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NIH MedlinePlus the Magazine, Trusted Health Information from the National Institutes of Health


Healthy Joints for a Lifetime

Remarkable advances are being made every day in the world of orthopedic health and disease treatment—our bones, muscles, tendons, ligaments, and related connective tissues. From reducing the crippling pain of arthritis to the miracle of knee and hip replacements, "musculoskeletal" research is changing how well—and how long—we can live an active, healthy life.

Most people take their bones and joints for granted—until something goes wrong with one or more of them. The human body has more than 200 bones and more than 200 joints that connect the bones.

"Almost every household in America is affected in some way by diseases of bones, joints, muscles, and skin," says Stephen I. Katz, M.D., Ph.D., director of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). It is NIAMS that is the nation's research arm on these challenging conditions.

"Joint damage can happen to anyone at any age," says Dr. Katz. "In fact, many of the diseases related to joints and bone problems affect women and minorities more severely. But there are steps you can take to help prevent or lessen the effects of joint damage."

One of the most amazing options now is surgery to replace damaged joints. Almost half a million such hip or knee replacements occur in the United States each year. Here is an overview of the most common challenges and treatments.

Fast Facts

  • The most common joint problems come from arthritis and injuries. Arthritis literally means joint inflammation. Although joint inflammation describes a symptom or sign rather than a specific diagnosis, the term "arthritis" often refers to any disorder affecting the joints. These disorders fall within the broader category known as rheumatic diseases, of which there are more than 100 kinds, and are characterized by inflammation as well as loss of function of one or more connecting or supporting structures of the body.
  • More than 46 million people in the United States have arthritis or other rheumatic conditions. By the year 2020, this number is expected to reach 60 million. These diseases more frequently limit activity than do heart disease, cancer, or diabetes.
  • The most common form of arthritis is osteoarthritis. It is seen especially among older people and is sometimes called degenerative joint disease. In osteoarthritis, the surface layer of cartilage (the hard but slippery tissue that covers the ends of bones) breaks down and wears away, causing pain, swelling, and loss of joint motion.
  • About 435,000 Americans have a hip or knee replaced each year. Because of its structure and weight-bearing capacity, the knee is the most commonly injured joint. In the case of hip joint damage, osteoarthritis is the most common cause.
  • Young adults who have had a previous joint injury are more likely to develop osteoarthritis. Researchers are looking for ways to prevent cartilage breakdown after injury.

To Find Out More

Go to the Arthritis and Osteoarthritis pages on MedlinePlus (

The Web site for the National Institute of Arthritis and Musculoskeletal and Skin Diseases has much more information on osteoarthritis.

Keep Your Moving Parts Moving

A man standing with his hands on his hips

Click to view labeled image

Common problems: Osteoarthritis, rheumatoid arthritis, herniated disk, injury.

Common problems: Dislocation, separation, rotator cuff injuries, frozen shoulder, fracture (break), arthritis, sprains and strains, bursitis.

Common problems: Back pain from injuries, herniated disks, spinal stenosis.

Common problems: Bursitis, tendinitis (including "tennis elbow"), overuse, traumatic or repetitive injuries.

Common problems: Arthritis (osteoarthritis, rheumatoid arthritis), bursitis, osteoporosis, fracture, tendinitis, sprains, carpal tunnel syndrome.

Common problems: Osteoarthritis, sprains and strains, rheumatoid arthritis, sports injuries (ligaments and tendons), bursitis.

Common problems: Osteoporosis, fracture, osteoarthritis, rheumatoid arthritis, bursitis.

Common problems: Sprains, strains, bursitis, tendonitis (Achilles tendinitis).

Common problems: Arthritis, tendinitis, gout, toe fractures, bursitis (big toe).

Spring 2009 Issue: Volume 4 Number 2 Pages 10 - 11