Episode 190 | Flexion vs. Extension: What Should You Prioritize Post-ACL Surgery?

What is up team and welcome back to another episode on the ACL Athlete Podcast. Today, we are on episode 190. I can’t believe we’re approaching 200 episodes here soon. It’s wild to think we’ve been at this for 190 weeks straight. And the thing that this was something I wasn’t going to do, and now here we are episode 190. Let’s get into it.

What should you prioritize after ACL injury and surgery: extension or flection? And I feel like this should be straight forward—see, what I did there straight for extension. I’m sorry. I do want to touch on this mostly because I talked last week on the concept of the honeymoon phase. And along with this comes people’s focus on different goals and exercises when they are post-injury and post-op for ACL. And I see this mistake all of the time. They go super hard on flexion, thinking that’s what they really need to prioritize. I’ve thought about this a lot now, working with over hundreds of ACLers and talking with them and going through it myself twice. It’s as simple as there’s just more noticeable range and change to us as humans. It feels like what needs the most work since we come out of the injury and surgery more in extension. We’re locked in extension usually, or just in that straight leg position. And so then therefore we feel like we’re almost already there. And the flexion is what’s going to take a lot of work. And then also we’re just hesitant to bend our knee. 

First, a lot of people aren’t giving goals to work towards, that’s one of the things that’s really challenging. It’s not explained what exactly is that goal. It might just be work on flexion and extension, not active knee extension matching the other side or a heel pop, or maybe it’s flexion matching the other side, or maybe is to 90 to 120 degrees to start. But even with that, there’s a lot more degrees of freedom you need to work back; getting with flexion versus extension. When you think about that knee coming out of surgery, and it is in that straight-ish position, even if it’s locked in a brace or not, you might just need to get a total of maybe 10 to 25-ish degrees max back. It’s not a lot of range of motion that you’re trying to regain. Versus flexion, you think about it, you need to try and get to a minimum of a 90 to 140-ish degrees back. There’s a huge range of that. That’s almost 5 to 10 times more than the amount of extension that you’re going to be trying to get back. And so that’s something that you’re going to notice more difference in flexion as well. Extension, not so much. You’re already kind of there. And so then therefore you’re like, all right, I really need to work on flexion, which is why people will hammer flexion and push off extension or think they’ll get it since it’s less range achieved. They’re like, I’m already, almost there. I work on this while I work more on flexion. But what I see is that this plays into difficulty getting into extension if they don’t prioritize it as number one post-injury and post-op. The further you get out from this injury and the surgery, the more challenging it is to get your extension back. You don’t have to pick one or the other. The answer is usually working on both. But then you do need to prioritize. We’re big on trying to set priorities in this process, even with our goals and making sure we are tackling this. 

Number one is going to be extension; it is number one. Number two is going to be your flexion. Your specific goals to get to those things are based on your case and restrictions. It might be graft type, other concomitant injuries that happen in procedures, meniscus involvement and repair, maybe it’s a meniscectomy, etc. There are other things that can happen in this ACL injury, but then also, especially surgically that there are restrictions potentially around the certain things you can do. Very rarely is extension getting to full extension, going to be a restriction. Now you might get a restriction on flexion. It might be to 90 degrees or to 120 degrees, depending on what it is. But for the most part, you can go after extension is very rare that you’re restricted in that with an ACL reconstruction or an injury. We want that back ASAP. 

In general, to give you guys an idea, our goals are to achieve extension matching the uninvolved side ASAP as number one. Now there is a caveat if you are a hyper-mobile athlete, if you’re super bendy and flexible, we might not be trying to get all the way to matching the other side because you might have minus 15, minus 20 degrees of hyperextension, which is a lot. And on average, most normative values are athletes are somewhere around minus five to maybe minus 10 of hyperextension. And so this is something that we want to make sure we try to achieve mostly using the uninvolved side as our target. Zero is not the goal. I’ve done a podcast on this previously. We do not want to get to zero degrees extension, unless for some reason that is your uninvolved sides normal extension, then we could be okay there. But for most people, we’re trying to tackle some hyperextension because that’s going to allow us to get that heel pop and allow us to get really solid quad contraction. And that’s going to be so important for gait for all kinds of other different movements, triple extension for acceleration and for jumping and different activities where we need full knee extension and hyperextension. It is a part of our normal human anatomy. We think about our elbow. It doesn’t just go to zero; it hyperextends as well. So the same thing with our knee, we’re going to have some hyperextension in most cases. 

And then for flexion, when we’re talking about in general, some goals we’re trying to tackle. We’re at least aiming for 90 degrees in the first two weeks and 120 in the first four weeks. These are targets we give our athletes. Just know people don’t hit this perfectly because these are just targets, and we update this as we go based on each person’s case and other factors involved. Again, other surgical procedures, maybe they’re dealing with a lot of swelling and maybe the pain is very limiting, maybe they had a hamstring graft. The quad graft could be feeling some pull there. There are a lot of factors that play into this, but we are going to try and work towards the 90 to 120 degrees, because that is going to be a very solid spot for us to be in, especially 120 degrees. But this is something that, as you can tell, if you’re going from zero degrees extension and working to 90 to 120, that’s a huge variation of degrees, that’s 90 to 120 degrees. But if the knee is starting in, let’s say somewhere around 20 degrees bent-in in flexion or where it’s normal resting state post-surgery, is maybe somewhere around 10 degrees, maybe 20 degrees, somewhere around that range, then you think about trying to get to hyperextension of minus 5. That might be 15 degrees in total you’re getting into, maybe 25 degrees you’re getting into, in total. It’s not a whole lot. And so that’s why I think a lot of people sometimes do prioritize the flexion over extension. 

And then the other thing is that they’re just not really communicated—”Oh, hey, prioritize this over the other one.” They’re just like, “Hey, like start working on these exercises.” Most of the time, people aren’t even given goals or targets. But that’s our goal here, is to make sure you have a focus on these targets. The heel pop, getting hyperextension, that is going to be important to prioritize that extension over the flexion while you’re still working alongside, both of these in this process. We just need to make sure you prioritize the right ones. Flexion, of course, getting to that 90 to 120 degrees, as I mentioned. And this also, if we are working on our extension, this inherently also prioritizes getting your quads firing and another big priority after injury and after post-op ACL. And while I know flexion is fun because it’s more noticeable and change and results and progress, you will also be able to start getting on the bike and being able to get your full cycle in revolution. I know all these things are big milestones.

I remember doing this and it was awesome. The thing that was super important though, is getting back your extension as it is literally, the heavy hitter in this process, and flexion is second to that. So when you walk away from this podcast, don’t think just do extension ignore flexion. Both of these matter is just when you hit priorities and you’re like, what is my number one? Extension is number one. And that is going to allow the quads to really join in, which is going to be incredibly helpful from the get-go for ACL rehab. And flexion is a close second to this. You’re going to work on it because that’s going to be important for you to build in this process as well. 

I hope that this is helpful team. This is one that can get a little confusing for people when they are post-op or post-injury, and they’re trying to balance all these goals. Honestly, they’re just given exercises. There’s no targets. It’s just like, hey, do heel slides, do quad says, do straight-leg raises. But there’s no outcome goal that is really focused on, is just do these exercises and you’re just kind of along in this process. But if you know where you’re aiming towards to be able to get to this end result, and you can use the uninvolved side to get a very good idea of what this comparison’s going to be, do a good quad set or a heel pop, to be able to see how high does your heel get off when you’re lying on the floor or you’re on a table, see how much distance there is from the heel to whatever surface you’re on. And then that’s the goal for the other side, the ACL, the involved side, if you will. And then for flexion, bring your heel towards your butt, usually you’re able to touch your butt with your heel. And so that’s going to be a goal with the involved side as well. 

These are things that will be helpful as you kick-started this ACL rehab process. And it’s one that gets overlooked all the time. You got to divide and conquer with a lot of these things you’re trying to tackle post-op and post-injury. This is a way for you to be able to say, all right, number one is extension. Let me get this stuff in. And number two is flexion. So when you’re working on this throughout your days, it might be 3 times a day, it might be 5 times a day where you spend 10, 15 minutes, maybe a little bit longer to continue to work on this range of motion. Being able to prioritize both and having extension number one and flexion number two. Until next time team, this is your host, Ravi Patel, signing off.