Episode 11 | What is a “Quiet Knee” and Why It’s Important in ACL Rehab

What’s up ACL athletes and welcome back. Today, we are going over what is a quiet knee and why it’s important in ACL rehab. And so first, before we get there, I just want to give credit where credit is due. I first heard this term “quiet knee” from Hughes, and I tried to dig a little further into where this exactly came from.

The first place that I can find that it originated from was articles back in 2015 and 2016 by, I believe the name is Fia Fila, F-A-I-L-L-A, in the research and they reference a quiet knee. Today, we’re gonna dive into more of the general perspective of what a quiet knee is, and in future episodes we’ll actually dive into more of the specific components of it.

So to get into that definition, specifically of what a quiet knee is, it is number one, full range of motion. Number two, quadriceps activation, which is your front thigh muscle. Number three, little to no pain. And number four, little to no joint effusion. So that means the swelling or the fluid that we see within the joint.

So these are the four that really make up what a quiet knee is. So you might be thinking, why is this so important and what I want you to think about is building a house on a poor foundation. You know, you’re not really gonna trust it. It might work okay for the short term, but long term it’s not gonna really withstand very much stress.

And then you might have to redo it. So this, in this same situation, I want you to think about these components. Being the foundation for the knee is going to be very difficult to build on what you’re doing if you don’t handle these prerequisites. and you can notice how each of these will interact with each other.

So if you have joint swelling, then it’s going to limit the amount of range of motion you have in your knee, and that will limit how you can straighten your leg, which will limit how you can activate your quadriceps. And then we know that pain also plays along in this process. I know for me specifically, immediately after my ACL injury, all of these things started playing into it, and your knee just goes in this freak out mode where there’s pain and where there’s swelling, and where there’s that limitation in the range.

It’s hard to really walk on it normally and then hopefully this normalizes. But a lot of those processes are important to take care of early on. So whether you are in the prehab stages before thinking about surgery, or if you’re in the process post-surgery, this quiet knee is very important and the research is something that really supports this as well because it shows that it has better outcomes long term.

And in my personal experience working with ACL athletes, they do better overall because they have gone into this process and calmed their knee down. Getting that range back, they’re able to control the quad. And then from the swelling standpoint, most surgeons won’t even operate unless the swelling is controlled.

So that’s really important as well. But sometimes what I will see is that the range will not be fully restored or that their quadriceps are not really functioning very well going into the surgery, and then they get out of the surgery and it ends up being such an issue later down the road. So this is something just to think about as you’re going through this process.

And the question that I get most about this is, what is “normal” for this? Like, what is the timeframe and what should I be comparing this to? And I’m just going to give an overall structure for this. And it’s always going to be dependent on your situation, whether you don’t or do have surgery, the type of graft you get, maybe the different trauma that you have to the knee, all this is going to vary. 

So early on you’ll see less range and it’ll be harder to get the quads to get going, and it makes sense, you know, you just had the trauma there’s more pain, there’s more swelling. So those things are going to counteract things that your knee is going to want to do, aka move and get activated.

So that is completely normal. It should just be trending in the direction of getting more range and getting more quad activation, and decreasing in pain, and decrease in swelling. When you’re looking at the mid to late stages, you want to make sure that you get that full range of motion, especially extension.

I cannot stress how important extension is in this early phase process, and especially getting into the mid to late stages. If you don’t have it, keep working on it. Because it’s gonna be very important from a mechanic standpoint when you’re looking at quad activation, that should be completely there and working on getting the quadriceps as strong as possible and then making sure that you can minimize as much swelling. Now, will that be completely absent in the process when you’re in the mid to later stages? Not necessarily, but you want to make sure it’s aiming towards the very little to none, and especially with pain.

Pain is always gonna be something that will kind of creep in every now and then. This is where you have to check with your medical provider you’re working with to see, you know, is this a healthy amount or not? But it will be there sometimes and you’ll deal with it, especially when you’re stressing the knee.

So these are the things that are going to be so important because it’s going to let us know, is my knee tolerating the stress that I’m putting on it? Is it tolerating it, and if you’re starting to notice a really quick uptick in your pain and especially in swelling, then it might be too much too soon and this might be the perfect time to check in with that and see, okay, what is it that I’m doing?

Maybe it is running. A lot of times what I will see is that people will not get their extension back. They will be in a more flexed position. Their knee has not been prepped for more of a dynamic position, and especially with getting the quad stronger. And so then that in return will start to stress certain areas of the knee, and then we’ll start to see the knee swell up some, and then as a byproduct, you’ll also see some pain.

Now, that’s not always the case, but it is something that I see very often, especially whenever the range is not gained. So this is something to keep in mind as you’re moving forward in this process, whether it’s fresh off of an ACL ijury or fresh off of ACL surgery. No matter where you’re at along the spectrum, if you haven’t gained these specific prerequisites and are making sure that you’re getting to a quiet knee, it is going to be difficult to build further on that.

So remember, the foundation needs to be solid before you can build further, and that’s where the quiet knee comes in. So let’s review. The quiet knee is full range of motion, full quadriceps activation, little to no pain and little to no joint effusion. These are the four main components that you will see that contributes to a quiet knee, and it is something that is going to be very important early in the rehab process to make sure that you can build and move forward with the things that you want to do, especially with the heavy loading and the jumping and the running that I know a lot of us want to get to. And it’s the fun part, the basics are boring, but they are very important to be able to build towards the things that you want to do. 

So these are the things to keep in mind, and we will talk more about these individual components of a quiet knee in future episodes.

If you have any questions or comments, please send them my way. I love hearing about all the feedback about this podcast, and I’m always trying to improve it and answer questions, and more importantly, just serve as a resource with this specific area. So do me a favor, please leave a review. If you don’t, you’re dead to me.

I’m just kidding. But this does help to push this further and to be able to expose it to more people, which hopefully in return allows them to be more equipped in this process. So I appreciate all of you. That’s it for today’s episode. Thank you all so much for listening. I hope you have a good rest of the day.

Good week. This is your host, Ravi Patel, signing off.