The Million Dollar Question: Why The Heck Are There Two Types of Cartilage?
WHY ARE THERE TWO TYPES OF CARTILAGE?
It seems to be very confusing that there are two different types of cartilage within the knee. Lets see if we can make this EPIC MYSTERY a little clearer and way easier to understand.
So here's the dealio: one type of cartilage is the cushion of the knee and called the meniscus, the other is a smooth gliding surface and is called articular cartilage.
THE RIVETING TALE OF THE #MENISCUS
The meniscus of the knee is C shaped. There is one on the inner side, medial, and one on the outer side, lateral. Think of this as a cushion or sponge between the femur and the tibia. In fact, it is the only cushion we have between these two bones for our entire life.
They don’t grow or change in shape or size during the course of our life. Unfortunately, the meniscus does undergo some brittleness changes because of blood supply changes during life making it more susceptible to tearing (A topic I've written about previously). It does not “wear down” and become thinner in life, unlike the articular cartilage which does eventually wear down.
THE ABSOLUTELY WILD STORY OF #ARTICULAR CARTILAGE
When you see the smooth, shiny stuff on the end of a chicken bone, that is the articular cartilage. VERY different than the meniscus, but still called cartilage. Think of this as a cap of low friction paint covering the end of a bone within the joint.
The function of articular cartilage is to decrease the friction when a joint is moving, giving it more of a gliding function. It is not like the sponge cushion of the meniscus or separate from the bone. The whole function of articular cartilage is to convert a cobblestone road into a marble drive. It becomes that slick.
Articular cartilage is much like the treads on your tires. They can get thinner from normal wear and tear after many years, or they can suddenly have some damage after running over something.
The LACK of articular cartilage in a joint is called arthritis, plain and simple. It really doesn’t matter whether the lack of cartilage is from wear and tear, which is called osteoarthritis, or from an injury where the articular cartilage is knocked off, which is called post traumatic arthritis.
If your own body is attacking the articular cartilage, like it does with rheumatoid arthritis, this is called inflammatory arthritis. There is lots more to talk about with cartilage health and cartilage injuries, both prevention and treatment options.
For now, remember that, just like the type of driving we do affects how long our tires last, the type of sports we participate in will affect both the risk of injury to the meniscus cartilage, and the wear sustained by the articular cartilage.
THE ANSWER MAY WIN YOU A MILLION BUCKS
Nobody was trying to confuse us with having two different types of cartilage within the knee, its just the way it is. So in case you find yourself on a game show and the million dollar question is "what are the two types of cartilage found in the knee"... well now you know!