And I think the return to sport decision-making in particular is extremely important. So regardless of what you've done, it's very important how you decide to return a patient to sport. These are my disclosures, none of which are relevant. So the reason this, we have problems with ACL return to sport, is that the majority of kids go back to play. And this is not necessarily true of high school adults. This is true of younger kids. More than 90% of young kids will go back to playing sports after they have their ACL reconstruction. The return to sport at the same level is probably a little bit lower, 75% to 85% in the literature, but it's still quite high. And the ones that don't go back, it's usually either fear of re-injury or a change in their school situation. For example, they tore it when they were 16. By the time they get through their rehab, they're 17. They missed their senior year sports opportunities, and then they go off to college. So their knee might be doing fine, but they still didn't go back to sport. Well, the problem with that is that they are going back to the exact same activities that caused the injury in the first place. And as a result, at least in the American literature and in the Scandinavian literature as well, one in three kids will have another ACL injury during their active years. That's about evenly distributed between the graft and the contralateral side, but these are dramatically high numbers, right? And really the highest risk group, and this is, I use the word tweeners, I don't know if you guys call them that at HSS, but this is based on Dr. Green's paper a couple years ago in AGSM where that group, not the really young prepubescence, not the older adolescents where you do a patellar tendon or quad, but those transphysial 12 to 14 year old, largely girls that often play soccer in this country, they are by far the highest risk group. And with graft rate failures, at least with hamstrings, around 20% and you throw in the contralateral side, I mean, they're very, very high numbers. And so I have personally taken a real passion in my academic practice of secondary ACL prevention, right? How do we prevent this from happening again? And I will tell you, I think any of the surgical techniques described today are good enough. So it's not that, man, I need to switch to Davide's technique or to Dan's technique. I think any of those techniques are very, very good. Secondary prevention is in how do you rehab these people and how do you make decisions about going back to sport? So the first point is this, you have to use objective return to sport criteria. It doesn't have to be the same at every institution, but you have to have some type of return to sport criteria that you're using, not just time. There's a great paper that was a collaboration between Norway and Lynn Snyder-Mackler showing 83% reduction in your risk of re-injury if you pass return to sport testing, right? What's interesting though is that if you look at six months, less than 25% of children can meet return to sport criteria. And so I think it is extremely unsafe to be returning kids to play at six months, but I would tell you in this country, that is still very much the norm. Most children, if you look at studies, and there's a great study in the middle there by Elliot Greenberg and Ted Ganley and Todd Lawrence, most children have neuromuscular deficits up to at least one year after surgery, probably up to two years. So is return to sport testing the only solution? Well, no. Some people are really convinced that this is the only way to reduce re-injury, but the problem is that it's not perfectly predictive. And this has happened to me. I had this kid, we called him LeBron. He was 13 years old. He was like six foot four and huge and strong. He passed every return to sport test and he looked great. And his first day back playing football, he tore his ACL. It just, it happened. So no test is perfectly predictive, but in 2022, you should be doing something. One of the challenges we have is that most of the tests use limb symmetry as a target, right? So you want it to be more than 90% equivalent to your contralateral side on quadriceps strength or hop testing or Y balance test. Well, the problem is that limb symmetry is not the right target. So on the right, this is a study I did when I was at Duke where we took a hundred normal children, healthy, normal children off the street, ages six to 18. And we had all of them do return to sport testing, like just like we would do if they'd had an ACL on both legs. And this is the percentage of children for all these given tests that had more than 90% limb symmetry. And if you look, only about half of kids could even pass an ACL return to sport test. And these are healthy, uninjured, normal children. So people have limb preferences, right? Or limb dominance, if you will. And you have to understand this because in rehab, you could either be grossly overestimating what a kid's function should be or worse in the other direction, underestimating depending on which limb they injure, underestimating how strong they need to be to go back to sport. And so limb symmetry alone is not enough. The other concept, and this has come from Lynn Snyder-Mackler, is she has shown that your non-operative limb deconditions during your rehabilitation. You're not playing sports. You're not going to the gym. And it usually loses about 35% of its strength. And so if you're using the non-operative limb as your target postoperatively, you're probably underestimating by 30% to 35% how strong that athlete needs to be. So they came up with this concept of EPIC, estimated pre-injury condition. And that is something that you can do. You can actually test your athletes at time zero on their non-operative limb, how strong they are, how far they can hop, and actually use that as a target as opposed to what it is postoperatively. And I think this concept here also gets magnified in these tweener athletes because these are kids that are transitioning usually from middle school to high school. And remember, when they got injured, they're 12 or 13. And by virtue of having an injury, they sort of get fixed in time. They're not really getting stronger. In fact, they're probably getting a little bit weaker. And then they go back to sport. Now they're in high school. And now they're going to be playing against kids much bigger, much faster, much stronger, yet they're sort of as strong as they were in middle school. And so that has led us to the concept of, and this is more work that I did at Duke, really should we be comparing kids to norms, right? Not compare them to their contralateral side, but what is normal for a 12-year-old girl strength-wise or hop test-wise? And so on that same cohort of 100 patients, we developed these growth curves. And this is published in OGSM a couple of years ago where you can literally plot the age of your patient on a single leg hop test or a BOSU squat test or a triple crossover test, and you can figure out they're in the 50th percentile for their age, they're in the 5th percentile for their age, and that's going to be very different. And I got hurt by this early in practice because I'd have patients who were really good on symmetry. They were 100% symmetric on all their tests, but they were symmetrically bad, right? And I didn't recognize that early on. And I think those are the people that probably had a higher risk of reinjury. So in my algorithm now, when I'm returning somebody to sport, I'm not just looking at, yes, you have to have good symmetry, just mechanically that makes sense, but I want them to be at least at the 50th percentile for their age and their sex on a given test. And we now have the data to figure out what that actually means. Do we just need to wait longer, right? Forget all the testing. Should we just wait longer? The truth is there's probably reason to be waiting longer. A study, one of ours from Duke, great studies out of Scandinavia, all showing significant risk reduction. So in our study, 13% lower risk for every additional month that you wait to return to sport. In the study out of Scandinavia, 51% risk reduction for every month you wait to return to sport up to nine months, and then that leveled off. And in a good study out of, I can't remember if it was Norway, but it's definitely Scandinavia, seven fold reduction in reinjury rate waiting more than nine months versus less than nine months. So maybe nine months is a magical number, but certainly in my practice, there's never a situation where I would let a kid return to sport before nine months. One question we tried to answer is, can we make testing more efficient? It is time consuming to do this. It's usually an hour long deal with a physical therapist. There's a lot of data. And so we did something called item reduction. This is basically statistical gymnastics to try to figure out which tests are actually contributing the most to your decision about return to sport. And we had come up with this as a paper from a couple of years ago, that if you're looking at their sort of their raw performance, meaning where they are in the percentile versus their symmetry, these are kind of your core tests. So it's basically a test of balance and a single leg hop are really your core tests. If you're going to do nothing else, check their balance, do a single leg hop and look at their quad strength. Right. If you're going to do nothing else. So my recommendations in 2022, I understand that one, kids are going to play sports again, but as a result, one in three are going to tear their ACL again. And you have to tell families this. Remember that really no kid is ready to go back at six months, nine to 12 months is probably a much more realistic timeframe. There's no perfect test. So even if your testing protocol doesn't look like mine, that's okay. Generally speaking, their knee has to be stable. You want to understand strength. You want to understand balance and you want to have some kind of functional test, whether that's a hop test or a dropline test, some kind of functional test. Remember that the goal of rehabilitation is to return them to pre-injury or normal performance, not just limb symmetry. Right. Don't get fooled like I did by the kid that is symmetrically bad. And keep testing your pediatric patients. There's actually a great paper yesterday, I believe, here where they looked at the value of testing people twice as opposed to once. And that's actually what I do. I test them at six months, not because they're going to be going back to sport, but to get a baseline. And I tell them, my goal is to figure out what you're bad at so that we can fix it. And then when you do the test in nine months, you're going to do better and you're going to have less issues. And they actually showed in this paper presented yesterday, I might've been out of Ohio State, that doing two tests as opposed to one actually dramatically improves patient reported outcomes, lowers failure rates, and increases return to sport rates. And so I would encourage you to do sort of two separate tests. Once again, thanks for your attention. I was just going to ask, I know we talked about Biodex is not necessarily translatable, but I think if you have access to that, like you were talking about the normalized strength to body mass ratio can be helpful to what you guys created, that if it's over 3.1, there's some pretty good data for that. So to your point about, if they're symmetrically low on strength, they should be able to do that. But I was going to ask how you use PROs in that, because in one of our prospective studies we've looked at, we look at ACLRSI and it's amazing to me comparing that with everything else. I mean, it's amazing to me that it matches perfectly. And as their strength and their biomechanics improve over time, their ACLRSI goes up. And then sometimes it's way off. They'll have really good objective strength, three or four normalized to body mass ratio. They'll have good IKPC and their ACLRSI is like 30. So how do you look at that? That's a great question. So for those who don't know, the ACLRSI is a psychological readiness for return to sport index. It's a questionnaire and you get a score of zero to 100, zero being I have absolutely no confidence in my knee, and 100 is I am perfectly confident in my knee for sporting type activities. I do get an ACLRSI on everybody at six months and at nine months. A couple of thoughts. One, there's a Goldilocks effect. And I credit Mark Paterno from Cincinnati Children's for sort of figuring this out. Below 67, basically no one should be playing sports. If their ACLRSI is below 67, their brain is telling you something ain't right, right? I'm not ready to play. So below a 67, I will not let them do anything on field. Conversely, above about an 85 or 90, those kids are actually at really high risk of reinjury. So the kids that are overconfident where there's a discrepancy between their objective recovery and their subjective perception of their recovery are at extremely high risk because they will not protect themselves. They won't take the rest when they need it. They will put themselves in dangerous situations in sports. And so you want to be kind of in this sweet spot. The other comment I found is that the younger they are, the bigger the discrepancy between their ACLRSI and their actual objective performance. So the nine to 10 year olds, they don't have a clue. They're all like, all right, I can play, I'm fine, right? As they get older and more psychologically mature, they're better at perceiving that issue that they're still having. And so I trust the ACLRSI a little bit more in the older adolescents than I do in the younger adolescents because I just don't think they get it. I will say, too, I think, and I don't remember, Dr. Green, when I was with you guys at HSS, how much sports psych they have built, but we just don't have it. I mean, it's mental health in general in this country, I think, but, you know, it's something that I feel like for us is a huge deficit. These kids struggle, you know, particularly for me ahead of that, as you said, the more tweener group. A lot of times it's girls that just really have a low ACLRSI and, you know, I do tell them, gosh, it should, your confidence should get better as you do more and we get you ready for it, but sometimes it doesn't, and I honestly don't really know what to do because we don't have any sports psych around, and, you know, and you know what telehealth is. This is perhaps a little bit Darwinian of me, but my interpretation of that is I've found that there's sort of two groups of athletes, those that are like really good, legitimate athletes, and they tear their ACL, and when they're objectively recovered, they're confident they go back, and there's a group of people who are sort of, they're involved in athletics, but they're sort of subcompetitive level, and when they get hurt, it is just, their world falls apart, and they're never able to regain that confidence, and those are often the people that do not return to sport or do not return to the same level of sport, and I have found that no amount of rehab or physical therapy will increase their ACLRSI in that situation. I have utilized, we have a good sports psychologist in Charlotte that I've utilized, and it's made a good impact, but part of me wonders, if you have a kid who was a marginal athlete to begin with, who tore their ACL within six to 12 months of starting a high-risk sport, is perhaps somebody up above sending them a message that that's not gonna be their chosen sport, and is it the right thing to kind of coerce them back into that same sport? I don't know the answer to that. Dan. I wanted to ask you how you and your team quantified balance in a practical sense. How are you assessing it? Yeah, so that's a good question, because that is a hard thing to do short of some really sophisticated motion lab kind of stuff. We do a wide balance test in our first phase of testing at the six-month mark. The other thing we do is we have them do single-leg squats on a BOSU ball. And we do max reps in 30 seconds. Single-leg squat on the ball, yeah. It is, I encourage every single one of you to try it. It is exceptionally difficult. Like, if you wanna feel old and out of shape, try to do a single-leg squat on a BOSU ball. And on average, a good recovered athlete can do probably 30 to 40 single-leg squats on a BOSU ball, and we do it to a target. So we measure 45 degrees of knee flexion, and we hold a bar there, and they have to single-leg squat and hit the bar for it to count as a rep. And we do it side to side. Is that a perfect test? No, but you will see people who have balance issues, they get like five, right? They can barely do it, they're falling off, they're having all sorts of issues. And so it's a combination of the wide balance test and the single-leg squat on a BOSU ball. Was there another question? Another question in the back? Well, that was gonna be my question, is whether you use a motion capture or a force plate to evaluate that. Yeah, so we don't have ubiquitous access to that. I had much better access when I was in Duke in a university setting. I'm now in a student-private academic setting, and it's harder. We do have a force plate where we can measure the reaction forces of just a straight vertical jump. The truth is, it's hard to know how to incorporate that into decision-making. What I do think is important is incorporating some metric of quality of motion. And there are various ways to do that. There's something called a less score or landing error scoring system where they jump off a box. There's basically five ways you can mess it up. If you get a score of five out of five, that's really bad. If you get a score of zero out of five, that's really good. That's sort of semi-quantitative. What I encourage you to do, find a physical therapist, one, that is really good in your community and who gives you a good, detailed, both quantitative and qualitative description when they do this return-to-sport testing and test all your patients with the same person. That's what I've gone to doing both when I was in Durham and when I was in Charlotte, because if the same person is testing all of my ACLs, I really start to trust what they are telling me, and I know how to interpret it, right? And you want the feedback of, hey, they did great objectively, but really their sagittal plane motion is bad, meaning they're staying in extension when they land and they're not absorbing forces properly. You know, they still have dynamic valgus when they do all of these tests and I have to constantly be cueing them to engage their glutes. And so the last part of this, and this is sort of the art of it, is the quality of motion, and I think that stuff is really important. So my other question was gonna be, how are you managing those marginal athletes that you mentioned earlier, that, I guess, don't have the self-awareness, they really wanna get back to it, a lot of it's social, but they were never really, you know, they never really had the genetics to begin with, and through the rehab process, they're never meeting the criteria you want them to meet to get back, but they're banging on your door to get cleared, get back to the team with their buddies, and it becomes almost a war of attrition. Like, at some point, are you gonna let him back, or her back, just to, you know, it's nine months to a year, and you're not- Absolutely right. Well, so I wait longer. So I will go up to 18 months, and just say, look, let's keep trying, let's keep rehabbing, let's try to see if you're safe, and some of them don't listen, they just go back anyway, but I will, and if at 18 months, we can't get them to pass the testing, that's a hard conversation, and I say, look, it's not that you can't play sport, but you have to understand that you're taking a very high risk, and if it's a primary reconstruction, I'm reasonably lenient and say, look, if you accept the risk, you can go back. When I have kids that are 12, and they've had two ACL tears already, and they're, like, dying to go back to soccer, and they're just a neuromuscular nightmare, I will actually have a conversation 18 months after surgery with them and their parents, and say, look, I'm never gonna tell you what to do, I do not think it is medically advisable for you to return and play soccer. Like, you can do cross country, you can do track, you can do all sorts of other things, but what you need to think about it, is it worth it to me to do this a third time, or a fourth time? You mentioned the track and the cross country, that's my favorite thing to do, even for the six, seven month person who's getting close to going back to a pivoting sport, I'm like, well, that's a great idea, please do cross country, please do track, and you're not gonna win the state, but by the next two or three months of you running long distance, don't do the hurdles, don't do steeple, don't do the jump, but two or three months of you running long distance, that's gonna get you ready for basketball or soccer. But then I worry about it a little bit, because if my RAs or folks are looking at, did that person return to sport? They might have, they might kick the box, because they were on the high school varsity cross country team, but I'm using that way more than I used to, swimming, rolling, leading track team. Another example, the kid I presented with a failed McKaylee, he was an interesting kid, so he came to me, he tore his first ACL when he was nine, tore his contralateral ACL when he was 10, so he'd hit two McKaylees by age 10, and then tore one of the McKaylees at age 12. 12 year old, he's had three ACLs, he's got increased tibial slope, he's a hyperextender, the nicest kid in the world, his name is Kobe, his parents are basketball fans, he was a really good basketball player, and I said, Kobe, like, you gotta stop. Like, you're 12 years old, you've already had a lot of complicated operations, he got a little tiny bit of distal fibromyalgia, it's not bad, but from the epiphyseal revision, and he decides he's gonna play baseball. I was like, that's great. And he's pretty good at baseball, but I think the family's actually really appreciate and respect you if you're candid with them about the risk. You can't be too paternalistic about it, but I'd say at least once or twice a year I'm having to have that hard conversation. Yeah, you need to keep them away from the operating room as soon as you finish your, there was one question. I did, I just wanted to kind of follow up with what he was saying, I'm a fifth year resident, I just had recently done a literature review on mental health evaluation in things that work out, and there is like barely anything out there, so I'm just curious how to, that's something I'd like to kind of delve into a little bit further once I go into fellowship, is researching more about just the mental health component of it, and just utilizing like calmness, anxiety of how this depression scales, or how can we incorporate that more? Because so much of it is just, you said, okay, 10% we do the surgery, but then if they mentally take this hit, or they have this injury, and now they're not even out with their buddies, and then they get depressed, or whatever the case may be, how can we incorporate that, or what do you guys do to try and assess that formally? Because the ACLRSI helps, but it doesn't necessarily, you know, say, hey, this person is at risk of depression, let's maybe give them a formal referral to a therapist, or whatever the case may be. So, I mean, that's a wide open field of research, I will tell you, I actually, this is a true story, I have a kid, I had to be kids on both sides, one when he was 12, one when he was 13. I got a, parents had my cell phone number, I forgot why, but mom called me at like 10 p.m. one day, it was weird, like, what's going on, so, pick up the phone, she goes, I need your help, my son wants to commit suicide. And he, I don't know what to do. I was like, first of all, why are you calling for an emergency surgeon? You know, so we got him admitted to the emergency room, and he got him at, you know, a psyche val, and all that stuff, but so, this is a kid who, his parents were putting tremendous pressure on him from a young age to get a D1 scholarship. And he was a good soccer player, but he had formed his, you know, two ACL tears by age 13, even through two years of rehab, and he just, he snapped, he couldn't take it anymore. And so the depression and the loss of your peer group, and the loss of your identity, which is often tied up in sports as a real thing, and we are, I think, severely under treating that, in children in particular. There's no validated metric, Dan, you might know better than me, there's no validated psychological ACL-specific metric for children, right? And that's probably something that should be done. And there is really very little resource for us to understand, you know, short of the mom calling and saying, my kid's having suicidal ideation, how do you identify those people who are not that far along the spectrum? But I now, I'm probably sending five to 10% of my teeth ACLs, and they are more common in women than men, to a sports psychologist at some point in their rehab. The other thing I would say that, I think, for me, similarly to kind of pain management, the more that you can talk about it up front, I think that matters a lot. I really do try to tell them ahead of time, hey, this is gonna be just as hard on you mentally as it is physically, and you're gonna go through these fluctuations, you know? Injury, low point, by the time you get to surgery, I'm ready, I'm gonna be, you know, I'm gonna be better than ever, or whatever, but they have these ups and downs, I don't know how to navigate, but I was thinking, Dan, what you were saying with running and some of those things, sometimes that's so good for them mentally, too, because they're just in these doldrums of, you know, five, six, seven months where they haven't achieved the power, they haven't gotten everything back, but they're safe to do some of that stuff, and it just seems like it's a huge mental win for them to be doing something athletic, and then also, as you said, the social part, being back on a team, being able to see those kids, see the coaches, I mean, I don't know how we quantify necessarily, so there's a different approach. The other thing that's really hard, and maybe you guys know more about this than me, is if you look at the literature on, like, when is it safe to do stuff, because people talk about, when can you run, sort of initiation of cutting, pivoting, and return to sport, but if you think about it, you need much more granular data than that. People kind of go like, hey, can I do this lacrosse drill? Can I run around cones with a soccer ball? Can I shoot the soccer ball? Can I, I'm a goalie, can I just take goalie practice? And you're like, well, shit, there's nothing right about that. Like, I don't know, so you're making this stuff up, literally, 100% of the time, and I think there's an interesting research opportunity, and I haven't wrapped my mind around how to do it, of like, how do we quantify when it is actually safe to do certain activities, and some of that's gonna be probably studying those activities in the motion lab to understand what forces are going across the knee, and then, you know, there's some interesting stuff. I'm working with a company that is developing a, basically, a suture button, think a tightrope that has a strain gauge in it, and so they have a little Bluetooth device that hooks up to an iPhone, and that can beam me in real time how much strain is going across their ACL at any given point in time, in vivo, right? So there's like cool stuff on the horizon where we might be able to be monitoring low, I bet you people can probably do more than we think, and finding that athletic outlet for them within their safe confines is so critical, but. But I also think that one of the things that's missing from our standard return to play, because that's all basically gonna PT gym, is just the ability to run a distance. You know, run distance time, why don't we do like a five minute run with good form, how far can you go? You know, because we don't have, like in New York City, I don't have park next to my office, you know, but I still think the endurance and running part of it needs to be part of our program. We have to be able to run a mile below a certain threshold before you can go on, but we don't have that today either. But I have a mental health question, which is a great question, I know they're starting to talk about it a little more than you, but put a plug in the prison, so there's the Pediatric Research and Sports Medicine Society meets every January or February, and it's PTOT, Primary Sport Orthopedic Surgeons, and it's, they spend a lot of time and effort in ICLs talking about it, so they're starting to do research on it. We're actually doing lactate tests, putting on the treadmill and doing the lactate tests in professional athletes, and sometimes you're impressed how out of shape these kids are. Sometimes they are more out of shape with it, just for fun, with a 60-year-old surgeon, sporting, not a triathlon athlete, but the kid was way, way, way worse than. Well, so, you know, I work with two pro teams, and we use this GPS-based system called Catapult, and actually, I think Lyle Kane was talking about this yesterday. So we get all sorts of data from this group, so once they start on-field work, we can track their max speed, their average running speed, how aggressively they're cutting to the right, to the left, and you can get really granular data about their actual performance, and what's amazing is when we say, you're cleared to play soccer, the trainers look at us, they're like, you have no clue. They're not even close to being able to play soccer. Like, they are so out of shape, and their overall, like, neuromuscular function is still far from that competitive level, and so, and those are professional athletes who have unbelievable rehab resources, right, and that's their full-time job. I would have to imagine that the average athlete that we clear to return to play is actually nowhere near a true performance level, and I think the biggest gap in this whole system is from when I say go to when they actually play games. It's the same thing. Every parent's like, can you give me a written progression for Johnny for the next six to eight weeks on what he can do week by week so I can give it to his coach? I'm like, that doesn't exist, and same thing. We should probably have sport-specific transition plans from physician clearance for on-field to actual competition, you know, and that's a tremendous lift, and you really need sport-specific expertise, but I think that is what we need to do because that's when a lot of people sort of fall through the cracks is, yeah, they look good on a hop test, but what are they doing on the field, and that probably does translate into risk of re-injury. Great. Thanks, everybody. Thank you.

decision-making

return to sport

ACL reconstruction

fear of re-injury

mental health

rehabilitation process