What is Cartilage?
Cartilage is a fundamental part of the human body. There are three main types of cartilage within the human body:
The first is fibrocartilage, which is found in the discs in between the bones of the spine and the shock absorbing menisci in the knees (shown below)
When skin is torn or cut due to an injury or an operation, the scar that is laid down afterwards is made up of fibrocartilage.
2. Elastic Cartilage
Elastic cartilage makes up tissues in the body, which have with a bit more movement such as our ears.
3. Articular (hyaline) cartilage
Articular cartilage lines our joints (as below) and forms our nose. It is involved in most activities, which load our joints and can lead to injury.
What Does Cartilage Do?
Articular cartilage is low friction and low wear so it performs well in allowing two surfaces to move over one another smoothly. It protects the bone that it covers from high stresses, and importantly, it ensures that no one area of bone takes the full weight of a load, so the weight is spread evenly over an area. It allows a little change in its shape, to enable forces to be spread over a larger surface area. These properties do not happen in bone, so if cartilage is lost or removed from the joint surfaces then these useful functions are reduced and the other parts of the joint bone must take up the challenge. Often this results in stresses and strains on these tissues and so wear and tear can occur.
The Problem of Poor Blood Supply
Unfortunately unlike other cartilage the articular cartilage has one characteristic that is not so good – it has a poor blood supply. This means that it is not very good or very fast at repairing itself when injured. We get the building blocks we need to repair tissues from our blood, so if a tissue doesn’t have a good blood supply then it cannot repair quickly. This can be likened to comparing a small village versus a big city. Small villages have tiny country roads entering and exiting them, where as cities have motorways and large A roads. This means that goods lorries carrying supplies can easily get to the cities, but its more of a challenge to get to the country villages, especially if you throw a little snow into the mix!
You will be most likely to have thought about your cartilage if you have ever thought you might have osteoarthritis. Osteoarthritis is a wear and tear condition in which cartilage, particularly articular cartilage covering our joint surfaces and fibrocartilage within, starts to become thinner or worn, or is affected by stresses or chemicals in our body. All joints in the body can be affected by wear and some but some more than most as below.
Some people have pain from this and some do not. You may have had a sporting injury when you were younger that upset the balance of pressure over the cartilage in your knee. Or you might have had a very challenging and heavy job all your life, where your younger cartilage could cope and repair easily, but your older cartilage is now unable to repair and becomes thinner and worn. Your body may also have started to secrete the chemicals that cause disruption to the make-up of cartilage, and so your cartilage has been affected even without any trauma or injury over time.
The image below shows how wear and tear can affect the cartilage in your knee joint:
We know quite a lot about cartilage these days, but there is still a lot we don’t yet know for sure. Experiments are currently taking place to fully understand the properties of cartilage and how we might one day be able to grow new cartilage to cover worn areas or to replace problem spots. Until then, it’s up to us to take good care of our cartilage and seek medical advice if you notice any problems.
Take Good Care of Your Cartilage
Aim to strengthen the muscles that surround the joints by doing certain strengthening exercises and also proprioceptive balancing exercises helps to reduce the rate of wear and tear to our joints. It is also worth trying a specific exercise programme suited to you set by your physiotherapist.