Well, hello everyone. Welcome to our next AAPMNR Pediatric Rehabilitation Virtual Lecture Series. We have a three-part series starting today. The following session will be on April the 1st, followed by April the 8th, led by Dr. James Carollo. He is the Director of the Center of Gait and Movement Analysis and Musculoskeletal Research Center at Jones Hospital of Colorado. I had an amazing opportunity to work with him with gait analysis reviews as a fellow at Jones Hospital of Colorado. I've really enjoyed his lectureship series on gait and looking through kinematics as well. I wanted to have this opportunity for all of us to have this platform to be able to walk through pediatric gait. I'm going to pass it over to Dr. Carollo. Thank you again. All right. Thank you, Dinesh, for giving me the opportunity to present to you all today. I'll just jump right into this. I can say that I've been at Children's Hospital Colorado for about 28 years and have had the great fortune of working with many skilled rehab medicine physicians, pediatric rehab medicine physicians over the years. This has grown out of our didactics at Children's and I'm happy to present it here. I would just start off about talking about, since we're talking about gait, I'd like to start off with just recognizing that we all understand the health benefits of exercise. Walking is really the simplest form of exercise. It's something everyone can do. It doesn't take any special equipment. In fact, for those individuals who have rehab, that will enter your clinic through rehab, walking is really essential, not just for mobility, but also for this exercise component. It can improve cardiovascular metabolic health. We know it also. There's evidence that shows that it can maintain cognitive ability. If you continue to walk and walk at a brisk pace, it's the health benefits are well-documented. In developing this, I came across this from the Harvard Health Publishing arm of Harvard Medical School and they had five other things that you often don't think about that are the surprising benefits of walking. I won't go into a lot of detail here. If you're interested, you can go and get this online. As you want. As you can see, the health benefits, they have identified that it counteracts the effects of weight-promoting genes. It helps tame a sweet tooth. This was a study that showed a 15-minute walk curve cravings for chocolate, which was, I thought, an interesting study just to have developed. It reduces the risk of developing breast cancer. There is some evidence of that. They have identified that women who walk seven or more hours a week had a 14% lower risk of breast cancer. It eases joint pain. I think we all have maybe that have had joint pain can comment about this because of this lubricating characteristics and the strengthening of muscles. It also has been identified to and associated with boosting immune function. On the other hand, losing mobility or having a mobility impairment has a significant cost. Patients with mobility disabilities suffer from increased morbidity and mortality. Mobility loss correlates with decreased activities of daily living scores. This is important not just for the individual, but for also the caretaker. It increases the caretaker burden, whether we're talking about adults, older adults who have the need for caretakers, or even our kids who have their parents or other caretakers involved in their care. Mobility loss is also negatively correlated with employment and annual income. It makes it more challenging for any family that has an individual with a mobility loss or mobility impairment. This study is from the National Healthcare Expenditure Survey and was published in Geriatric Nursing in about 2018. They went ahead and came up with a mobility limitation index, and they identified none, moderate, or severe. You can see from this chart that falls, healthcare utilization, and healthcare expenditures all increase as the mobility limitation increases. I would especially point out this healthcare expenditure increases. They're nearly double the healthcare expenditures in terms of per member per month healthcare expenditures and drug expenditures as you go from no mobility limitation to severe mobility limitation. There's plenty of evidence that supports the need and the importance of walking, but what I really think just encapsulates it all is this quote from Aftab Patla, a colleague that passed way too soon, but he characterized this, and I really appreciate this, especially all of us that think about mobility should think about this. Nothing epitomizes a level of independence in our perception of a good quality of life more than the ability to travel independently under our own power from one place to another. We celebrate the development of this ability in children and try to nurture and sustain it throughout the lifespan. I think this is a great mantra for any pediatric physiatrist working with kids who have mobility impairment to think about as the justification for why we do these things. This series of lectures is a didactic to try to help you understand how to do observational movement analysis, but also to understand the characteristics of normal gait and the instruments that are available to you to help understand gait in a better fashion. What we'll be working on in this is for the first two lectures is to provide an overview of Dr. Jacqueline Perry's eight gait phases and 13 critical events of normal gait. This is much, in many ways, this is the foundation for instrumented gait analysis, but in fact, she developed these for observational movement analysis. And as I'll describe through this, observational movement analysis and instrumented gait analysis go hand in hand and both are important in the development of understanding gait and understanding what interventions can be done to resolve gait impairments. I'll present some patient examples that illustrate gait pathology that result in critical events are altered or absent, just to try to drive home each of these critical events. And then I'll suggest options for treatment to restore critical events and subsequently improve walking ability. I'm not going to have a comprehensive description of how to solve all the gait problems or anything like that. It's really more to put it in the context of Dr. Perry's gait phases and 13 critical events that you can look for without any instrumented gait analysis, but gives you the roadmap for when you use instrumented gait analysis to help with that decision-making. So, any discussion of movement analysis really needs to start with Dr. Vern Inman, who is an orthopedist and professor of orthopedics at University of California in San Francisco. He had a long career that he summarized all of his work in movement analysis in this book. And if you're interested in clinical movement analysis, I would encourage you to see if you can find this book. It still is in print, but it's difficult to find. There's a lot of really foundational information in this book, and I found it very helpful when I started. But probably some of the highlights from here are he had identified that regardless of how impaired a movement might be, bipedal walking requires you to be able to support your body weight with each step and have an alternating basis support to move the center of gravity forward. But in moving that center of gravity forward, the linkage that is the legs below leads to an inherently cyclical and symmetric pattern. And that cyclical and symmetric pattern is repeated over and over and over again. And that is at the heart of how we analyze gait. We analyze it one cycle at a time. And so the gait cycle, many of you are, I'm sure, familiar with this. The gait cycle in terms of movement analysis begins with initial contact on the ipsilateral leg and ends with ipsilateral contact on the same leg. And that breaks up the gait cycle into zero to 100% of the gait cycle. And then at about 60% of the gait cycle, you also have another event that occurs, and that's foot off. We usually refer to that as foot off and then initial contact. So we have foot off rather than toe off and initial contact rather than heel contact because of the fact that in gait impairment, it may not always be the toe that comes off the floor or the heel that makes first contact. So it's going to be making and breaking contact with the floor with the ipsilateral leg. That's the basis for the gait cycle. Stance period then is defined as this period between initial contact and foot off of the ipsilateral leg. And swing period is then the remainder of the gait cycle until the cycle begins again when the foot is off the ground. And then if you go ahead and bring in the contralateral side, double limb support is the first approximately 10% of the gait cycle, and it ends when the opposite foot comes off the floor. So you have foot off on the contralateral side. Then single limb support is that entire period where there's only one foot in contact with the floor. And then it ends with a second double limb support period when the contralateral leg achieves initial contact. And then swing period obviously is the period of time when the foot is swinging forward to accept weight again. So this concept of the gait cycle was really reinforced with Dr. Inman's work. But there's another really interesting thing about his work, and I think it really helps understand some of how all of these activities and how everything that occurs during the gait cycle is controlled by the phasic activity of muscles. And he's well known for having commissioned these incredible drawings. And so in this particular case, he starts the gait cycle with, in this case, right foot initial contact. And then you can see the red color of a muscle that increases in intensity over the gait cycle or completely is absent. In this case, this is gluteus maximus, and you can see that gluteus maximus, based on the intensity of the color, the intensity of the color is proportional to the amount of EMG activity. And then you can see how that intensity of the color occurs. And this indicates that the gluteus maximus, as a hip extensor, stabilizes the hip during initial contact and then during loading response or weight acceptance task that occurs right after initial contact. And if I just go through, and we're not going to dwell on this timing here, but I just want you to appreciate the activity of the muscles as illustrated from his book and just understand conceptually what's going on. This is the gluteus medius, and you see it has a similar timing, although a bit longer prolonged during loading response. And then it kicks in again right before initial contact. The quadriceps, they have a long period of time. They start just before weight acceptance and then continue throughout the early parts of stance period. You'll notice that in this one, there is an additional amount of small activity that occurs right about right before foot off on the right side. That actually is not all the heads of the quadriceps, as that's referring to the rectus femoris, which is a two joint muscle, which actually operates to be able to provide hip flexion at pre-swing or at foot off to go ahead and drive that limb forward. The hamstrings, again, are firing. They fire earlier in swing period to decelerate the advancing limb and then fire in co-contraction with the knee extensors within the quadriceps group to be able to stabilize the knee during the time of weight acceptance. And then this last one is tibialis anterior, and it is showing, again, is firing just prior to weight acceptance and then continues through the beginning and acceptance of weight. But its dominant cycle is as a dorsiflexor as the foot comes off the ground to help with clearance. In contrast to that, notice that the calf muscle, in this case gastrocnemius and soleus, they are active out of phase from the tibialis anterior. And then the point of this is to show that while some of the muscles more proximally are seen to be co-contracting to provide stability, the tibialis anterior and the gastrocnemius and soleus fire out of phase and have different responsibilities. So when you look at all these together, you can see that when you put all these muscles on this, you can see that there's some very interesting things that come out. Inman was first to really point out that most muscles are active at the beginning and end of swing and stance period, even though that's the point of minimum angular displacement. But there's minimal muscle activity in mid-stance, mid-swing, despite these being the periods of maximum angular displacement. So you can see that muscles really are trying to constrain the momentum that's built up as you walk and that these characteristics sometimes are a bit counterintuitive. But obviously, if this is the case and this is what he found through fine wire electromyography and his experiments in this area to map the normal muscle timing, the principal action of muscle is to therefore is to accelerate or decelerate angular motions of the leg. There are several references that show normal EMG timing. This one is from Sutherland in 1984, and it's actually been republished in Chris Kirtley's book on clinical gait analysis theory and practice. But again, there are references for the normal muscle timing, and those references can be used, and we use those routinely when we're comparing the muscle activity that we see during instrumented gait analysis to the reference values for normal gait. So that's a bit of an introduction and an overview of the gait cycle and the importance of importance of having muscles and how muscles operate dynamically to produce the inherently efficient bipedal gait pattern that we call walking. So now to move on to Dr. Perry. So Dr. Perry was a physical therapist in the army during World War II. She attended medical school and completed the orthopedic residency program at UC San Francisco on the GI Bill after the war. She was identified as being the first woman orthopedic resident at University of California, and where she really developed these ideas was as a resident working under Dr. Inman, who infected her with the enthusiasm of doing clinical movement analysis. And then she proceeded to have a 60-year career at Rancho Las Amigas National Rehab Center in Downing, California, and during that period of time, that's when she developed the information that I'm presenting here. Now, to try to understand Dr. Perry's phases of gait, I like to go ahead and take that gait cycle that we just talked about and have that gait cycle wrapped around a unit circle. I'm trained as an engineer, so unit circles make sense, and it also inherently shows that the beginning and end of a cycle actually occur at the same point around the circle. So if you take a look at this and you put the events, initial contact, opposite foot off, opposite foot strike, and terminal contact or foot off, you put those temporal events around the unit circle, you can see that you have actually symmetry. This really points out the symmetry and that one leg is 180 degrees. In the ideal situation, it's 180 degrees out of phase from the ipsilateral leg. So the contralateral leg and ipsilateral leg are 180 degrees out of phase in the ideal or normal gait cycle. And so these are temporal events for making and breaking contact with the ground. They're wrapped around the unit circle, they identify in the unit circle initial contact and foot off. It shows that there's symmetry between sides. And then it also points out these time periods, the time between temporal events, a stance time, swing time, double support time, single support time, and step time. All of these can be measured and are routinely measured in an instrumented gait analysis, but you can also measure these in your clinic with less sophisticated technology to be able to go ahead and actually look for where symmetry breaks down. There's no reason and there's no particular requirement for there to be asymmetric. So if there is asymmetry present, it's usually an indication that there's something wrong, some impairment of gait. And the stance time, swing time, double support time, single support time, and step time, all can help you identify these asymmetric patterns, which give rise and give you notification of there being a gait impairment on the side that's asymmetric. Now the reason I wrap these around the unit circle is because it helps understand how Dr. Perry breaks up the gait cycle into eight phases of gait. And so in this particular case, you can see that this is just the temporal events that break up the gait cycle, making and breaking contact with the floor. But if you add three additional temporal events, heel-off, feet-adjacent, and tibia-vertical, and these are just approximate locations, they're not all equally spaced. But just recognize that the heel-off occurs during stance period and then feet-adjacent and tibia-vertical occur during swing period, you get the idea that you can use these to now break up the gait cycle even further. Heel-off is self-explanatory, is not always present. But in normal walking, heel-off is the delineation that you have in stance period. Feet-adjacent, think about looking at someone walking, looking directly from the side, and it's the point when the swinging limb passes and is at the same level as the stance limb. So that's what we consider. And that's looking perpendicular to the direction of progression. And then tibia-vertical is same, when you're looking at them from the side, the tibia is at the point where it's perfectly vertical or perpendicular to the ground. So those are the events that observationally are easier to see, and they allow you to be able to identify the beginning and end of each of these phases. So if you think about it in that regard, now I have each of these temporal events in the circles around the unit circle. But then in the time periods between those, those are the phases that Dr. Perry has identified. So the first phase, and so this also is going to include the three functional tasks that Dr. Perry has identified. So Dr. Perry took Dr. Inman's approach one step further and identified that there were really three functional tasks that have to occur during locomotion, and these phases of gait include those functional tasks. So for example, the start of this is initial contact. Now initial contact is both a temporal event, so the green dots identify where it is, and that's the task of weight acceptance. And initial contact is both a temporal event, but it's also a phase of gait. It's the only phase that has a short duration and is associated in this case with both a temporal event and a phase of gait. It's because having an initial contact and how the foot makes contact with the floor is especially important when you're doing observational movement analysis. So initial contact occurs first, and then the next temporal event is opposite foot off. And so the period, the phase of gait from initial contact temporal event to opposite foot off is called loading response. That's what she defined that, and it's called loading response because it's a functional task that's associated with weight acceptance, and the phase of gait is referred to as loading response. The next task is single limb support. The foot is now off the ground, and it gives rise to two phases during the single limb support period. The first phase is called mid stance. It continues until heel off occurs on the ipsilateral leg, and then that marks the delineation between mid stance and terminal stance, and then so those are the two phases that are associated with the single limb support task because the next temporal event that occurs is opposite foot strike, and at opposite foot strike that begins the task of swing limb advancement and is shown in the with the blue dots here. Swing limb advancement actually begins before the foot comes off the ground, and there are many important things that have to happen during this phase. This is equivalent to the second double support phase. Perry calls it pre swing because there are lots of things that are going on to be able to prepare the swinging limb for limb advancement, and so she has preferred to call that pre swing, and then that's followed when the foot comes off the ground. You now are in swing period, but it's considered initial swing until the feet are adjacent. Once the feet are adjacent, that marks the beginning of mid swing, and that continues until the tibia is identified as being vertical. Once you're at the tibia is vertical, that begins terminal swing, and that continues until initial contact occurs again, and in that particular case that's the point where swing period ends and the next stance period begins, and notice we're at the beginning of the units of the unit circle again, and so the cycle begins all over again. So just to reiterate this, I'm going to march through this linearly. We start with initial contact. We then also, that marks the beginning of the loading response phase in green. These are the phases of gait. Along the top are the temporal events that mark the beginning and end of each of these phases, and then at the bottom is the functional task, so from zero to 10 percent, you have initial contact and loading response and the task of weight acceptance. Once opposite foot off occurs, you are now in mid stance. It continues until heel off, which then begins terminal stance, and then you finally end with opposite initial contact, and that marks the end of the single limb support phase, which is the functional task that occurs. Then pre-swing begins. It ends with foot off. Initial swing ends with feet adjacent. Mid swing ends with tibia vertical, and terminal swing ends with initial contact, and all of that is the swing limb advancement phase. All right, so that is the overview of Perry's eight phases of gait, so the reason that we are meticulous in terms of identifying the beginning and end of these phases is it allows us to have a common language when we communicate when a particular gait abnormality is occurring, but it also allows us to go ahead, and it was necessary to understand Perry's 13 critical events, which I'll introduce now. So Perry's 13 critical events of normal gait, first of all, she called them critical events because the event must be performed during the appropriate functional task if normal walking is to occur. Missing critical events reflect specific gait impairments, and therefore, intervention should focus on restoring critical events. If you take this approach and look at gait abnormalities within the context of Perry's 13 critical events, I believe, and I think many believe that that gives you a framework for identifying the actual impairments and classifying those impairments in such a way that you can identify interventions to restore critical events, and therefore, overcome a mobility limitation by your intervention. And that's basically the approach that we take with both observational analysis and an instrumented gait analysis approach. So now I'm going to introduce, let's see, we're about halfway through, so I'm going to introduce some critical events in weight acceptance, and I think we'll probably try to take a couple of minutes before the top of the hour for a few questions, so I'll cut it off a little bit early, and then we can see if we can take some questions. So critical events in weight acceptance, the initial contact is our first, and we have, and so the first critical event is heel-first contact. It must be present to redirect and preserve momentum of forward progression and allows a smooth transition into stance period. So this is the importance of the heel-first initial contact. Then the other phase of gait that's associated with weight acceptance is loading response, and here we have three critical events. Controlled knee flexion, this is to provide shock absorption during this loading response phase and during the point in time in the gait cycle where you're transferring weight to the leading foot. It's provided by eccentric contraction of the quadriceps and also stability around the hip. So not only are you getting shock absorption around the knee, you're also getting stability and shock absorption around the hip, and this is a dynamic joint stiffness in sagittal and frontal plane to prevent unnecessary pelvic tilt. This is under the control of hip extensors or increased pelvic obliquity under the control of hip abductors during this change from a swinging leg to a stance supporting leg. The last critical event is controlled ankle plantar flexion or the heel rocker, and this prepares the new stance limb for weight transfer, and it allows for this plantar grade foot position as it develops during loading response. This is under controlled eccentric contraction of the dorsiflexors that pulls the tibia forward, stabilize the entire limb, and it has co-contraction with the quadriceps during this period of time. And as we saw from the muscle diagrams and the general overview of the muscle activity, at this point during loading response, you have lots of co-contraction for agonist and antagonist muscles around the joint to be able to smoothly control first the stability of the limb, but then also to lower the foot to the floor. So these are the first four of the 13 critical events. I want to say a little bit more about this first rocker or also known as the heel rocker because it's part of what is commonly referred to as the three rockers, the heel rocker, will come later in stance period. But the heel rocker is called the heel rocker or the first rocker. It's the same first, second, and third rockers. You also refer to the first rocker as the heel rocker because the axis of rotation is around the calcaneus. And again, the action is to lower the foot to the floor to achieve a plantar grade foot. The second rocker is now the foot is plantar grade, and as the center of gravity moves over the base of support, there is considerable motion and angular displacement associated with the tibia moving over the talus as the center of gravity moves forward. And so now the axis of rotation is right at the ankle as it's moving forward. And then finally, the forefoot rocker, the center of pressure moves forward to the metatarsal heads, and this is associated with the heel off position. But now the axis of rotation is at the metatarsal heads as the center of gravity continues to move over the base of support. So these are the three rockers. Heel is controlled ankle plantar flexion during weight acceptance, pivoting at the heel. It's eccentric, and there's power absorption going on in the tibialis anterior. The second rocker is controlled tibial advancement during single limb support. You're pivoting at the ankle. It's eccentric, and there's power absorption. Again, in this case, it's eccentric of the ankle plantar flexors. And then the forefoot rocker limits dorsiflexion and starts heel off during terminal stance and single limb support. You're pivoting at the MP joint. It's concentric, and there's large power generation. And we'll talk more about these power generators in a moment. All right. So to give you just a little bit of an example of this, first we're going to talk about the critical events. And right now we're talking about the critical events in weight acceptance. And what we want to show here is the absence of the heel first initial contact. And these are two toe-toe examples of toe-toe gait patterns, sometimes referred to as a toe-toe gait pattern because you're going from toe contact to toe contact on ipsilateral and contralateral side. So let's see if this will play. So this is a five-year-old child with spastic diplesia. And you can see that there's forefoot initial contact all the way through the gait cycle, consistent with this idea of it being a toe-toe gait pattern. Here's another child, five-year-old spastic diplesia, CP. I have to point out this is not the same child. They just happen to be having the same outfit, the same leg wrapping during a gait analysis. Aside from the fact that there's some slight technical differences in that we have streaming EMG signals for the subject on the right of your screen, you can see, too, how this one would be identified as a toe-toe gait pattern. So the question is, is this the same gait pattern? And if you say that it is the same gait pattern, I would suggest that you look a little closer at the knee joint. And if at this point, you may be able to see that there's greater knee flexion in the subject on the right. Even though these are both toe-toe gait patterns, the subject on the left is an example of a true Aquinas gait pattern, which is dominated by ankle plantar flexion throughout stance and swing period. That's what leads to a toe-toe gait pattern, despite having perhaps only a slight amount of disability at the knee where the knee flexion is a little bit greater than you would expect. The subject on the right, we consider this more an apparent Aquinas gait pattern. The apparent Aquinas, if you look closely, it's difficult to see, but most of the time it's given away by the knee joint. If you look at the knee joint, there's greater knee flexion bilaterally in knee flexion for the apparent Aquinas subject. The importance of that is that the ankle, while there might be a small amount of Aquinas on measurement and with instrumented gait analysis, you can identify that ankle is basically at a neutral position and that the toe-toe gait pattern is not happening because of Aquinas. It's happening because of lack of knee extension at terminal swing. Why is this so important? It's because it's been identified that if you go ahead and the typical surgical procedure that can come up as an option to deal with a toe-toe gait pattern that's because of true Aquinas is you can use Botox for a period of time, you can do serial casting for a period of time, but eventually if it's not correcting or not responding to that, the next step is to go ahead and consider a tendo Achilles lengthening or intramuscular lengthening. Both of those solutions can get you the foot down to a more plantar grade position and get rid of the toe-toe pattern, but the challenge is that if you do it to a apparent Aquinas individual and don't realize that the toe-toe pattern is occurring because of increased knee flexion, you could push that child into what's called a crouch gait deformity, which is a high-energy, low-efficiency gait pattern that can have significant consequences. In fact, Murray Goldstein from United Cerebral Palsy Research and Education Foundation feels and has made the statement many times that failure to recognize apparent Aquinas is the most common error in observational gait analysis and is more than academic importance. What he means is that it can have important consequences for the child or family. So that's a subtle difference that sometimes is not picked up and I guess the take-home message is all toe-toe gait patterns are not the same. Okay, this is just to reinforce some of the things I've already said, that true Aquinas displays toe-toe gait with forefoot initial contact. It's primarily due to excess ankle plantar flexion at initial contact and throughout stance period. And apparent Aquinas is a toe-toe gait pattern with forefoot initial contact, but it's attributed to increased knee and hip flexion with a neutral ankle. So I hope that that brings up the concept of true Aquinas versus apparent Aquinas because it's an important distinction to make. I should say that observationally, when you start looking for it, sometimes you can detect the knee flexion observationally, but this is a great example where instrumented gait analysis can really give you the numbers on the dynamic ankle dorsi plantar flexion throughout the gait cycle, and it's much easier to detect using instrumented gait analysis than it is observationally. But if you look and you get used to looking for it as a possible gait deviation, you can pick it up. All right, so that's heel first initial contact. Now let's look at loading response and controlled knee flexion. This is the second critical event, and this is associated with shock absorption provided by the eccentric contraction of the quadriceps. So this is absent controlled knee flexion in loading response. So one of the consequences of true Aquinas, and she's displaying true Aquinas on the right side. It's a young lady, six-year-old with spastic diplesia. So focus on that right side. Although it's present on both, it's a little bit more pronounced on the right side. And as this plays forward, you see the forefoot initial contact from true Aquinas has an impact not only on the ankle or the toe-toe pattern, but also, it's very pronounced right here. You can see with forefoot initial contact, there is no loading response peak. There's no shock absorption going on. She's actually going into knee extension, potentially knee hyperextension. And as that happens, it eliminates any shock absorption at the knee. So in this particular case, the critical event of controlled knee flexion during loading response is absent. And the driving force in this particular case, there could be spasticity in the quadriceps, or it could be any number of, but biomechanically, when you have a closed kinematic chain, the forefoot initial contact drives that knee backwards and eliminates the natural loading response. This illustrates the importance of having that heel-first initial contact because in the loading response phase that follows initial contact, the ramification is it impacts all the way up the kinematic chain. So the obvious intervention for this, if there is sufficient dorsiflexion range, is to use an ankle foot orthosis. And so, let's see if we have this. Yeah. So now, this is the same subject same subject walking through the laboratory now with a more neutral ankle. And you can see that while the loading response peak still may be a little bit attenuated, you can see that it might still be present. It's attenuated with the AFO. It's not moving into rapid knee extension, and there is a slight amount of knee flexion during movement analysis. Observationally, I think it does show up. It's not the dramatic push into full knee extension, but the best way to be able to see it is with instrumented gait analysis, where you're actually looking at the exact knee curve, and you can pick out that the AFO is helping to restore the critical event of controlled knee flexion during loading response. And it's driven by having a more natural foot strike and restoring some of the power that's necessary from a heel first initial contact. And you're probably saying, well, I don't really see that she has a heel first initial contact, that it may be more of a foot flat initial contact. The point is, is that because it's not forefoot initial contact, there's not as much driving force to push the knee back. Now, you'll notice that we want loading response, we want a loading response peak during weight acceptance and during the loading response phase of gait, but we want knee extension at terminal stance. So you don't want to completely eliminate the knee extension. You just want to push it further back in the gait cycle, and AFOs are a good way to try to achieve that. Okay. All right, so that's controlled knee flexion using shock absorption provided by the eccentric contraction of the quadriceps, and facilitated by removing the strong plantar flexion, knee extension couple, that's the name of when you have forefoot initial contact, that's what's driving the knee back, plantar flexion at the ankle, couples to knee extension. So we've shown that one, and now we have hip stability. So hip stability is referring to the dynamic joint stiffness and sagittal and frontal plane to prevent unnecessary pelvic tilt. That's under hip extensor eccentric contraction or increased pelvic obliquity, which is hip abduction and eccentric contraction. This is a 13-year-old of a spastic diplegic cerebral palsy, and as you're doing the observational analysis, everyone develops their own kind of pattern for how to conduct this. You can see that there is not a heel first initial contact, there's more forefoot initial contact. Again, there's a driving force to try to move the knee backwards. In this particular case, I want us to try to look at this in the coronal plane, and especially from the back. If you notice that there's a lateral, strong lateral trunk and head movement toward the right side. What we're thinking about now is the hip stability during this period of time. Remember, hip stability is both in the sagittal plane provided by the hip extensors, gluteus maximus, but also in the coronal plane with the hip abductors. If you notice that lateral trunk lean to the right and lateral head movement to the right really should direct your attention to hip weakness and hip abductor weakness. What is interesting about this particular gait pattern, it's somewhat subtle. You can tell that there's more of a displacement to the right side, and that is considered a compensated Trendelenburg gait pattern. It's compensated because the movement of the torso and the head toward the right side reduces the demands on the hip abductors. This is a compensated movement to try to reduce the demand on hip abductors. That's called a compensated Trendelenburg gait. What's interesting is that she also has a bit of hip weakness on the left side. While she's not compensating, probably because the right hip abductors are weaker than the left hip abductors, she does show, and it's pretty subtle, but there's a drop during stance period on the left of the pelvis. Now, this is almost impossible to see the uncompensated Trendelenburg gait because it requires you to see very small angular displacements of the pelvis in the coronal plane. To distinguish between these two, it really requires instrumented gait analysis to be able to measure that motion of the hip. What you can see observationally is the compensated Trendelenburg, and that is always more pronounced because of the fact that there's a strong shift to the right, and in her case, also a shift of her head to the right. That moves the center of gravity closer to the hip joint that allows the hip joint to be able to be stable in the coronal plane. All right. I think that the last one I'm going to talk about is a controlled ankle plantar flexion, and I think we'll end there, and then I'll stop for a moment and see if there's any questions, and then we'll pick up at the next lecture with the critical events in single limb support. This last one is controlled ankle plantar flexion or the heel rocker. Now, we're talking about how it prepares the new stance limb for weight transfer in a plantar grade foot position. It's controlled by eccentric contraction of the dorsiflexors that pulls the tibia forward to stabilize the entire limb with co-contraction of the quadriceps. Let's take a look at this, an example of this critical event being the same. This is a young lady who is a six-year-old with an L4 myelomeningocele. This spina bifida pattern, we often see it has weakness out of the calf muscles and leads to this what's sometimes referred to as a calcaneal gait pattern. It also has a, not only weakness in the calf, but also weakness in the tibialis anterior, which leads to, which affects the heel rocker during loading response. So, remember the heel rocker is where you're, you have eccentric control of, you have a heel first initial contact with eccentric control of the foot, lowering it to the floor. And where, when there's weakness there in both the calf and the tibialis anterior, you lose the ability to be able to have the normal heel rocker. The obvious solution to this is again, an ankle forward orthosis, which provides some stability in both the calcaneal gait pattern, so some stability for the weak ankle plantar flexors, but also allows you to be able to not let excess equinus occur during swing period, so that you can achieve a heel first initial contact. And you can see with this ankle foot orthosis, there's a lot of important improvements. So now she's achieving a heel first initial contact because we're holding the foot up. Notice that her step length is longer. Notice that the stability that the AFO also provides a terminal stance allows her to have a longer step length because she can hold on for a longer period of time from one step to the other and allows her to get better knee extension and terminal swing. Again, improvements in critical events, restoring those critical events with an intervention that addresses which critical event is missing during the gait cycle. All right, let's stop here. I'm going to stop the presentation. We'll go back and let's see here. Thank you, Dr. Krollo, for the first part of this gait lecture. Just as a reminder, everyone, we will have part two and part three in April. On April 1st, we'll have part two building off of this and then part three on April 8th to continue this gait review. This week, we do also have a board review session on the 27th from 5 to 6 p.m. Central Standard Time on Spina Bifida. For those that are able to attend, we'll be doing a high yield Q&A session building off of our virtual video lecture series from last month for that. I'll open it up to the floor if anyone has any questions for Dr. Krollo and hope to see everyone at our upcoming few lecture series. Thank you again, Dr. Krollo. All right, well, thanks for everyone's attention. Next time, we'll continue where we left off and we'll finish up with Perry's critical events. Then our plan is to go ahead and have most of that done so that on a third lecture, I can give you some examples of instrumented gait analysis and how we use those in our decision making. Thanks, everyone.

pediatric gait

gait analysis

Dr. James Carollo

heel-first contact

gait cycle

equinus

mobility limitations

ankle-foot orthoses

Spina Bifida