Cartilage damage never heals well; even when it does, it’s never to its original self
BY DR JONAS FERNANDEZ
That’s a surface that’s never straightforward to navigate. Once you lose your bearings on such a surface, it is difficult to, although not impossible to recover from. So, where am I going with this? Which part of the human body could I possibly be referring to?
It’s the articular cartilage. Found in the joints of our body, it primarily acts as a surface on which two articulating bones meet and form a joint. Simply put, it functions to reduce friction and distribute loads in the joints.
Without these slippery surfaces, we could never have joints, and humans would probably have to move around like a massive tree from a cartoon.
Looked at under a microscope, the cartilage comprises layers of cells called chondrocytes stacked on top of one another. They make up one of the substances found in cartilage. Others include water (up to 60-80 per cent
of the total cartilage mass) and collagen.
When looked at by the naked eye, cartilage is a white, shiny and smooth material. When this surface is bathed in synovial fluid (a gel-like substance found naturally in joints), it becomes lubricated and thus slippery. It makes up an essential part of a well-functioning joint.
Being the surface on which two bones move on each other can have its downsides. Like an old shirt, no matter how good the quality, it will eventually have wear and tear effects. It is usually my go-to analogy when explaining to patients why the cartilage in their joints, the knee especially, isn’t like what it used to be.
Reasons for cartilage defects
With age, the cells within the cartilage increase in size but reduce in number. The amount of water found within the cartilage also decreases, making it stiffer and less elastic.
Although degeneration is the most common cause of cartilage defects, there are many other reasons why this can happen. Chief among them is acute trauma, be it from a sporting injury or an accident.
During these events, the joints experience abnormally high pressure on their surfaces, resulting in focal damage. This is not to say that exercise is bad for the cartilage, quite the opposite in fact.
Under everyday loads/stress, cartilage thickness can increase. However, when there is excessive force, the opposite effect may take place. A pressure of over 24 MPa (Megapascal) will disrupt normal cartilage.
In the elderly, cartilage disease tends to present as osteoarthritis, which may be primary, after a previous trauma or even as a form of inflammatory disease. This form of articular damage is more diffuse within a joint.
Treatment, as described in my earlier column titled “Getting stuck in, literally”, ranges from conservative to surgery. Surgery will involve either a realignment surgery or a partial or total joint replacement.
For younger patients, articular cartilage damage tends to be smaller and more focal. As mentioned above, these injuries occur in younger people due to a particular trauma. However, in some younger patients, it can occur due to a vascular problem or hereditary.
This particular presentation of cartilage disease is called osteochondritis dissecans. As with everything else, it can be treated conservatively with physiotherapy and bracing in its milder forms. Surgery is indicated in patients who have failed non-operative measures.
Surgical options depend on the size and depth of the cartilage defect. Treatment may range from something less invasive, like bone marrow stimulation to stimulate cartilage growth or arthroscopy and stabilisation of a defect.
In more severe cases, something more extensive, like bone grafting (taking bone and cartilage from elsewhere and pasting it at the site of the defect), may become necessary. More recently, the use of BioPoly implants to “patch up” these defects is gaining popularity.
So again, why the title slippery slope? Well, we now understand that the surface of the articular cartilage is slippery. But why a slippery slope? The cartilage damage never heals well; even when it does, it’s never to its original self. This disease often tends to progress. It’s usually not a matter of if but a matter of when.
While we can’t completely halt the progress, we can try and slow it down. The slope may be slippery, and you may fall, but your friendly neighbourhood doctor can help you get back up again and prevent you from tumbling down the hill. – The Health