What Is the Function of Cartilage?

Cartilage is the fibrous, elastic tissue that cushions joints and provides organ structures.

Cartilage is a connective tissue type (one of 6 major types) that is an essential part of many of the structures in the body. Cartilage is stiffer and less flexible than muscle, but not as rigid or hard as bone. Cartilage provides shape to some parts of the body, and acts as cushion between bones in joints.

Cartilage is composed of cells known as chondrocytes which produce specialized proteins that stick together to form a gel-like, cartilaginous matrix. The proteins in the matrix include:

• Collagens
• Proteoglycans
• Non-collagenous proteins

The proteins in the cartilage absorb water which gives cartilage its rubber-like consistency and ability to hold the shape of flexible body structures. Cartilages do not have blood vessels, nerves or lymphatic ducts; instead, nutrients diffuse through the layer of dense connective tissue (perichondrium) surrounding the cartilage.

Cartilages have different properties depending on their location in the body, and their function. The three three main types of cartilage are:

• Hyaline cartilage: Also known as articular cartilage, hyaline cartilage forms a thick layer over bone ends in joints. Hyaline cartilage is also found in the ribs, the septum of the nose which separates the nostrils, and the breathing tube (trachea).
• Elastic cartilage: Elastic cartilage is principally made up of elastin protein fibers which make it more flexible and is found in the external ears, part of the nose and larynx.
• Fibrocartilage: Fibrocartilage is a tough, flexible and elastic cartilage that is found in the joints of the knee (meniscus), hip (labrum) and shoulder (labrum), and in between the vertebrae (discs) in the backbone.

Cartilage serves various purposes depending on its type and location in the body. Cartilage gives shape to organs like ears and nostrils, keeping them stiff but flexible. Cartilage attaches the ribs to the breast bone (sternum) and provides flexibility to the ribcage to allow expansion of the chest while breathing. Cartilage helps keep the trachea open and flexible.

Cartilage in the weight-bearing joints such as the vertebrae, knees and hips absorb impact from movement, and help disperse the body weight. Cartilage cushions all the joints, allows gliding movement, and reduces friction between bones.

Cartilage can be damaged or worn down by:

• Injury to the joint
• Degeneration with age (osteoarthritis)
• Excessive weight
• Overuse and/or excessive activity
• Inflammation and infection

If cartilage in a joint gets damaged, the joint can become stiff and painful, with reduced range of motion. Untreated cartilage damage can lead to further degeneration, causing the joint bones to rub against each other. Bone spurs (osteophytes) may also form, adding to the pain in the joint.

Any damage to the cartilage in the trachea can lead to breathing problems. Inflammation of the cartilage in the ribs leads to a painful condition known as costochondritis. Damage to the cartilage in the nose or ears does not have an impact on functional health, but can be a cosmetic issue (for example, cauliflower ear in boxers).

Damaged cartilage has minimal capacity to heal itself or grow back because it does not have blood supply. There are several types of treatments to repair damaged cartilage depending on the extent of damage. Cartilage treatments include the following:

Non-surgical treatments:

• Making lifestyle changes such as losing excess weight, avoiding activity that can cause further damage and doing appropriate exercises.
• Physiotherapy and use of supportive aids such as braces.
• Knee joint injection of hyaluronic acid, a component of synovial fluid, which is the natural lubricant in joints. It can improve joint lubrication and limit further damage to the cartilage.
• Dietary supplements of compounds such as glucosamine and chondroitin which naturally occur in the body. Supplements are thought to help with limiting cartilage damage and reducing pain, but it is essential to check with the doctor before taking any.

Surgical treatments:

Surgical treatments for damaged or worn out cartilage include:

• Joint repair
• Joint fusion
• Joint replacement

It may not be possible to prevent age-related cartilage degeneration, but cartilage health can be preserved to a great extent with appropriate care. Following are some measures that can help:

• Maintain a healthy weight
• Eat nutritious food
• Avoid energy drinks and sodas, drink water instead
• Avoid smoking
• Stay active and exercise regularly
• Strengthen the core muscles and muscles around the joints
• Warm up before and stretch muscles after workouts
• Mix up exercise routines to avoid overstressing joints
• Seek prompt treatment for injuries