Cartilage is the tough but flexible tissue that covers the ends of your bones at a joint. It also gives shape and support to other parts of your body, such as your ears, nose and windpipe.
Healthy cartilage helps you move by allowing your bones to glide over each other. It also protects bones by preventing them from rubbing against each other.
There are three main types of cartilage: hyaline, elastic and fibrous. They have different properties that correspond to their specific functions in the body and make it the most appropriate type of cartilage at that particular site.
Hyaline, or articular cartilage, is found in the joints, septum of the nose (which separates the nostrils), and the trachea (air tube). Elastic cartilage, which has elastic fibers that make the cartilage more flexible, is found in the ear, part of the nose and the trachea.
Injured, inflamed, or damaged cartilage can cause symptoms such as pain and limited movement.
STRUCTURE OF ARTICULAR CARTILAGE
Articular cartilage contains only one cell type, the chondrocyte. In the adult this occupies <5% of the cartilage volume the remainder is occupied by an extensive extracellular matrix. The structural backbone of this matrix is the collagen fibril. This is composed mainly of type II collagen.
Glycosaminoglycan chains serve an extremely important function in that they bind large amounts of water and thereby create, with the containment of the collagen fibrillar network, a swelling pressure causing a compressive stiffness that resists deformation and compression of cartilage.
WHAT IS CARTILAGE DAMAGE?
As cartilage is a highly organized structure and lacks a blood supply, it is particularly difficult to restore or duplicate once it is damaged or lost. Injury to any part of this complex system can disrupt the functional properties of cartilage:
• If articular cartilage is involved, this may lead to further degeneration of the joint
• If airway cartilage of the is involved, this may lead to breathing problems
• If cartilage of the ear or nose is involved, cosmetic problems might result.
Articular cartilage can be damaged through accidents, such as a tear to the anterior cruciate ligament (ACL), or degenerate slowly over time, eventually leading to osteoarthritis. Poor alignment of the joint, excessive weight, excessive activity, overuse, or injury can all cause cartilage to wear away. If the cartilage is damaged or worn, the joint becomes painful and stiff, and with reduced range of movement. In severe osteoarthritis, the hyaline cartilage can completely wear away, leaving the affected joint without its cushion. This causes the bones to rub against each other. Osteophytes, or bone spurs, may also form at the margins of the joint due to the extra stress on the ends of the bones. This leads to significant pain, loss of movement, and poor function. The damage can start as a local ‘pothole’ in the cartilage – called a cartilage lesion. When a lesion is left untreated, it will most likely enlarge over with time until all the surrounding cartilage is worn away. Since cartilage has minimal ability to repair itself, even small lesions, if left untreated, can cause deterioration to the joint surface and lead to osteoarthritis. It is therefore important to diagnose cartilage damage as early as possible and have it treated.