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National Institute of Arthritis and Musculoskeletal and Skin Diseases


Key Words continued...

Estrogen – the major sex hormone in women. Estrogen is known to play a role in regulation of bone growth. Research suggests that estrogen may also have a protective effect on cartilage.

Glucosamine – a substance that occurs naturally in the body, providing the building blocks to make and repair cartilage. See the “glucosamine and chondroitin sulfate” section under Complementary and Alternative Therapies for more information.

Heberden’s nodes – small, bony knobs associated with osteoarthritis of the hand that can occur on the joints of the fingers closest to the nail.

Hyaluronic acid – a substance that gives healthy joint fluid its viscous (slippery) property and that may be reduced in people with osteoarthritis. For some people with osteoarthritis of the knee, replacing hyaluronic acid with injections of agents referred to as viscosupplements is useful for increasing lubrication, reducing pain, and improving function.

Joint capsule – a tough membrane sac that holds the bones and other joint parts together.

Ligaments – tough bands of connective tissue that attach bones to each other, providing stability.

Magnetic resonance imaging (MRI) – provides highresolution computerized images of internal body tissues. This procedure uses a strong magnet that passes a force through the body to create these images.

Muscles – bundles of specialized cells that contract and relax to produce movement when stimulated by nerves.

Nonsteroidal anti-inflammatory drugs (NSAIDs) – a class of medications available over the counter or with a prescription that ease pain and inflammation. Commonly used NSAIDs include ibuprofen (Advil, Motrin), naproxen sodium (Aleve), and ketoprofen (Orudis, Oruvail). For information about the risk posed by NSAIDs, see “NSAIDs” in the “How Is Osteoarthritis Treated?” section.

Osteoarthritis – the most common form of arthritis. It is characterized by the breakdown of joint cartilage, leading to pain, stiffness, and disability.

Osteophytes – small growths of bone that can appear on the edges of a joint affected by osteoarthritis. These growths are also known as bone spurs.

Prolotherapy – an unregulated, unproven therapy for chronic musculoskeletal pain. Prolotherapy uses an irritant solution, which is injected into painful ligaments and adjacent joint spaces to promote inflammation and subsequent healing.

Proteoglycans – components of cartilage. Made up of proteins and sugars, strands of proteoglycans interweave with collagens and form a mesh-like tissue. This allows cartilage to flex and absorb physical shock.

Rheumatoid arthritis – a form of arthritis in which the immune system attacks the tissues of the joints, leading to pain, inflammation, and eventually joint damage and malformation. It typically begins at a younger age than osteoarthritis does, causes swelling and redness in joints, and may make people feel sick, tired, and uncommonly feverish. Rheumatoid arthritis may also affect skin tissue, the lungs, the eyes, or the blood vessels.

Stem cells – primitive cells, usually taken from the bone marrow, that can transform into other kinds of cells, such as muscle or bone cells. In the future, researchers hope to be able to insert stem cells into cartilage and stimulate them to replace cartilage damaged by arthritis or injury.

WebMD Public Information from the U.S. National Institutes of Health

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