease that mostly affects the cartilage. Cartilage is the slippery tissue that covers the ends of bones in a joint. Healthy cartilage allows bones to glide over one another. It also absorbs energy from the shock of physical movement.

In osteoarthritis, the surface layer of cartilage breaks down and wears away. This allows bones under the cartilage to rub together, causing pain, swelling, and loss of motion of the joint. Over time, the joint may lose its normal shape.

Also, bone spurs—small growths called osteophytes—may grow on the edges of the joint. Bits of bone or cartilage can break off and float inside the joint space. This causes more pain and damage.

People with osteoarthritis usually have joint pain and limited movement. Unlike some other forms of arthritis, osteoarthritis only affects joints, and not internal organs.

For example, rheumatoid arthritis—the second most common form of arthritis—affects other parts of the body besides the joints. It begins earlier than osteoarthritis, causes inflammation, and may make people feel sick, tired and sometimes feverish.

The Warning Signs

• Steady or intermittent pain in a joint
• Stiffness after getting out of bed
• Joint swelling or tenderness in one or more joints
• A crunching feeling or sound of bone rubbing on bone
• Hot, red, or tender? Probably not osteoarthritis. Check with your doctor about other causes, such as rheumatoid arthritis.
• Not always pain. Not everyone with osteoarthritis feels pain. In fact, only a third of people with osteoarthritis in their X-rays report pain or other symptoms.

Usually, osteoarthritis comes on slowly. Early in the disease, joints may ache after physical work or exercise. Osteoarthritis can occur in any joint. Most often it occurs in the hands, hips, knees, or spine.

Hands: Osteoarthritis of the fingers is the one type of the disease that seems to be hereditary; that is, it runs in families. More women than men have it, especially after menopause. Small, bony knobs appear on the end joints of the fingers. They are called Heberden’s nodes. Similar knobs (called Bouchard’s [boo-SHARDZ] nodes) can appear on the middle joints of the fingers. Fingers can become enlarged and gnarled, and may ache or be stiff and numb. The base of the thumb joint is also commonly affected by osteoarthritis. This kind of osteoarthritis can be helped by medications, splints, or heat treatment.

Hips: Osteoarthritis in the hip can cause pain, stiffness, and severe disability. People may feel the pain in their hips, or in their groin, inner thigh, or knees. Walking aids such as canes or walkers can reduce stress on the hip. Osteoarthritis in the hip may limit moving and bending. This can make daily activities such as dressing and foot care a challenge. Walking aids, medication, and exercise can help relieve pain and improve motion. The doctor may recommend hip replacement if the pain is severe and not helped by other methods.

Knees: The knees are the body’s primary weight-bearing joints. For this reason, they are among the joints most commonly affected by osteoarthritis. They may be stiff, swollen, and painful, making it hard to walk, climb, get in and out of chairs, and use bathtubs. If not treated, osteoarthritis in the knees can lead to disability. Medications, losing weight, exercise, and walking aids can reduce pain and disability. In severe cases, knee replacement surgery may be helpful.

Spine: Stiffness and pain in the neck or in the lower back can result from osteoarthritis of the spine. Weakness or numbness of the arms or legs can also result. Some people feel better when they sleep on a firm mattress or sit using back support pillows. Others find help from heat treatment or an exercise program to strengthen the back and abdominal muscles. In severe cases, the doctor may suggest surgery to reduce pain and help restore function.

Who has osteoarthritis?
Osteoarthritis is one of the most frequent causes of physical disability among adults. More than 20 million people in the United States probably have the disease.

Some younger people get osteoarthritis from a joint injury, but osteoarthritis most often occurs in older people. In fact, by age 65, more than half of the population has X-ray evidence of osteoarthritis in at least one joint. Since the number of older Americans is increasing, so is the number of people with osteoarthritis.

Both men and women have the disease. Before age 45, more men have it, while after age 45, osteoarthritis is more common in women.


How does osteoarthritis affect people?
Osteoarthritis affects each person differently. In some people, it progresses more quickly; in others, the symptoms are more serious. Medical researchers do not yet know what causes the disease, but they suspect a combination of factors in the body and in the environment. Also, diet, weight, and stresses on the joints from certain jobs affect the disease and how a person reacts to it.

Osteoarthritis hurts people in more than their joints: their finances and lifestyles are also affected.

Financial effects of osteoarthritis include:

• The cost of treatment
• Wages lost because of disability

Lifestyle effects include:

• Depression
• Anxiety
• Feelings of helplessness
• Limits on daily activities
• Job limitations
• Loss of everyday family joys and responsibilities

Despite these challenges, most people with osteoarthritis can lead active and productive lives. They succeed by using osteoarthritis treatment strategies such as:

• Pain relief medications
• Rest and exercise
• Patient education and support programs
• Learning self-care and having a “good-health attitude”

Source:
National Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse
National Institutes of Health (NAMSIC/National Institutes of Health)
1 AMS Circle
Bethesda, Maryland 20892-3675

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