Knee Anatomy and Mechanics Explained Before You Start Rehab

This is session number 32 of the Performance Place Sports Care Podcast. Hope you're ready. Welcome to the Performance Place Sports Care Podcast, where you can learn about sports injury theory, rehab, diagnosis, and how to understand the doctor lingo you didn't understand at your appointment. And now, your host, Dr. Sebastian Gonzales. Hey, everyone. It's Dr. Sebastian Gonzales from the Performance Place Sports Care Podcast again. And today, we're going to get some really boring information, sadly. It's going to be just me on the podcast today, and we're going to go over some anatomy of the knee.

And the reason why it's so boring is because, basically, I'm going to be teaching you a little bit of a terminology lesson and a little bit of biomechanics. And biomechanics, if you don't know what that is, it's how the joint really moves when we move or how we use it in real life. So, this is a really critical podcast, though, because if you've heard some of the other ones where I've talked to some experts, I think I really need to do everyone the service and lay a good foundation of terminology. Because, basically, I mean, some of these experts come on, and especially the one with the knee that's going to come on, might use some terminology you don't understand.

And to really get the most out of what they're saying, I think we need to go a little bit into this terminology. So, hang in there tight for this one. If you need to listen to it a couple times and digest it, it's totally understandable. But this is what it is. We've sat through, people who do sports medicine have sat through classes upon classes on terminology like this. So, it is a different language. And I totally understand that. And the general public or athletes use another type of language to describe the same thing that we're trying to describe as well. So, I'm going to try to match those things up today.

And if you have a knee condition, this is a must-listen-to podcast, a must-listen-to, as well as one to follow it. Because learning how the knee works, as well as the parts, will help you understand the reason why you're doing certain types of rehab. And this is a foundational. I think I'm going to put together, just call it the foundational podcast. And this is just going to be this boring stuff and just me. So, hang in there tight. Let's do it. So, the knee, I'm going to break it down into a few different parts. We're going to first talk about bones, then joints, muscles, cartilage, ligaments, tendons.

Okay? I'm going to repeat those again. So, bones, if you don't know what a bone is, it's the hard area of your body. When you basically die, at some point, all your softer tissues melt away and all there is is a skeleton. So, the skeletons are bones. Where bones come together are they make joints. Now, the areas that you don't see on the skeleton are the ligaments, the muscles, the cartilage, the tendons. You might see some of this if the body is really fresh. But the muscles are, if you think about the bicep or the quad, these are muscles. These are muscles. They are the flesh of the animal. They're what you're going to eat if you eat a cow, a pig, most of the time.

I know there's some fat in there too. But for the most part, anything that is red and striated and feels like a steak, it's going to be muscle. So, ligaments are attached to muscles. They're extensions of muscles. They're basically the same complex. So, we're not going to go too much into tendons today, but I will name some off. But there are some tendons which are actually tendons of multiple muscles. So, it is a little bit of a complex too. Ligaments attach bone to bone to formulate that joint right there. And cartilages are, it's a unique structure. It is kind of gummy sometimes, sometimes it's smooth.

There's different types of cartilage, but the cartilages of the knee are really, really important. One that you probably heard about is the meniscus, but we'll go into this in a second. So, let's start with the bones. So, the first one, the big one that comes down from your hip is called the femur. And a lot of you will call it the thigh bone. And again, that's the femur, the thigh bone. The next one, which is below the knee, the big one, the one that if you bash your leg or your shin into something and it started to hurt, it's probably going to be this bone, your shin bone, which is also known as your tibia.

Now, there's one more bone down there on that section of the leg. By the way, that's technically called the leg. Above that, where the thigh bone is called, is actually the thigh, the thigh bone. I mean, it makes complete sense to me. So, below that, down there where the tibia or the shin bone's at, there's one more. It's on the outer side. If you run your hand along the side of the knee, it's going to feel like this little bony area popping up. It's really prominent, and that's part of a long bone called the tibia. And lastly, we have the kneecap on the knee, which is technically called the patella.

Now, as all these parts come together, the joint names, I know the collective joint is called the knee, but they actually have, say, where the femur attaches to the tibia, that's called one joint, and where the tibia attaches to the fibula, that's called another joint. So, where the bottom part or the leg or the tibia or the shin bone attaches to the thigh bone, that is called the tibiofemoral joint. Okay? We're basically just blending those two technical words together, tibio or tibia femoral joint. So, you're going to see this a lot in literature, and if you guys choose to do some of your own research on how to rehab knees or what the injuries are and so on, you're going to see all these terms everywhere, and it'll be super confusing.

So, the next joint, which is also called a syndesmosis, so it's a little different type of joint than the other ones. I won't go into what a syndesmosis is, but just know that when you read it in literature, it's a style of a joint. Kind of like a ball and socket is a style of a joint as well. Now, this one is where the shin bone attaches to the one on the side, which is that fibula. By the way, the fibula is called the, I guess I heard it called the calf bone. I've never heard that before at all. So, this is where the shin bone attaches to the calf bone, and it is where the tibia attaches to the fibula.

So, it's called the tibiofemoral joint, or sorry, the tibiofibular joint. Okay? Tibia, fibula, joint. Got it? Next, we have where the actual thigh bone attaches underneath, or it's underneath kneecap. Okay? So, if you all remember what the kneecap is called, it's called the patella. Okay? So, this joint is where the patella or the kneecap contacts the femur or the thigh bone. So, it's called the patellofemoral joint. That's it for the joints, and that's all for the knees. And this is probably, that was probably the most boring of all the stuff right there, because some of the technical names for the muscles, or for the bones, people don't know.

And especially combining, I remember going through ankle anatomy, and we had all these ligaments that were named after the tarsal bones that it connected to or from. And sometimes it was one joint, or sorry, one bone first, and then you go to another one, and it's the other bone first. It was really, really odd. I don't know why they named it like that. But now we're past that. Okay? So, muscles, in reality, the knee is affected by muscles, actually, that don't even touch it as well. So, the reason why I say that is because in this section, I'm going to classify them as muscles that are above the kneecap.

They go all the way into the hip, as well as in the direct vicinity of the knee, or sorry, the knee joint. And I'm going to talk about ones that are below the knee joint, which go into ankle anatomy. Now, we can't really separate these at all. Like, this is just the way it is. Like, these muscles that go up to the hip and go up to the ankle, they are affected, or they do affect the knee. So, the ones that are above the kneecap, which go on the way to the hip musculature, are, you might know some generically as the quad. So, the quad muscles are actually the vastus lateralis, the vastus medialis, the intermedius, and the rectus femoris.

And by the way, the rectus femoris is the only one that attaches above the hip. Now, the next ones we have are the hamstring. The hamstring, there's actually four in the back. There's only three that pass the hip joint. There's one that stays locally around the knee. So, these ones are the semimembranosus, the semitendinosus, the biceps femoris longhead, and the one which really doesn't go past the knee, or sorry, it stays locally around the knee, doesn't go up into the hip, is called the biceps femoris shorthead. Now, we're going to the inner part of the thigh, and this is the adductor group, quote-unquote, which you probably know it as.

So, the adductor magnus is one of the large ones. The adductor longus is another one. Then we have gracilis and sartorius, okay? I'm going to name those one more time. Adductor magnus, adductor longus, gracilis, and sartorius. Lastly, I know there's muscles on the side of the thigh into the hip as well. The one that you probably think of all the time is going to be the IT band, but realistically, the IT band is not a muscle at all. Muscle's attached to it. It does function in some knee stabilization, but it really doesn't contract. It's just a hard, dense structure. It's almost like the plantar fascia or some dense structures in the body which really don't stretch and bend, okay?

So, the iliotibial band's right there. But if you're holding the side of your thigh and you're thinking, no, there's muscle there. There sure is. It's actually the vastus lateralis, and it is a section of the quad. It just extends so far to the side that if you look really on a really strong person and you only see, like, so you see their leg and you see them flex, it'll seem, it'll be part of the quad. So, it'll make complete sense when you see that. Now, muscles into the direct vicinity of the knee, which are to note, one is a populateus. It is actually important in regards to locking and unlocking in the knee, which is called the screw-hole mechanism, which we'll talk about a little bit later.

And the other one is called the articulars genu, or gyneu, G-N-E-U. I don't hear a lot of references on it. I do know there are some treatment protocols for these muscles. They are not as commonly found in research as well as Google searches as the other terms would be. Okay, so just to recap, before we go below the knee, there's muscles above the knee. We have the quad group, the hamstring group, the adductors, and the IT band. And the ones directly locally at the knee in the direct vicinity are the populateus and the articulars, gyneu or genu. I am not sure how we said it. I've heard it said many different ways.

Next, we have muscles below the knee, and this is going into ankle anatomy again. And I'll say the ones that you probably know first, the calf, okay? The calf on the backside is actually known as the gastrocnemius lateral and medial head. And these are the ones which present as a, it looks like a ball. So when you see someone with really massive calves, like that big ball formation on the back of their calf, that's the gastrocnemius. The one deeper to that, called the soleus, is actually a flatter muscle. It is for different purposes, but both of those blend into the Achilles tendon, which then will go into the ankle anatomy as well.

And then we have one of the accessory, quote-unquote, calf muscles called the plantarus. Yes, there are other muscles which are made up of ankle anatomy, and there are some on the front side of the shin, but those actually don't cross the knee. So I'm not going to talk about them in this podcast. Okay, other muscles you need to be familiar with if you're going to be talking about knees are some of the hip. And I know this is going a little bit further than probably what you want to, but it's too bad. You can fast forward a little bit, a couple, probably about a minute, and I'll be through it all.

But these are the muscles which are important. And when you listen to the next podcast, you're going to realize how important the hip and the trunk are to knee function, and actually the ankle as well. So you might as well be super familiar with these as well. So the first one is called the iliopsoas, or what you'd call the hip flexor. Okay, iliopsoas. Some of you know it as the psoas muscle. The rectus femoris, which is on the front side, which we did talk about in the quad group. Then there's the hamstrings, again, part of hip anatomy as well as knee anatomy. Then we have the gluteal muscles, the glute medius, the glute max.

All those are super important as well. Those are on the back side. They're basically the buttocks on people. The tensor fascia latae, or the TFL, it attaches to the IT band on the front side. And the iliotibial band, it actually starts up at the hip, and it is controlled by some of the gluteal muscles as well. But it's right up there on the side of the hip. On the back side, we have deeper than the gluteal muscles, we have some of the rotators. The piriformis muscle, other ones called the gemelli, the obturator, quadratus femoris. These are ones that you probably won't hear too much about. But I always consider them as the rotator cuff of the hip.

They do some small stabilizing motions, and they do get injured from time to time. On the front side, we have one kind of similar called the pectineus. It's a small one up inside the groin. Actually, if you put your fingers across your hip, thumb behind, and your index finger and middle finger will start to descend towards the groin area, you'll be right in and around the area of the pectineus, especially when you're seated. Now, we have the adductor group as well from there, the adductor longus, magnus, and brevis. I think you're starting to see that these terms are seeming to repeat. So, longus, and brevis, and so on.

Then we have the sartorius, the gracilis, and those are also part of the adductor group, which I noted in the other part of the knee description. So, lastly, lastly, we're going to go into muscles of the trunk. And the reason why I'm talking about muscles of the trunk is because trunk stabilization is extremely important. And there's different terminology that people use to explain how to properly stabilize and have the trunk function. Some of it incorporates breathing. Some people call it postural stabilization. Some people call it midline stabilization, core strength, trunk control. I mean, it goes on and on and on.

But for the most part, you have to understand that the trunk has to be, or the trunk controls the pelvis. The pelvis controls the hip. The hip controls the knee. And then this is why we're talking about this whole thing. Some muscles that you will hear in regards to core stuff are the internal and external oblique. They're on the sides. They do wrap around more towards the six-pack muscle called the rectus abdominis. The one deep to those, actually, a lot of these muscles of the trunk, they come in layers. And they're kind of in the same area. The transverse abdominis, or TA, you'll call it, you'll see it a lot in research, is below those internal and external obliques.

And then we have muscles in the backside, which are also known as core muscles called the QL, or quadratus laborum, the multifidus, the paraspinalis, and lumbosacral fascia, which are all in the backside there. Now, other muscles, which obviously, we're blending into the hip as well as moving up the chain. But other ones to note, which are extremely important in regards to core stabilization, are the latissimus dorsi, which also go to the shoulder, as well as the diaphragm and the gluteal muscles. So let's not forget about all that stuff. By the way, if you guys do have questions on some of these areas for the core, I have an article on my site called 14 Secrets to Back Pain Your Mother Never Told You.

I believe number three goes into a lot of this in isolation without considering the knee. So if you want to learn about interabdominal pressure as well as proper breathing patterns and some things you can do to improve on that, if you're looking to do that already, and if you have knee conditions, then these are things that you want to. This is something you're going to want to read. We're going to go into carlages next, but before I do, I just want to let you know that if you do have a knee condition, you need to go see somebody. And the reason why I say this is because when you go into the next podcast, you're going to hear that doing the right rehab is extremely important.

Now, the term that we use is, or that this expert's going to use, is called earning your surgery. And knowing the right rehab is, and doing it for a period of time, is earning your surgery. And a lot of times you will come out much better from the surgery after the fact if you need it in the first place. But you have to put the time in, okay, and it all starts here. Now, carlages of the knee, there's mainly two you have to be familiar with. And the meniscus is one. This is the one that, it's C-shaped. It's on the inner and outer part of the knee. And if you look at the anatomy in the, actually, I will have, I don't think I have it yet, but we're going to have a whole knee section, knee anatomy, on the website.

So click on the knee on one of the people on, about your injury, and you're going to see that all this stuff is going to show pictures. So you should probably listen to that, listen to this podcast while you're looking at that article as well. I should have started with that, huh? So anyways, we have the meniscus lateral medial, and we have the articular cartilage, which is on the femur head as well as the tibia. The ligaments of the knee are ones that you probably heard about as well, especially the major one called the ACL, or the anterior cruciate ligament. Then we have the posterior cruciate ligament, which is kind of the same thing, but going the opposite direction.

And we have the lateral collateral ligament and the medial collateral ligament, or MCL, LCL. By the way, the ACL was the ACL, and PCL is the posterior one. So those are the major four. There are a bunch more, which include ones which make up the capsule of the knee, which really, think of the knee, think of wrapping your knee in an ACE bandage and just wrapping it, wrapping it, wrapping it. And that's kind of how the capsule of the knee is, but it's made up of all these different fibers of the ACE bandage in all these different directions to stabilize against different types of motion. So those are the big four.

The other ones I wouldn't get too concerned about just because they're going to get way more complex than you're ever going to want to know. This is a good starter course. Now, knee anatomy does include tendons. And like I said before, tendons are extensions of muscle, extensions of muscles, and it's basically a complex. Okay, tendons attach the muscle to the bone, which then allows that muscle in tendon complex to move the joint. Okay, so the quadricep tendon is an example of those. There's four muscles, which we noted before, which then combine to form the quad or the quad tendon. Okay, the quad muscles become the quad tendon.

The quad tendon then attaches to the knee cap or the patella. And then there's another tendon, which comes off of this. And by the way, the patella is a sesamoid bone, which is almost like a floating piece in a tendon. It's a floating bone in a tendon. So this tendon is almost the same as the quad tendon, but now it goes even further. And now it's called the patellar tendon. I mean, crazy, right? I mean, like you have the same type of structure, which is called a couple different things. But just know that they are extensions of the muscle. Okay, so when you have an issue with a tendon, a lot of times you have an issue with a muscle.

When you have an issue with a muscle, we have usually an issue with a movement. Okay? Where there's been something which occurs, which creates that complex to become symptomatic or painful. And this goes along with some of the other types of conditions, too, of cartilage and so on. And I'll explain the reasons why here when we go into mechanics. Now, a couple different terms we need to be familiar with that you're going to hear are flexibility, mobility, and stability. Okay? I'm not going to spend a ton of time on these things because I feel like the definitions are changing a little bit, especially over the last four to five years.

The flexibility, for the most part, is I would consider it as how far you can move a joint without the supporting muscles or the muscles around there even being on. Imagine that you're laying on a track and one of your teammates comes up to you and they want to. Like, hey, you need help stretching your hip? Yeah, sure. So, they put your foot in the air, they lock your knee out, and they stretch your hamstring beyond belief, and it's further than what you feel like you can do on your own. Okay? So, that's passive. That is someone else doing the work, and that range of motion that you attain is your flexibility.

Okay? Now, when we go into mobility, I mean, it sounds like a similar thing. And to kind of play devil's advocate with this, since there's so many different terminology flying around now, with it, I wanted to see what most of the Google searches are actually pulling up. And I found some really extreme ones or large ones. One was by Kelly Starrett of MobilityWOD, which it was a really long, complex statement. By the way, you can look that one up if you'd like. I thought it was a good explanation. But then I found some really simple ones, you know, which were basically the range of motion that you have when your muscles and tendons are contracted or when you're doing it yourself.

So, I'm not going to say which one of those I agree with more, but for the most part, I think I have a responsibility to explain a little bit. Now, I'm going to go one step further and tell you at least my thought on the range of motion and flexibility or whatever we're going to call it from now on, is that for the most part, if you're going to attain a certain range of motion or quote-unquote flexibility, you have the responsibility to control it. If you can't control the motion that you have, then you are prime for an injury, just prime for an injury. So, I'm all about keeping people within the bell curve, the normal range, the normal range of motion that you need to accomplish a motion.

Okay, an example of that, let me just talk about the shoulder for a second here. If I can reach my arm over my head 180 degrees and I can control it, that's great. That's all I need because all I need to do is get my arm over my head and reach and grab something off the fridge. Okay, that is the movement. That's the purpose that we're using it for in this case. Now, do I need to have my arm being able to dislocate and go beyond 180 degrees and be able to put suntan lotion on like obscure portions of my back to then do that same motion, to do that same purpose, to reach on top of a fridge? No, I don't.

But if you do have that extreme range of motion, you darn well better be able to control it too. Because if that's just that motion that someone else can stretch you into like Gumby and you're like a contortionist, I guess contortionists kind of move themselves. But let's just say if someone else is moving you and you're a contortionist, that's a little bit of range of motion. I think it's just a high risk of injury. Now, so my definition of mobility is going to more or go around, it has to be a controllable range of motion that allows quality motion or patterning to accomplish the movement pattern that we're trying to do.

An example, if we're talking about lifting, being able to deadlift from the ground requires, or a Romanian deadlift requires a certain amount of hamstring flexibility. If you can't do it, then you have to work from a higher starting position such as blocks. Now, you need to make sure that if you're going to go from the ground, you have proper hamstring motion or hip range of motion, inflection as we call it. Because if you don't, then it'll create rounding at the back and that's not going to be wanted on something like a deadlift. So my go-to is that we need to make sure that we have a controllable range of motion that allows for that movement pattern that we're looking for.

That's my standpoint on mobility, at least at this point. I'm sure it'll change over the couple of years. Now, stability is the ability to resist a position, okay, or to be able to resist something or someone changing your position. Now, probably a good example of this is if we're talking about doing, let's just say squatting. If with weight, you're able to do a proper squat, the knees are stacked over the feet, you're not caving or anything like that, and then also we put some weight upon you and we start diving around and starts caving inward and so on, that's not good stability, you know, and I think that we, it's, I always think about a drunk test on this, okay?

Ideally, we want to be walking on the line when you're getting tested, okay? Now, if you fail the test, you would come off the line in some degree or fashion. Now, if you think about how far you come off the line, let's just say I took a step off, like a slight step, you know, like maybe six inches, and then I could, I controlled along that path of the line. That'd be pretty good stability in my opinion. Now, if I was following that path and I fell off the line, okay, and I had to get back up and I was about a foot off of it, and then I went back to the line and I fell off the other way, that undulation of stabilization I think is terrible, absolutely terrible.

So, it doesn't matter if I finish at the end of the line, at the end of the line or not on the line. It's how I get there and how far I deviate from the path that's intended, okay? So, imagine that again, just close your eyes, sit there and think about that drunk test line, okay? How are you going to pass? Are you going to pass by falling all over, hanging on to the cop, getting to the other end and saying, I did it? Or are you going to make sure that you only deviate slightly from the line? And in that case, if you deviate slightly from the line, you're less probable of getting injured, and that is better stability.

Now, really soon we're here, we're going to go into actually the mechanics of the knee and how it works, and a couple different analogies. But first off, you're probably wondering how you stop having injuries in the first place, or how do you limit injuries of the knee? And I would say that first off, you have to make sure you have high quality motion, you have to have proper training volumes and intensities. An example of that is, let's just say you're running, if you usually run, your volume is 30 miles a week, and all of a sudden you jump it up to, you know, 60 miles a week, that's double the jump.

It's kind of irresponsible, and you're looking for an injury, okay? Versus the intensities of some of those training days. Let's say you've been normally doing four days a week, let's say, gosh, what's going to be easy? Easy math here. Say about three days a week, 10 miles a day, and that is your 30 mile a week volume, okay? Now, what happens if one day, you know, like, you know what, I'm going to be busy the next couple days. Why don't I just do 30 miles a day, all in one spurt? So that's a three times jump in intensity or distance, and that's a little irresponsible too. So these are the things you have to consider as well.

You have to have proper training volumes as well as jumps in intensity when you're doing different things, and this comes to squatting as well as golf and baseball and all these different things. And then lastly is you need to make sure you act your age, okay? The age difference on recovery is pretty significant, and I remember being, you know, early 20s and being able to just go out and do sprints. The next day you're a little sore, but now being like 35, I kind of pay the price a little bit. And although that I'm pretty active during the week when I play baseball on Sunday, the next Monday, God, I can't move, you know?

Like, just stealing a couple bases and running after balls. I mean, it's much less activity than I usually do during the week, but the intensity is different. So the recovery is different too based upon my age. So the mechanics of the knee that we're going to go into are, first we're going to go into the concept of open versus closed chain mechanics, okay? Next one, I'm going to go into my analogy of, and I have told this to a lot of patients, I actually take two foam rollers and I stack them together, and I call it the cylinder stacking analogy. I don't think this is a technical analogy that a lot of other people use, but it seems like it works very well in understanding how the knee works to me and my patients.

The next is the door hinge analogy, and then we have a little bit about the screw home mechanism. And I think that's all we're going to go into, and then I'll just talk about the meniscus slightly. So first off, we had, what did we have here? Open versus closed chain mechanics. So open chain basically means your foot is off the ground. And by the way, the chain is the kinetics chain, in case you've heard that term before. It's basically how the linkage of your body or your extremity or leg and trunk work, okay? I don't know how they came up with the term kinetics chain, but for the most part, we can leave the kinetics part out and think open and closed, okay?

Open chain, foot's not on the ground, so you don't have the ability to push off the ground for anything. Closed chain is the exact opposite. You have your foot on the ground, and you're able to push off, so it changes the way things move, okay? So let me ask you this then, just think about it. So the muscle, what muscle actually extends the knee when you are performing a seated knee extension machine at the gym, okay? So you're sitting there, let's think about this, the knee is floating, the foot is floating, and you're extending the foot into the air. So this is actually the quad group which does this, and this is why people do this machine, because they want to enhance the size of their quads.

And there's nothing wrong with that, in my opinion. It's just a means to an end. If you're looking for increasing the size of something, then definitely doing a quad machine or joint-specific activity or exercise would do it for you. But now let's think about that same joint. Let's think about that knee. Which muscle group actually extends the knee when you're running, okay? It's probably some of you are thinking that this is still the quad group, but it's actually not. It is actually the movement of the hip into extension. And this comes from the hip extenders, the glute max, as well as the hamstrings, okay?

And I know it sounds ridiculous to think that, but if you look up, actually if you stand there, if everyone stood right now, and then put that foot on the ground and they kind of propel themselves slowly over that, they're going to see that the extension of their hip relatively extends the knee, okay? When I first learned this, it was kind of mind-blowing because it made me think about rehab and how we should rehab a knee realistically to get people back to the activity they want. If they want to do only quad exercises and they want to work on muscle growth, by all means, that's no problem. Like, they might never do closed-chain exercise.

They might not run, jump, cleans, squatting. They might not do any of that stuff, which is perfectly fine. It's not for everybody. But if the job is to get you back to doing what you want to do, then I think we need to rehab it in that way, too. And we probably start with a lighter load. And we go from the concept of proximal stabilization to distal motion. And let me explain that for a second. So, stabilization, we talked about that concept before. It's being able to hold something in the desired position or path that you want it to. And proximal, in relationship to the body, it's actually closer to your center.

Distal means further away from your center. If we're talking about a leg, the knee is more proximal than the ankle is. Okay? The hip is also more proximal than the ankle is because it's closer to the center of your body. Now, like I said, the knee is more proximal than the ankle is. But the knee is more distal than the hip is because the knee is further away. So, you want to make sure that everything closer to your body, your core, your pelvis, your hips, your knees, are stable before you got to that ankle, say. And the same thing happens with rehabbing knees. So, we want to make sure that the core, in breathing patterns, intra-abdominal pressure, hip, pelvis, gosh, muscles of the thigh are all working well before you really get down to the knee too much.

And, obviously, there is an art to programming a program for the knee. There are specific things you want to do locally right there to the knee in the beginning to increase range of motion, increase a little bit of function. But we have to consider why this happened in the first place. And majority of knee conditions actually don't happen from trauma, slip and falls, someone sliding into you. A lot of them happen just from nothing at all, it seems like. Although, you might say, like, well, a 10-mile run wasn't that, like, it wasn't nothing at all. But, realistically, if you look back, you can probably see this thing happening and starting over time.

There was not one specific run, I doubt. There could be. You could prove me wrong. But majority of the time, it's not. And you have to look at why this injury is happening in the first place. Okay, so remember that concept of proximal stabilization to distal motion. We have to make sure that we stabilize closer to the midline first if we're going to be responsible at getting that whole leg working. Now, back on to the concept of open versus closed chain mechanics. I originally said that the knee is extended open chain with the quad as well as closed chain with the hamstrings and hip extenders.

Just remember that. Okay? So when we're strengthening the knee, we also have to strengthen the hip. We have to strengthen the core. I'm being very general with the term strengthen, by the way. Let's just say improved function. And also the foot and ankle. The knee is right in the center and it takes a brunt force of a lot of things there. So the next analogy I want to go through is the cylinder stacking analogy. And usually what I do is I take two cylinders and I put one on top of each other. And if you don't know what a cylinder is, just think of a Coke can. And you can actually take two soda cans and do this.

Probably right. You can do this right now. These cans stack really, really well when they're in the right position. And they're really strong. And you can probably make, I mean, you can make a coffee table out of soda cans. You know, like especially ones that aren't open and just stack them there. Make the legs. Make it three, four times as high. And as long as you don't push it off from the side, it's going to be fine. You can probably sit on the table, I bet. Gosh, just don't wiggle around too much. But basically, when these cylinders are in the right position, they're really, really strong.

And they can be stacked, stacked in position. That's why I call it the cylinder stacking analogy. But when they're off even a little bit, I mean, consider sitting on that coffee table. If one of your friends is playing a joke, he just barely kicks a leg. And all of a sudden the whole thing comes crumbling down and it degrades really fast. The knee's kind of like this. I mean, you need to make sure it is stacking well and in a proper position. And my analogy of the columns originally came from the cylinder bones above and below. And the femur or the thigh bone is a long cylinder. It obviously has butt ends at both ends of it, as well as to make up different types of joints or where they connect with the other bones.

But the tibia is kind of the same way too. It's just a cylinder. It's a long bone. And they're really good at controlling or taking downward pressure. And I think that's why the body was designed this way is because these cylinders are great at controlling the force of gravity downward. But it's our responsibility to keep these cylinders stacked. Now, I know the knee is more complex than that. And just for all the other healthcare providers out there, just realize that I'm trying to make this easy for everyone to understand. Yes, there is a lot more going on. There's a lot more to that knee joint and the other joints around it to kind of tear this analogy apart.

But for the most part, we're talking about how to stack properly against gravity there. Now, the next analogy that I've used a lot is the door hinge analogy. And the reason why I started thinking about this in the first place is because the knee is actually, by categorization, it's called a hinge joint. Okay? It only likes really one direction of motion. It tolerates the other ones a little bit. So it likes to be extended and flexed. And it does really well in those motions. It does it really, really well. I mean, there's a ton of range of motion into flexion. And you can basically touch your heel to your butt if you have complete range of motion of the knee.

But it doesn't like rotation and lateral bend too much. And by the way, I realize there is some rotation in the knee. We're going to cover that in the next section, which is going to be the screw home mechanism. But for the most part, too much rotation. And by the way, it doesn't take a lot. Too much rotation and lateral bend that we're basically creating those cylinders to break apart. Now, the reason why I like the door hinge analogy is because, let's just say you took a door. And you had to put a new hinge upon it because the old one was really, really rusty and grimy. And it was squeaking and stuff.

So just shut your eyes and imagine this door analogy. So we've got a brand new door. We've got a brand new hinge. A brand new frame. Everything about it is perfect. Okay? The drywall is nice. We've got a nice stained finish wood. Maybe even some glass inside it, you know, so you can see outside in case the doorbell rings. You want to see who it is, right? So now imagine this perfect door, perfect hinge on this old rotten wood plank. Okay? And this wood plank can be as wavy as the swells of the ocean. If you're waiting for surf, you just get these ups and downs and undulations. And so in this house where we put this brand new door and hinge and frame and wall and glass and everything, we have this really terrible floor which has been weathered and just wavy around.

So when we shut this door, or actually when I, we say when you put it on, it has tons of clearance and it doesn't hit anywhere. It doesn't hit the ground. But all of a sudden now we're shutting it and it goes, it dunk, dunk. It hits the waves here and there. Okay? And what happens there is when you press that door hinge shut, or when you press that door shut, the pressure actually goes on to the hinge. I mean, the door itself is pretty strong, but it kind of wiggles that hinge. And that's what's going to wear this hinge over time. And the knee is a hinge joint. So this wavy analogy, or the door hitting the waves, is pretty analogous to subjecting the knee to rotation and lateral bend over and over and over again.

And for you runners out there or repetitive motion athletes, cyclists, these are the types of things that are going to get you. So the ways you control this wavy floor, in this analogy anyways, there's a lot of things that can cause it. So poor core function, poor hip strength and endurance, poor ankle mobility from maybe an old injury, maybe hip impingement that you've had for multiple, multiple years, maybe an old hip surgery. Maybe you had an old injury from way back when it's never really 100% went away. Perhaps you stubbed your toe years ago and you couldn't run on it and had poor running mechanics, poor shoes.

I mean, the list can go on and on and on. But for the most part, it's our responsibility. If we're going to decrease the possibility of knee injuries, we need to address the reasons why the hinge is going to rot away anyways. Now, the more technical of the local knee mechanics is called the screw home mechanism. And I'm really going to try to make this super easy for you guys because it is, it's one that I remember when I was in school, I'm like, gosh, is this really cool? It's really that important? You know, like, but the screw home mechanism is a great example of how the body mechanics change again versus open and closed chain.

So it's based upon which point is being fixed. And if we're open chain or the foot's not on the ground, the contact point or the thing that which is fixed is going to be the femur. Okay, because say if we're doing that knee extension machine, then the femur or the butt, the entire like the entire thigh is fixated on the machine and the tibia or the foot is free floating. Vice versa happens when you're actually standing or squatting. Then the thigh is the moving part. And the same thing happens with running and jumping and so on. So now that we know that the major contact points in the knee are between the femur or the thigh bone and the tibia and the shin, you should know that there is some rotation which happens between those.

And it happens in order to properly lock out the knee joint so you can actually propel yourself and use it as a driving force when you're running or when you're doing the knee extension machine. Now, I was trying to come up with a good analogy that would be a good visual for you guys on this one for this little bit of last of a turn, but all I could think of was tent poles or poles onto like an easy up. So you're basically just extending the pole and all of a sudden you have to lock it out or a pin has to hit a certain point to actually fix it. This is kind of that same way. And I know I said that rotation is bad for the knees, but it has about 10 degrees of rotation just before it locks out so you can actually use the light to drive you forward again, okay?

So this is why I said the cylinder stacking analogy is not 100% perfect because it doesn't account for this, but I'm sure I could probably modify those things up a little bit to show that they lock after about 10 degrees of rotation. So I said the bones actually move upon each other. I know I said that. And this sounds like a terrible thing and it sounds like they're rubbing. It sounds like you're just tearing your joints up. But realistically, the way that the bones are formed also help guide it into the movement that it needs. And for the screw home mechanism, some of the contour and architecture of the bones guide it that 10 degrees so it locks, okay?

So remember I said it guides the joint. It doesn't... These contours don't move the joint. They guide the joint. The muscles and the tendons are the ones which move the actual joint, okay? So the screw home mechanism as an open chain... Again, this is when the foot is not in contact with the ground. We're going to cover this first. This is when the tibia actually moves on the femur or the shin bone moves on the thigh. And you might wonder why is this? And again, it's because as I said, when you're sitting on a knee extension machine at the gym and you want to lock that knee out to make sure you get the last bit of quad contraction that you can get, the thighs are fixed.

And the shin is kind of free to do whatever it wants to do. So in open chain, we're looking at the lock of the knee into full extension happens around the last 30 degrees. And this is where the shin bone starts to externally rotate to actually lock the knee into extension. And external rotation of the shin and what it's going to look like is going to kind of look similar to like your toes flaring outwards. And this is not a 100% precise analogy again because there is an ankle in the way. But for the most part, it is that motion where you're flaring away from the center. So remember that again.

We have an open chain. We have the tibia or shin bone moving to create the locking. Now in closed chain, it's the other way around. And it's basically 100% opposite. So in closed chain, we have the last 30 degrees. The thigh bone begins to rotate. But instead, instead of rotating externally, it rotates internally. Okay. I'll say it again. The thigh bone begins to rotate instead of the shin bone because the shin is now fixed in position by the foot being in contact with the ground. Okay. In closed chain, the thigh does the rotation to lock the knee into extension. But this time, internal rotation occurs, not external when the tibia does it.

Okay. So I know I'm being redundant, but this is a concept I want to drill in a little bit. Okay. The femur spirals in about 10 degrees to match that same point that we had in open chain. So in the end, it's kind of the same knee locking. It's just based upon what moves to get it there. So yeah, the muscles and tendons and ligaments are all involved into the screwing mechanism. But to keep this really simple, I'm not going to go into it too much. That would probably confuse you guys. But for the most part, just be aware that there is a flaw in the cylinder stacking analogy and is mainly that last 10% of screwing the knee together to lock it out.

Now, the meniscus is the last thing I really just want to talk about. I won't talk about it too much. And the meniscus is a cartilage of the knee which helps glide the two bones together. The femur bone as well as the thigh bone as well as the shin bone and the tibia. And I said before that it almost sounds like the bones are grinding together, but they're really not. It creates a little bit of a buffer, a shock absorber, but also helps transfer load between the thigh and the shin. And the reason why it's important to realize that the meniscus is there is because that to let it do its job as well, we need to make sure that that lock home or the screw home mechanism has actually occurred.

The meniscus was not designed to take a ton of force. And this is the reason why a lot of times it shreds and tears. And going back to, again, the other analogy of the hinge, think of this cartilage of the meniscus in that door hinge just getting shredded up because we're requiring too much ambient motion and different planes of motion in it. So this is all I have for you guys in regards to this. And I know it was a boring one, and it was a long one, but you held in there. You did a great job. If you listen to the next podcast, you are going to fully understand the reason why I went to so much detail because we're going to be flying through some terms.

And in up-and-coming podcasts, I'm going to have other experts talking about knee rehab as well, but in different populations. So the person that we're going to talk with next is going to talk about runners, but also he alludes to different types of athletes as well. Now, if you guys have not been on to the P2 Sports Care site again, some of the show notes for this podcast are going to be on there. They'll be cliff note version. But for the most part, if you dig through that site, if you look through, most of the content is actually under the About My Injury section. And if you click on to some of those hot spots on those athletes, you're going to see all this information pop up.

And I do my very best to keep it simple, similar to this podcast. I realize that we're speaking a different language than general public, and it's our responsibility to educate you guys about what we're talking about, or we should make it into easier terms. One way or another, we need to understand each other. But for the most part, those pages, I've spent months and months of my life writing. I'm not even lying. And if you talk to anyone who knows me and has read my stuff that has not been proofread, oh my God, I actually had to pay a proofreader for this thing because I'm terrible with that stuff.

I'm good at getting content out, and I'm good at digesting this material to make it easy for you guys. So if you find any typos, please let me know. But spend some time on the site, okay? The podcast is intended to feed you the content in a different way. If you're traveling, if you're driving, if you have friends that do the same, suggest this podcast to them. But really, if you're a visual learner or you like reading, then it's going to be on the website, okay? And I also do have some YouTube videos and a YouTube channel. If you YouTube Performance by Sports Care, you'll find a ton of videos that I have for free on there.

I have a ton of free content for you guys. So I hope this was helpful. Go to p2sportscare.com. Again, that's P, the letter, two, the number. Sports is plural. Care.com. And you're going to find a way to subscribe to my YouTube channel in there. Just go through the book button. Go to the patient resources. You can find how to subscribe to this podcast as well as some of the YouTube channels and all the free content that you're going to love about knee conditions. And by all means, suggest this podcast to your friends. Please, please, please. It helps me out a ton. Actually, our podcast rankings, they actually, iTunes doesn't tell us how many subscribers we have.

And it actually doesn't, it actually ranks us based upon how many subscribers as well as views, or sorry, downloads. No, sorry. Reviews that we get. So please, please review it. I would love that. I want to share this information as much as I possibly can. And the best way to get it to people is for you guys to subscribe and review. So take care. Again, this is Sebastian Gonzales from Performance Place Podcast. Talk to you guys soon.