Interesting Facts About Cartilage

Cartilage is an important component of healthy joints. In osteoarthritis, your cartilage becomes damaged or wears away. 

What Is Cartilage? 

This essential building block of your body serves a useful purpose. Your body contains three different types of cartilage—hyaline, elastic, and fibrous. Hyaline cartilage, also referred to as articular cartilage, is the type that is most familiar to arthritis patients.

Hyaline cartilage is present in the joints, nasal septum, and air tube. Elastic cartilage is found in the ear, part of the nose, and the air tube. Fibrous cartilage is found in the meniscus. Cartilage is a tough, but flexible tissue that has two components: water and matrix. About 65% to 80% of articular cartilage is water, but it decreases with normal aging.

The matrix is comprised of collagens, proteoglycans, and noncollagenous proteins. While cartilage is a highly-organized structure, the different types of cartilage have somewhat different properties that allow for specific functions in the body.

Cartilage lacks a blood supply, nerves, and lymphatic system. Chondrocytes are the only cells normally found in cartilage. Chondrocytes produce and maintain the cartilage matrix.

Hyaline or articular cartilage is very smooth and has low friction, allowing the bones in a joint to glide over one another upon movement. The articular cartilage serves as the cushion within the joint, and as a shock absorber. When cartilage is damaged or worn away, the affected joint becomes painful, stiff, and limited in its range of motion.

What Happens When Cartilage Wears Down

Cartilage can degrade over time if you're not careful. Cartilage damage occurs for various reasons. Growth or repair of cartilage, however, has limited potential. If a joint is burdened by improper alignment, excessive weight, excessive activity, overuse, or injury, articular cartilage can wear away.

Progressive cartilage degeneration causes pain and inflammation. With severe osteoarthritis, articular cartilage can completely wear away so that the affected joint no longer has its cushion and it begins to rub bone-on-bone. In such cases, there is significant pain, loss of motion, and functional disability associated with the affected joint.

Damage to the articular cartilage can be seen on X-ray. On an X-ray, cartilage damage is seen as a narrowing of the joint space between the bones that form the joint. In the knee, loss of articular cartilage typically correlates with loss of meniscal cartilage.

Loss of articular cartilage creates extra stress on the ends of the bones that form the joint. The extra stress on the ends of the bones in the joint can cause osteophytes, or bone spurs, to form at the margins of the joint.

New techniques are being tried to restore articular cartilage. Osteochondral grafting, autologous chondrocyte implantation, and mesenchymal stem cell regeneration attempt to restore articular cartilage.

With osteochondral grafting, a plug of bone and healthy cartilage is harvested from one area and then transplanted to the other site. Currently, this procedure treats knee injuries. Autologous chondrocyte implantation involves the harvesting of healthy cartilage cells that are then cultivated and implanted at the injury site. This technique also is currently used for knee injuries.

Mesenchymal stem cell regeneration is still experimental, but it is thought that MSCs can be derived from bone marrow, placed in a gel matrix, and implanted at the site where new cartilage would develop. Early detection and early treatment of osteoarthritis can help to prevent further cartilage damage. The best chance for preventing or slowing cartilage damage comes with early treatment.

Medications that are used to control osteoarthritis and other types of arthritis, joint protection techniques, and good body mechanics help to maintain healthy cartilage. After joint damage becomes severe and interferes with daily living, joint replacement surgery may be the best option to restore function. Your healthcare provider will help you decide what's best for you.

A Word From Verywell

Loss of cartilage in one or more joints can be very painful and eventually lead to functional limitations or possibly even disability. Preserve cartilage by keeping your joints healthy.