Harold Schoenhaus, DPM discusses the use of arthroeresis to correct hypermobile flat foot. Dr Schoenhaus also discusses the indications and advantages of arthroeresis and describes the procedure in detail.
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Harold Schoenhaus, DPM
Surgical Editor for PRESENT e-Learning
Penn-Presbyterian Medical Center
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Male Speaker: I’m going to be sharing some thoughts with you at this point on a topic that I have enjoyed for many years, and that is dealing with an approach to hypermobile flatfoot. Current concepts in arthroereisis, and I specifically use this term very carefully and creatively because I think it has tremendous impact on what it can do for the control of what I consider an uncontrollable hypermobile flatfoot. And the other day, I alluded to the fact that when we looked at etiology of deformity such as hallux abducto valgus, hyperpronation is a component of that that we recognize, we talk about and then we probably don’t go ahead and treat it carefully or thoroughly enough. Some of it is because of patient compliance. That patient walks out of our office with a pair of orthotics. We have no idea what they use them for after that. If they’re in the cold weather, they can use them for an ice scraper of the windshield for all we know. We don’t know how often or how much they’re wearing them. Disclosures, learning objectives, understand the concept of arthroereisis, explain various materials for this procedure and discuss the role of subtalar joint in hypermobile flatfoot. When one looks at an approach surgically to correct some form of deformity, I like the procedure to be as least invasive as possible with maximum results. And there are many hypermobile flatfoot that I treat surgically with osteotomies, transpositional calcaneal osteotomy, Evans osteotomies, Cotton. You name the procedures that we can do that are far more invasive and those are extraarticular. And then we have to get into the more advanced procedures in the adult flatfoot that might include fusions, talonavicular, triple arthrodesis, subtalar fusions, far more ablative in nature, far more disruptive to the locomotion of the lower extremity, and the foot as it relates to the rest of the body. Arthroereisis advantages, extraarticular, it’s reversible, ease of implantation, ease of removal and allows for early weightbearing. What is an uncontrollable hypermobile flatfoot? We certainly can look at it in the pediatric population recognizing that this is a foot that you put on orthotic inside a shoe and the foot swims all over. It’s not being controlled. Some of uncontrollable is related to the poor selection of the orthotic we want to use. When Martin Ruth [Phonetic] talked about biomechanics way back, he talked about the fact that the subtalar and the midtarsal joints are triplanar in nature. That theoretically, if you could control one plane, you’re going to control the other two. That sounded logical, except when you’re dealing in a pediatric population which goes from the ages of two, three on up to adolescents, that premise doesn’t work. We need orthotics that are going to be very controllable with deep heel seats, with lateral flanges, medial flanges. That foot needs posting, that foot needs to be controlled from the point of heel strikes through midstance into propulsion. Otherwise, a foot slides right off an orthotic that’s posted. So if you put a rear foot or forefoot post on an orthotic and you think that’s done it, you watch that patient walk, they’re going to slide. You went right off. Some of those postings even encourage transposition of the forefoot on the rear foot and supination of the long axis in the midtarsal joint so you’ll get a concomitant supinatus because of a forefoot post. We have to be extremely careful of our type of orthotic. A UCBL is far more controlling. That foot needs outriggers on it. Well, there are certain problems with that because of the shoes that people wear. We can get away with the younger population because sneakers are appropriate form of foot gear. When you start approaching adolescence and young adult, now we’re looking at more stylish shoes, regular shoes, they do not want to wear this cumbersome type of insert.
And yet, we allow this foot uncontrollable now to go on to develop all of the signs and symptoms that we associate with hyperpronation syndrome. There are deforming forces that render a foot uncontrollable, such as equinus. Primary equinus, the inability to dorsiflex that foot 10 degrees above the level of the ankle from neutral up to 10. You need that. Fifty to 60% of the stance phase of gait, the subtalar joint in the normal foot is back to normal position, neutral position, and the foot is 10 degrees dorsiflex to the leg. That’s where that dorsiflexion number comes from. The knee is extended at that point. It’s the only time in the gait cycle we see that happen. When you don’t have the ability to dorsiflex, mechanisms within the foot are available to provide additional dorsiflexion. No, we all know that. There’s a biomechanics. The problem is if I pronate the subtalar joint, it only deviates 16 degrees from the sagittal plane. That axis provides very little motion in the direction of dorsiflexion. So the next joint has to be unlocked, which is the oblique midtarsal joint that provide significant dorsiflexion. Unfortunately, when you open that joint up, you get dorsiflexion on a sagittal plane and transposition in the transverse plane, abduction. And on top of it now, the long axis of the midtarsal joint is opening, you get supination. You get a terrible uncontrollable hypermobile flatfoot. The foot that I called pes pancakus, this thing is flat. No, you’re not going to put an orthotic in there and build up an arch and push and pull and do everything because of the uncontrollable component from the equinus deformity. We have to evaluate the patient biomechanically to determine if we can control it. Can we change the position of this foot and can we convert it into controllable if we eliminate a single deforming force? When you think about it, how old is a patient that comes into your office with a hypermobile flatfoot? If you’re dealing with a lot of kids, usually, five, six, seven years old, maybe eight to 10, youngsters have growing pains. And the pediatrician tells the parent, “Don’t worry they’ll outgrow it.” The only thing they outgrow is the fact that they no longer are growing so someone says, "Oh, you don’t have growing pains anymore.” Now, we talk about is leg transitions points. It’s an indicator of something that is abnormal. We also recognize that the articular facets within the foot develop early and the shapes of those facets establish what they are going to look like into adult life. The child’s foot is supple, it’s moldable, it’s malleable. The bone is not dense. In the child, the bone is the soft tissue, the soft tissue is the bone. We can actually change the contour. Functional adaptation can occur very nicely in the younger population that’s growing. Wherein the adult population, you’re not getting functional adaptation, you’re now going to get the typical changes that one sees of degeneration. The golden age of opportunity, in my opinion, really deals in the younger patient, sometimes a difficult concept, however. What are our primary goals in this extraarticular procedure called arthroereisis, reposition subtalar subluxation, block excessive motion but allow normal motion to occur, allow for this functional adaptation and enable a foot to be controllable. We want to realign the TC relationship, the midtarsal complex. We want to see a reduction in supinatus, prevent the pronatory pressure on the medial column. And unfortunately, as we get older in the patient population, this PTTD patient has a problem that’s uncontrollable but may still be able to benefit from arthroereisis and allow for normal function.
The foot has to function normally as it relates to the rest of the body. The subtalar joint, we know it is a torque converter to the leg with every step that we take. There’s a dynamics that occurs during gait that we need to allow to happen. Indications, adult acquired flatfoot and I’ll show you some of that without any of the associated degenerative changes, resection of calcaneonavicular bar with a potential that you may be able to support that foot internally. And then, of course, uncontrollable in the sagittal plane, midfoot, forefoot. If we take a cross section of the midtarsal joint, that’s what you’re looking at, the portion that says neutral. Look at the relationship of the talus to the calcaneus. That’s the articular facets distally on those two bones. As we supinate, the talus sits way up on the calcaneus. As we pronate, the talus drifts away somewhat from the calcaneus. And the more it drifts away, the more we’re going to see closed chain pronation with the calcaneus everting. If you look at the x-ray on the bottom, you will see a significant transverse plane hyperpronation of 35 degrees the talocalcaneal relationship. And you want to bring that back to a more normal position. We can see abnormal pronation. Here’s a youngster. Look at the hyperpronation that’s taking place during gait. I stated yesterday, watch your patients walk, gain analysis, critically important. Genu valgum, internal torques, early heel raise, things that are suggestive of the etiology of this uncontrollable hypermobile flatfoot. As the arch depresses, take a look at the first metatarsophalangeal joint. You could see it’s prominent dorsally on the one foot. And the other foot, you see what we call an abductory twist. The foot abducts and moves away. It doesn’t have that dorsiflexion capability. One of the other mechanisms of compensation for equinus is to abduct the foot, that’s exactly what you’re seeing on that one picture. The foot is abducted, applying a force of abduction on the hallux. So the hypermobility of the first ray is already identified. And just give it time. It’s a slow insidious process that leads to hallux limitus rigidus, hallux abducto valgus. We can look at etiology of a flatfoot. We all know the different causes. Certain ones are more so than others. Signs of this hypermobile flatfoot, growing pains, leg cramp, sedentary activity. The list goes on, heel pain syndrome, postural problems, fatigue easily. Youngster doesn’t want to wear shoes, can’t tolerate neutral position orthotics. Poor posture and breakdown of the shoe medially. Everything that we see every day associated with hyperpronation syndrome. I got to talk to Warren [Phonetic] if I can get some onychomycosis associated with this hyperpronation. That would be great. We look at this patient standing and observe the amount of pronation and we would certainly like to take this foot from that position, relocate it. These are hypermobile feet. You could tell the patient stand in position and you externally rotate the leg. Obviously, look at the difference in position from pronated to neutral. That’s what I want to accomplish. And we’re also going to want to change the position of calcaneal stance, which I will tell you more times than not, the calcaneus doesn’t evert, it abducts with the rest of the foot. And it looks like it’s everted relative to the leg because it’s abducted so you will still see what appears to be Helbing's sign. An axial view from the back will help differentiate that. X-rays are important, calcaneal inclination angle. I look for obliteration of the sinus tarsi. When you look at an x-ray, if you don’t see a nice clear sinus tarsi, you know that talus has dropped down into it associated with the pronation.
Superimposition of metatarsals in the forefoot, pathognomonic of forefoot supinatus, the arch is dropping. We certainly do all of these things. It’s helpful for the residents to evaluate and understand. It’s also important for the patient to be able to look at it and understand. Dorsal plantar view, you see obviously the uncovering, if you will, of the talonavicular joint. It’s a ball and socket joint. It’s easy if we have a pronatory component for the talus to rotate medially out of the cup. And when you see cuboid abduction of this type, that is critically important to understand that that may be an advanced deformity that you may have to consider doing lateral column lengthenings. I evaluate these things very carefully before I select a procedure for a patient. And here is an example of just tremendous transverse plane domination. This is not a patient that I’m going to use a lateral arthroereisis for, and hope that I’m going to relocate the whole forefoot which is subluxed at the midtarsal complex. No, I’m going to have to do extraarticular osseous procedures if the patient is young enough. What’s the concept? If I take the foot as you see up on the top right, with the pronated position and the talus falling right down into the sulcus, I ideally want to get it propped back up. So that the subtalar joint still congruous in position, by the way, in either the flat or the neutral position, it still can be congruent because of functional adaptation. But I want to take this foot and bring it back up. Relocate the talus on the calcaneus. And if equinus was the deforming force, the talus will be able to sit back up on it. Now, how do you keep it down? I call the sinus tarsi the canal that God gave to podiatric surgeons, because very few professions really appreciate the power of that canal. And if you read orthopedic literature, there are some articles written on lateral arthroereisis. Giannini, an orthopedic surgeon that Guido quoted the other day talking about ankle replacements also was involved in doing a lot of arthroereisis, [indecipherable] [17:49]. So our European colleagues recognize how powerful this area is. Now, the question is, what do you put in there? Now, in my younger day, obviously, bone was something you can consider but that’s a Grice-Green procedure. You’re going to get an extraarticular fusion. We don’t want that. I needed something I could put into the canal to block motion. So I used in the early days, silastic, black silastic that I would carve into the shape of an implant that could go in to the sinus tarsi. Now, I’m going to show you some other things as we go. The arthroereisis considerations, again, extraarticular ease, ease of removal, early weightbearing, reposition the subluxation, block the excessive motion but allow motion to take place. Evolution of materials, there was the implant I carved on the top. And the reason I had a little groove on it is this thing was like a watermelon pit when it was saturated with serous fluid. You could squeeze that right across the room which has saline on it. It would extrude from the sinus tarsi, I didn’t like that. I actually tied a suture around it and pulled it through the medial side and tied it to hold it in place. Then I used the polypropylene plug. This is a buck plug. It’s actually something that was used in medullary canals before you put methyl methacrylate in the canal so it stops how far it’ll go down the canal, had flanges on it. I like that. I would trim some of the flange but now it would allow for circumferential fibrosis, what I thought, to hold the plug in place. And it was still soft enough. Now, there’s other materials that have come out with absorbable plugs, none of which I have liked and used. And then the metallic range. Holy cow, how many different companies have metallic implants of various shapes and sizes for the subtalar complex, because of the value of arthroereisis and the fact that so many of us are recognizing it?
Now, I tell you that the biggest concern that I’ve experienced and have heard from other surgeons in using any of the sinus tarsi plugs is they hurt. The patient doesn’t tolerate it well. The adult, definitely, when I use it on PTTD, I will say six to seven out of 10 of those patients have to have it removed. It serves a purpose for a while and then it causes pain. Youngsters, the same thing, they are far more tolerant. But I will tell you, probably four out of 10 may have to be changed. The other tendency is to use too big of a plug, by the way, which is another reason why they hurt and fail. For some reason, if a little is good, bigger is better. Well, not always. And in the sinus tarsi, all I want to do is block excessive motion and I can feel that on the operating table. Don’t put too much in there and don’t leave the OR with a supinated foot. That’s a disaster. Now, the other thing that I began to realize is I wanted another material that might be more adaptive, more spongy, more forgiving and yet still be solid enough to provide stability. And I actually have been using acellular dermis, and I roll it up into a little tootsie roll. Based upon the size of the canal, based upon the amount of control I need, I put sutures around it and I place it directly into the canal. I have yet to have one patient complain of pain in the sinus tarsi with acellular dermis in the canal. And yet the control has been incredible. The adult, it’s definitely the first line if I’m going to do an arthroereisis procedure now. And the majority of kids that I’m doing, I’m using the rolled acellular dermis. Now, companies come out with different sizes and shapes which make it easy. It’s kind of a no-brainer system. Podiatry likes cannulation, I’ll show you that. We have companies that recognize and suggest you go right across the sinus tarsi, go all the way into it not only the lateral canal, go into the medial canal. I caution you because if you look in the medial canal, you have the interosseous talocalcaneal ligament. The neurovascular supply to the talar body, excuse me, comes right through that ligament. I don’t want to create harm if I don’t need to. Do not violate that ligament. When we look at the canal, I don’t like that picture. There it is. When I make an incision over this canal, it’s about 1.5 to 2 centimeters, I immediately use a little hemostat, gently and bluntly dissect down to the ligament. And you’ll see a very strong ligament sitting on the outside part of the canal. Don’t cut it. As you can see, I just separated the fibers gently. That’s going to be my outside barrier to the canal, by the way. Through that little aperture, I take a rongeur, go in and remove the fibrofatty plug. And now, I’ve got a space that I can park my car in. Now, you’re going to determine what size is going to be most appropriate. You can use the sizes from the companies, you can just use instrumentation you feel. Pronate the foot, supinate the foot, palpate the talonavicular joint. I want to be able to feel that talar head coming out a little bit. I want to be able to see that that foot can pronate. Once I put the plug into that canal now, I close that ligament up and I’ve got to close barrier to prevent extrusion. And I don’t care what material you use or what company you use. The concept is the same, block the motion but don’t overcorrect. And everybody’s got a design with circumferential fibrosis and they got slats and grooves and it’s going to possibly compress with the foot as you pronate and it’s a shape that’s more conical, pointed, I don’t care. And these are all the things that make our life easy in the OR. Cannulated approach. To me, do I need this approach? No. The first few times you do a lateral arthroereisis, if you’re not sure where the sinus tarsi is, God help you. I don’t know. It’s that easy delve that you feel right distal to the fibula a little bit anterior, bang, you feel it. It’s there. Make a cuddle for it.
Now, some people like to put a guide wire into that canal, here it is. And some of the implants go directly over the guide wire. If you feel that’s essential, by all mean, do it. I’ve seen procedures where they push that guide wire out the medial side, grab it with a hemostat and then put your implant down over it. Wow. Who needs that kind of trauma? Unnecessary. But here we are being sure proper placement of the implant to relocate subtalar complex. And once you’ve got that baby controlled, the rest of the foot beautifully responds. Now, here is an example. Take a look at that MRI on the bottom. Look at the extrusion. That was with one of the old silastic implants I put in. Determination of size, there’s nothing wrong with using a C-arm in the OR. Pronating and supinating the foot to determine position, have I gone into the canal far enough, and is it controlling the amount of pronation that I truly want to control? And talonavicular congruity is important in determining that. Interestingly, age is not size dependent. You can’t tell me in a three-year-old, you’re going to go with a 6 millimeter but a 10-year-old, you’re going with a 10 or 12 millimeter. No way. The canal is very good size even in the younger population. And that’s the incision. That’s what it looks like. Check your range of motion. Get your plug in place and you watch a dramatic change in the foot. The supinatus reverses. Why? Because it’s triplane soft tissue deforming, it can reverse. Calcaneal stance position, height of the arch. Look at the difference in this position. If you have to do a TAL because that was the deforming force, do your TAL concomitantly. And it’s unbelievably dramatic, the impact of these procedures comparing. Look at the pictures on top, the ones on the bottom with arthroereisis of different types. The talus is the important bone that we need to relocate. It wants to be in the position that it should be. And then the rest of the foot can undergo plantar flexion, inversion, adduction and function from heel strike, midstance and propulsion. These are dramatic results with extraarticular implantation. No orthotics, obviously. Misconceptions, fuses the subtalar joint, needs to be changed in pediatric patients as the foot grows, must be taken out. And if removed, foot will excessively pronate. The misconception is simple. You want to get that foot as early as possible if it is a severe hypermobile uncontrollable foot. Control it immediately, and watch that foot develop through functional adaptation as the arch grows and the need for orthotic is diminished. That’s the orthotic, by the way, that I worked on, probably, 25 years ago, called the Dynamic Stabilizing Innersole System that is totally controlling of the foot. That is diagnostic as well as therapeutic. If the patient can’t tolerate that insert, I know that foot is uncontrollable. Metadductus, beware. Be sure you take a neutral position x-ray before you operate on your patient in your office. If there’s a lot of adductus, do not do an arthroereisis procedure because you will unmask the metadductus. And I think I’m just about out of time so I’m not going to bore you anymore. But I will tell you, I do use it on my posterior tibial dysfunction patients when I repair the tendon, block the motion as long as there’s no associated degenerative joint disease. And I don’t care what Achilles procedure you select to do, whether you do in gastroc or Achilles lengthenings, if that’s the deforming force, knock it out. I share with you my thoughts on hypermobile flatfoot and just offer you an opinion as to what I’ve been doing for 46 years, 43 years, very successfully. I thank you for the time. I want to thank everyone for coming to this meeting. The amount of time it takes to prepare and put forth a meeting like this is incredible.
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No, you can clap too.