Cartilage structures and functions can relatively easily be harmed, often resulting in damage. Cartilage is a tough, flexible connective tissue that is found in many areas of the body.
This fine, rubbery tissue mainly functions as a cushion for bones at joints. People with cartilage damage commonly experience joint pain, stiffness and inflammation (swelling).
The English word "cartilage" comes from the Latin word cartilage, which means "cartilage" or "gristle."
In this article, we will describe the function of cartilage, how it can become damaged and how that damage can be treated.
Contents of this article:
Fast facts on cartilage damage
Here are some key points about cartilage damage. More detail and supporting information is in the main article.
- Cartilage is a fine, rubbery tissue that cushions joints
- It has several functions, including holding bones together and supporting other tissues
- There are three types of cartilage, the most spongy of which is yellow cartilage
- Two of the main symptoms of cartilage damage are swelling and stiffness
- There is a range of ways in which cartilage can be damaged, including overuse or underuse
- Telling the difference between cartilage damage, sprain or ligament damage can be challenging
- Diagnosis of cartilage damage will normally require magnetic resonance imaging (MRI) or arthroscopy
- There is a five point scale for grading cartilage damage
- Cartilage damage is often treated with non-steroidal anti-inflammatory drugs (NSAIDs)
- If cartilage damage is not treated, it can worsen until an individual can no longer walk.
What is cartilage?
Cartilage serves a number of purposes in the body.
Cartilage has several functions in the human body:
- Reduces friction and acts as a cushion between joints - cartilage reduces friction between bones by covering the surface of joints. If there were friction the joint would soon be damaged and destroyed. Cartilage also helps our weight-bearing functions when we run, bend, stretch or engage in any type of movement.
- Holds bones together - the bones on our ribcage are held together thanks to cartilage.
- Acts as a mold - some of our body parts are made either exclusively or almost exclusively from cartilage, for example, the external parts of our ears.
- The formation of bones - when we are young children the ends of our long bones are made of cartilage, which eventually turn into bones.
However, unlike other types of tissue, cartilage does not have a blood supply. Blood cells help repair tissue damage by diffusion. Consequently, damaged cartilage takes much longer to heal, compared to other tissues in our body which have a blood supply.
There are three types of cartilage:
- Elastic cartilage: also known as yellow cartilage is the most springy and supple type of cartilage. This type of cartilage makes up the outside of the ears, some of the nose, the larynx, and also the epiglottis.
- Fibrocartilage: the toughest type of cartilage, and it is able to withstand heavy weights. It is found between the discs and vertebrae of the spine and between the bones in the hips and pelvis. It is the only type of cartilage that contains type I collagen in addition to the normal type II.
- Hyaline cartilage: both springy and tough. It consists of a slimy mass of a firm consistency, however, it is also extremely elastic. It is found between the ribs, around the windpipe, and between the joints. The cartilage between the joints is known as articular cartilage. Hyaline cartilage has a pearly bluish color.
Elastic cartilage, fibrocartilage and hyaline cartilage can all suffer damage. For example, a slipped disk is an example of fibrocartilage damage, while a hard whack on the ear can cause elastic cartilage damage - hence the term cauliflower ear.
When cartilage in a joint, such as the knee joint is damaged, the consequences can be severe pain, inflammation and some degree of disability - this is known as articular cartilage damage (damage to the cartilage in a joint). According to the NIH (National Institutes of Health), USA, one third of US adults aged over 45 suffer from some kind of knee pain.
Symptoms of cartilage damage
Patients with damage to the cartilage in a joint (articular cartilage damage) will experience:
- Inflammation - this is the basic way our bodies react to irritation or injury (as well as infection). The area swells (becomes inflamed), becomes warmer than other parts of the body, and is tender, sore and/or painful.
- Range limitation - as the damage progresses, the range of movement in, for example the limb with the articular damage has a smaller range of movement.
In severe cases, a piece of cartilage can break off and the joint can become locked. This can lead to hemarthrosis (bleeding in the joint); the area may become blotchy and have a bruised appearance. Articular cartilage damage most commonly occurs in the knee, but the elbow, wrist, ankle, shoulder and hip joint can also be affected.
Causes of cartilage damage
- Direct blow - if a joint receives a devastating impact, as may happen if you have a bad fall, an automobile accident, or receive a powerful kick during karate training, the cartilage may be damaged. Sportsmen and sportswomen, especially those involved in high impact sports, such as martial arts, American football, rugby or wrestling have a higher risk of suffering from articular damage.
- Wear and tear - sustained stress on a joint over a prolonged period may eventually take its toll. An obese individual is more likely to damage his/her knee over a 20-year period than a person of normal weight, simply because the knee or hip joints are undergoing a much higher degree of wear and tear. Inflammation, breakdown and eventual loss of cartilage in the joints is known as osteoarthritis.
- Lack of movement - the joints need to move regularly in order to remain healthy. Prolonged periods of inactivity or immobility increase the risk of damage to the cartilage.
On the next page, we look at the diagnosis, treatment and complications of cartilage damage.