• LecturehallA Biomechanical Approach To Surgical Decision Making
  • Lecture Transcript
  • TAPE STARTS – [00:00]

    Male Speaker: Continuing along the lines of biomechanics, our next presenter is going to be discussing a biomechanical approach to surgical decision making. Jared Shapiro is a graduate at California College of Podiatric Medicine, did a three-year residency in Michigan. He is on the staff at Western University Hospital. He is an educator. He has been to many of our meetings. He, at the present time, is the editor of Presents Practice Perfect. He holds your feet to the fire. He wants outcomes, he wants literature to support decision making and if nothing else, he questions just about everything we do. So please welcome Dr. Jared Shapiro.

    Dr. Jared Shapiro: Thanks Dr. Schoenhaus. Good evening everybody. Thank you for coming. I'm going to get into this so we don't take too much time. So I have no conflicts of interest. We are going to talk about thought process. So the focus here is really about surgical -- really surgery but in my opinion, biomechanics and surgery -- really all of the treatments we do have the same kind of aspects to them. So we are going to kind of talk about this. When I went to school, I was taught a biomechanics class and I was taught a surgical class and they were separate things. And I don't look at this as being the right way to approach things. So biomechanics doesn't equal orthotics and surgery doesn't mean you don't think about biomechanics. In reality, really, I think better way to look at this is that these are different components of the same continuum of treatment that you can choose surgery or you can choose nonsurgical options and each of them have their place and it's not one or the other. Sometimes, it is a combination of those things.


    So you have heard this before more than once I think, what makes podiatry unique and I would agree with everyone else who said this that's really about biomechanics. So if you would perform a transmetatarsal amputation, we talk about why we do a tendo-Achilles lengthening as one option for those, why lengthen the posterior muscle group. So we are aware of this and oftentimes you will see this in your practices, you will see somebody who had a transmet amputation or amputation of some sort. They have increased plantar pressures and we know how to take care of these things. If we are thinking about this in these terms, why not consider this for all of the ways that we're taking care of patients. So as a quick step back, consider that there are really two main aspects to biomechanics that we are talking about. We have kinematics, which is really looking at positions, how joints are related to each other, how joints are functioning, those types of things and then we have kinetics, which is pressures and forces, those types of aspects of foot function. So I spent some times in my education was -- we looked at surgery, oftentimes it was about making the foot straight. So root biomechanics and the surgical approaches that we see in the literature oftentimes about looking at ankles on a radiograph, taking those abnormal angles and in some way trying to make them straight. Same thing with orthotics. We oftentimes talk about trying to make it a straight foot and get back to neutral position and make it as straight as you can. So back in really the late 80s, even Pressman made this comment. Certainly, the goal of operating on a deformity is to have complete correction.


    I guess it's true that you want complete correction but really the goal of your operation is to make your patient better, not about making a straight foot. So straight doesn't necessarily equal better. I am going to advocate a slightly different approach and I don't think there is anything huge and major new about this type of thing but it's really just looking at things in kind of one sort of approach and I call this a kinetic or kinematic approach. This really is just taking kinetics and kinematics looking at them together for your patients to try to make your decisions as far as surgical approaches or even nonsurgical approaches. The first step is to figure out what part of your patient is damaged. What's the anatomy? Your history and physical are going to figure this out. You have been doing this for quite some time. Then you are going to clarify what that underlying biomechanical cause is. So it's really easy to diagnose plantar fascitis but then you really need to start figuring out what's it about that patient that is causing extra strain on the plantar fascia and then you are going to apply that knowledge to fix the patient in whatever way. Whether it's nonsurgical or surgical, you are going to correct the deformity if you need to but you are also going to adjust forces and that's the kinetic part of this. So consider this. Look at this, you have on one side. This is a curvy heel skive kind of picture. You can modify your orthotic and curvy heel skive is supposed to increase ground reactive or orthotic reactive forces, medial to the subtalar joint access to create a supinatory rotation. Well, I would suggest to you that a medial displacement calcaneal osteotomy will do exactly the same thing except you are doing it internally. So you are moving the calcaneus over. Yeah, you are getting the calcaneus directly under the tibia, so you are getting the mechanical access realigned.


    You are also pulling over the insertion of the Achilles tendon. So those things really are the same thing, just doing it in two different ways. So here is a kind of looking at these in little bit more detail. Two different patient situations. You have a neuropathic ulcer. I think that's pretty obvious as a first step to figure out what the damage structure is. That one is pretty obvious. It's a hole on the patient. If you can't figure out what's damaged in that point, there is something wrong with you. And then you have somebody with plantar fascitis. Similar kind of thing. You can push on the heel. You can get history. You get post static dyskinesia. You have that plantar medial tubercle pain. That's all pretty obvious. I can figure out what's wrong with this patient. I have got a diagnosis. That part of thing is pretty easy. So then you want to look at clarifying why those things exist and you really have to consider the mechanics of the foot and then the forces that are acting on the foot. So for the residents in here, I know you have to log your biomechanical exams. I know you hate it. Nobody loves it but I think you should stop considering it as a biomechanical exam and just think of it as a physical exam. You are examining the patient to figure out why they have a particular problem. I would like to look at a standing exam first. See the patient overall, see their super structural issues, their knee, their leg, their hip, really easy to see resting calcaneal stance position, how reducible things are. Those are really quick and easy things to look at from a standing exam first. Then comes gait. Your patients are walking and let's say just happened to stand still and hoping around, they are going to be using their foot to do something. So gait becomes important. You are going to look at all those things you typically were looking at. Heel strike, mid stance, toe walk, all those different aspects about them. You see leg length considerations.


    You are going to look at all those things to try to figure out what is causing that problem. And then finally comes your seated exam. So all the things again you are trained to do. Subtalar motion, look at midtarsal stability. Is the medial column mobile, is it rigid, are there calluses? And then you might choose special test for specific issues. Think of things like a dorsal drawer test for digits, those type of things. You can see this is approaching with a forefoot supinatus. That picture on your right is using Kirby's method to determine the transverse location of the subtalar joint access. And in that case, it's a medially deviated subtalar joint access. You could see that hallux valgus associated with it. The rear foot is causing the forefoot problem. So you have done this exam. You have got in the physical. You know what's going on. You are trying to figure things out. This is an interesting test that was published in literature relatively recently. It's called the neutral heel lateral push test and you are looking to see if the spring ligament is damaged in a patient with posterior tibial tendon dysfunction. So we know from prior research the spring ligament is really a primary supporter of the arch. It's a stabilizer and you can use this test to determine if the spring ligament is damaged. So if you have a patient with PT dysfunction, you do this test and perhaps you might need to choose a spring ligament repair in order to take care of that patient with posterior tibial tendinitis. I think this starts to bring up questions about what are procedures are really doing. And we are oftentimes taught in school that a lapidus procedure is for hypermobile first ray, whatever that is and however you define that or it's for very high intermetatarsal angles, but not necessarily.


    There is plenty of research that shows that the medial column moves in areas and joints that are not just the first met cuneiform, so this kind of landmark study by Rolling and Christiansen group shows that you almost have a 50-50 amount of motion between the first met cuneiform joint and the navicular cuneiform joint. So that will tell me that if I refuse the first met cuneiform joint in my Lapidus, I'm going to make the arch about 50% more stable or more rigid. There is also a locking mechanism that occurs. If you realign the first met cuneiform joint, you are going to recreate a locking mechanism by creating a closed pack position. So the surfaces of each of that part of the joint are going to line up well and then you are going to have a more effective arch that's going to result from that. We also know that the peroneus longus is involved with stabilizing the medial column. So if you put these things together, you can see the Lapidus, yeah, maybe it's going to fix your bunion but it's also going to be an arch stabilizing procedure. So that becomes again very important once you know what the procedures are doing. So the work from Kirby of course is very important. If you haven't read it, from the resident's standpoint, I think you should start reading his work. He is really looking at where the subtalar joint access is located. If it's medially deviated, which really kind of focus your attention on the right side of the screen, that medially deviated access when you hit the ground is going to cause a pronatory force and you want to try to decrease that, right? So you need to do something to move that subtalar joint axis so that it's more lateralized in relation to the rest of the foot. So that will have affects of having the ground push the foot into a supinatory position but it will also cause the muscles and tendon units to work in a position that they were supposed to be working in the first place.


    And that brings up the question about a gastroc recession or tendo-Achilles lengthening for patients with PTD. So if you medialize the calcaneus in somebody with posterior tibial tendon problems or flatfoot, do you really need to do a gastroc recession? It's a question that's important because if you have medialized that Achilles, then do you want to weaken the gastroc when it's now in a position that is better. So again it brings up things to consider, things to think about. This is Kirby's exam to figure out where that subtalar joint access is located. Basically, you are just kind of loading the foot. It's not neutral position. So you load the foot. You are going to palpate until the point where you can't heel invert or evert that is right on the axis and then you mark that on the foot until you kind of find out where it is. It's really supposed to kind of run about to the second toe or between the first and second digits. So the next step the, you know what the problem is, you know where it's coming from and what the causes are. Now, you address your treatment to those causes and whether it's orthotics or any nonsurgical treatment is that's important and the same thing is going to happen with your surgical treatment. You're really going to do this by adjusting the forces but you also need to know what your procedures are actually doing. So here is a simple one. So typical neuropathic ulcer in the second digit. This patient was diagnosed with osteomyelitis on an MRI, which is unfortunate. She didn't have osteo. We did a very simple digital arthroplasty and MP joint release. We did make it straight but at the same time the real effect is that you are decreasing the force on the skin, which is allowing it to heal.


    So we're kind of doing this in two ways. So knowing your procedure effects is a little bit more difficult. The research is starting to become a little bit more robust. We have a long way to go before we are going to really truly rely on all of the research but we are taught the Evans procedure is one example here that you are trying to correct a transverse plain deformity and that's true. Maybe you have a transverse plain dominant flatfoot but this has other effects as well. So it will also decrease loads on the medial column, which is exactly what you want to do in somebody who has adult acquired flatfoot. So how about that medial displacement calc osteotomy? It does exactly the same thing. So you not only are realigning things, that's the kinematic approach that we're well trained in but it will also decrease first metatarsal load, it will decrease the movement and the pressures around the talonavicular joint but it will also have the side effect of increasing the lateral column load. So you have to remember that if you went too far, you might end up having a patient with lateral column problems. So again just like giving a medication, it's going to have a side effect and understanding the mechanics of how these procedures work will have a significant effect on your choices of procedures. So here is a gastroc recession. I kind of beat up on it little bit before. We know that it increases ankle dorsiflexion, that's pretty obvious. We also know that it reduces peak plantar pressures in the forefoot. That's really important for patients with forefoot plantar ulcer and those types of things, but importantly, it has not been found to change ankle or knee mechanics.


    So a good thing. You don't want to create new knee problems or ankle problems for your patients. So I am going to round this off with a couple of examples of sort of how I used this to sort of determine some treatment. So this is a patient who has problems on two sides at different time periods but for the sake of our discussion, I am kind of squishing on sort of together. So on the right side, the patient has basically sinus tarsi kinds of complaints. So pain on palpation to that spot, you can see she is pronated, the foot with a line on it is that side there -- I'm sorry, that's for the other side and so we kind of take a look at her. We know the area of complaint. Look at her mechanically. She has as medially deviated subtalar joint axis. She has excessively pronated at the subtalar joint and she has increased medial arch strain as well. Then we look at her pathomechanics and I know if you guys could run the video there. Let's see if that works. As she externally rotates her leg, you can see she becomes rectus. She has got a very flexible deformity. She is a big lady. You can definitely see by the size of her legs and her calf. Obesity is a significant part of things. She is easily correctable with external rotation and so we can tell here that she has really easily overloaded medial structures. So she is going to need some extra support. We did surgical procedures where we're adjusting kind of looking to adjust the forces and instead of doing, I was originally trained to just basically evacuate the sinus tarsi and do a sinus tarsectomy instead.


    We did a medial displacement calc osteotomy and a gastroc recession and she did okay. So this is looking at her surgical results. I came also close to missing the calcaneus with that screw. I got lucky, I guess. Good thing. Nothing is perfect, I guess. She healed and did fine. So if you looked at her from a kinematic standpoint, she is reasonably rectus, she still has some navicular cuneiform breach, not terrible. Her symptoms completely resolved with that, so she is doing fine. I still see this person. That side of things is doing great. So what about the other side. The other side she came in sometime later. She has a kind of typical posterior tibial tendon dysfunction, adult-acquired flatfoot complaints. We did our exam, chose procedures. This is her preop radiographs. You could see from the lateral view there that she is not terrible. She has got a low calcaneal inclination angel and she has a pretty heavily uncovered talonavicular joint. So you would say maybe she has a transverse plain dominant flatfoot if you are looking at things from a plano dominant standpoint. And postoperatively, this is what she looks like postop. And what we chose to do on her was a double calcaneal osteotomy. We repaired her posterior tibial tendon, which had a tear in it and we also did a sort of modified spring ligament repair using an allograft and two anchors. So that's what you see in her talar neck and her navicular.


    So kinematically, looking at positions, she looks pretty good. She is feeling better. The medial column pain she had is completely resolved. I would call that a success not because of how she looks on the x-ray but because her symptoms resolve in that. So again this is kind of looking at her preop and postop. Yes, she is rectus and if there is an artist side of us, you would like to see things be straight but really I just want her to be pain-free. That's really the main goal of things. We have resolved her problems by looking at both kinetics and the kinematics in this patient. Here is a last example. This is a diabetic patient, has a neuropathic ulcer under the tibial sesamoid, which had been previously removed. The patient continued to have the increased plantar pressure despite the tibial sesamoid being gone. You could see I have achieved little lesion marker on that kind of medial side of the first metatarsal head on the DP view showing that the pressure is really kind of inside the joint. If I had wanted to, we could have used the gait analysis system and looked at plantar pressures. I think in this case, it's pretty obvious where those pressures are. I don't necessarily have to spend the money for that type of things and you can kind of see he has a cavoid foot. Metatarsal is pretty deeply plantarflexed. The procedure that we chose to do was sort of modified first met cuneiform fusion and a gastroc recession. This patient did fine. So I didn't excessively dorsiflex him because I am really concerned about the side effect of that procedure to increase the pressure under the second metatarsal head. It's not a huge dorsiflexion. It was just enough to remove the pressures of the forefoot to get rid of his complaints and his problems. Again, I see him and hasn't recurred in that area at all. So really looking at things kind of globally from this view, this patient was treated successfully. I am not getting rid of his cavus foot though. In conclusion to make better surgical decisions, you should look at this as determining what anatomical structures are damaged, figure out why by looking at the pathomechanics and the forces behind those things, fix it by choosing to adjust those forces and then making sure that you understand the procedure effects. I think as the research really continues to evolve on this, eventually we will have better technologies and a better feel for what our procedures are really doing for us. On that, I thank you very much for your attention.

    TAPE ENDS [22:45]