Bones, Part 1: Babies Don't Have Kneecaps
In almost every week of my anatomy class at U of T, I find out something that absolutely surprises me, that I never would have guessed could possibly be true. We learned a few weeks ago about the types and composition of bones. There were a few cool things that I maybe sortof knew but didn’t really have a grasp on before, and some that I was totally shocked by!
Bones are ORGANS and can be classified by their shape as long, short, flat or irregular. But have you ever heard about this other category of bones called the sesamoid bones? I definitely hadn’t. Sesamoid bones are bones that are not present at birth and develop within a tendon in response to strain in that tendon. Most sesamoid bones are pretty tiny but the largest one is a bone that we are probably all familiar with: the patella (aka kneecap)!
When babies are born, they are patella-less (go find a baby and take a look at their knees!). As they start kicking their legs (before they have started walking) there starts to be friction experienced in the tendon that crosses in front of the knee joint. In response to the repeated experience of that tension, part of your tendon starts to turn into bone (well, first cartilege, then bone!). That bone continues to develop as you get larger and keep kicking your legs and crawling and then walking until eventually you end up with the patella you have right now.
This can technically happen anywhere in the body where there is a tendon that is subject to enough friction over a long enough period of time. So apparently cowboys sometimes develop a sesamoid bone on the inner knee as well from all the time in the saddle!
My knees have always been a bit of a point of sensitivity for me (literally and figuratively). I’ve always thought that my knees looked funny. And my knees have been a literal point of discomfort and sensitivity for me - I’ve been dealing with knee pain for a long time. I ended up stopping running when I was in university because, despite going to physio, I just couldn’t run regularly without experiencing knee pain in my everyday life.
Then about this time last year, I partially dislocated my kneecap after I slipped when stepping down from a chair after returning a hanging plant I had just watered to its place. It’s not the first time that has happened to me, but it was the most severe time. I ended up limping for several weeks. I since recovered and my knee feels mostly fine most of the time but I still go to see a physiotherapist and I still have to be super careful. I have had to eliminate a lot of seated yoga poses from my life, like any of the padmasana variations, because I just don’t have the external rotation in my hip or the stability in my knee to be able to handle them!
I found learning about sesamoid bones helpful to understand my knee issues, and to understand the importance of finding the support from all your accessory muscles, like your glutes, to allow your kneecap to move in the way that is most functional for it. It’s also interesting because this is a more extreme example that shows just how dynamic your bones are - they naturally grow in response to force, which can be a good thing (aka so many things in your body, like your kneecaps or greater trochanters) but also in unwanted ways (aka your bunions!).
So… how do you feel about your knees? Do you think that sesamoid bones are as crazy as I do? Let me know!
And thanks for reading my first real blog post!