Episode 146 | What is EPIC Scoring and How Can It Be Helpful in ACL Rehab?

What is up guys, and welcome back to another episode on the ACL Athlete Podcast. Today, we are answering the question: what is EPIC scoring and how can it be helpful in ACL rehab? One metric we use in ACL rehab is limb symmetry index or LSI in short. So that is a ratio of comparing your injured or ACL-operated side to your uninjured or uninvolved side.

A lot of times what we’ll look at is range of motion, we’ll look at quad strength, we’ll look at your hamstring strength. And we’ll basically just see, all right, how does it look on that involved side versus the uninvolved side? And that gives us a benchmark and we get a ratio or a percentage with that. This is used in a lot of different areas within ACL rehab, from the range of motion to strength, to functional testing, to even hop testing and the jump testing and things of that nature. We’re always trying to see how we compare one side versus the other. 

A lot of research shows that better outcomes are in ACL rehab when this LSI is above 90%. We’re roughly within 90 percent of that uninjured side and there are better outcomes related to that. What’s interesting about this is that this has also come into question, given that there can be a fault or some sort of skew in this metric. What I mean by this is that you’re comparing it to something, maybe not so great, like comparing a bad apple to a not-so-great apple. While this is not always the case and we use LSI, and if you are training well, if you’re able to intervene early, and if you’re strengthening and doing all the things you need to do on the uninvolved side, then LSI is a great metric to use. I’m not here to knock it. It’s just one of those things that I have seen where athletes can come into this process. Maybe there’s a long time between the injury and getting into rehab, maybe they had surgery and they did not have really good training on the uninvolved side, or maybe it’s just something that there was not a lot of attention and there’s a lot of time has passed. 

And so what happens is, is that the uninvolved side ends up dropping. And so then we are comparing our ACL-operated side, involved side to maybe a limb that is not up to par, right? We’ve used this analogy before of the flat tires where you have two tires. One that is full, let’s say, for example, that’s the uninvolved side and the other side is flat. So that’s kind of how we’re comparing the uninvolved versus the involved side.

But let’s say, for example, the uninvolved side is half full. We’re trying to take that flat or the ACL side and bring it up to the half-full comparison. It makes it seem like it’s symmetrical, basically that 90 percent is of two half-full tires. And while this analogy can get a little extreme here, this is just to help hammer home the example of this. It’s pretty common that we can see with athletes where that uninvolved side can drop.

So that’s why we want to make sure not only do we have a limb symmetry index that we are following, but other ways that we could potentially measure this, right? We don’t want to throw the baby out with the bathwater. LSI has its place. And if you do train, like I said, and strengthen that uninjured side, then it is a great proxy to continue to use. But we just want to make sure we are cognizant of this and that 90 percent does not give us a false sense of security of being ready. 

Here are a couple of things that we can do. One, we can compare it to body weight, making sure that you’re creating an output relative to your body weight. A lot of times we will use torque to body weight ratios. We will get a quad torque or quad strength output. And from there, we’ll compare it to your body weight. Same thing with your hamstrings. This will allow us to see how it not only compares side to side but also relative to you as a person. This is always a good measure. 

The second thing that you can do is EPIC scoring. And that’s the focus of today’s podcast is EPIC scoring and EPIC stands for estimated pre-injury capacity. And the way that we’re going to kickstart this and where it came from is. A study from Wellsandt in 2017, where she looked at limb symmetry indexes can overestimate knee function after ACL injury, which is a very interesting topic because most of the ACL research is dictated based on limb symmetry.

And so here’s what they did in this study. They looked at quad strength and hop testing and they compared them. They looked at the uninvolved limb pre-operation, so before they had ACL surgery, they looked at the uninvolved limb, and then they looked at the involved limb at six months post-op. The way that this worked is that they looked at the ACL injury that happened, and then after that, they had a PT eval. At the initial pre-op eval for rehab, they measured the strength of the quad of the uninvolved side. And then a little bit later, they did some hop testing, still pre-operative, to be able to get an idea of what the hop test looks like on the uninvolved side. ACL reconstruction happened. And then six months later, they looked at involved and uninvolved quad strength and hop testing. Basically, the values on the uninvolved before, and then involved and uninvolved after six months after for quads and hop tests. 

And here’s what’s interesting about this. At 6 months post-op, out of the 70 patients, only 28 percent of patients met greater than 90 percent EPIC criteria on all strength tests and hop tests. However, 57 percent achieved greater than 90 percent of LSI criteria on the strength and hop tests. Six-month testing was chosen because it is a common time for people to start sports activities which is listed in the article. That’s why they used that timing for this. Basically, 28 percent passed the 90 percent EPIC criteria and then 57 percent passed the 90 percent greater than LSI criteria. More people passed the LSI than they did the EPIC criteria out of 70 patients. 

What they did is they did a two-year follow-up. And out of these 70 patients, 11 of these patients tore their ACL again for a second time within that two-year follow-up period. Eight out of those 11 people passed their 90 percent or greater LSI criteria on all the strength and hop tests at 6 months post-op. Six out of these eight who did pass that LSI did not pass the 90 percent or greater for EPIC criteria on all the strength and hop testing at 6 months. So their conclusion was, is that greater than 90 percent EPIC criteria was superior in predicting second ACL injuries than the current method of greater than 90 percent in LSIs.

Now, personally, I’m not a huge fan of ACL injury predictions because I don’t think at this point we can predict who is going to go on to tear and who’s not. Obviously, with the research, 90 percent is a benchmark that a lot of people use in the research. Do they have a higher increased risk of injury? Yes. But I don’t know that we can necessarily say like, okay, if they do not pass this epic criteria of 90%, then they are likely to go on and get a second ACL injury. I get what the study’s doing. They’re trying to just look at this and they are trying to say: Hey, this is more predictive than LSI, which is fair to say.

The thing that I find very interesting with this and with EPIC scoring in general is the timing. In most situations, people are injured, right? They get their ACL injury and so the last thing they’re thinking about is getting a max test on their uninvolved side. That’s just not something that comes to mind.

Most surgeons are not recommending that they go in and they get their max test for their uninvolved side. This is not a very popular thing to do. So that’s what makes this interesting plus you just had an injury. The last thing you want to look at is doing a max test. You want to sulk in it and be able to just move on with getting your normal function. But I do understand the importance of trying to get this max testing because the thing is that the strength dramatically drops in your ACL injured side. We need some sort of good benchmark to anchor to as we work through the process. 

The other thing that’s tough with this is that people aren’t usually going straight into prehab immediately, but it is becoming more common which is awesome. The other thing is that many clinicians don’t have strength tests, to begin with, which makes a whole other problem in and of itself that I’ve talked about. But this is something that I think can have a lot of merit to it. So let’s say somebody does come in for prehab, if you’re that person who is in prehab listening to this, or you’re a clinician and you have athletes who are coming in before they go have surgery. Let’s get some numbers here and do you need to do it based on these specific EPIC criteria? No, but it is helpful to have these EPIC criteria or just get some baseline quad and hamstring strength testing just to see where this sits, right? 

And I know that this is not a very common topic or a popular thing in the space. I guarantee if you ask most people, they would not be familiar with it. And there’s not a ton of studies on it. There’s only a few studies about it. You combine people not knowing plus not testing in the first place and it does make it harder to pursue. You’re probably wondering what’s the main takeaway here. Well, let’s make this practical. If you are an ACLer who is fresh post-injury — I know it’s probably the last thing you want to do. But go and get your uninjured side strength tested, especially the quads and especially the hamstrings. It may feel like being extra, but man, it’ll be a game changer in all honesty. The athletes that we have been able to grab this from, it’s awesome to just have that data, it’s awesome to have that information as a benchmark. It really does add value because then we know what we’re trying to at least work towards something versus just trying to get both sides really strong. We’re in the dark a little bit about whether that uninvolved side which we use as a benchmark is going to be impacted or not. 

Of course, we got the relative to body weight that is very useful for us. But it’s going to be essentially as close to a full tire comparison as we can if we get that baseline testing. Ask your surgeon or PT, if you can get tested via an isokinetic machine ideally, or even a handheld dynamometer where they’re fixed at 90 or 60 degrees, which tests the torque of the knee isometrically. It’s not moving with an isokinetic machine. The isometric is in a fixed position. And you’re just pushing or you are kicking into this particular dynamometer and it puts out a specific force output.

Worst case, you can go to the gym and find a leg press, leg extension, and leg curl machine and do a three to five-repetition maximum so you don’t have any reps left in the tank after you complete it. You’re going to do it on your uninvolved side to get a proxy of where that strength sits, which I think is still at a bare minimum, super valuable.

If you’re a clinician or a coach or anyone working with an ACL and you get them post-injury or in for prehab, measure their strength on the uninvolved limb via one of these valid and reliable methods, it’ll be super helpful. And this is something that we do try to do for our ACLers. We get to work with and get that measure if we do get them during prehab because there’s something that we can use along the way.

The only tough part is given the way most systems are — healthcare and when people enter them, you don’t get a contact point until after it’s been a while post-injury and the majority of the time post-surgery. That’s when most of our athletes come in contact with us anyway. Of course, if they do the research or they find out resources before, then we’re able to work with them before that. But even if it’s post-surgery, right, that doesn’t necessarily mean it’s invaluable, it just depends on your history. There are certain situations where we’ll still grab that. And I think that is better to get an idea of where that sits, measure that uninvolved leg, and get it as strong as possible through the process. And then just continue to keep measuring it alongside just like we normally do with limb symmetry index. 

EPIC scoring is something that I think does have value and I’ll be curious to see if there are more and more research studies that come out to try and assess essentially some baseline testing. I know people are starting to come around more to doing pre-op or post-injury testing just so we can make sure that we know where that baseline sits more accurately to understand where we need to get the athlete back to. And that’s the goal here with the EPIC scoring. 

It did in this study has shown to be more sensitive, which I think is saying something, it’s still a smaller sample size, if you will. But of those who re-injured, there was a relationship there. I don’t think that we can just skip over this. I think that there is decent merit to being able to get these values. 

If you’re someone who is in prehab or pre-op, then go and try and get some numbers on the uninvolved side. If you’re a clinician or a coach working with an ACLer, then this is your opportunity to get that and something that you’ll use to measure as you go through this process and you can almost have more confidence knowing, okay, this is where this athlete was pretty soon after the injury. Therefore, this is at least a certain target to get to, of course, always trying to surpass whatever it was before, but at least we have a number there to work towards. 

I hope this was helpful team. If you have any questions, you could always email us, or send us a message on Instagram. We are here for any support or any questions. Until next time, this is your host Ravi Patel, signing off.