National Institute of Arthritis and Musculoskeletal and Skin Diseases
Osteoarthritis Basics: The Joint and Its Parts continued...
A Joint With Severe Osteoarthritis
With osteoarthritis, the cartilage
becomes worn away. Spurs grow out from the edge of the bone, and synovial fluid
increases. Altogether, the joint feels stiff and sore.
Ligaments, tendons, and muscles are tissues that surround the
bones and joints, and allow the joints to bend and move. Ligaments are tough,
cord-like tissues that connect one bone to another. Tendons are tough, fibrous
cords that connect muscles to bones. Muscles are bundles of specialized cells
that, when stimulated by nerves, either relax or contract to produce
Cartilage: The Key to Healthy Joints
Cartilage is 65 to 80 percent water. The remaining three
components – collagen, proteoglycans, and chondrocytes – are described
- collagen(KAHL-uh-jen): A family of fibrous
proteins, collagens are the building blocks of skin, tendon, bone, and other
- proteoglycans(PRO-tee-uh-GLY-kanz): 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
- chondrocytes(KAHN-druh-sytz): Found throughout
the cartilage, chondrocytes are cells that produce cartilage and help it stay
healthy as it grows. Sometimes, however, they release substances called enzymes
that destroy collagen and other proteins. Researchers are trying to learn more
How Do You Know if You Have Osteoarthritis?
Usually, osteoarthritis comes on slowly. Early in the disease,
your joints may ache after physical work or exercise. Later on, joint pain may
become more persistent. You may also experience joint stiffness, particularly
when you first wake up in the morning or have been in one position for a long
Although osteoarthritis can occur in any joint, most often it
affects the hands, knees, hips, and spine (either at the neck or lower back).
Different characteristics of the disease can depend on the specific joint(s)
affected. For general warning signs of osteoarthritis, see the box on the next
page. For information on the joints most often affected by osteoarthritis,
please see the following descriptions below:
Hands: Osteoarthritis of the hands seems to
have some hereditary characteristics; that is, it runs in families. If your
mother or grandmother has or had osteoarthritis in their hands, you’re at
greater-than-average risk of having it too. Women are more likely than men to
have hand involvement and, for most, it develops after menopause.