This was gonna be a tall lecture, but I'm gonna bring this down a little bit because it's not me. So today, we're gonna talk a lot about some of the long-term consequences after a concussion. We were talking kind of about the initial injury and how to identify it and management, but now we're gonna flip to the end. So now we're ready to go back to play and what are some of the long-term issues that we're seeing after a concussion? So as many of you are aware, there's many different aspects of concussion that we can treat and manage from all healthcare providers' perspectives, and these are just a few of them. And in theory, when everybody's symptoms are resolved and there's no more deficits in any of these categories, our athletes are ready to return to play, right? Well, unfortunately, that's not the case. What we end up seeing is that there's these long-term subclinical deficits that our testing for return to play is not sensitive enough to pick up on. And specifically, what we tend to see is that after dual tasking, we see some changes in cognitive effects compared to our healthy controls and our healthy athletes. Particularly, we see things such as changes in our medial-lateral sway, our joint coordination, and then our more conservative gait pattern. Now, these are only tested usually with a simple force plate where you're walking and you're doing two tasks, like you're answering a question while you're walking. However, I don't know about you, but I don't know any sports where you only have to do two things, right? Normally, there's a ball, there's another player. I have to make a decision. I'm reacting to them. I'm also running or swimming, whatever it is. So we can extrapolate that these sorts of deficits that we're seeing are even bigger with more complex tasks. And why does this matter? And this matters because some of the research what we're seeing now is that after a concussion, once athletes have returned to play, there's a very significant association with lower extremity injury risk. Right now, all of the data is in lower extremity injuries. This is kind of easier for us to track, and there's a lot more acute lower extremity injuries versus maybe some of the chronic ones that we might see with an upper extremity injury, such as in our baseball athletes. But that's probably coming down the pipeline in our research. But what we see is in our lower extremities that there's almost a three times increased likelihood of sustaining a lower extremity injury after you've had a concussion, compared to those athletes who haven't sustained a concussion. So this is pretty big, right? We don't want somebody coming right back in the office just after they've left. And we know that after an athlete has had a lower extremity injury before, such as like an ankle sprain, they're at risk for more ankle sprains or more lower extremity injuries. However, even when you control for this factor after a concussion, they're still at a further increased risk of a lower extremity injury. So we're compounding on this in somebody who's had a concussion. Particularly the types of injuries that we're seeing are lower extremity muscle strains, sprains, and even ligamentous tears, such as ACL injuries. One study found that up to three years out after a concussion, there's a 1.6 times likelihood of having an ACL injury. So that's huge, right? And we see this a lot. And a lot of my colleagues, physical therapists, will say that, hey, I don't treat concussion. And I would argue that that orthopedic patient in front of you might have some confounding factors from a past history of concussion that you just aren't aware of. So I think we're all treating some of the long-term deficits after concussion in our athletes. And so who is this happening to, right? Is this happening to all of our athletes or just some of them? And what we see is that about 50% of athletes in this particular study sustained a musculoskeletal injury within 90 days of returning to play. But however, compared to our healthy controls, there was no difference in the amount of time that they lost after they go back to play, meaning that that severity of injury was no different than their healthy counterparts. So we're getting injured more often after concussion, but not necessarily a more severe injury than our athletes who haven't sustained a concussion. Particularly, this was the first study that actually identified a difference between males and females, showing that males are actually at a greater risk compared to females. That could just be due to different sport participation. It's really unclear at this time based on the research. And then in our participation, we're seeing that reserves are more at risk than our starters. So this is an interesting one and could be attributed to a couple of different things. It could be due to experience of playing, right? Our starters are usually gonna be more experienced, have more play time. Also, our reserves may have different neuromuscular control patterns and different movement patterns that are less efficient than our starters, which is why they might be reserves rather than starters. And so that might affect their risk of injury already. And then what about those athletes that have had a history of multiple concussions? And we see that when athletes have had multiple concussions, they're at three times risk of a lower extremity injury compared to only a single history of concussion. And what's really interesting is that their time to injury is quicker when you've had multiple concussions, meaning that if you have one athlete who has had two or three concussions, they're gonna get injured within 45 days versus somebody who's had one concussion might take 180 days, right? And those are just numbers being thrown out there. But they're more likely to get injured sooner when they've had a history of multiple concussions. Once again, we don't really know why this is yet based on the literature, but there's some theories that it could be due to buildup of our neuromuscular deficits over time in those athletes who have a multiple history of concussion, or it also could be to their player behavior, right? If somebody is having a multiple history of concussion, they might have a more aggressive play type to begin with, which might already put them at an increased risk of lower extremity injury as well. So we really can't control for that yet in what we know. So when is this happening to our athletes? And this is termed the window susceptibility, and currently research ranges anywhere from 90 days to 365. We know that there's a strong slope of the line, as you can see here, within the first 90 days of returning to play. You would think that this line would get less and less as we get further out, but research actually shows that we only get down to about two times the increase of risk once you get up to 365 days. So up to a year later, our athletes are still at double the risk of sustaining a lower extremity injury compared to their teammates who didn't have a concussion. So this is something we should be watching for in all of our athletes, and can be really affecting them. So then the next question is, so why is this happening? Because we wanna know why so that we can help fix it. So a couple different theories are that there's changes in our motor cortex function, particularly reduced excitability within the motor cortex, which is gonna change our motor output. Or that there's persistent changes in our neurocognition, which is gonna lead to our decreased capability for other functions. I always explain it to my athletes as, you know, you have a bucket of water, and this is the water that you're able to use to play your sport. When you have to allocate more water to the visual component of watching another player, you have less water to distribute to the rest of the things you need to do, such as running or cutting or reacting. So we've now taken up more than you normally would to do one thing, and we've taken it away from somewhere else. So maybe this is one of the reasons that we are seeing some of these injury risks. As was mentioned before, that increase in reaction time after concussion. So right, we have a less reactive ability, and so if somebody's on the line, and they have to react, and they're slower, that's another chance that somebody might blindside them, maybe have a lower extremity injury that way. We also see from other research that there's an increased risk of lower extremity muscle strains, some of the same type of injuries we're seeing after a concussion in athletes with a higher reaction time. So that could be potentially a contributing factor. And as I mentioned before, those changes with the dual tasking conditions might be something that's contributing to our athletes' ability to perform on the field and their risk of injury. And then the last one is a failure to integrate afferent information. So we see that there's cerebellar dysfunction after a concussion, and athletes who go back to sport may develop faulty movement patterns that they aren't able to correct because of a disruption in that feedback loop. And we know from biomechanical studies that athletes after a concussion actually demonstrate increased internal rotation and knee valgus with drop landings, as well as increased stiffness in their landings compared to healthy controls. And all of those are movement patterns that we've identified in athletes who are at risk for things such as an ACL injury. So what do we do with this from a rehab perspective, right? That's why I'm here. Well, the great thing is we don't know, because we don't know why it's happening, so how do we treat it? Just like a lot of other things, okay? So everything is a little bit theoretical at this point as to how we actually intervene to prevent these lower extremity injuries from happening. Some of the thought processes are we could implement some of the lower extremity injury prevention programs that we use for things like hamstring strains, or ACL injuries, or ankle sprains, but there's no studies that have actually implemented that yet and seen the outcome over time in our sports-related concussion population. So it's kind of theoretical at this point, but that would be one suggestion, is use some of the commonly used lower extremity injury prevention programs that we have and see if we can help our athletes reduce that risk after going back to sport. Other thought process from other pieces of literature is implementation of eccentric exercises throughout their rehab process. Particularly, these have been shown to improve neuromuscular control deficits, so maybe during their rehab as they're recovering, we can start implementing eccentric exercises early on to help improve these neuromuscular control deficits. And then we can start integrating motor tasks with cognitive and visual components, so use all of the sensory systems and really try and work on some of that dual or multiple tasking components to really help with those deficits later on. And so these are just some of the things that we can think about manipulating from a rehab perspective. So for your physical therapists, your athletic trainers, to educate your parents and families on in case they don't have access to any of that. These are things that they can work on. We can work on changing their focus of attention throughout rehab, making more complex tasks. We can change their visual input. Everybody's probably seen those. They have different brands now, but the shutter glasses, those can often be used to help with visual input. I also work in a place in a collegiate training room where we have access to some of that and some in a clinical setting where we don't. And I'll take cheap sunglasses and cover them with tape in different places to change the visual input. So it's just a more friendly take-home version that I can also give to my athletes. You can also change the cognitive load for the athlete, asking them more in various complex tasks. We're gonna work on reaction time because we know that that is an issue. We can change things like ball tracking. We can get other people involved in the rehab and other players and force our athletes to make decisions in rehab, making it more complex. And then we can also, like I said, all of this combined together to work on our multiple and dual tasking issues. So even if you don't see concussion as one of your primary diagnoses in your practice, think about this the next time you see your orthopedic patient as well. Maybe this is a missing piece in why they're getting injured so often or why they had that ankle sprain or why they had that ACL tear. Because after a sport-related concussion, our athletes are at an increased risk of a lower extremity injury, particularly our males, our reserves, and those who've had a history of multiple concussions. And because of this, the return-to-play process that we put them through, not only during the rehab phase but as they clear rehab and they go into an on-the-field process, should be very individualized to help treat these deficits and then continue to treat the ones that we know are still there but aren't able to detect anymore. I have a lot of resources, so if anybody has any questions, please feel free to reach out. My email is up here as well. And these are just some of them. So, thanks. Thank you.

consequences of concussions

subtle deficits

lower extremity injuries

multiple concussions

rehabilitation process