How the body works – Part Two

How the body works – Part Two

II: Cartilage

Welcome to our continuation of the blog series ‘How the body works’. In today’s article we will step through some understanding of cartilage. If there was ever a ‘bad guy’ of the MSK system it would be cartilage. It seems that our cartilage gets blamed for a lot of pain and disability in our body. Today I’d like to challenge your perspective and say that this may not always be the case. Just like the naughty kid in class who got blamed for every misdemeanor (even the one’s they didn’t commit), we need to understand that whilst cartilage may have a bad name – it’s actually a really helpful tissue!

When we talk about cartilage we are talking about the tissue that is somewhat hard but still malleable. A bit like those silicon cooking trays that my wife makes such delicious baking in! Some well known places of cartilage are the nose, ears and the front of the ribs. In reality though, cartilage is found throughout the body at nearly every single joint. Cartilage can be subdivided into three major groupings; Hyaline, Fibrous and Elastic Cartilage. Cartilage is made up of both cartilage cells and a mixture of substance and fibres. This mixture is the material that keeps everything together. The main difference between the subgroupings of cartilage is both how the cartilage cells arrange themselves and also the composition of the fibres around them.

Fibrocartilage is often found in the intervertebral disks of the spine and at points where tendons attach to bone. Elastic cartilage is like it name suggests; elastic. It is found primarily in the ear, larynx (voice box) and epiglottis (the trap door that makes food go to our stomach and air go to our lungs). Hyaline cartilage is the most widely distributed form of cartilage and is found on the surface of bone at joints as well as at growth plates in the immature skeleton. In this article we are going to focus on hyaline cartilage.

Remember how I said that cartilage was really helpful? Well if we didn’t have cartilage, none of us would be able to grow! Cartilage is often a precursor to bone and is found at numerous growth plates throughout the body. If we consider that each person has on average 206 bones, that is a huge proportion of cartilage material in our bones!

Secondly, hyaline cartilage is found on the surface of joints. Here it is called articular cartilage. Articular cartilage’s main role is to decrease friction at joints by providing a smooth surface at the meeting of the two bone joints. Remember how we talked about cartilage being made up of cells as well as a surrounding mixture? This mixture is called the ‘extracellular matrix’. In articular cartilage, this mixture is made up of approximately 80% water! The abundance of water in cartilage allows it to withstand repeated and fluctuating stress and load at various intensities. Another substance called collagen provides structural stability. Lastly, proteins (think of a protein like the blueprint that a cell uses to manufacture something else) called proteoglycans are found in abundance. It’s important to understand that it’s this mixture ‘the extracellular matrix’ that determines the health of cartilage.

Ok, so here’s where I want to challenge your perspective. Articular cartilage (the form of hyaline cartilage that lines our joints) does not have any blood vessels. It has no lymphatic vessels (the vessels that transport waste in the body). It’s through very complex processes kicked off by loading the joint that the cartilage gets its nutrients and waste is taken away. Many people think and believe that their cartilage has been ‘worn out’ by general wear and tear or by ‘doing to much manual labour’. In actual fact, regular joint movement and dynamic load is essential for maintain healthy articular cartilage. In reality it’s actually inactivity of the joint that has been shown to lead to degradation of cartilage. This kind of degradation in cartilage is often seen in joint diseases like osteoarthritis (more on this condition when we consider joints).

Now of course, all tissue in the body has a maximal stress point and acute cartilage injuries do occur. A common example is meniscal injury in the knee. Sometimes these conditions can be tricky to treat depending on where the injury occurs and involvement of medical specialists are sometimes required. However, because cartilage does not have nerves there are many options available to help deal with your pain and restore your physical function. Physical therapy interventions have some of the best evidence for managing these conditions. Whether you’re looking on ways to manage your cartilage health or recovering from an acute injury we are always happy to help here at Up & Active.

Remember, if you want to maintain healthy cartilage don’t deload, it’s much better to regularly load!

Rowland Briese