Section: Canada Category: Foot Conditions Pathomechanics Radiology

Peri-Talar Subluxation

Harold Schoenhaus, DPM

Harold Schoenhaus, DPM discusses the pathomechanics and etiology of peri-talar subluxation in the pediatric and adult populations. Dr Schoenhaus also discusses procedures that may be performed to adequately account for a patient’s pronated subtalar joint.

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Goals and Objectives
  1. Describe the concept of Peri-talar subluxation
  2. Explain materials used for the procedures that address peri-talar subluxation
  3. Recognize the role of subtalar joint in hypermobile flatfoot
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  • CPME (Credits: 0.75)

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  • Lecture Transcript
  • TAPE STARTS – [00:00]


    Harold Schoenhaus: Our first speaker is myself, who as you know, I'm Harold Schoenhaus. I've been a podiatric physician and surgeon since 1970. So that gives me like 48 years of experience doing something, something repetitive, and hopefully, something that's been in addition to our profession, educationally, because I've devoted my life to education at all levels, whether it's residency, whether it's at meeting such as this, whether it's writing articles, whether it's doing research. Education is critical in my mind.

    At the present time, I'm an attending physician at Penn-Presbyterian Medical Center, full professor at Temple University School of Podiatric Medicine. Although, all that being said, the topic that I selected for this first session is what I refer to now as peritalar subluxation. Excuse me. Now, you may wonder, what does peritalar subluxation truly imply and what does it mean? And why don't we use this term more frequently?

    I have no disclosures. Learning objectives are important to understand so we're going to understand the concept of peritalar subluxation, various materials that had been used in the past to treat it. And certainly, discussing the role associated with hypermobile flatfoot. We're going to be talking about procedures associated with peritalar subluxation. We're going to be talking about something that goes into the sinus tarsi. You've referred to this as an arthroereisis procedure. We've associated it with uncontrollable hypermobile flatfoot.

    [02:02]

    So we are going to be looking at something that's extra-articular, reversible, ease of implantation, ease of removal and allowing for early weight bearing. So I'm sure you've heard the term uncontrollable hypermobile flatfoot. It's a generalized type of term, not really specific as to what joints are particularly involved, where the destructive component begins or emanates from, and what the result is on the position and the function of the foot.

    So I've always been in the opinion that you want to reposition this subluxation. It's an abnormal position between the talus and the calcaneus with dramatic effect at the talonavicular articulation because that's the ball and socket joint. So we will see different planes of deformation as a patient stands and walks. So what's our goal? We want to block excessive motion, always allow normal motion to take place.

    In a younger patient, we would like to allow for functional adaptation, change the shape of the arch, the position of the foot. That often entails dealing with some of the deforming forces that are leading to peritalar subluxation. Some, we may be able to control with an orthotic. Some, we may have to deal with, with surgical intervention. An example is equinus, a primary type of equinus is a destructive force on the foot. It breaks down the subtalar and midtarsal joints. We need to obtain this dorsiflexion that is lacking because of a tied Achilles. The only place in the foot we can get it is through triplanar motion, which is at the subtalar level.

    [04:05]

    That is part of this peritalar subluxation and then the midtarsal level. These are pronatory, supinatory joints of which dorsiflexion is an element or a component. The midtarsal joint in fact gives us more dorsiflexion than the subtalar complex. So we need to open that up to get that dorsiflexion. That occurs as a subtalar joint pronates additionally. So we now will look at peritalar subluxation.

    So what are we trying to do? We want to realign this joint complex. It's very interesting that we do everything to deal with circumstances around this deformity but do we truly identify or deal with the actual subluxation that's taking place between bones? What's the goal if you have banged our toe and sublux or dislocate a joint? Are you going to put it back into position? That's what we need to be thinking in terms of realignment of this subluxation, and it's a question of, how you're going to go about doing that?

    Certainly from a conservative standpoint, orthotics will play a role. This afternoon, I'm going to be talking about orthotics in hypermobile flatfoot, discussing different types, and what in my mind, is essential to have incorporated in an orthotic to make it both diagnostic and therapeutic, and we'll deal with that later.

    So what are the indications? Indications associated with this subluxation is it's an adult-acquired flatfoot. That's what we see. That's what the patient comes in with, a flatfoot condition, whether it's adult or pediatric.

    [06:01]

    So once again, what are we doing? Realigning the subtalar joint complex with direct influence on both axes of the midtarsal, as well as the first ray. All right. We're going to take this foot and actually spring it back, put that recoil back into the foot itself, but allow normal motion during the different phases of gait.

    So if we take a look at the position or a transection through the midtarsal joint, we see what happens as we move from neutral, this is the talonavicular component, actually the head of the talus. Here's the portion of the calcaneocuboid joint. So as we start to pronate, we have divergence of these two bones, talus on calcaneus. When we supinate, we come back up on top. And when we start to look at X-rays, we obviously observe what happens as we move from neutral to pronated. This angle of divergence in the dorsal plantar view increases dramatically. And as that happens, we expose the head of the talus. It simply rolls right out of the cup of the navicular. That's a ball and socket joint.

    So the arch collapses. The forefoot goes into the dorsiflexion eversion in an abducted position. That's the three planes associated with pronation. How bad is it and when should you initiate some form of treatment? Here is a youngster walking and you can already see the changes taking place in the longitudinal arch, which is dropped. The first ray, which is prominent because of hypermobility, the abducted gait as they go into the propulsive phase. All of this leads to changes within the forefoot and rearfoot position, which leads to eventual symptomatology.

    [07:59]

    And if we wait, which has often been recommended, take the child and wait for them to outgrow this hyperpronated position or peritalar subluxation, it's not happening. Why won't it happen? Because the deforming forces, such as equinus, internal torques, forefoot varus, flexible forefoot valgus, these are deforming forces. They're not going away. Equinus when you're born with it or have that as a deformity, that's not going away.

    So to wait for this arch to smack, come back up, we can wait until the cows come home. And when we start to look at what is the response of the foot to these deforming forces and what is bad about hyperpronation, is we will start to develop forefoot deformities even in the juvenile, such as hallux abducto valgus.

    So of course, there are signs and symptoms associated with this deformity of hypermobility and subluxation, growing pains, leg cramps, sedentary activity, you can read them. They are unbelievable. That's what brings the patient into your office or the mother that's concerned that the baby's foot is flat. The pediatrician has said, "Don't worry. They are going to outgrow it." They are watching them grow, grow, grow, grow, and they're not outgrowing it.

    Interestingly, kids adopt pretty good. And in today's world where everybody is on their little computers, they are sitting down more, not doing anything else. So the sedentary component actually goes to their advantage that they are not producing the symptoms at an earlier age that they used to, but the deformities are still there.

    [10:04]

    So we could see the compensated position and our goal is to get them out of that position. When we look from the back of the foot, we could see a foot that looks like the calcaneus is everted to the leg, and here we have we the forefoot abducted. The fact is the calcaneus is actually transposing, moving lateral, and the medial column is driving the foot down into the longitudinal arch, looking as a completely flat or hypermobile flatfoot.

    As we look at X-rays, we see the destructive changes associated with severe hyperpronation as the talus plantar flexes dramatically and what do we notice happening here? Obliteration of the sinus tarsi. The talus slides right down into the sulcus of the calcaneus and we lose the sinus tarsi in its appearance.

    So it's nice to put all kinds of little lines on this for patients and for yourself to get an idea of where deformities are present, and can we change those? Can we reverse them? And there is the abduction component that we see. Cuboid abduction relative to the calcaneus, talus moving away from the navicular. The forefoot going laterally and that is the beginning of pulling on the hallux, leading to hallux abducto valgus with hypermobility the first ray.

    So I am very careful in my evaluation and examination about patient going from history to physical exam, which entails and includes gait analysis.

    [12:05]

    I want to watch that foot as it's going from heel strike mid-stance propulsive phase. Where is the stability being lost and can I regain stability? And you could see how much abduction is taking place on a foot such as this.

    Extra-articular osteotomies are used in more severe or advanced cases. But when you think about it, what are we doing when we lose those type of osteotomies? We're trying to change the structure around the peritalar subluxation. You still have to address the components of the joints that are breaking down.

    So how do you do that? Now, through the years and through 47, 48 years of me doing surgery, I've always looked at a sinus tarsi as God's gift to podiatry. Because if I can hold that sinus tarsi up – sorry about that. If I can maintain the shape of the sinus tarsi, the talus comes up on the calcaneus, it relocates the entire forefoot. That's the simplest thing I could do in a foot with most dramatic influence in effect. So I take it from what you see here and move it to there. Now that it's open, what do I do with it?

    Through the years, you've seen many procedures recommended and done, which have been referred to as an arthroereisis procedure. Various materials, I put everything in that canal in hope that it would block the excessive motion, eliminate a deforming force and allow for functional adaptation. That's in a younger population.

    [14:06]

    In the adult, the blocking of that subtalar motion is more reliant on what's going into the canal. So polypropylene, polyethylene, absorbable materials and certainly different metallics. And through the years, I realized that one of the things that we are lacking in this deformity is ligamentous integrity has been compromised. The strongest ligament in the foot happens to be the interosseous talocalcaneal ligament. Spring ligament is strong as well but the interosseous talocalcaneal ligament is holding those two key node bones in position. It's like any other joint.

    If you sprain your ankle a number of times and you have laxity, or you've ruptured a ligament, that joint is unstable forever. You see it in the knee when they tear and – a ligament in the front, a collateral ligament, a cruciate ligament. They don't repair, they need to be repaired. And we have not really identified an approach to repair the ligament that helps tighten now, realign and reestablish the normal relationship.

    So these different materials certainly block the motion and then I got into utilizing acellular dermis as a material that goes into the complex, and now will become a new ligament supportive of the interosseous talocalcaneal ligament and the cervical ligament over the canal.

    [15:59]

    And what I ended up doing is just taking acellular dermis, roll it up to almost in a form of a tootsie roll, or a big joint, whatever you'd like to think of it as. The body accepts acellular dermis. I've been using this to repair tendons, ruptured tendons, posterior tibial tendon dysfunction, ligament disruption, anterior talofibular ligament tears. I've used acellular dermis because the body accepts it, recognizes it, and incorporates it into the structure you're putting it at, which is an amazing phenomena, without reaction.

    So I say, why not use acellular dermis in the canal? Now, you could see in different foot types how we can utilize something that is clear, that you can't see on an X-ray, or the metallic implants that also perform the same function of support but not incorporating into a new ligament. That to me becomes critically important. So the realignment phenomena that we've utilized with arthroereisis is now converted by utilizing acellular dermis, which will block the motion, and then become the new ligament of support in the canal.

    I've never gone into the deeper part of the canal. The interosseous talocalcaneal ligament also allows for neurovascular structures to come through and up into the body of the talus, so I never go in that deep. The outer part of the canal is where I place the acellular dermal plug, which is now going to convert into a ligament.

    [18:00]

    When performing this type of procedure, I gently dissect or separate the outer fibers over the canal of the sinus tarsi as you could see here. Just make a little opening. Separate the fibers. Remove any fiber fatty material. I'm now going to implant the actual acellular dermal plug. If you want to use a cannulated system, some people like to put a canal – a wire in the canal, and then follow the plug, putting it directly over so you know exactly where you are. I rarely use intraoperative fluoroscopy on these procedures. The sinus tarsi is a place you could find rather easily without the use of fluoroscopy, but certainly if you want to use it, you can.

    These are a lot of the metallic ones and the other materials that I've used. Take a look at this in the bottom. Here is an MRI showing an extrusion of a plug because of the material. One of the complications I've seen through the years after doing well over a thousand arthroereisis type of procedures is patients don't always tolerate that metal in the canal. That's why I always experiment it with other materials that are strong enough to block the motion, but not until I found the acellular dermis to be the most effective, am I satisfied with where I am now in arthroereisis.

    Now, certainly there's different sizes. Anybody who has done an arthroereisis with other materials, you realize it comes in different sizes. The tendency is to overstuff the canal. You don't need to do that. You don't want to turn a flatfoot to a cavus foot.

    [20:03]

    Patients walking on the outside versus a pronated foot. Cavus feet are rigid. They are not good functioning entities. So you always want to allow a little bit of pronation and I might need an orthotic to help control that overtime as this adaptation takes place, but never oversupinate.

    So I assess and evaluate the extent of hyperpronation on the table. There are actual cannulas that you could put in the canal, pronate and supinate the foot, palpate the talonavicular joint and determine how much control you actually need. So obviously, the goal, look on the bottom, you could see this foot is now back to a more vertical looking position. His was a gastroc lengthening that was done, a little higher than back down here where TAOs are done. And now, we have a foot that is realigned, repositioned.

    This is our zero radiograph which really gives you great definition. Take a look at the hyperpronation in this foot. You have superimposition of metatarsals so you have forefoot supinatus. So the forefoot effect, the talus is down. The sinus tarsi is where the obliteration takes place. And when we reposition, prop up the talus on the calcaneus, the entire foot changes. That's incredible control of the foot and certainly if there's an equinus, I'm going to eliminate that force with a TAO or a gastroc.

    [22:03]

    Patients who you suspect are going to have to wear orthotic for the rest of their lives who were pediatric cases, anywhere from three years of age right into adolescents. They're not going to want to wear orthotics forever. They are not going to wear them. So why not relocate, reposition, do something internal within the foot to allow this patient to function normally?

    Here's a device that I will be talking about a little late this afternoon. This is a DSIS device. It's a very controlling orthotic. I use this for diagnostic and therapeutic purposes. The diagnostic part, if the patient can control or have their foot controlled with this type of device, they may not need surgical intervention.

    If the patient cannot tolerate that device now, it becomes diagnostic, in a sense. It tells me that I cannot control this foot, some form of surgical intervention is going to be necessary. Anytime you're doing any type of arthroereisis or a subluxation repositioning, we have to be very careful that one of the deforming forces is metatarsus adductus. You can't get an abducted foot inside a shoe or as soon as you try to do it, the foot pushes – the shoe pushes the foot. Laterally, you abduct. Where does that abduction occur? Talonavicular articulation. So we now abduct and drop the foot down. But if I reposition the subtalar joint and hold it in place, you may unmask the deforming force of adductus. So now you may have a great rearfoot position and a kid with his toes in.

    [24:01]

    So this is why I recommend you take neutral position versus calcaneal stance position X-rays. These are hypermobile feet. Reposition the foot. Take an X-ray. Allow it to compensate. Take an X-ray. You will identify an unmasked adductus. And if adductus is present and is the deforming force leading to peritalar subluxation, I'm going to have to treat the adductus at the same time.

    So I may have to do metatarsus adductus surgery, breaking five metatarsals to relocate, reposition them in addition to dealing with the rearfoot. Interestingly, in cases of juvenile hallux abducto valgus that I see, I often will treat the HAV deformity, correct it, utilizing whatever technique you're most comfortable with. And then, deal with the deforming force that led to it.

    I wrote an article many years ago that appeared in The Journal of Foot and Ankle Surgery on the ideology of the bunion. There's certainly a genetic component or a hereditary component, but the fact is what you have at birth is not a foot with a bunion. You developed it over time. And what you are developing in the deformity of the forefoot is the direct result of the unlocking of the midtarsal joint coming out of the rearfoot, leading to the imbalance around the great toe joint, allowing the abductor to pull a hallux in a sesamoid apparatus in a lateral direction, and having a first ray going in the opposite direction.

    So the ideology to me is clear. The mistake that we often make even in adolescent or adults, is we will correct a deformity and not deal with a deforming force that led to the development of that deformity.

    [26:06]

    So you have patients come in and say, "I have a bunion but I have heard that bunions come back after surgery." Now, if you're doing a Lapidus, you diminish that chance of recurrence because you blocked the first medial cuneiform articulation. The IM angle will be controlled, very critical. But the majority of bunions we do are not Lapidus, probably osteotomies. Maybe closing base wedges. I don't care what procedure you're selecting other than Lapidus. If you don't do something to control a hyperpronation after you've corrected the deformity, what's going to happen?

    The deforming force continuous again and the slow insidious process leading to recurrence is why patients develop a recurrent hallux abducto valgus. It's not that your surgery was bad on the operating table. You always give yourself a high-five when you look at it and go, "Wow, isn't that beautiful?" And you look at the resident, you can say, "Great, beautiful job. Close it up. We're done." No, you're not done. You just started. That's the internal architecture that you just corrected.

    Now, what are you going to do for the deforming forces? Have you even realized that those are the ones that led to the HAV? Do you explain that to your patient? Do you tell them, "We have to do the following post-operatively to retain the correct position and alignment"? Let alone the fact that if you have peritalar subluxation, you're going to have other symptoms, whether it's heel pain, arch pain, leg pain, knee pain, a little back pain. The entire chain is going to be influenced by this peritalar subluxation.

    [28:01]

    Posterior tibial dysfunction. Unfortunately, we see a fair amount of that. I think it's less than somewhat, and I'm not sure why. So here's the adult flatfoot that there are still stages like stage one and two that there's a hypermobile component. We don't develop a secondary degenerative changes of the subtalar and midtarsal join quite yet. So if I can repair the tendon that's bad, then I've got that under control but what am I going to do with the peritalar subluxation? Because the posterior tibial tendon is the strongest supinator of the foot.

    Because of it breaking down, the peroneus brevis gains mechanical advantage. The foot moves in a pronated position and that's where it wants to stay. We got to relocate. We got to reconstruct that ligament in the canal. That is going to now neutralize the deforming force or the resultant position because of the breakdown of the tendon. That's where going into the sinus tarsi with acellular dermis has also been extremely effective in this type of flat foot.

    And then of course, adjunctive procedures, probably one of the most common ones you'll do with flatfoot where this subluxed foot with a TAO or a gastroc lengthening, and I don't care which one you want to do.

    So at this point, I'm going to stop because I think I bored you enough with this presentation. But just again, I want to stress how dramatic the influence the sinus tarsi can be when it's repositioned and placed where it should be, and then allow for ligamentous integrity to be reestablished. That's where we are today, in my opinion, the state-of-the-art in the sinus tarsi. So I thank you for your time.

    TAPE ENDS [0:30:10]