 To open up our next session, we have Dr. David Howell. Dr. Howell is assistant professor and assistant director of clinical research in the department of orthopedics at the University of Colorado School of Medicine as a master's of science and a doctorate of philosophy from the University of Oregon. So he's a doc, excellent, active current collaborations both domestically and internationally. Dr. Howell currently has collaborations with Boston's Children's Hospital, the University of Delaware, Qing Mao University and the University College in Dublin. Ladies and gentlemen, welcome, Dr. David Howell. Thank you for the invitation to come talk today about some of the research that we're currently doing related to preventing injuries after sport related concussion. So rather than preventing the primary concussion after an athlete has sustained a concussion, it's clear to return to play. How do we identify who's at risk for further injury in that next six months, a year, two years? And what can we do about it? So for those of you who don't know me, my name is David Howell. I am a researcher at the University of Colorado School of Medicine in the Department of Orthopedics and the Sports Medicine Center at Children's Hospital. I have research support from NIH and Minds Force Brain Injury Network actively. Those are kind of my primary disclosures so that you know that. Really I wanna kind of talk about three different things today in the 15 minutes or so that I have. Number one is just to get on the same page about the kind of existing literature and the theory about increased injury risk after concussion. Number two to outline the potential factors that contribute to increased injury risk after concussion. What are the things that people have investigated? And then at the end, a little bit of pilot data from some of our ongoing work and some theories about what can we do to actually intervene for individuals who have sustained a concussion and clearly go back to sports to reduce their potential risk of further injury. So we'll start with the first one. So number one, from a large-scale perspective, what do we wanna know? Well, if you sustained a concussion as Clay Thompson did here a number of years ago, whether or not you continue playing or go back into the game or come out of the game for a prolonged period of time, and then you go through the normal kind of symptom-free waiting period as a part of the return to play protocol. You do everything cautiously and by all signs and symptoms have gone away of the concussion, we kind of, again, this is under the auspices of best clinical practice. When you say, okay, yes, you're clear to go back to sports, your brain is recovered from the concussion. Is there now increased likelihood that you're gonna land funny on your ACL, for example, or I guess on your foot, tearing your ACL? And I know that this is kind of maybe a little bit of a dramatic example because these two happened a couple of years apart, but is there some relationship? And is that relationship potentially bi-directional where maybe it's just those that are injury prone, more likely to get hurt? We don't really know, but those are the things that I wanna discuss today. We're taking a step back from routine clinical practice or kind of taking it from that perspective. We have these kind of commonly available tools, the SCAT-5, computerized neurocognitive tests, balancer escoring system that most clinicians use in their assessment of concussion, but we know that they're not super reliable tools to actually measure recovery from concussion. At the same time, we know that we can identify persistent physiological deficits after athletes have recovered on these kind of clinical tools, but what's the feasibility of doing a transcranial magnetic stimulation diffuser tensor imaging, EEG on a routine basis, right? They're really good for kind of experimental research grade purposes, but as far as clinical implementation, there's not a whole lot that we can glean from that at this point, certainly a lot of work is being done. So how do we kind of find that best balance between? So if we look into the literature, as far as what's been published thus far on increased injury risk, or I guess just generally injury risk after a concussion, we see two meta-analyses that have been published thus far, one showing 2.1 increased odds of sustaining a lower extremity musculoskeletal injury after a concussion in the year after a concussion relative to those who haven't, and one showing about a 2.5 increased odds. So both showing a significant effect across multiple. And if we kind of break it down and look at the individual hazard ratios, injury rate ratios or odds ratios that have been published, we see a fairly consistent effect. Obviously it ranges from about 1.3 up to about 3.4 increased odds at times, increased odds of sustaining an injury after returning to sports from concussion. One thing I do wanna point out though is that a lot of the data that's been published across multiple populations, professional, military, collegiate, high school, recreational, a lot of the data comes from male athletes, primarily male collegiate athletes. And so women really, I mean, among this table that I've created here, only about 13% of the subjects included. So I think that's something that we need to consider moving forward, or kind of implications being that there's a 2.1 to 2.6 greater odds for subsequent injury after a concussion. This phenomenon exists across high school, collegiate, professional athletes, military personnel. But again, I think that that's important to know that we see it across populations, but important to understand that females have not been studied to the degree of males. We know that there are some sex-based differences that exist as far as concussion recovery. So let's look at the potential factors that might contribute to the increased injury of concussion. So if we think about dual tasks in sports, so I thought it's not just movement, there's a cognitive element to it. And I have to credit Rob Lionel at the University of Georgia for finding this Twitter post from a soccer club, somewhere in Europe, I believe. And I think this is a player's decision to pass. You think about all the different cognitive processes that have to go into, I think this was from the perspective of, parents stop yelling at your kids is what Rob had said. But I think that even if there's a subtle deficit that's resulted from the concussion, by all signs and symptoms have cleared, all the tests you passed, you're ready to go back in, there's a complex cognitive pathway that has to be executed for an individual to simply make a pass to their teammate on the soccer pitch. And that involves distributing attention across different internal and external sources of stimuli, selecting the appropriate motor responses in response to those stimuli and then rapidly kind of implementing those responses and monitoring those responses, suggesting how you're gonna move in a way that's gonna protect you from injury. Now, what are the things that might contribute to this? Again, this is kind of a conceptual theory. I have not published it. It has not been vetted to take it for what it is, but just a couple of things that have been proposed in this pathway of what causes MSK injury incidents after a concussion or what might modulate that risk. So one, as I just mentioned, is these lingering motor deficits. So we're not testing the ability of an athlete to kind of do these complex motor tasks, such as running, cutting, jumping in the real world with our commonly available concussion tests, like something like the balancer scoring system. How often in sports are you standing on one foot with your eyes closed for 20 seconds? Very rarely, I would hope. And then at the same time, kind of these lingering attentional deficits. So if you can't distribute your attention properly across these different sources of stimuli, then perhaps you're at an increased risk for further injury. A couple of other ideas that have been proposed include deconditioning. So if you take an athlete who's used to exercising and undergoing the demands of their sport, take them out of their sport for a couple of weeks and put them back in. Maybe there's an increased likelihood that they'll get an injury. A couple other theories that have been published recently is the concept of perception action coupling or maybe just that injury-prone athletes exist. And if you're gonna get a concussion, you're more likely to get a musculoskeletal injury. If you're a risk taker, you're more likely to get any sort of injury. And those two things may be, but let's kind of go through a little bit of what exists thus far in this literature. One of the studies a couple of years ago from Berman and colleagues showed that while risk of injury, just in general, maybe related to poor motor control, that might not have anything to do with the concussion itself. It may just have to do with how the athlete controls himself on the field. And they've showed that athletes with a concussion have an increased likelihood of a lower exterminated injury both before and after the injury. So there may be an effect of just the individual. Something like risk-taking behavior. So athletes who engage in quote-unquote risky behavior may be more likely to get any sort of injury. So if you lead with your head on the football field, maybe you're more likely to get a concussion or a shoulder injury if you missed or something like that. Again, this is kind of conceptual or in the case of this rock climber, I'm unlikely to die or get injured falling from a height because I don't rock climb, right? So simply stated, this person is engaged in a quote-unquote risky behavior. They're more likely to have a fall from height than someone like me who's marginally afraid of heights. De-conditioning is another kind of thing that has been purported. And if an athlete rests following their concussion, they may have a reduced kind of cardiovascular or neuromuscular control. And that may affect their risk profile when it comes to sports. Interesting, I mentioned Rob Lionel earlier. He's done a lot of work in this. And his data actually suggests that this is not the case. This is collegiate athletes, but the increased likelihood of a subsequent musculoskeletal injury after a concussion was not in that initial zero to six month post-return to play timeframe, but actually in that six to 12 month after a concussion and return to play timeframe. So it doesn't appear that based on the existing data that we have, that that's a real strong driver of this likelihood. Two other theories that I mentioned have been kind of put out there relate to perception action coupling. So there's some sort of alteration in your ability to perceive information and couple that with the action. And if you haven't reestablished that following concussion or return to play, you might be at an increased likelihood of a subsequent or neuromechanical responsiveness. So kind of this complex path of various things that are affected by concussion and then modulate your future risk of injury, whether that be reaction time balance, how your brain processes neural input, how you align yourself and how you respond to stimuli and different muscles. We published kind of a scoping review paper a few years ago looking at kind of this idea of neuromuscular control and kind of paired the existing literature at the time on musculoskeletal injuries after concussion with what we call neuromuscular control deficits or I guess commonly assessed, we use dual task gate paradigms. And we see that neuromuscular control deficits after concussion may or are likely to be undetected by clinicians, right? What clinician has the time to go through a full gate analysis in a 3D motion capture lab and then what do you do with that information? It's just not feasible. And if we know that these deficits can modulate injury risk independent of a concussion, if they're not recovered by the time the athlete has returned to play, then perhaps that's putting them at greater risk once they are actually recovered. And some of our freedom data or published data, I guess, that has its limitations for sure, based on, this at least was based on self-reported injuries in the year following the concussion, but we grew people into those who reported an injury in the year after returning to play following concussion versus those who didn't. And those who had a subsequent acute time loss injury showed kind of a worsening across time panel B there on the right on their dual task gate cost, which is the ability to kind of do two things at once, essentially we're measuring how fast a person walks under dual task conditions versus single task and calculating that change. So there may be some relationship. This was just published by Jesse Oldham in MSSE, just maybe last week, I think. And I would encourage you to check it out, but what she found was that following a return to play decision or at return to play after a concussion, the athletes who went on to get a musculoskeletal injury in the year following the concussion had a slower gate speed. And in addition, kind of just this more conservative gate strategy, but this also kind of existed before their concussive injury as well. So this gets to kind of that poor motor control potential, as I mentioned earlier. So in the last kind of couple of minutes, I just want to explore some ways to detect, intervene, risk of injury, risk of injury, concussion and really a lot of the work we focused on is these top two, these motor and attentional deficits, as I mentioned, kind of with this dual task we've been using. Now, a lot of work led by Greg Meyer and a lot of his colleagues have established these injury prevention methods. Knee injury rates have been shown to reduce ankle sprains in youth soccer, basketball athletes and a lot of female athlete studies. They're relatively simple to administer and they incorporate plyometric strength training, technique training, things like that to try to retrain that neuromuscular, kind of combining all of these things together. We say, well, we know that these work independent of a concussion. Perhaps as a part of return to play we can incorporate some of these exercises, lateral jump and hold, lateral jumps, hop and hold, things like that that go through. And we have some ongoing work that unfortunately, like a lot of things is disrupted due to our ongoing COVID-19 pandemic, but at six months post return to play, we're having kind of this, we're having people randomized to a neuromuscular training program or nothing at all kind of the standard of care return to play. And we see 9% at six months that underwent this training program have an injury, one out of 11, whereas about 57% have had a subsequent injury who did not complete this and similar exposure between the two groups. So again, this is very preliminary data and I would ask you not to share it or kind of advertise it, but I wanted to put it out there so that we're starting to think about how do we actually intervene as a part of return to play and what can we do from a neuromuscular training standpoint? There may be some continued beneficial effects on injury risk following return to play clearance further training the neuromuscular. So we see the concussion leads to a greater injury risk and there's measurable objective deficits after the concussion. So again, this is a pretty widespread problem. We don't have it down to a single factor. So I think this multifaceted approach is probably the best way that we can approach it right now and start considering whether it's motor or attentional training within routine return to play decisions. It may be appropriate. I don't think it's gonna certainly cause any harm at this point and it might be interesting to see if this continues and is something relevant that we can actually change within the return to play paradigms. So with that being said, thank you so much for the time and I look forward to the question and answer.