Knee Disorders

Condition

Articular Cartilage Injury
Cartilage is a white, glistening tissue which exists in a number of locations in the body including the ear, nose, ribs, and within the joints. In the joints, it functions to minimize the friction of the bones as they move relative to one another. It is composed predominantly of water but also includes a population of cells and proteins such as collagen. The most important quality of cartilage is its negative electrical charge. This electrical charge attracts water molecules which are responsible for the very good ability of the tissue to lubricate the joint during motion. When the cartilage is damaged, it has a very low healing potential. In some cases, the impact from an injury can lead to complete loss of the cartilage surface from the end of the bones.

This is similar in concept to a crater. As one can imagine, the loss of this cartilage “cushion” can lead to much higher pressure on the surrounding areas of cartilage and also lead to damage to other parts of the joint. Such “craters” in the cartilage, particularly when they are large, can lead to significant pain. The source of the pain is unclear as the cartilage itself has no nerve endings. Some experts argue that the “irritable” joint proliferates chemicals which lead to an inflammatory response, This inflammatory response can lead to the classic signs of pain, redness, swelling, and warmth. Others think that the exposed bone is the source of the pain because it is now directly exposed to loads which were dampened previously by the cartilage. A number of treatments are available for cartilage defects.