understanding the joints

Most joints (the place where two moving bones come together) are designed to allow smooth movement between the bones and to absorb shock from movements like walking or repetitive movements. The joint is made up of:

* Cartilage: a hard but slippery coating on the end of each bone. Cartilage, which breaks down and wears away in osteoarthritis, is described in more detail below.

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

* Synovium: a thin membrane inside the joint capsule.

* Synovial fluid: a fluid that lubricates the joint and keeps the cartilage smooth and healthy.

* Ligaments, tendons, and muscles: tissues that keep the bones stable and allow the joint to bend and move.
o Ligaments are tough, cord-like tissues that connect one bone to another.
o Tendons are tough, fibrous cords that connect muscles to bones.
o Muscles are bundles of specialized cells that contract to produce movement when stimulated by nerves.

Cartilage: The Key to Healthy Joints

Cartilage is 65 to 80% water. Three other components make up the rest of cartilage tissue: collagen, proteoglycans, and chondrocytes.
# Collagen: a fibrous protein. Collagen is also the building block of skin, tendon, bone, and other connective tissues.

# Proteoglycans: a combination of proteins and sugars. Strands of proteoglycans and collagen weave together and form a mesh-like tissue. This allows cartilage to flex and absorb physical shock.

# Chondrocytes: cells that are found all through the cartilage. They mainly help cartilage stay healthy and grow. Sometimes, however, they release substances called enzymes that destroy collagen and other proteins.