Episode 193 | Navigating Hyperextension in ACL Rehab: When Equal Isn’t the Goal

What is up team and welcome back to another episode on the ACL Athlete Podcast. Today, I want to talk about a situation where you may not need to get full hyperextension, matching the uninvolved side. I’m going to read this comment and question from an ACLer, and I want to dive into a little bit of detail here, because extension is something we are always chasing immediately, post-injury and post-op. This might be a situation where we might not try to get matching the other side. Let’s talk about this question here first, and then we’ll get into it. 

This ACLer says the one thing that I just don’t know what to think about is hyperextension. I know your podcast say that you should get equal hyperextension to non-operative knee; however, my knees hyperextend quite a bit over 10 degrees. I’ve gotten the heel pop in my operated knee a while ago and was working hard to get it equal. Then I started getting popping in the lateral side of the back of the knee with some pain; nothing too major during hyperextension. My PT suggested to start working on the hyperextension as that could be causing it. The surgeon also agreed with that, and was happy with the hyperextension that I’m at, around five degrees negative. My gait is good. But when I’m standing, I don’t feel balanced on both legs. My question is if you ever have times where equal hyperextension is not the goal. 

I think this is a very good question and something I haven’t talked about on the podcast, because it doesn’t apply to majority of people. But I do think that there is a subset of humans that exist in this world that don’t need to get full hyperextension matching the other side. So that’s what this episode is going to try and tackle. She brings up a very good point. Basically, her being hypermobile is what we call it, where she can get beyond minus 10 degrees of hyperextension. She’s able to achieve the heel pop, she’s able to do normal walking, but she doesn’t feel balanced on both legs, which is normal in this situation when you think about the awareness. Everyone knows, even if you’re someone who doesn’t have full hyperextension and non-excessive range of motion on the other side. When you’re standing, you notice, are your knee might be in a little bit of a more locked out position on the unoperated or uninvolved side. And then on the involved side, if you’re still trying to get your extension back, you notice a little bit of bend in it, or it just doesn’t feel equal to the other side. 

Now with this athlete, she actually feels the opposite. It’s where her hyperextension isn’t matching her very accessibly hyperextended knee, if that makes sense. One is probably minus 15 or so, and then her ACL operated side is sitting somewhere around five to 10 degrees. It still feels off and that’s okay in this situation. Now I want to get into the details of this and understand the background of it. 

Basically, what we’re talking about in this situation is an athlete who is hypermobile. Hypermobility is something where your collagen in your joints is just a different ratio and so it creates more laxity around the ligaments and the soft tissues in the joints creating more hypermobility. Basically, these are super flexible people. And it could be more so related to women than men, but it still can happen in men, of course. But we know that just the flexibility of women in nature and just the genetics of it. It tends to lean in that direction. And most athletes I do know who are hypermobile, tend to be more female than it is male. This is something that I see with my ACLers, especially if you fall into this category.

What happens in this situation is that this can be assessed a number of different ways, depending on how it manifests itself. The easiest and most common way that people look at it, even as physical therapist, what we will assess is a Beighton score. This is a test where you do five different tests and you can score a total of nine points on it. And so four are done on the left and the right and then one is done at your trunk where you’re just leaning to touch the ground. Can you put your palms on the ground? And then others, where do you have elbow hyperextension, knee hyperextension beyond 10 degrees. You have a pinky coming towards the back of your form, if you will, or your thumb coming towards your wrist. If people can excessively touch those particular areas or have excessive range of motion and they score four out of the nine then therefore that is a positive Beighton score. Basically, saying you are hypermobile. 

Now there’s ranges in the research, but this is a general rule of thumb here for this particular situation where someone is hypermobile. If you notice yourself like that, then you are likely someone with hyperextension at your knees that is pretty excessive, if you will, more than typically 10 degrees. There can be some other genetic components for hypermobility. But then also aside from hypermobility, it could also be someone who’s just naturally born with excessive hyperextension; not a hypermobile athlete, but someone who just has very hyper extended knees and that can also exist. Of course, this is not the “norm.” But the thing is, is that people have these types of situations when they’re born based on genetics. The usual range of motion, if you will, for this is beyond negative 10 degrees of hyperextension. And so that usually is a fair cutoff because what we typically see with knee extension, people range anywhere from zero to minus 10 degrees of the normative data and somewhere landing in the middle of around minus five, I would say. Of the knees that I’ve assessed, people probably sit for the most part around minus five. Very rarely are they sitting at zero degrees, which is not full knee extension for majority of human beings. It’s usually somewhere in the negative, somewhere around five, and it can go all the way towards 10 for normative values. So then therefore, when you get outside of the minus 10 into minus 15, 20, it can even go beyond that, which exists, then therefore you might be categorized into this hypermobile group or just excessive hyperextension. 

Your goal is essentially, if you are normal in this range, not hypermobile in a sense, and we’re all looking at this based on the uninvolved side, then our goal with ACL rehab is typically to try and get you to match the uninvolved side with that heel pop and getting that ASAP post-op. Now, if you are in this hypermobile group, or just have excessive hyperextension, if you will, into that minus 10 plus into 20 degrees, what I will do in this case is we will work to get you back towards, around minus five degrees of extension and then let the rest come. We’re not trying to push you back to minus 15, minus 20. 

The thing that I’m looking at is, can we get a really solid quad contraction on the involved side? With other movements where we need normal hyperextension of the knee, do they look good from a movement quality standpoint? If we’re looking at gait, if we’re looking at any positions where it might be acceleration-based, where there’s triple extended positions, to be able to see, can that knee get into position and be able to produce the force and be able to bend and extend in the appropriate ways without there being too many compensations and the appropriate muscles that need to be engaged. Then, I’m not too worried about it and we let the rest come versus aggressively working into minus 10, minus 15, minus 20 degrees of extension. The thought here is that we’ve establish the prerequisites and the adaptations we needed with getting towards minus five and then being able to do all their movements and engage your quads really well. 

Now, some considerations about this. What if this hypermobility or the excessive range of motion was a player, a factor into the injury initially that happened? Maybe, maybe not. I can’t really say improve that, but this is going to be very dependent on the injury itself. But a less stable joint, if you will, with lots of range of motion leads towards a higher risk due to the nature of it being less stable, if you will, given the hypermobility. 

I’ve had athletes who easily dislocate their range on this hypermobility scale and they’ll have joints that can sometimes dislocate. It’s just something where the joints don’t feel as stable. They feel very flexible. There’s a lot of excessive range of motion. In situations like this, what we want to ultimately do as a physical therapist, as a performance coach, is to create stability because they have a lot of mobility; therefore we want to try and stabilize the system in order to find a delicate balance between the two. For our hypermobile athletes, this means decreasing that excessive movement and degrees of freedom, if you will, that excessive range of motion by making the supporting tissues around it stronger to provide more stability. So that’s where strength training really does come into place. 

Can we really affect the soft tissues in terms of the collagen and the ligaments and things of that nature? Not necessarily. But with the supporting structures, just even think about what we do with a torn ACL that’s non-operative. We’re going to try and create a stable joint to support it by making all the muscles around it much stronger. In this same situation, if we have more lax ligaments or more degrees of freedom, we’re going to try and strengthen everything to help support that as much as we can. In a situation like this, we are not trying to force excessive hyperextension to 15 to 20 degrees in the negatives. We will try to get them towards minus five and then allow the rest of it to come and just continue to assess and see.

One thing that is interesting and as this athlete reported, was that as she started to work into more and more extension, she started to notice just discomfort in the back of the knee, some popping. This is actually something that I’ve noticed some athletes when they get their hyperextension and especially someone who isn’t even hypermobile. I’ve had athletes, they really take, hey, let’s get that heel pop and extension back ASAP. I’ll see them a week or two later, depending on our frequency. This is something where they’ve come in and they’re like, yeah, the back of my knee is starting to get like really sore and I’m starting to get discomfort. And I start to see that their heel pop is almost higher than their uninvolved side. And so that’s where I’m like, we just want to match the uninvolved side and from there we are good if we are talking about a normal knee anatomy and range of motion. And with this athlete, she felt it with getting into the hypermobile position, the minus 15 or so. And that played a role into potentially her knee was responding to that. It’s normal to have some stretch and discomfort in the back of the knee, but it is always in comparison to the uninvolved side and also what we would want to establish as your normal. If you are someone who is not hypermobile, we’re trying to match uninvolved side and then we’re good to go. Don’t feel like you need to keep going more and more. And that’s where some of these athletes started to have some discomfort issues with their knee and in the back of the knee, or feeling some excessive popping. Then, that’s where we were like, hey, we’re good with just where we need to match it. 

This is just some consideration for working with athletes and you ACLers, who might be in this hypermobile scenario, where we want to make sure how can we make sure the extension itself is getting back to a place where it’s going to help to make sure you can walk normal and also, for the long term, in terms of getting back to your sport and not being too worried. Did I get enough of it? Did I get too much of it? 

Hopefully, this is helpful. And of course, this is a case-by-case basis for my hypermobile athletes. But this is where you have to consult with your surgeon and with your physical therapist. But for me, it always comes back to—what are the things that we’re trying to get back to in terms of walking, in terms of just different movements and can we get the quads going? And if that’s the case, we’re probably in a pretty solid spot to be able to move forward with our knee extension and let the rest of it come. I hope that this was helpful team, until next time. This is your host, Ravi Patel, signing off.