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Melanie Cole (Host): Welcome to UAB MedCast. I'm Melanie Cole. And here to highlight identifying and reducing risk factors for ACL injuries is Justin Kirk. He's a physical therapist at UAB Medicine. Justin, it's pleasure to have you with us today. Tell us how injuries occur to the anterior cruciate ligament and how common this is.

Justin Kirk: Well, first of all, no one tears their ACL when their foot is in the air. A lot of ACL injuries are non-contact injuries from decelerating or slowing down, landing or pivoting in an athletic environment where the knee buckles forward and typically collapses inward. So it's kind of that valgus stress with a little bit of anterior tibial translation is what we call it when that shin bone moves forward underneath the knee.

Melanie Cole (Host): Then tell us who's most likely to sustain an ACL injury. We hear that girls are more susceptible to ACL than boys. Do we know why this is?

Justin Kirk: Yeah. So I think ACL injuries are common widely among both males and females, but females are more likely to sustain an ACL injury than males. And a lot of this is still speculation. There is some pretty good research on it, but I think we need more research to say definitely this is the cause. But a lot of times, they think about joint anatomy, joint laxity, joint shape, angles of the joint, females with slightly wider hips can tend to have a little bit more of that inward knee position. But a lot of it can come down to males typically have tighter joints, just females tend to be a little bit more lax. And then, a lot of females, especially in high school sports, don't like the weight room because they're afraid it's going to make them bulky. But truly, that just leads to strength and balances that can set them up for an ACL injury. And we see this really commonly in soccer, but it's also prevalent in football, basketball, lacrosse, volleyball, gymnastics and, for the recreational athlete, snow skiing.

Melanie Cole (Host): Wow. I didn't even really realize about snow skiing, but that makes perfect sense as you're moving your knees back and forth in that lateral way. So let's talk about treatment. First of all, first line, tell us a little bit about symptom management first. If it happens, how do we know, how's it diagnosed, what happens?

Justin Kirk: Yeah, I'm glad you bring that up because ACL injuries are often misdiagnosed. And in about 50% of the time, they're misdiagnosed as a knee sprain. And it's not until a little bit later when things are not clearing up, swelling's not going down. The knee is still buckling that we go and get an MRI. The college athlete, they might get an MRI a little bit sooner just to be sure because teams have access to that kind of equipment. But for the younger youth athlete or high school athlete, they may not have access to that quite as quickly. But stereotypically, you'll have some sort of twist and a pop, typically with pain, but it's not always painful. Some people, you know, going back to skiing or football, they'll tear their ACL and finish the game. And it's not until later when the knee swells up and becomes painful that they realize they've done something.

Melanie Cole (Host): Well, then, what's the first line of defense? What's the first treatment that happens. It's not always direct to surgery, right?

Justin Kirk: Right. And I think best evidence now is kind of suggesting unless you have a very tight timeline, to go ahead and not go directly into surgery on day one after the injury. Let some of that inflammation cool off, and then get a quiet knee and then perform the surgery after that, after hopefully you've gained a little bit more of your quad strength back, So that's an ideal scenario. For a lot of athletes, time is money and they want to go ahead and get them in for surgery day one after an injury. Because every day they delay is another day that they're missing an opportunity. So that's just kind of an ideal scenario.

Melanie Cole (Host): So then, let's talk about rehab and/or prevention. So tell us about limb symmetry and single leg training for preventing ACL injuries. What does that entail?

Justin Kirk: So since the ACL is in the category of potentially avoidable injuries, and what I mean by that is it's a non-contact injury, you can't really avoid contact injuries, but you can hopefully prevent some non-contact injuries. And a lot of times, your athletic resilience is directly tied to how good you are on one leg. So these glaring asymmetries in strength and stability, body control, coordination, how you land on one leg, how you land after you get bumped in the air, they don't necessarily guarantee an injury, but they do set you up for either risk or success. So some of these injuries are bound to happen no matter what. But if you get really, really good at single leg movement and exercise and body control, I believe you can prevent some of these avoidable injuries, like an ACL that are non-contact injuries.

And even the current research shows for people who are returning to sport after ACL reconstruction suggests that if you can get 90% or greater on strength symmetry tests, single leg hop tests, range of motion tests for symmetry, single leg squat tests, your risk for reinjury is significantly less. And off the top of my head, I think it's between three to six times less likely to reinjure.

Melanie Cole (Host): Well, you just got to my next question, but the second part of that then is how is return to play determined after the fact?

Justin Kirk: I think the biggest kicker is how good they are with strength symmetry. So Biodex is the gold standard there, but some functional tests are the hop test, strength symmetry test on knee extension for the quads and the hamstrings as well if you have access to that. Range of motions, single leg squats, there's the Y balance test, and then just overall movement quality and confidence in the knee. Because in theory, you could have all these strength scores and perform well, but if you're still fearful and avoidant of certain activities and you're just not psychologically ready, then I believe that's just as important as the physical readiness.

Melanie Cole (Host): I agree. And so as you're giving us some recommendations for providers, for coaches, when working with athletes that are at high risk, how do you address after injury scarring if someone did have a reconstruction, if they did go through surgery and now they're getting ready to return to play, but range of motion is now decreased? Tell us a little bit about working with these athletes and what's involved.

Justin Kirk: So unfortunately, when the body heals, it lays down scar tissue, it doesn't lay down native normal tissue, whatever that is, which is a good thing because it helps us to heal, but it's just not as good as the real thing, whereas the ACL graft has shown to be sometimes stronger than the native ACL. You do just get this scar tissue that builds to try to stabilize the joint and help you heal. But you really have to be early and aggressive with that scar tissue management, with range of motion. Stereotypically, the years past, they would cast you after an ACL or put you on bedrest, and tell you to not move the knee all. Now, most of the time, we're seeing these patients day one post-op and immediately getting them to bend their knee, much to their surprise.

Melanie Cole (Host): See, that's what I find most exciting about what you're doing. As we wrap up, that's one of the changes right there that you mentioned, is that we get the athletes right up postsurgery. Back in the day, it's kind of like when someone would have a cardiac event and lay in bed for weeks and weeks, and now we get them right up. So I'd like you to wrap up with your best advice about prevention of ACL and changes that you've seen in management of these tears over the past five years, what you find most exciting.

Justin Kirk: I think the best tips to prevent ACL injuries are thinking about things from biomechanics and neuromuscular function. How much can you move? How strong are you? How do you move? What's the movement quality? How do you land and absorb force? Because that's all the body's trying to do, is it's you versus gravity. How do you land? How do you absorb force? Is gravity dominating you or can you withstand the forces of gravity and momentum? So hamstrings, hip rotators, ankles, glutes, quads, all of these things we really need to be up to full speed to counter the demands of side to side rotation and front to back motions in sport, all about global movement sharing.

And I think one of the things you mentioned, what's been changed in the past five years or so, looking at former return-to-play guidelines, it was around six months and now it's around nine months, and that's just what it takes to regain that strength and focus on the ankles, the hip rotators, the hamstrings, the quads, and just get everyone up to speed.

And with that in mind, they've kind of shifted where we might be going in the future, is they used to use the patellar ligament graft for the bone tendon bone anchor, because it could heal and be ready by six months. But now, if we're not returning people at six months, the emerging graft is actually the quad tendon graft. And Dr. Momaya here at UAB has been doing these and have been seeing a lot of his patients who have that. And it seems to be getting a really nice stable knee without that residual anterior knee pain that a lot of people talk about as one of the most prominent sequela of an ACL reconstruction. So I think I'm really hopeful for that. And I think that's only a glimmer or a glimpse into the future of what could we could potentially expect as more technology emerges and more data comes out.

Melanie Cole (Host): That's cool. Very excellent podcast, Justin. Great information for coaches and primary care providers that are working with these athletes and hoping to prevent these types of injuries. Thank you so much for joining us today. And a physician can refer a patient to UAB Medicine by calling the MIST line at 1-800-UAB-MIST or by visiting our website at uabmedicine.org/physician. That concludes this episode of UAB MedCast. I'm Melanie Cole.