• LecturehallRadiographic Evaluation of Flatfoot
  • Lecture Transcript
  • TAPE STARTS – [00:00]

    Male Speaker: Our first speaker is Jared Shapiro. I have learned to become very familiar with Jared's speaking ability, his knowledge, his reputation and he has education at his heart. He brings a fund of knowledge from the west coast, sometimes little different in thought than east coast. At some point, maybe we blend, I don't know where it's bad as politics. We have just managed to keep east coast thinking and west coast thinking. Keep an open mind, listen to everything that he states for you. He provides good bibliographies, outcomes research. This is where we are headed. Jared works at Western Hospital. He is board certified in foot and ankle surgery, board certified by the American Board of Orthopedics as we used to call it and Jared is going to be sharing his thoughts on radiologic evaluation of flatfoot. So please welcome my good friend Jared Shapiro.


    Dr. Jared Shapiro: Good evening everybody. Thank you so much Dr. Schoenhaus. I will completely fail to respond to all those accolades. I also thank you to Present for inviting me to speak. How many organizations around the country will make one if not two programs that are just for residents. I think that's fabulous. We should have that so much more. So I'm going to talk today about flatfoot. I don't have any conflicts of interest. So our objectives here really, a lot of this is stuff you might know and you might have seen but I'm hoping to provide maybe just a little bit of thought provoking information for you. What I am going to talk about is flexible flatfoot. I'm not going to talk about rigid issues.


    I'm not going to talk about tarsal coalition or Charcot or that type of thing. So let's start this off with a little bit of a case. So this is an 11-year-old child, comes in with painful bilateral flatfeet, complaining of their issues, the stuff that you see in the office all the time, lot of times. Really commonly, you are going to get set of x-rays, take a look into what's going on with that and I want you to start this kind of conversation by thinking about how you would evaluate this patient. So of course, radiology, specifically radiographs have their advantages and disadvantages. We know that they are cheap, they are quick, relatively easy to do. The disadvantage is of course just like any imaging, they are not the actual patient but representative of them. There are of course variations with the techniques, so we're going to talk a little bit about that today, how the variations and how you take a radiograph are going to change some of your results. There are of course minimal soft tissue considerations and needless to say, there is radiation involved with this. So a quick review or look back on some biomechanical issues that might become pertinent. There is kinematics and there is kinetics. Remember that kinematics is about position and kinetics is about forces. And if you put those two things together, that's pretty much biomechanics in a nutshell. Those are the two things that we are going to be able to measure and deal with when we talk to patients. So radiographs are mostly kinematic because they are really taking a look at positions of bones and orientations of things as opposed to the forces and pressures and stress that are on them. So let's start with planal dominance. So I am going to get controversial right off the bet and kind of go over where planal dominance sits currently. We know this is a major concept that's been around since the 80s.


    It has been used for choosing procedures for flatfoot reconstructions, green characterized this in this picture from his article kind of show you. You can evaluate a foot and clinically if you see heel eversion, they have a frontal plane deformity, if you see more abduction to forefoot, that's transverse plane and if they have a loss of arch, that's sagittal plain. So that sounds pretty good. I think that's a very reasonable approach to look at. You have got your compensation from subtalar and midtarsal joint movement and that's going to create a certain foot appearance. So then a little bit down the line, Borrelli and Smith started to classify this. They kind of mentioned this idea of deforming force, didn't really talk about it too much in their paper but then kind of described this as a primary deformity and then made a few recommendations as far as surgical procedures that you might do directed at the dominant plane. So little bit later down the line, Dr. Labovitz, actually one of my partners at Western University would love to hear me talk about his paper. He used this to kind of move this a little bit further and so he broke up the different radiographic angles and relationships, applied those to specific plane and then added in the idea of CORA and apex of deformity. And then it was a bit more comprehensive in the types of procedures that could be chosen. So that sounds okay so far. That doesn't sound too bad. But the problem with this concept and these approaches is that it's really used for something a little bit more than it might have been intended for. First of all, it's based off of a hinge axis. Remember this from school. We talked about axis of motion, joints rotating around an axis.


    This is actually proven to be untrue. It's quite a bit of biomechanical work that's showing that the axis concept itself is not exactly what we think. Let's consider the subtalar joint is an example that axis move as the bone moves. So you have what's called a bundled axis of motion and the talus axis is a screw and it rotates in different directions based on which foot you are talking about. So we're not a hinge around like kind of the way a door, it's a little bit more complicated than that. Planal dominance seems to focus more on the subtalar joint into some extent the midtarsal joint. It has never actually been validated in researches, kind of been applied but no one has ever actually validated the use of this and the main thing that I have a problem with is you really have a very hard time determining the dominant plane. So Labovitz in hs article started out, he made these different algorithms for each dominant plane and this is an example of one of the three. So he starts this up by saying there is a transverse plane dominant deformity but then he mentioned about rearfoot valgus. That's a frontal plane problem. Then he goes into the sagittal plane and each of these is adding on recommendation for more surgical procedures. So my question to you is, based on this, what's really the dominant plane. What he is really talking about is treating this thing as if it's three planes, which is really what it is. So here is a kind of picture. You can see some of these abnormal angles and I would challenge you to tell me if this is a sagittal plane dominant flatfoot or a transverse plane dominant flatfoot. And if I just took the angles it maybe added up how far from abnormal they are, I might come up with something that's a combination of those two. And the reality is that the movement is actually triplanar.


    So the dominant plane is really hard to actually figure out. So then if you believe me and you say, well, great. If not planal dominance, then what can you use? So I kind of advocate a new term something I'm coining the kineticokinematic approach or KK approach. It's kind of a long word, so we go for short things. And I am trying to simplify this a little bit. So the first thing is when you see your patient, you are going to examine them, get a history, going to determine the damage or strained anatomical structure. If they have plantar fascia, it's a plantar fascia that hurts. If it's a PT dysfunction, maybe it's a PT tendon or deltoid ligament or such thing like that. You will then determine the underlying biomechanical cause, so you get that via your rest of your physical exam. Some of the research literature shows there are certain types of deformities that predispose us to a certain problems. And then you are going to fix that by adjusting the forces and correcting the deformity. So you are really taking both the kinetic and a kinematic approach to how you will choose to take care of these things. So then from this kind of paradigm, radiographs are really important for what they are going to tell us about the function and not just the position, which is what they had told us before. So instead of just making a foot straight, we really want to take care of what is really causing the problem. So just to very quick review of some abnormal radiographic positions and angles. You can see this is a pretty severely dislocated hindfoot. It's a pretty bad peritalar subluxation with TN and covering, increased CC abduction. Here is your uncovering and your abduction. You have a pretty large talar first metatarsal angle and the Kite's angle is enlarged. That's all pretty obvious. We have known this stuff for years, so nothing different than before. He is your talar declination.


    The calcaneal inclination angle is low on this one. There is kind of small mid foot breach. There is your very small mid foot breach. The Meary's angle is enlarged with that talar declination and the metatarsals overlap. So the other thing we can take a peak at if you're not already doing this in your office is to look at the hindfoot. So you have on the left side here the long leg calcaneal axial and the hindfoot alignment view, both are ways that you can look at frontal plane components of the hindfoot. So which one is better I suppose is the question. So calcaneal axial versus hindfoot alignment. So this study that was done by [indecipherable] [0:10:47] back in 2010 kind of compared the two and then looked at intra class correlation and inter class. So between different readers and within the same reader, were they able to get the same values. What they really found was that the long leg calcaneal axial was the one that was more reliable. That makes me a little happy because to get a hindfoot alignment view you have to have some special technology. You have to have the box for them to stand on. You have to be able to tilt back the x-rays plate 20 degrees and do all that kind of stuff. And that may be a little bit more challenging for a lot of folks to do. So the other thing I would be cautious about with long leg calcaneal axial is that the direction of the beam is really going to change the position of what the appearance of what you are going to see. So this is a clinical view. You can kind of see in the central area. This is just the camera beam, I guess you could say it's facing between the two feet. You can see that there is pretty significant abduction. But then if you were to take the camera and put it directly posterior to each of the feet, you see a lot less of that forefoot abduction.


    Now the same thing is also true with a long leg calcaneal axial. So if you have the patient stand at angle and base of gait, and then take an x-ray of both and put it through the center portion, you are going to see a bit more abduction. So Boffeli and Waverly kind of studied this. They looked at if you can actually figure a way to better align the hindfoot. So their suggestion was to take this view with the second metatarsal and the foot aligned to the plate and the beam aiming sort of at the tibia so that it's overlapping the second metatarsal. So basically, foot is kind of 90 degrees to the tibia. So this is kind of what it might look like. This is in my office at the University. So patients in angle and base of gait, they are standing in a resting calcaneal stance position, their heels with the back of the cassette and the beam is basically focused right on the posterior tibia and the foot is positioned so that you have to actually rotate the whole patient instead of just the foot in this case. I like that they have a standardized intraoperative to look at this too and they are using a cutting board, just a plastic cutting board that they got from the store, which I think is kind of neat so that you can see that this is kind of a nice way that they can check things intraoperatively. Let's move on now, medial column. So we are going to talk about some different things about the medial column and how we can use it in a more dynamic fashion. So let's start with hallux limitus. I was taught when I was in school that hallux limitus and elevatus come from increased motion to first metatarsal cuneiform joint. This picture is showing a patient who has a functional hallux limitus. So they are standing in their RCSP. They have decreased hallux dorsiflexion. If you put them into neutral, their dorsiflexion increases but you will notice on the standing lateral radiograph, there is no elevatus. So where they go?


    How can they have a limitus if they have no elevatus? So here is another one. So here is -- you could see a pretty large met primus elevatus there. So there is your elevatus. You can see that there is no gapping at the first met cuneiform joint. So if it's just dorsiflexing at the first met cuneiform joint, we should generally see some gapping but if you take the arch and you sort of divide it up into pieces, everything that's kind of congruent with each other, the first met and the medial cuneiform are pretty much in line and then if you kind of look at the hindfoot, there is the talus and navicular. They are both kind of in line with each other and this is really showing movement at the navicular cuneiform joint. So that's kind of around the joint. So you don't have to necessarily see a lot of gapping at the bottom in order to appreciate motion of that. So that's really where it's coming from in that patient's foot. It's not that the patient needs a lapidus per se. So Christensen's group did a great series of five papers. They looked at first ray and kind of related function in these and one of the things they did was they looked at motion of the medial column. And what they found really was that motion, that excursion that you might check when you are looking at the patient with a bunion is really a mixture of joints. So think of it as kind of 50-50 first met cuneiform joint, navicular cuneiform joint. They got 41 and 50% with 9% of it at the talonavicular joint. So the motion is really coming from more places than we're thinking of. So the other issue here is that the standard lateral really isn't going to show us dynamic motion. This is a static image. So there is a way that you can actually sort of start to look at the medial column on your radiographs and see kind of where some of that motion is coming from.


    So there is this modified common block test. You all know the common block test of pes cavus. So they are looking at this to determine the amount of plantar flexion and dorsiflexion that you need and where that motion is coming from. So here is an image from their paper that shows a lateral and what they did was they put something underneath the first metatarsal head and they are looking to see where the dorsiflexion occurs and what joint. So you take a standard lateral, then you take this modified kind of common block lateral and then you see where the motion is coming from. So here is a patient of mine. So there is a regular bearing lateral. You see there is no elevatus. This looks -- maybe looking at that, you see a navicular cuneiform fault. You see increased talar declination angle. And if I did a Meary's, this would look like it's a little closer to the talonavicular joint. I eyeballed these angles on PowerPoint. So you have to bear with me as far as my inaccuracies. So here is a common block lateral. And if you take a look at that, you could see now all of a sudden there is an elevatus. So if I then were to redo Meary's in this view, I can see that the angle is now moved anteriorly where the apex of that is now anterior. So that's telling me that the navicular cuneiform joint really is the culprit when it comes to the amount of motion at the medial column. If I was going to pick a surgical procedure, maybe an NC fusion or something along those lines would be where I would then look to do the procedure. So that was medial column but there are few other things and this is the area of caution that I'm going to suggest to you. We are going to talk about adding this to cuneiform, elevatus and then bone appearance depending on the angle of course.


    So that's going to be the first one. So if you take a look at the navicular, sometimes you will see that it might be a little bit more rectangular and sometimes it's going to look a little bit more wedge-shaped. And if you get a patient and you take your typical standard dorsal plantar view, you are going to get a pronated foot and you are going to see a bit of wedge shape with kind of larger medial cortex and then the lateral side is a little thinner versus the supinated side, which is a bit square. So if I take a look at what patient of mine, this one is a little harder to see but if you kind of look, there is a pronated view and then the supinated view on the right. It's a little bit more square and little bit less wedge-shaped in that case. So nothing that you have to do different. Just be cautious. Remember that your navicular is really going to change appearance based on the angle of your beam and then the position of the patient's foot. So what about elevatus? So when I first learned about this from one of my colleagues at the university, Dr. Chrisman, who is a fabulous radiographer, I wanted to cry because I had spent all this time learning about elevatus and how I am supposed to do a lapidus or something like that and then I find out that there is this study that was done by Dr. Chrisman where they looked at a phantom. So it's sort of a like a fake foot and they changed the tube head angle and the elevation of the beam. And they found that if you change the tube head angle or you change the elevation of it, you will create what looks like an elevatus in a patient that may or may not have it. So if you increase the tube head angle upwards or if you raise it to sort of towards the dorsal side of the foot, you are going to get what looks more like an elevatus.


    So I had to test this because I couldn't believe it at first. So here is one of mine. The one on the left is right at 90 degrees to the foot. Then I elevated it off the ground 5 mm and you can there is a little bit more of an elevatus and then I brought it back down to kind of normal position and then I angulated it up dorsally, so that by 20 degrees. That looks like an elevatus. Now if you were to get Seeberg's angle where you're comparing the distal to the proximal side, it's not so much. It's not so much there, but you have basically created what is a fake elevatus by just having the radiographic beam facing the right direction. So that's elevatus. How about atavistic cuneiform. This is another one I was taught in school about atavistic cuneiform and this may be the cause of bunions potentially and when you do your Lapidus, you have to cut out a bunch of the lateral side of the cuneiform. So Brag loaded seven cadaver feet on the plexiglass apparatus and he took radiographs and used this, kind of modified MC angle where he looked to see what that angle was based on different radiographic angles of the beam. The thing that matters on this is if you look at that 10 degrees and it goes from 10, 20, 30. If you look at that first MC angle, you will notice that the apparent angle changes. The IM angle doesn't change, thank god for small miracle that IM angle still manages to stay the same regardless of what x-ray beam we're taking look at. So that ankle that we're talking about really lessened significantly as the orientation of the beam changed from 10 to 30 degree tilt.


    There is another study that corroborated this just in case like me you can't believe at first. Yes, there is a second study to corroborate this and they did something similar. They looked at 515 random cadaver bones from a museum and they also found something similar that the atavistic cuneiform appearance was more apparent when the first met was in a declined position and when it was inverted. So basically, the same result. So just to kind of show, this is from their paper, different angles of declination and what you are really seeing is overlap of the base of the first metatarsal and the medial cuneiform. It's creating a kind of sort of fake appearance of angulation of the first met cuneiform joint. So here is a real life example and so the one on the far left here is 0 degrees of -- looking at it just straight down onto the foot as 0 degrees. This is a dorsal plantar view. So I bisected the first met and then that sort of the angle, at least that it appears at. So there is MC angle. So these lines are going to be exactly the same now. So it's the same bisection, same angle from the first x-ray and as we go laterally, so this one is now at 10 degrees angulation and you can see that there is a slight difference in the angulation and then here is 15 degrees, a little bit more so. Again, the red lines are same for all of these and then look at the difference between this one at 20 degrees. All of a sudden, that atavistic cuneiform just disappeared. It's gone. The first met cuneiform joint is nice and straight.


    I was not happy to see that. So what the recommendation is that you get a regular lateral and you measure the declination at the first metatarsal and then you angle your beam according to that same first metatarsal declination angle. You are basically looking down the met cuneiform joint and when you get that, you will get what we think is a more accurate way to look at the first met cuneiform joint angle. Now that recommendation has not been validated, so I would urge you a little bit of caution if you are using that. I am going to sort of finish things up here by kind of talking about some corrected radiographic views. So this is one, so you can see this is -- on the right, there is the pad that we used to get sesamoid axial. These are readily available. It's kind of a high dermometer pad you put the patient on and you can get a nice sesamoid axial weightbearing. That looks really nice but you can also use it to get a lateral view and kind of see if you are dorsiflexing the hallux and you are engaging to win this mechanism. What happens to the foot is kind of maybe help you predict a little bit what you might see during surgery. So you could see that in this case, this patient -- the appearance of the foot does improve a bit. The talar declination angle decreases. It looks a little bit better, but it's not a perfect correction. So I would note to expect that during surgery and maybe I might adjust my procedures accordingly. Here is another one. So this is that same sort of original kind of patient. I showed you this was severely subluxed hindfoot. This is her uncorrected view, so you could see a dorsal plantar and the lateral view. I'm sorry I don't have calcaneal axial. I made myself a lair by talking about calc axial and then not including it in this.


    So here is a corrected view. And you can see my fingers are there. It's terrible technique. Don't irradiate your fingers. There is a calcaneal axial. So what we did was this patient is extremely mobile. She has really poor ligamentous control and we basically held her hindfoot in the erectus position and then engage her in this by dorsiflexing the hallux and you can see she has got a really nice correction. That's pretty good. I almost pretty much turned her into cavus foot by doing that. We brought her into surgery and we used this to kind of help make decisions as far as what we are planning on doing but also went into the procedure knowing what to expect to some extent. So what we did was a double hindfoot fusion. So subtalar fusion, TN fusion, a cotton and gastrocnemius recession. That's what we ended up doing on this patient. She is very flexible and then if different patient, I might have chosen osteotomies as opposed to fusion but this patient was super flexible, even some concerns about Ehlers-Danlos. So we opted for fusions on this particular patient. So there is the end result. Really, all we did during the procedure was just really we debrided the joints, we held the foot in the proper position and then we applied our fixation and we managed to make a reasonably rectus foot as a result of that. It's a little -- I'm sorry, there is a little under exposure on the lateral, there is a cotton in there too, so we added that in just to improve that part of things. Her forefoot supinatus did not correct entirely while we are doing her surgery, so we added the cotton in. So to conclude this, I recommend you consider planal dominance, maybe it's two- unit dimensional. We need to kind of think about some other. This kineticokinematic approach needs a little bit more work of course and needs validation but it might be an alternative method to help kind of with your decision making. You definitely should be cautious about interpreting the radiographs and consider using somebody's alternative use that others have come up with very creatively to utilize static radiographs to give you some more dynamic information. So on that, I thank you very much for your attention.


    TAPE ENDS [28:35]