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In this episode, Associate Professor at the University of the Sciences and Director of BTE Laboratory, David Logerstedt, talks about monitoring and responding to load injuries on the knee.
Today, David talks about the most common loading injuries on the knee, difference between external and internal loads, and how to improve tissue capacity. What is mechanical loading?
Hear about David’s most recent research paper on mechanical loading and the knee, how therapists can monitor and respond to loads, how clinicians can apply the information in the paper, and get David’s advice to his younger self, all on today’s episode of The Healthy, Wealthy & Smart Podcast.
- “A lot of the stresses that cause the injury also are some of the same stresses that you can use to rehabilitate the injury.”
- “Most of us have enough tissue capacity to walk, but we might not have the tissue capacity to run a 10k.”
- “You really are trained to look at how the joint is reacting to the loads that you’re placing on it. Measuring irritability is probably the best way to describe it.”
- “Even just asking how they feel can give a lot of information.”
- “If people understand the ‘why’, then maybe they’re more likely to do it and follow through.”
- “Don’t say no. Always say yes to opportunities. Especially in that early career, if an opportunity comes along, take it.”
More about David Logerstedt
David Logerstedt, PT, MPT, PhD is tenured Associate Professor at University of the Sciences and Director of BTE laboratory. He graduated with a Bachelor of Science degree in health and human performance from the University of Montana and a Master of Arts degree in exercise physiology from the University of North Carolina. He earned a master’s degree in physical therapy from East Carolina University and a doctorate in the interdisciplinary program of biomechanics and movement science from the University of Delaware.
Dr. Logerstedt has been a practicing rehabilitation specialist for over 25 years and is board certified in sports physical therapy. He has presented his research on knee disorders at national and international conferences and has published in high-impact sports medicine journals on ACL injuries. He has co-authored several clinical practice guidelines on knee disorders.
His goal to improve the implementation of clinical research into practical and accessible for all clinicians.
Healthy, Wealthy, Smart, Knee Injuries, Loading Injuries, Tissue Capacity, Stress, Research, Rehabilitation, Recovery, Physiotherapy
Effects of and Response to Mechanical Loading on the Knee
To learn more, follow David at:
Website: David Logerstedt’s Bibliography
LinkedIn: David Logerstedt
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Read the full transcript here:
Welcome to the healthy, wealthy and smart podcast. Each week we interview the best and brightest in physical therapy, wellness and entrepreneurship. We give you cutting edge information you need to live your best life healthy, wealthy and smart. The information in this podcast is for entertainment purposes only and should not be used as personalized medical advice. And now, here’s your host, Dr. Karen Litzy.
Hey everybody, welcome back to the podcast. I am your host Karen Litzy. And today’s episode is brought to you by Net Health so when it comes to boosting your clinics, online visibility, reputation and increasing referrals, net Health’s Digital Marketing Solutions has the tools you need to beat the competition. They know you want your clinic to get found get chosen, and definitely get those five star reviews on Google. They have a fun new offer if you sign up and complete a marketing audit to learn how digital marketing solutions can help your clinic when they will buy lunch for your office. If you’re already using Net Health private practice EMR, be sure to ask about his new integration, head over to net health.com forward slash li tz why to sign up for your complimentary marketing audit. And it’s great, I use it and it works. So I highly recommend it. Now onto today’s episode. So I’m really really happy to have Dr. David lager stead on the episode today. And we are talking about monitoring and responding to load injuries on the knee. So Dr. Lager stat is a tenured associate professor at the University of sciences and director of the BT EE Laboratory. He graduated with a Bachelor of Science degree in Health and Human Performance from the University of Montana and a Master of Arts degree in exercise physiology. from the University of North Carolina. He earned a master’s degree in physical therapy from East Carolina University and a doctorate in the interdisciplinary program of biomechanics and Movement Science from the University of Delaware. He has been a practicing rehabilitation specialist for over 25 years he is board certified in Sports Physical Therapy. He has presented his research on knee disorders at national international conferences and has published in high impact sports medicine journals on ACL injuries. He co authored several clinical practice guidelines on knee disorders. His goal is to improve the implementation of clinical research into practical and accessible, make it practical and accessible for all clinicians. So yeah, so today we’re talking about a new paper, that he co authored the effects, the effects of em response to mechanical loading of the knee to great paper, you can go to podcast at healthy, wealthy, smart calm, to find a link to the paper. And a big thanks to Dr. Lager stead for breaking it down for us and everyone enjoyed today’s episode. Hey, David, welcome to the podcast. I’m happy to have you on.
Thank you for having me. Yeah, and I’m excited. Today we’re going to talk about a new paper that your co author on that came out on to be very precise, October 20, of 2021. And it’s the effects of response to mechanical loading on the knee. So of course, my first question, I’m sure this is the first question everyone asked you is, why write this paper? What is the why behind it? You know, as a, as a clinician, as well, as somebody who is now in academia, I’ve always kind of had this question myself, you know, what kind of loads are on the knee? And I’ve always had this, you know, concern about dosing and trying to figure out like, how can we can best dose exercise around the knee. And as I, as I really started to think about this more, really started to find that there hasn’t been any review, or any kind of clinical commentary kind of brings at least the concept of mechanical loading, kind of in one place. And the knee is always a good model, because it does seem to have a lot of a lot of research around it. And it’s an area I’m familiar with, because of my work in ACLs. And so I, we, you know, we just started, started thinking about, okay, how can we best talk about what kind of loads are being placed on the knee and, and some of it kind of kind of came out of some conversations I had with another colleague of mine, where we’ve really started to talk about the use of inertial measurement units and how those can start to give at least some general indications of what loads are occurring through the lower extremity. And so we decided to just kind of put a team together
who had expertise in in loading? And then expertise in specific structures related to the knee? And so that’s kind of how it kind of came together. And when we’re talking about loading of the knee, so in this, in this paper, you’re talking about mechanical loading. So let’s, let’s go with some more definitions here. So what is mechanical loading? And why is it important in respect to the knee will stick to the knee? Yeah. So, you know, in the paper, we really describe mechanical loading, this is the physical forces that act on are free to make demand on the body, either at the system’s level, or even on structures at a specific organ or tissue level. And so if you think about mechanical loading can kind of subdivided into different variables, such as, like the magnitude of the load, how long the load is being applied, how frequent it might be applied, or even maybe the direction or the nature of that load. So
so when we think about loading, though, all those components kind of interact, can interact with one another, and then create different loading patterns that can impact again, the knee is the organ itself, or specific structures within the knee. And when we’re talking about loading, I think most people think of loads as external, so something that we are placing on that knee, but there are external loads in their internal loads. Can you kind of differentiate those for the listeners? And how, and why are both important? Yeah. So when we think about, you know, external loads, to kind of think about is like, really kind of that work that’s being performed? So like, how far did I run today? Or how high did I jump? So when we think about like, like that, it’s almost, it’s almost kind of like that outcome in, in an essence when we think about external load. But when we think about internal load, you can either think about what what’s the physiological process that’s going on inside the body related, potentially related to the external load, or maybe even the psychological. And again, maybe even that biomechanical response to that external load? So So usually, when we think about internal load, it’s like, you know, how what, you know, what is your heart rate doing related to how far you run? Or what is the extra? Or what’s the amount of stress that’s being placed on the knee after you land from a jump? Yeah, so so both are important, especially when it comes to knee injuries, and loading injuries. So let’s talk about what are some of the common loading injuries on the knee?
Yeah, so if you think about some of those different types of loads, you can kind of really subdividing at least at Deneen to kind of three major categories. In essence, whether it’s a compressive load, a shear load, or a, you know, a tensile load that occurs, there’s some other loads that can occur, such as some hydrostatic pressure loads, but the primary ones are really related to that. And so then if you break that down into specific structures, such as a ligament, you know, like the ACL, which is one of the more common injuries that occurred the knee, you know, that’s usually related to some kind of tensile load that’s occurring on that ligament, it can occur either from, you know, cyclical loading, where you can continue to put stress on that ligament until that ligament ultimately fails. But usually, it’s one usually large load that occurs that relates in, you know, a traumatic tear. That’s probably an example of kind of one of the more common ones. But, you know, we, you know, we commonly see other tissues damaged, you know, the meniscus is another common injury. And that’s usually again, that’s really related more to some compressive with shear load. And then, you know, cartilage also kind of was kind of relies on
a shear load to be damaged. So
all those different loads occur on the knee, it just sometimes it depends on again, all those other variables that we’ve talked about, you know, the nature of it, or the compressive versus the shear versus the tensile load, but then again, how quickly does it occur? Maybe at what angle your knee is bent that can impact all those types of things? Yeah, I would think angles, speed, fatigue levels, hydration levels, you know,
All of that I can only imagine goes into
a type of injury from one of these loads, right? And you say, you know, and if think about, you know, again, you have that that external load, but then, you know, think about some of the other internal loads, you know, the muscles around the joint contracting, to maybe unload the knee at a specific time, because, you know, we have, you know, you’ve seen many athletes like they cut and pivot 1000s of times in a career, why is it that one certain time, they do the exact same maneuver, they’ve done 1000 times before, their ligament tears or their meniscus tears. So there’s, there’s so many other underlying factors that lead to it.
And so part of this papers, at least trying to describe some of those things, so people have an understanding of what is the underlying loads that can can lead to an injury. But then,
what can we do after that? How can we use those exact same parameters of same loading parameters to rehabilitate them? Because the same, a lot of the same stresses that caused the injury
also are some of the same stresses that you can use to rehabilitate the injury? Right, and I would think have to use to rehabilitate the injury. Right? Right. Yeah. So so they, so they can adapt to that stress and be ready to handle the stress the next time it occurs. Exactly, exactly. And now what one of the figures we were talking before we went on the air within this paper is figure four. So for everyone who is listening to this, we’ll leave a link to the paper in the show notes. But when you go through, you’ll see there’s one figure it’s figure four, it’s a conceptual model of loading of the knee. And it’s like a monster of a figure like it is. It’s large, it looks very intimidating, and very complicated. So can you break it down for us? Yeah. So this is how, you know, we started to think about taking a lot of these other models that have been out there that have described, you know, maybe the physical stress model, or many people have commented on the,
on the die model, related to the envelope of function, and also the dynamic recursive model related to injury, probably the, is the best one, best way to describe it. But you got to take into all those factors that can influence or just leave somebody susceptible to an injury,
as well as including this their underlying physiology. And again, that could just be related to those non modifiable factors such as your age and your sex.
And then again, your underlying physiology, you know, your genetic makeup, maybe even just some kind of a little bit of your underlying fitness level. And then what are some things that can predispose that tissue to injury? And again, it could be, you know, do you have a strong tissue or a weaker tissue? Does the, you know, do you have certain types of muscle fibers, you know, that can influence again, things like fatigue? And then what are the external factors that lead into it? So, some of these models have already been kind of described in the ACL related literature, you know, you know, shoot a surface interactions, whether that occurs out there is, is it turf versus grass. So, those types of things can all potentially influence an injury and then,
you know, moving into the next part, then you just think about the mechanical load. So, again, all those factors related to magnitude and duration and frequency. And then we wanted to kind of
try to articulate that, again, if you took, you know, just conceptually took it is looking at each of the different major structures in the knee that could be impacted, and then talked about how those tissues respond to some kind of stress and strain. So, you know, if you put it,
again that load under a specific type of compressive versus shear strain, how does it respond to that, and William Thompson did a really nice review in ptJ a couple of years ago, looking at some of the Meccano therapy and McKinna biology that occurs at specific
tissues that Karim Khan had kind of initially proposed back, God 10 years ago or so. And then if you take all those things account, and the stresses and strains, so then you start to look at how that impacts how the tissue adapts to those stresses and strains. And, you know, using kind of the fitness model, or the fitness fatigue model is, is if you apply the right stresses at the right time. And you do that consistently over time, it basically builds up into tissues adapt to it, and it gets stronger, and fitter. But if you don’t do it, or you do it at a delayed time, it may stay at a homeostatic level, or than if you do it too infrequently, or the loads are too much, too frequent, then you can actually fatigue the tissues. And, of course, if you get too much fatigue, and you get the right amount of load placed on it, then that can result in injury. And then you kind of go through, go through again, and go through it again. And again, that’s part of the rehab process is taking all those things into account. And so
that’s how we tried to really try to conceptualize it and think about, you know, and so we really kind of focused more on the the tissue levels and the response to injury, and how you can use that kind of this conceptual model of kind of stress and strain along those other factors, too. I think it’s important to note that we’re not only talking about ligaments or meniscus when we’re talking about the tissues around the knee, ligaments, meniscus tendon, articular, cartilage bone. It’s not just, we’re not just talking about ACL 10. Lien, you know what I mean? There’s, it’s really the all the structures that that make up that knee joint, correct? Correct. Yeah. And, I mean, I think that’s even a really important point to like, when we’re rehabbing. You know, somebody and you know, you take somebody with a meniscus tear, not only are you impacting the meniscus that you’re working on, you’re also impacting a lot of the other structures around it. And so you can influence the all that rehab, or that rehab impacts all those tissues, depending on how you’re providing the specific load. Right? Absolutely. And, you know, one of the the words that’s in that figure is tissue capacity. And so during the rehab process, certainly after injury, but even, let’s say, without injury, right, I think one of the goals is to always improve tissue capacity. So can you kind of talk about what exactly that means? What that What does tissue capacity mean and as physical therapists, what where do we stand in the improvement of that capacity. And on that note, we’ll take a quick break to hear from our sponsor and be right back.
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Kind of an in a general layman’s term, you think about just tissue capacities, it’s all related to the under I think sometimes so the underlying tasks that’s being performed, right, you can have a certain level of tissue capacity that allows you to, to walk or run the tissue can meet the demands of that load placed on placed on the body by that specific task. Right. But if the task is too high, or the load is too high, relative to what the tissue can handle the tissue than this doesn’t have the capacity to handle that load. And again, it may be able to handle that load one or two times. But over a repeated bout, it may fail much quicker. And so I think sometimes tissue capacity is it’s also related to the task that’s being performed. may know most of us have enough tissue capacity to to walk community levels and things like that. But you know, we might
not have the tissue capacity to run a 10k, even though that we may have the underlying structure that we could build up to that, I think those are the things you have to take into account. And from a rehab perspective, you know, you always have to think about kind of that starting point of what people can handle, and then how, how you can adjust the rehab process to improve that capacity over time. So that that leads into what are some ways we can monitor load and respond to that load? So we’re the therapist, we’re taking care of our patients, how can we monitor and and, and change that load as necessary? Yeah, so.
So from, you know, a clinician standpoint, you know, most of us probably in the clinic, you know, we don’t have high tech equipment, like global GPS units are inertial measurement units to measure
you know, how far people have gone
a certain amount of distances they walked or jogged or done the whole thing, like you have seen with some of the devices like catapult or, or
I measure use IMU units. But I think from a clinician standpoint, we still have a lot of great tools that I think are that we still under utilize, to some degree. So,
you know, I, I always like to tell my students
that you really are kind of training to look at how the joint is reacting to the, to the loads that you’re placing on it? And are you making the tissues more irritable or less, irritable, measuring irritability is probably the best way to describe it. And the knee, you know, you can see things like, you know, increase swelling, you know,
which is a common, probably a common measurement to see for, for increased irritability, but it can also be, you know, is the joint getting sore versus the muscle getting sore, right? And so trying to be very clear,
the person you’re working with is, you know, does it hurt inside the knee, or is it just hurt in the muscles around the knee, because we’d expect to see some muscle soreness if you’re working those, right, but you don’t want the, you know, the irritation to be in the knee. Um, so those are probably the two major major, major ones that I like to use. But
you can also look is, you know, do Did they have a sudden decrease in a range of motion, you know, which can be an impact, or, you know, a factor of them, having some irritability, has their strength gone down, which is probably a little bit harder to assess more consistently, but those are probably the major things I would consider looking at is, if you’re starting to see some of those means the tissues become a little bit more irritated. But if you don’t see those, then you know, the next, you know, maybe the next session, the next couple sessions, you can start to slowly increase the load a little bit, and see how they respond. And I think that’s always the challenging part. Like, I like to challenge my students with is, but that’s one of the great things about being a therapist, who is we get to see them again, and see how they respond to our treatments. And we can regress or progress them as needed. Yeah, and and I think that’s a really great thing that you said at the end, we can regress or progress as needed. So if someone if you give someone some exercise or some loading, and they come back with like an angry knee, it doesn’t mean stop everything and go back to passive range of motion. It means okay, let’s just take it down a notch. But continue. Yeah. Yeah. And I think when the the last one I meant should have mentioned is, you know, just even just ask them how they feel. Mm hmm. You know, how are you how do you how does it feel today can give a lot of information then you can use things like you know, a session RPE schedule, you know, scale, say, Okay, your knees a little bit angry. Let’s back, let’s back your exercise session down two or three today, instead of working at a seven. Mm hmm. So you can still do something still keep the knee moving. Still keep it kind of moving forward, but you’ve kind of backed off in gave it a little bit time to, to calm down. Yeah. So it’s, it’s sort of this combination of what you’re seeing objectively and then asking them how novel What a novel idea you’re doing or you’re having
Having trouble? Yeah. The other day you were doing stairs really well. And now you’re having trouble doing stairs, you know, some of these functional day to day things? Yeah, exactly. I mean, I think, like you said, those are just really simple tools, I think we, we get so focused on, you know, what we like to call the objective data, instead of just asking people, how do you feel today? Yeah.
Absolutely. And now, how can we and I say myself, we, I’m a clinician, how can how can we clinicians use the information in this paper to start applying load to a REIT to the rehabilitation of an injured knee? Or post surgical knee? Or what however you want to categorize? Yeah, yeah. I think, you know, as we were talking before, there’s a, there’s a, there’s a lot of data in this in this paper, too, that the clinicians can think canoes, and so I don’t want them to get overwhelmed with all the numbers in the data, but it’s really there to be is it as a resource for clinicians to say, Okay, I have somebody who has a pretty irritable knee, and these are the activities that we’re doing before, you know, and we can get a sense of, okay, that that activity, you know, was, you know, three times body weight, I need to find an activity, that’s maybe two times body weight.
So we can regress them a little bit. And this is an activity that kind of fits that or this was an activity that put this amount of stress on the ligament, we know that that stress is still within us safe range to, to push it a little bit to the next level.
Because, you know, I think some of the, some of the fear is, is that if we’re putting stress on the ligament that we’re going to injure it, or even on any tissue, right. But we, as we know that, especially after the initial inflammatory phase, you need to start putting a little bit of stress on the healing tissues, because that’s how tissue gets stronger is that it has to respond to stress. But if you’re putting, you know, if you’re putting state and I’ll put an air quotes, safe, safe stresses, or stresses that are below kind of the the below the failure rate, and you’re monitoring the knee for those inappropriate responses, then you can use that information to slowly progress them through a rehab safely and adequately the healing structure to then kind of into the next level of repair. The one of the tables, we talked about this, again, before we came on, was table seven, within this paper, where you have some activities where it’s like this is like you said, maybe it’s 1.4 times body weight, or this is 20 times body weight, or this is eight times body weight. And I think that’s a really nice guide for clinicians. But I think it’s also a really great educational tool for the patient. So you can show this too, because most patients get it. I think a lot of times we underestimate our patient’s ability to understand. Yeah, a lot of these concepts, you know, and and so I think if we can say the patient, hey, listen, this is X amount, your body weight, this activity is less than that. And let’s say you’re a month out of like some sort of surgical procedure, hey, let’s go with the one that’s less times body weight than this. And because people say, well, what’s the big deal? It seems like it would be fine. But I love that because I think it’s a great way for clinicians to use the paper also is a great educational opportunity. Yeah, no, no, I think that’s a that’s a really valid point, is it? I think if we can educate the patients on, you know, these are the activities that you should be doing right now. And as you strong, get stronger and get better than you can move into these activities the next time, right. And so they’re always asking, patients are always asking, like, what can I do now? What can I do now? And so, you know, this table can give them some insight of, okay, this is where you’re at. These are the things that you start doing now. And these are the things that probably wait a little bit longer. I think that the patient will really understand the why behind, you’re giving them the exercises that you’re giving them. Yep. And that’s really important, because if people understand the why then maybe they’re more likely to do it. Yeah. And follow through. Yep. So I mean, I think it’s great. I think this paper is great. Is there anything
thing that we didn’t touch upon in the paper, the process of doing this paper that you would like to share before we start to wrap things up, no, you know, I’d really like to, you know, first of all, thank my co authors who were willing to, to sit down and write this, it was, it was no small feat, you know, pulling together, clinicians from around the world to, to do this. And so, you know, definitely want to, you know, think tour MacLeod, Brian higher shyt, J uebert. Tim Gavitt and Brian eckenrode, for, for agreeing to do this, you know, this, like I said, this was a paper that had been mulling around in my head, probably since I was in PT school, you know, for a long time. And, you know, this just felt like the opportune time to pull it together. And fortunately, you know, in the last several years, last 20 years or so, we have, we have the data now to support a lot of the things that we do is physical therapist that I think intuitively, we’ve always done. But I think now that we can, we can demonstrate a lot of what we do, and some of the value that we bring to, to rehabilitation into to patients and to clients. Yeah, and and I mean, I like this paper from a rehab standpoint, but I think it’s also really great from a strength and conditioning standpoint, right? Because as physical therapists, we don’t have to just be the people there when the athlete or the person is injured, we can also be the person that helps to keep them strong and kind of improve, especially in I know, in a lot of professional settings. You’ve got strength and conditioning coaches, and athletic trainers and pts. But for the average physical therapist, like if you’re in a small town, maybe you’re it. Yeah, you’re doing it all. Yeah. So I think this paper is really helpful not only to progress, people after injury, but to kind of look and say, Hey, this is the load that we can place on you that will hopefully help to decrease your chances of getting injured. Yeah. So I appreciate that in this paper. And now, where can people find you? And like I said, we will have a link to the paper in the show notes. But where can people find you if they have questions of you specifically? Yeah, I’m fairly active on Twitter. And so that’s primary, my primary social media outlet so you can find me It’s Dave, log PT. You know, if there’s any questions or anything like that, that’s probably the best, best way to reach me is either directly through DMS, or, or through my Twitter feed. Perfect. And now before we wrap things up, I have one more question. And it’s a question I asked everyone is knowing where you are, in your life and in your career? What advice would you give to yourself? Let’s say as a new grad, right out of PT school, I would probably, I would say, at that early stage advice, actually was given to me before is don’t always don’t say no. Always say yes to opportunities, especially in that, that early career, that if an opportunity comes along, take it, it may or may not be the perfect opportunity. It may not be what you dreamed of, but it more likely or not, will
be the a value to you. And many times it’s a huge stepping stone. I would say you know, an opportunity comes along, say yes. Especially when you’re young. Yes, yes. Young and full of energy. I think that’s great advice. So listen, David, thank you so much for coming on the podcast breaking down this paper. It’s a great paper. So congratulations on that. So thank you for coming on. You. Thank You, anytime and everyone. Thanks so much for listening, have a great couple of days and stay healthy, wealthy and smart. And a big thank you to Dr. David lager stat for coming on the program and talking all about load parameters around the knee joint and of course, a big thank you to Net Health. So again, their digital digital marketing solutions can help your clinic win by allowing you to get found get chosen and get those five star reviews on Google. They have a new offer if you sign up and complete a marketing on it to learn how digital marketing solutions can up your clinic when they’ll buy lunch for your office. Head over to net help.com forward slash li T zy to sign up for your complimentary marketing audit today.
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