Episode 132 | Know Your Numbers (KYN) for ACL Rehab

What is up guys? Today, we are talking about Know Your Numbers For ACL Rehab. And this is something that has been front of mind for me, in terms of just conversations that I’ve been having with ACLers who reach out. And I think that this could be a helpful topic to dive into. So that’s going to be the focus today.

First off, this ends up coming back to just the current state of ACL rehab. Why is knowing your numbers is so important? Well, we know that ACL injuries in general are pretty high. It’s calculated that somewhere around 100,000 to 200,000 happen just in the U.S. alone. And I think that that’s an underestimated actual calculation, in terms of the number of ACL injuries. And we’re starting to see this more and more, actually, and starting to see this rapidly incline and increase. 

Let’s talk about re-injury rate because that’s the thing that is the most problematic. People who tear their ACL have a one in four or one in three chance of that happening again. We’re looking at a 20% to 30% re-injury rate. That is really high for something that happens a lot. This is something where we start asking, well, why is this the case? There’s so many factors that we can’t just name a single factor that plays into why this happens. From the gender to the graft types, to the type of injury to the field, the court, and the sport. There are so many different pieces that play into this, so we can’t just pick one. ACL in general is one of the most researched musculoskeletal injuries in the world. There are thousands of studies on this, yet we’re still not 100% sure what it is that we can put a finger on in terms of why they’re happening so much.

The two factors that I do know play such a massive role in this re-injury rate, and whether people get back to what they love doing safely and at the lowest risk possible. One comes back to just poor rehab and poor clearance in return-to-sport testing. Those are two very big buckets. That, in my opinion, really caters to why re-injury rates are so high. Now, today is about knowing your numbers, why? Because if we know our numbers, that means we are getting tested. We know objectively what we are looking at, and also where we need to go. If we don’t know your numbers, well then, you’re operating blindly. If you say your range of motion is increased, cool. Put a number to it that is accurate. If you say your strength for your quads is increased, cool. Put a number on it. I’m not going to take this based on just you being able to walk in up and down stairs or being able to go through your day without pain and swelling, or being able to do this one movement better. We need to make sure objectively we are isolating that muscle and we are testing that thing to know, okay, you are stronger. Here’s objectively what that number looks like. 

And in terms of knowing your numbers, we call them KPIs. Key performance indicators are how we decide to know what we want to intervene with, and basically knowing what those are. Any company has KPIs, whether it’s from the revenue that they bring in, to the number of leads, to really any project that you’re keeping track of. Usually, there are certain metrics that you are tracking and these are your KPIs. It’s no different. You think about school, for example, your KPIs are essential; how are you doing in this class, how are you doing on this test. Those are all kinds of KPIs that you’re measuring, ultimately. And then what is your ultimate class grade and even your GPA is a KPI. These are all the things we’re familiar with from the school setting. 

Now, let’s apply this to the rehab and specifically ACL setting. We need to make sure we know the numbers, know the KPIs. And I’m going to start this by quoting Matt Jordan, who is a brilliant sports scientist, who has worked with a lot of ACLs and has very extensive experience with especially the testing and sports science background of this population. And he goes through this very simple process and this step-by-step process, if you will, on framework that it’s how I organize my brain and I heard it from him. And this is how we attack all of our KPIs for any of our ACLers and our framework — it is to determine what matters, measure what matters, then change what matters. You’re going to determine what matters. So that variable or what we call quality, this is your KPI, what? Assessing peak quad strength. Maybe it is your knee extension range of motion, or maybe it is your reactive strength index. These are all things that are what that we are testing. Or, for example, measuring, and then you’re going to actually measure it. How are you going to measure it and measure what matters? So that is going to be via means of testing and assessments. If we’re going with the assessing peak quad strength example, then we are going to be measuring via isokinetic or isometric through a handheld dynamometer. Or you might be doing a one- to five-repetition maximum of 90- to 45-degree knee extension machine because you just don’t have that many resources around. And let’s say you’re in a different country where they don’t have isokinetic or any type of isometric device. This is what you’re left with, but guess what? It’s still an objective measure that you can measure, especially side-to-side comparisons. 

Next is going to be changing what matters. Normative values are what’s going to help anchor us, as well as what are values that are going to be important based on you as an individual, and the goals that are established based on the population, the sport, the gender, etc. This needs to be supported by research and science. A lot of the ACL return-to-sport research shows that if you are at 90% limb symmetry index or higher, your chances of re-injury decrease drastically. Now, let’s say your other side is pretty weak. Well, how can we anchor this to something that is more established? Well, that’s where we compare it to you as a person and your body weight. And that’s where we measure peak torque to body weight ratios. 

Therefore, we are anchoring this number maybe to 3.0 Newton meters per kilogram body weight. And that allows us to be more intentional, more objective, and more targeted. And guess what? This is going to be the thing that is going to help you to change what matters. If we are aiming for 1.8 Newton meters per kilogram body weight for you to start running, well, and if you’re only at 1 or 1.2, we have some work to do. And that is the low-hanging fruit that we’re going to be tackling alongside other requisites that we need to hit and criteria in order to do that. So that’s what we are going to be changing if it’s not met. Attacking that low-hanging fruit and the rate limiters that are important at that current time. Determine what matters, measure what matters, and change what matters. And this is all based on actually getting objective measures alongside this. But if you or your PT or surgeon don’t know what these are, how do you do that? How do you know if there’s a problem if you never test for it? You don’t. And that’s the big problem. And I think the thing that we need to make sure is very transparent here.

I literally just got off of a call right before this podcast with someone who had an ACL repair 12 months ago. She just reinjured it. And this was a very questionable process in general, in terms of the repair. But then you talk about when I ask: Well, what was your PT process like? Well, she said that she had insurance available basically up until the 4-1/2 to 5-month mark. And then they cleared her to basically be discharged from PT but also cleared her to just start doing stuff on her own. The only measures that she said were taken to test were a Y-balance test, which is basically standing on a single leg and reaching with your toe forward, to see if you can move your knee over your toe essentially, or maybe in other directions, to the side. And then the only other thing was hop testing.

Hop testing has been basically shown to not show us anything about strength. It basically just lets us know that we can hop to a relatively similar distance, but the way we get there is not really analyzed. And depending on the physical therapist’s background, they might just be like, oh, cool, this is within 90%. We’re good to go. And so that’s how people typically measure. But this is what happened to this athlete. She didn’t really have good testing. She got cleared. She went to go and do her workout. She caught a jump and she tore her ACL. Now, with that said, who’s to say that that wouldn’t happen even if she cleared everything? I will bet you anything that it was more of a lack of preparedness and not having the adequate strength to be able to do the things she was doing.

And that’s the case for a lot of people we talk to, which is why it’s important to know your numbers. I can’t stress this enough. And making sure that you can ask your physical therapist: Hey, what are my numbers? Where am I relative to where I need to go? Then that way you also know you’re not operating blindly, and you also know that you’re working with a physical therapist who knows what they’re doing. And if they can’t communicate that to you, that’s a red flag. For us, this is where we establish different areas buckets, and KPIs within this process. You’ll hear them referenced as criteria, oftentimes with ACL rehab. What’s the criteria to get into school? What’s the criteria to land the job? What’s their criteria to move into phase two for this project? What are the criteria to clear this athlete? We are familiar with this in many different areas of life. But for some reason in ACL rehab, we are still missing the boat on this. 

And if you guys have listened to probably more recent podcasts, I’ve had a little bit more fire to me because I’m just honestly sick of hearing about these stories. This lady just tore her ACL. She literally has her life on pause now. She has to change a bunch of things, and this could have been avoided with really good healthcare and really good physical therapists guiding her. And instead what happened? We just let re-insurance do their thing and then she went out and did something that she normally should be able to do if she was cleared. It was just improper care, in my opinion. And if she knew her numbers, but more importantly, her physical therapist knew what they were doing, she would’ve likely not been in this position. So, yes, I am fully fired up because it continues to piss me off to hear this and see that people are dealing with this. We have to do better. And if you are a physical therapist listening to this, you better do your job and you need to make sure you do the research if you’re working with the ACLs. If you’re not, refer out to someone who can do it, who can test, and who has the bandwidth to do it. And if you’re not, then this is something that’s a call to action to you, to check yourself and to make sure that we are doing our people’s rights.

Now, I’m going to get back on this topic before I continue down this path. This is all going to be based on a battery of tests and measures to come to a conclusion of clearance. This happens with all the things that I mentioned before, getting into school, landing a job, building a house, and moving on to phase two. It’s not just time. We’re going to make sure that the infrastructure is built for the foundation. And then we’re going to move on to phase two and phase three and phase four. They’re not going to build the internal until they have the framework built out and the foundation. And you better make sure that there are going to be checks and balances with that and criteria to clear. Otherwise, if that building is messed up, there’s going to be a lot of people responsible because of something bad happening. Same thing with this clearing of criteria. I wish that this was still the case and people were held accountable for this. But it’s just the way we are. And the way that things are in this system right now. I’m going to equip you guys with the knowledge to know your numbers. That way you aren’t this person who has to go out and just operate blindly, not knowing where you’re at. And you can also pivot when you need to because you have the tools and the knowledge to do that. 

First, we have to navigate the subjective versus objective reports. Subjective is more gray and feel; it’s qualitative. It’s what you share that you are feeling in this process, like pain, or you’re like, I feel stronger, or I feel like this is what I’m feeling. It’s kind of that just like gray hard to kind of describe. It’s subjective if you will. There’s open to interpretation. With objective, it’s more black and white. It is quantitative. There is typically a number associated which makes it objective like minus four degrees of extension, like peak quad strength being 1.8 Newton meters per kilogram on the ACL injured or operated side like hamstringing index strength being 78% of the other side, and that’s where the symmetry is sitting. Reactive strength index is a value that we are aiming for for this specific population and phase you’re in for a drop jump. We’re looking for a good number with that. These are numbers we can attach our subjective assessments with, and they go hand in hand. 

And I honestly don’t love seeing one or the other. I’m not like, all right, your subjective report is great, and just testing and getting objectives is great. It’s married together. I want to see them both so they can show me the full picture. Otherwise, it feels a bit incomplete. And I don’t know that I can confidently say, hey, yeah, you feel better. That’s cool. And subjective is very, very valuable, but we need to have the objective to back it up. And the point of today’s episode is to know your numbers. What is your range of motion? What is your peak quad strength side to side? What is your peak hamstringing strength side to side? What is your quad peak torque to body weight ratio? Even if it’s just grabbing this from a leg extension, or leg curl machine due to a lack of resources, you still need to know those numbers, especially side to side.

If I could say anything, knowing what your peak quad strength is and hamstring strength will be an absolute game changer in this process. If there’s anything you can leave with this podcast is that, if you can know what your quad and hamstringing strength is for your ACL side versus the uninjured side or the opposite side, it will be a game changer. And most people don’t typically know that besides maybe doing some leg extension stuff, because most places don’t necessarily test this unless you are lucky to be with someone who is very familiar with this. But we still have a lot of work for that to be more common than uncommon. And when someone says they feel stronger, that’s awesome. I love to hear that. Let’s back this up with objective testing with a variety of means that we can do that. So while you feel good, it could just be relative to what you’re also being challenged to or not challenged with at the moment. 

And that’s the thing that I see a lot of times is that people get a little further in this process. They’re out of the post-op. They might be in the mid-stage if you will. They’ve been kind of in the gym and they’ve been doing stuff at PT. They’re like, yeah, I feel good. I feel like I can go and do this thing. And especially, if it has a higher level of cutting, pivoting, just more athleticism and demand from the knee, you need to make sure that that has been met with your physical therapy or what you’re doing. Because you might just be saying, I feel good relative to what you’ve been challenged to, and you probably just haven’t been opened up to really be challenged with the things you need to be yet. And so, therefore, it gives this false sense of thinking, I’m good to go. I mean, I feel good, I don’t feel pain. My knee’s not swelling. But that is like the bare entry point to getting you ready. 

Next is making sure that you have the strength, you have the capacity to do it over repeated events, to be able to have the power, if it’s specific to your sport. Maybe it’s to be able to decelerate, accelerate, change the direction, and react to gameplay. Those are all pieces that are going to be important. And then you talk about the skill specific to it and contact potentially. So many different buckets we need to work with. And I wish I could say that this is your PT’s responsibility to make sure that you’re fully challenged and prepped. But as I said, until the system changes, It is up to you as the ACLer to provide this insight for yourself and ask questions. It will be until there’s something different that is created or some sort of accountability or standard that is completely changed. 

But as of 2023, we’re still here and we’re still riding this wave, so we have to continue to advocate for ourselves. And this is how you take control of the process versus relying on the system that is built in the U.S. or even in any other place that exists. We have ACLers all over the world. Whether you’re in a social system, there’s drawbacks to that. There are so many different healthcare systems in general. They all have their pros and cons. But nothing has perfected it yet. This is where we just have to make sure we are able to take control and make sure that we are able to take ourselves from start to finish, and knowing your numbers will help that so much.

Think about this as your athlete report card or dashboard. Everyone remembers the report cards or getting scores, knowing how you did on tests and assignments, and that ultimately reflects on your grade. Think of your numbers as the same thing, your ACL rehab. When you’re trying to get this A score or 100%, and your goal is to slowly accumulate that over time. And if you take these different categories and buckets, maybe overall can build up towards that, that detail of 100% or an A. And it’s a cumulative effect to make sure that you’re getting there, however, you want to look at it. But this is something that can help in terms of knowing your numbers.

As a caveat, we also want to make sure that the tests that we are using are valid and reliable. If we use a bad test and then the numbers we use it from that we infer something or do something from it, well, if the test wasn’t good, it doesn’t really matter. Going back to the athlete who hurt herself, the Y-balance has value in the anterior reach, especially if there’s less than a four-centimeter difference. But it doesn’t really tell you a lot. It just tells you that you can reach forward and bring your knee over your toe maybe unless you have other strategies available. And so that’s the thing that’s crazy, is that that test — I did research on it in PT school. I collected tons of data on the Y-balance test itself, so I know all the ins and outs about it, and what the research says. We did massive research reviews on it, and I presented at the national conference on it. The thing is, that thing is not that valuable for ACL rehab, besides the fact that it can show your knee can go over your toe a little bit. 

When someone’s like, hey, Y-balance is a clearance test? Cool. That is an entry point. But it’s not, at the end of the day, a great test to show if you’re cleared to do something, especially for return to sports. And so that doesn’t really necessarily tell us anything about quad strength. It’s just how can you move your limb in space and reach forward or in these different directions. So with that said, that test gives you a false sense of what’s going to help you to be cleared. And so that’s what happened in this situation. And so what I’m saying here is that we got to make sure the test is valid and reliable for what we’re trying to measure. And I think what the assumption was is that this was giving some sort of quad strength output that is helping you to know, okay, this athlete has a strong quad — not necessarily. And so that’s where I’m getting at with this, is that we got to make sure that the tests are testing what they’re supposed to test. If we use a bad test, but we use the information from it to make decisions, then it gives us a false sense of where we are in terms of this process. And really it was just a test that sucks. 

The other thing that I want to bring into this that I think doesn’t get shared enough, you might hear it on the social spaces, but I think it’s just a red flag. Essentially, it’s MMTs used as strength testing. MMTs are manual muscle tests. This is where basically you’re sitting on the table or some sort of elevated height. Your knee is bent at 90 degrees like a knee extension machine. And the physical therapist, surgeon, whoever is testing your strength, this happens a lot in surgeon’s offices when the people go in for revisits because it’s quick and it ” makes” people think that they’re testing strength. Basically, they will stabilize the end of your thigh and then they will put the hand in the front of the ankle and you’ll kick into it. You’ll basically engage your quad, and use your knee. And they’ll be like, all right, yeah, let’s test out the strength. Strength looks good. This is something we learned in physical therapy school that was actually one of the basic things of any assessment in an exam, a manual muscle test for strength testing. This is something where it’s objective scale. It goes from zero to five.

 And it’s subjective, really, because it’s based on the person you’re pushing against its strength. How much are they pushing into your leg? How strong are they? How much body weight is the person you’re resisting against? If you have someone who’s 300 pounds you’re pushing against versus someone who’s 120 pounds. You’re probably going to be able to think that you are stronger than the 120-pound person versus the 300-pound person because the 300-pound person is heavier and they’re stronger likely. This is something where the test is not really testing strength. This MMT (manual muscle test) was actually created during the polio epidemic for physical therapists and docs to screen. And it only tells us a value if a muscle can’t activate in general, so basically whenever it’s zero. And this is because the neurological system is impacted. That’s why they were trying to figure out, okay, if they can contract the muscle itself, then we know that they are not as much in trouble versus someone who can’t activate a muscle.

The other levels, in my opinion, create more harm and a false sense of security than anything. Actual strength measures are from isokinetic machines, isometric machines, handheld dynamometers, to even one to five repetition maximums of an isolated repetition of maybe the knee extension or leg curl. And the other thing that I want to make sure I clear up here is the subjective versus objective; knowing that one isn’t more important than the other. But the objective numbers will keep us honest. That is the big piece here, is that if someone says they’re strong, I want you to back it up with numbers. And if they’re saying like, hey, I’m good to go. Well, let’s back it up with numbers and normative values to make sure it is good. 

Any good business uses KPIs to continue to grow and assess what’s working and what’s not. They make adjustments based on this. And ACL rehab is no different. We take the subjective and objective and marry the two to paint the best picture possible at this very moment. Combine that with the end goal, find the rate limiters and low-hanging fruit, and bridge that gap. That’s what’s going to be important here. What numbers you ask for are important. If you’re saying, hey, I need to know my numbers. Well, what numbers are those? This is based on the criteria being measured and managed for us, the bare minimum is going to be the range of motion. Where’s your extension? Where’s your flexion capacity testing side to side of a single-leg squat to box, or a split squat, hamstring bridge, or calf raise? There’s going to be strength 100% that we are testing to see the peak, quad, and hamstringing strength, the symmetry side to side, and the ratio of hamstring to quad. 

Our peak torque-to-body weight ratio for our quads is currently the most important based on current science and research. Reactive strength index, our plyometric capacity is going to be key here. There are other variables that we’ll look at from the penultimate step to the antepenultimate step. We will look at specific criteria to return to running for specific criteria for return to sport and performance, reintegration back to sport. These are all going to vary a little bit based on the person. But these are at the minimum what we’re going to be looking at and setting targets for all of our athletes. And we’re going to make sure that they know their numbers and that we know their numbers, especially to make sure we can continue to evolve the plan and adapt anything we need to. And the testing is going to help inform us of that. And then you’re going to compare a lot of these values to normative values and also from one side to the other, as long as the uninjured side has been training hard and hasn’t gotten weak. 

And now I’m going to give you guys a super practical example. And let’s say that you have really low resources. You’re in an area that is just hard to get to. Maybe finances are tough, not good providers around you. And you’re like, well, I’ve got a gym. Cool. Let’s, let’s make this practical. When appropriate in your process, this is going to be key here. This is not medical advice. You just need to know whenever it’s appropriate for you in your ACL rehab process, and get an idea of a side-to-side comparison. Aim for a three to five repetition maximum, meaning you want to aim for that many reps and go for it side to side. If you end up doing 10 reps per side, that ends up being a little too light, in my opinion. It is not really an assessment of strength. One is just aggressive. Getting somewhere around three to five-repetition maximum still gives you a fairly accurate representation without feeling like you need to grind out for a single rep on something, maybe like a knee extension. You’re going to aim for a three to five-repetition maximum, and you’re going to do a single-leg leg press comparing each side. You’re going to do a single leg extension full, or maybe through 90 to 45 degrees, and then you’re going to do a single leg hamstring curl. It might be a seated one, or it might be one on your stomach where it’s prone. Either way, you’re going to compare a side to side and you’re going to aim for a three to five-repetition maximum whenever it is appropriate in your ACL rehab process. You can look at symmetry by dividing the involved by the uninvolved side and then multiplying by 100%, guess what, you have a real quick symmetry value objective. And some people will say that this is useless in terms of symmetry. But if you’ve been training really hard and gotten strong, then it’s an accurate number to use.

Also, again, if you have limited resources, then at least is something objective versus just saying you’re strong and operating in the dark. This gives you an overall idea of basically what your compound single-leg strength is with the leg press side to side, as well as your isolated quads and hamstrings. This at least gives you some sort of a litmus test and idea of, okay, where are you at? You have your numbers and know your numbers, and you can present that to your surgeon, or to your physical therapist. Maybe you’re operating by yourself and you can present that to yourself and be like, all right, cool. My quad is 70% off. I need to get 90%-95%. Let me keep working on knee extensions and other things that are going to facilitate getting my quad stronger. Maybe it’s the hamstrings ‘because you had a hamstring graft. 

Well, there’s a 40% deficit. Let’s get that thing up. It allows you to know more targeted what you are aiming for. But you won’t know this until you know your numbers. This isn’t something that is comprehensive as there are nuances to each area from clinical to functional to the strength, to the performance side of things. And it’s going to be specific to each person to some degree, based on what they have available, graph types, all these different pieces. But it is a solid start to know where you stand and we’ll let you know you have the foundations and the base, most importantly, that range of motion. And then also that you have your quad and hamstringing strength at the least, or you need to play catch up. Then from there, you can measure dynamic components from running, cutting, and jumping, as well as sport-specific load and exposure along the return to sports performance continuum.

So that’s going to be something that is going to be essential in this process. I just want to hammer home that knowing your numbers can help so much, not only as feeling like you’re on the path to where you need to be. But then also knowing where you need to go. And a lot of athletes that I work with, just as human beings, we’re competitive. We want to know where we are and we want to know what our targets are. We want to make sure we do our best. If we aim to hit a certain number, we’ll be a little bit more targeted and focused to reach a certain number, which therefore can open up opportunities for decreasing your injury risk, and increasing your performance, but getting back to most importantly, the stuff you want to do. And that’s what I care about here. I know I shared a lot in this episode. It is super long. Thanks so much for hanging with me. That is going to do it for today. 

Thank you all so much for listening. This is your host, Ravi Patel, signing off.