Amanda Wilde (Host): When they're working, we hardly think about our knees. Our knee joints are in constant use, keeping us mobile and bearing the weight of our bodies. So, injuries to the knee joint are not unusual. Nearly half of all knee injuries are related to the anterior cruciate ligament or more commonly known ACL. Today, we'll look at how to understand and treat ACL injuries and strategies for prevention. My guest is Dr. Robert Corey, Orthopedic Sports Medicine surgeon at Guthrie Clinic.

This is Medical Minds: Conversations with Guthrie Experts. I'm Amanda Wilde. Welcome, Dr. Corey. Thank you so much for being here.

Dr. Robert Corey: Thanks so much for having me. I really appreciate you taking the time, and I look forward to discussing all about the anterior cruciate ligament with you today.

Host: Let's start with the basics. What exactly is an ACL injury? I mean, is it a stretch, is it a tear of a ligament? Or neither of the above?

Dr. Robert Corey: I'll start with the basics. What is the ACL? For a lot of times, people who follow sports and people who have been through life, so to speak, know someone that has torn their ACL and we hear the term ACL thrown around a lot, but we don't actually know what that stands for. And as you very well mentioned, it stands for anterior cruciate ligament. What that is, it is a ligament inside of our knee joint that connects the femur, which is the thigh bone, to the tibia, which is the shin bone. We have two of those inside of our knee. There's an anterior, which means in front, and there's a posterior, which means behind the knee, and they cross. So, anterior because it's in front, cruciate because it crosses, and ligament because it connects bone to bone. That's really what that stands for. We shorten it quite a bit in sports talk, but that's what it means. And it has several functions. Inside the knee specifically, the ACL functions to make our knees stable, rotational stability.

The main function of the ACL has very little with normal activities of daily living. So, for those of us that aren't athletes, who are getting older and may not run, jump, pivot, shift, you know, those type of activities, you don't need an ACL for most activities of daily living, which includes walking, going to work, driving your car. Even going to the gym and working out, you can have a tear in your ACL, or you can be ACL deficient, but you really need that ligament. It provides stability of the knee and the ability to kind of pivot and shift, change your momentum very quickly.

Host: So, you're saying we don't typically need it for daily activities, and yet it is the source of nearly half of all knee injuries. How do ACL injuries typically occur?

Dr. Robert Corey: Most of the time, these are traumatic injuries. It's very uncommon, exceedingly uncommon, for someone to tear their ACL and not know about it. So, the vast majority of these injuries happen in sporting events or changing direction, cutting, pivoting, shifting type of activities.

There can be contact injuries to the knee, which we occasionally see. But actually, these injuries tend to be more non-contact than contact. So if you follow sports and your favorite athletes shifts or plants their leg to change direction very quickly, oftentimes you can see their knee buckle. Now, what that looks like is oftentimes these athletes will drop right to the ground. Almost always, when people tear their ACL, they hear the dreaded "pop." They'll say, "I went to change direction and I heard a pop in my knee." And then, they immediately have swelling in their knee, it's tough for them to walk, not always. But I'd say about 70-80% of the time, patients say, "I knew I injured something because I heard a pop in my knee, and then my knee swelled up like a balloon."

Host: Yeah, it's like a sickening sound and you just know something went dreadfully wrong. It sounds like it's coming a lot then from twisting and pivoting, and you say these ACL injuries are particularly common among athletes. Are there sports where you see the highest incidence of these kind of injuries?

Dr. Robert Corey: There are several risk factors, which we can change and risk factors which we can't change. And we can certainly talk about that later. But from a sports perspective, I'll see a lot in soccer, football, basketball, those type of sports where you're changing direction quickly. There is a little bit incidents or a little bit of a higher risk factor in females, particularly adolescent females than males. Most of the time, these are our high school, these are our college athletes who are involved in some form of very competitive sporting activities that we see.

Host: So, you've described who might commonly get these ACL injuries, and you've also touched on common symptoms, the pop and the swelling. Are there any other symptoms that we should be aware of?

Dr. Robert Corey: Patients tell you what's wrong with them if you listen to them and in the rare events that there isn't a traumatic injury, where they may have been more chronic in nature or patients for whatever reason may have ignored it for several months. And then, the other thing, sometimes they'll come in and they'll say, "Hey, I injured my knee a year ago, but my knee's unstable," and truly they use the exact terms that are in the textbook, which is "My knee feels unstable. If I go to stop, it feels like my knee's buckling or giving out." And in more of the chronic case, that'll clue you right in.

Now, in terms of diagnosing it, it's fairly obvious on physical exam for someone that does Sports Medicine. And this is something that I do, you know, several times a day. But how you confirm when you suspect that the patient does have an ACL injury is you perform a physical exam. As I mentioned, they have swelling. The medical term for that is an effusion inside their knee. They'll oftentimes have limited motion.

But there's a couple of different tests. One of which is called a Lachman's exam where with the patient laying on the table, you see how much you can move the tibia, which is that shin bone in relation to the femur, which is the thigh bone. And when you have a strong, stable ligament in there, there's only a certain distance for which that bone should move. And unfortunately, when you don't have an ACL, because there isn't a restraint to that, it moves much further than it should. Now, the vast majority of times, as an Orthopedic Sports Medicine surgeon, I kind of know right off the bat what we're dealing with is an ACL. To confirm that, we do order what's called an MRI, which gives me the diagnostic imaging that I need to not only confirm that there is an ACL tear, but also to assess the status of any of the other ligaments and look at kind of some common associated injuries that we see with an ACL tear, such as a meniscus injury, which oftentimes can be seen in an ACL tear as well.

Host: So, you've identified several non-invasive techniques to confirm an ACL tear, but then what happens in terms of treatment? I think of that as very invasive, only because the people I've known that have had ACL issues almost inevitably have to get surgery. What are the treatment options that are available?

Dr. Robert Corey: You know, as I mentioned, when we first started talking, the function of the ACL for activities of daily living really is minimal, meaning oftentimes, older patients, patients who are less active can do reasonably well with a torn ACL that does not require surgery. If you're a little bit older, a little bit less active, if you enjoy going to the gym, working out, but aren't involved in cutting, pivoting, shifting activities, oftentimes we discuss non-operative management, which basically includes formal physical therapy. And while the ACL won't ever re-heal or regrow, you know, oftentimes older patients can do fairly well with physical therapy. And how that works is it can strengthen the surrounding muscles, tendons, ligaments of the knee. And in so doing, the stronger those muscles, tendons, and ligaments get, you can make up for a little bit of that ACL deficiency. So, it's not wrong in older patients to try physical therapy, and sort of see how they function. Unfortunately, in younger patients, and particularly athletes, that's when we start having a surgical conversation. So, sometimes physical therapy still is necessary prior to surgery. One of the things that the goal of physical therapy can do prior to surgery is to decrease the amount of swelling inside the knee, which can be a risk factor for some stiffness after surgery. But what a lot of physical therapy does for the first few weeks after the injury is to get the swelling out of the knee to restore full range of motion, if at all possible, and create sort of an optimal healing environment when we do have to go in surgically.

Host: So, can you walk us through the typical recovery process after surgery? What can patients expect in terms of timeline and milestones on that timeline?

Dr. Robert Corey: As I just mentioned, the ACL does not heal itself when it's torn. So, what we do is rather than repair the ACL, we have to do what's called an ACL reconstruction, which is building you a brand new ligament. There are a number of different options to build you a new ligament. There's both using your own tendon, which is called an autograft reconstruction. There's using cadaver tendon, which is called an allograft reconstruction and they both have their advantages and disadvantages, depending upon your age, your activity level.

But in terms of what the surgery entails, it's basically building a brand new ligament to connect the femur again, which is the thigh bone to the tibia, which is the shin bone. And how that's done is we place the ligament where it belongs and we put it inside of tunnels that are basically reamed throughout the bone and allow it to heal. Now, that is a same-day surgery. Generally speaking, it takes about two hours or so inside the operating room. You go home the same day, and there's quite a bit of rehab involved. You know, everyone thinks I always tell patients same-day surgery, not necessarily same-day recovery. Even though the surgery takes us a couple hours, it can be nine months to a year for a full recovery.

Host: So, physical therapy can be positive when it's done as a monotherapy. It's absolutely crucial for a good long-term outcome when you've done surgery. Now, how do you decide the best course of action for each patient?

Dr. Robert Corey: The vast majority of these injuries are treated with surgery, particularly in the younger patient population. Not only does the ACL function from a stability standpoint of the knee, which I had mentioned previously, but there's some secondary function as well, meaning there's a very high incidence of other associated problems of the knee when someone tears their ACL. So, they don't always occur in isolation. And by that, I mean, oftentimes patients can tear their meniscus. They can damage the cartilage inside their knee. So, the goal of performing an ACL reconstruction in a younger patient is primarily to give them a stable knee. But equally as important, it's to prevent any secondary injury that may occur as a result of being ACL deficient.

And by that, I mean, younger patients that are walking around without an ACL, you can damage your meniscus, which are those shock absorbers between the two bones. You can damage your cartilage. So, not only are we trying to give patients a stable knee, but to prevent any meniscal injuries or arthritic changes later on in life. So, most of the time in young patients and young athletes, we almost always treat them surgically. Again, not just to give them a new ligament to prevent further injuries, which may be a result of being ACL deficient or not having that ligament work properly.

Host: It makes sense. And how long do the results of the surgery last?

Dr. Robert Corey: It's a very long rehab. Reconstructing that ligament it generally takes about three months for that ligament to heal inside the two bones to your body. So, the first several weeks of physical therapy are primarily aimed at simply restoring your gait, your ability to walk, most of the time patients are walking within a week. There may or may not be a brace involved depending upon if there were other injuries, but you are able to place weight and walk about a week after surgery. Physical therapy will help get that swelling and that fluid out of your knee, and you start kind of slowly training your muscles. We wait for sort of three months before we really start targeting your muscles within more endurance training and strength training, because we try not to overload that ligament for the first three months. A full recovery is about six to nine months, meaning most people for simply walking around, for going to work, for going to school or feeling better much sooner. But in terms of returning to sports, oftentimes it can take nine months to a year for athletes to get back to running and jumping and those types of things.

Host: That is a very good overview of what is involved in recovery. Now, moving to prevention, is there such a thing as preventing injuries to the ACL?

Dr. Robert Corey: Yeah. That's probably the million-dollar question, which so many people have been working on throughout the field of Orthopedics. Now with every type of injury, there's always certain risk factors, some of which are modifiable and some are non-modifiable, meaning you can't prevent bad luck from happening. Sometimes it's just a result of playing sports or, unfortunately, putting your body in certain situations. But over the last several years, we've looked at what we can do to prevent these from happening. And a lot of that has to do with being physically and mentally optimized for sports or for these activities. And by that, I mean, so much of the rehab after surgery is focused on the surrounding muscles, tendons, and ligaments. And what we found is if you can optimize your strength with certain plyometric activities, with certain strengthening, they've been shown to decrease the likelihood of you tearing your ACL. So, athletes who are involved in a lot of jumping if you train your body with certain types of plyometrics to land in certain positions to offload the ACL, those have been shown to be very beneficial.

The other thing is listening to your body and how much fatigue you have in your body. Oftentimes, these injuries, as I mentioned earlier, are non-contact injuries. So, generally speaking, you know, they don't tend to happen at the beginning of practice when you've got all your strength and your endurance. Oftentimes, they're seen more towards the end of practice or the end of a long day of training where you're pushing your body for that one extra rep, that one extra set, that one extra route you're trying to run, and your muscles are fatigued. And as a result of that, you change your technique. And then, in so doing, unfortunately, injure yourself. So, again, that's the importance of off-season training and building up your muscles to the best of your ability.

Host: Yeah. Always be prepared for how you're going to use your muscles and ligaments. That's a really effective strategy that you can incorporate into your daily routine. Now, in your career, have you seen any notable advancements in the treatment and prevention of ACL injuries?

Dr. Robert Corey: Yes. So, over time, our techniques for this surgery have improved drastically. Years ago, we used to do these operations through much bigger incisions. The rehab was longer, the re-tear risk or the risk of re-injury was much higher. But the advantage of modern medicine is every few years, new techniques and new things come out which not only solidify the surgery itself, but make our outcomes better.

Nowadays, the way we're fixing these grafts inside the bone are much stronger than they used to be. We've done extensive research on the importance of physical therapy and the proper exercises you should be doing, not only to prevent these injuries from reoccurring, but to give patients the best optimum. So, you know, every few years, there's something that comes out, not only from implant standpoint, but the fixation and the healing rates are so much better than they used to be. And we've also developed techniques to do these through even smaller incisions over the years as well.

Host: So, we can probably expect those techniques to continue to improve.

Dr. Robert Corey: Absolutely. Yeah. There is there's so much great work being done around the country, people studying these. It's exponential, the amount of progress we've made over the last several years in truly understanding the ACL.

Host: Now, is it true there's a lot of misinformation out there about ACL injuries?

Dr. Robert Corey: I think there's all sorts of great information out there on the internet. Some common misconceptions that I hear are the ACL can heal itself. Once it's torn, unfortunately, it cannot, and we can spend a lot of time on why that is, but ligaments inside the knee joint don't heal themselves. There are ligaments that can be outside of the knee joint that can heal themselves and be stable. But unfortunately, the inside environment of the knee when something's torn, it doesn't heal. So, that's one thing I hear.

I think the other thing is oftentimes patients will come to me and they want an accelerated rehab program. They say, "Hey, you know, my son or daughter, they are basketball or football seasons in six months, and we need to be able to get back in six months. We can't wait the nine months. Is this rehab?" And the number one risk factor for re-tearing is making sure your strength has fully returned. So, there really isn't ways to cut corners in the rehab to get you back without increasing your risk for re-injury. So, I always try to tell patients my job as a surgeon is to get you back to 100% when I safely can.

Host: Well, it is hard to be patient in such a long recovery. Do you have any advice that you would give someone who's just been diagnosed with ACL injury and is feeling overwhelmed about the recovery process?

Dr. Robert Corey: What I always tell patients, it's, "Nice to meet you. I wish I met you under better circumstances," meaning nobody comes to me because they're doing great. This is a conversation I have several times a day and one that I've had several times this morning.

Tearing your ACL is certainly not the end of the world. It is a bump in the road. And you will be back and you will be doing the things that you enjoyed. It is a minor setback in what's coming up on, as I mentioned, sometimes up to a year recovery. So, when I talk to patients and I tell them this, and I lay out the treatment plan and what we need to do to optimize their outcomes. There's obviously a lot of anxiety, there's obviously a lot of nerves. And everyone can take that differently. But, in today's day and age, everybody knows somebody that's had an ACL tear. And, you know, the great thing about my profession is I get to see people several times a day, not only with new ACL tears, but who are a year out and who are back playing sports and doing things. So, the great thing about so many of my patients is they volunteer themselves to be resources. They volunteer themselves to talk to other patients. I had a high school girl in here recently who was a year out who's back playing soccer and she's doing great. And in the very next room, I had somebody I was delivering the message to that they're going to need to undergo the same surgery that they have. So, they oftentimes volunteer themselves. If you have patients with questions or concerns, what can I do to help? Because they remember where they were nine months or a year earlier. And they see the light at the end of the tunnel because they're there now and they've gone through it. And again, my patients are great resources, and they've done nothing but volunteer to help with new people that have injured themselves. So, talk to someone who's had it done.

Host: Yeah, that helps. It's really good when you're facing this to see the other side. Dr. Corey, thank you so much for sharing your expertise.

Dr. Robert Corey: Thanks so much for having me. I really appreciate it.

Host: Dr. Corey is Orthopedic Sports Medicine surgeon at Guthrie Clinic. For more information, visit guthrie.org/sportsmed. If you found this podcast helpful, please share it on your social media and be sure to check out our entire podcast library for other topics of interest to you. This is Medical Minds: Conversations with Guthrie Experts, a podcast from the Guthrie Clinic. Thanks for listening.