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Board Review Diabetic Foot

Surgical Management of Charcot Foot and Ankle

Guido LaPorta, DPM, MS

Guido LaPorta, DPM, FACFAS, MS reviews the presentation of midfoot and ankle Charcot, describes the medical and surgical management, use of internal and external fixation and treatment goals.

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Goals and Objectives
  1. Review the clinical presentation of midfoot and ankle Charcot
  2. Describe the Schon classification system
  3. List indications for surgical management
  4. Identify surgical techniques and proper use of internal and external fixators
  5. Relate treatment goals
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  • CPME (Credits: 0.75)

    PRESENT eLearning Systems, LLC is approved by the Council on Podiatric Medical Education as a provider of continuing education in podiatric medicine.

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    Release Date: 03/16/2018 Expiration Date: 12/31/2018

  • Author
  • Guido LaPorta, DPM, MS

    Director Podiatric Medical Education
    Community Medical Center
    Scranton, PA

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  • Lecture Transcript
  • Male Speaker: Now for our final speaker, certainly, last but not least, I always like to have my old friend Guido LaPorta give us his unique perspective on surgery for the Charcot foot. He’s got a great deal of experience in this regard with both internal and external fixation and deformity correction. I can’t think of no one better to invite to speak on this topic other than Guido LaPorta. He’s from Scranton, Pennsylvania. He’s been involved in residency and student, podiatric medical education for many, many years. I still think he remains one of our best and brightest speakers in podiatry. With that, let’s have Guido LaPorta wrap up today’s session. Okay.

    Guido LaPorta: Those were unusually kind words from you Bob. Okay, so I’ll finish up today’s session with my experience with the surgical management of Charcot foot and ankle. When I look at this, it looks like a very complicated scheme and it certainly is. But it can involve any combination of bones and/or joints. But I think primarily, what we see in our clinic is either midfoot presentation or ankle presentation. I’d like to cover those two particular areas today. When I look at the Charcot foot and ankle, we deal with a number of problems, not the least of which is deformity. There may be soft tissue infection, osteomyelitis, inter, intra and periarticular fractures. Certainly, all of these results in an instability and gait dysfunction for this particular patient. When I look at all of these, what I was initially impressed with was that if I were to ask anybody in the audience, what would you do or what would you use for an open intra or periarticular fracture that is probably infected? Well, the majority of you, I think, would say external fixation. That piqued my interest in the use of that particular modality for this particular deformity and I’ll show you some of the ways that I’ve used that. Whenever we embark on a surgical management of this particular deformity, we have to have, I think, some reasonable goals with respect to what we are trying to achieve. Certainly, as was mentioned by Karen, we’re interested in producing stability, eradicate infection when in fact it is present. Presumably, if we can do the first two, we can get an ulcer to heal or prevent further ulcers from occurring. We may simply want to alter their biomechanics. We may simply want to make them a better candidate for bracing or for shoeing their foot. I tell all of my patients that my goal is to make them a community ambulator. I’m seeing this in younger and younger patients and they all want to know how active they can be after something like this is entertained. I’m not trying to make anybody anything but a community ambulator and they should know that. They also should know that they’re going to need some type of protection in the future and just the fact that they’ve undergone a surgical intervention does not necessarily lessen their risk from this happening again. Consequently, they have to be vigilant about protecting their extremity. Our ultimate goal, of course, is to prevent amputation. I should point out that when all of this surgical intervention started some 12 to 15 years ago, these were done on patients who were about to lose their limb. If you’ll notice the literature recently, recently meaning within the last five to six years, now we’re seeing these done on an elective basis where a patient may not be in imminent danger of losing their limb but the thought process let’s in fact try to stabilize this extremity and prevent problems down the road. The ankle presents its own set of problems and I like to divide it into whether or not the talus is normal or whether the talus is abnormal. An abnormal talus can either mean that it is infected or that it has avascular necrosis with collapse and sometimes both are present.

    [05:04]

    Consequently, even though there is a dissociation between the foot and the tibia, there can in fact be a normal talus which might change the way we approach that particular ankle. Who needs surgery? Well, I think most of this has been mentioned but certainly those patients who are unable to be braced successfully and who have malalignment of the extremity are certainly candidates. Patients who have recurrent ulcerations and instability, a nonplantigrade foot and those who are amputation candidates, I think are all candidates, at least, to be assessed for whether or not a surgical intervention would be beneficial. The Eichenholtz classification which we have now changed somewhat due to the recommendations on the consensus panel into active versus inactive Charcot. But there’s always a discussion on how really you can intervene. I think I heard Karen mentioned that the acute Charcot patient, basically, what we’re dealing with are dislocations and/or periarticular or intraarticular fractures, sometimes both in the presence of an intense inflammatory response. I think many times the decision on whether or not to intervene early depends on the amount of deformity present. I’ll show you what my thought process is on that in a minute. With respect to the classification of midfoot Charcot, I like to use the Schon classification. There are many good ones. I use the Schon classification because it fits my thought process and it makes me better able to teach when I’m trying to teach to residents and students. Now, obviously, there are exceptions to any classification. But at least it serves as a starting point. The Schon classification will break this up anatomically into a Lisfranc, navicular cuneiform, perinavicular and midtarsal joint. You can look at this one of two ways. They have described the type A, B and C corresponding to the various columns of the foot. From the standpoint of severity, they have divided it into alpha versus beta. Beta being the most difficult foot to reconstruct and it is earmarked by the presence of dislocations, various angular relationships between the talus and the first metatarsal which suggest that it may not be a very easy task. These are the anatomic representations of those particular areas of involvement and I would point out that the one difference between the Lisfranc involvement and the navicular cuneiform involvement is the location of the ulcer. In a Lisfranc Charcot of the midfoot, the usual presentation of the ulcer is medial and it occurs very quickly, whereas in a navicular cuneiform presentation, the lack of an ulcer medially may sometimes fool you into thinking that you’re not dealing with a very serious presentation. But in fact, what happens because it starts so much proximal in the volt, it is not until the lateral column collapses and then you begin to get a lateral ulcer initially and by that time, the entire midfoot has collapsed. The navicular cuneiform presentation sometimes can be confusing. Now as you look at this classification and you go down the grades from 1 through 4 and across the top from A to C, I teach that as requiring more involvement with external fixation or possibly the complementary use of external fixation and internal fixation. Certainly, I feel in the midfoot that if your Charcot changes, but primarily in the medial column, in the absence of an ulcer with infection, you can usually handle that very confidently with internal fixation alone. But as you involve more of the midfoot and especially the lateral column, that becomes sometimes more difficult. When I look at acute onset Charcot, I ask myself one question, is there acceptable alignment or is there dislocation?

    [10:06]

    If the alignment is acceptable, I think the goal is to halt the process with any form of immobilization that you can implement. Usually, an eggshell or Jones-type cast to help reduce the swelling frequently changed. I’ve seen the process diminish in most cases within a 12 to 20-week period. Although as Karen mentioned, the entire process may take six to eight months in order to be shut down. If in fact, the alignment is not acceptable and there’s dislocation then you have to make a decision. Should I do an open reduction and do a primary arthrodesis right on the spot? There’s only one article I know that’s had any success with doing that and that’s Simon’s article out of Ohio State which showed in 14 patients, 14 successful interventions in acute Charcot. I would have to tell you that has not been my experience and I try to avoid that as much as possible. I would, even in the presence of dislocation, much rather to halt the process somewhat before I consider any intervention. Consequently, I lean more towards closed reduction with or without percutaneous pinning. If I have a chronic deformity, I also ask myself a question, is it stable or unstable? If it’s a stable chronic deformity, you may be able to handle this foot with exostectomy. My only warning about exostectomy is that sometimes, not often, but sometimes when you remove the exuberant bone that is producing the ulcer, you may also be removing the bone that formed to stabilize a dislocated joint or a fracture. Additionally, if it’s stable, you may be able to do this with bracing and/or shoe therapy. If it’s unstable, however, you may want to consider reconstruction. Reconstruction in my mind can be done in one of two ways. It can be done acutely on the table or it can be done gradually over a period of time in order to protect the soft tissue envelope. Our own Bill Grant was the first to point out to us the influence of the Achilles tendon in Charcot and he showed that the collagen changes within the tendon had decreased the tensile strength of that tendon and made it less likely to be able to stretch in the normal gait cycle and consequently lead to midtarsal joint breakdown. It was he who suggested that it would not be farfetched to propose that these changes also occur in bone and ligaments in the midfoot leading to fracture and collapse. There are many, many devices that are at our disposal for use in the midfoot. One of the more popular ones in this country are the use of polyaxial locking plates and certainly every company has one of these. The question is to whether or not locking plates are the answer to this particular problem has yet to be answered. The use of these, I think, has skyrocketed and I’m not quite sure my results with locking plates are any better than they were with non-locking plates for these particular deformities. But sufficed to say, it appears to be the norm right now in most people doing internal fixation. A medial column approach is the plantar plate popularized by Schon is still a very good technique. The only problem I have with the plantar plate is the amount of dissection necessary to place it in its appropriate position. It certainly makes sense it’s on the tension side of the bone. It’s on the side of the bone that collapses. Consequently, it is biomechanically efficient in this particular area. One can see good results in a number of patients. This one, for example, who presented with a midfoot collapse in ulcer which was excised and then the medial column was reconstructed using a plantar plate with a very good fusion along the medial column and a very usable foot. We have also used many off-label approaches to fusing the medial column. This plate may not look familiar to you because it’s not a foot plate. It’s an anatomic distal fibular plate.

    [15:00]

    I use this frequently for medial column fusions because proximally, the screw cluster for the distal fibula fits very well into the talar head and then simply, you can just alter the length of the plate depending on how many joints you attempt to fuse along the medial column. It’s a very good application to the foot. Additionally, you can do arthrodesis assisted with external fixation and the use of a simple pin-to-bar constructs that have the ability to distract and compress can help you position a foot while you are applying your internal fixation. Here, you see the simple external fixation bringing the foot out to length reapproximating the anatomic position and then while that is in place, the application, in this case, of a locking plate to fuse the medial column. Now, what about gradual correction? I use external fixation quite a bit. Most of my approaches to midfoot Charcot are for gradual correction. I do this because I can do most of these corrections without making any incisional approach or minimally invasive approach to the midfoot. There are two strategies. One is the hindfoot is normal and all of the pathology is in the midfoot. In that case, I use a Taylor spatial frame using a butt joint application, meaning the 2/3 ring around the forefoot is the active ingredient that’s going to correct this deformity and I am moving that ring with respect to the stirrup ring around the heel. This is what it looks like clinically. There are two half pins in the tibia, two wires in the heel and two wires in the forefoot. By using the software, I will then move the forefoot into a position so that it realigns with the hindfoot and I will follow that with a beaming technique that has been described by many in the literature. Interestingly enough, Bill Grant, once again was the first to show this beaming technique in our literature. He pointed out that a 7.2 minimum diameter screw was necessary to withstand the force of a 300-pound individual through the midfoot. I should point out that he use cannulated screws and we have found the use of 6.5 solid screws to be sufficient to support that weight. My strategy in using this has changed somewhat. In the beginning, I use the frame through the entire process and waited for fusion to recur. At this point in my life, what I’m doing is realigning the foot. I then take the patient back to the OR, remove the frame and then put in the beaming as soon as I can. What that means to me is that the frame, instead of being on four months average is now on four weeks average. I get the patient under the ex fix as soon as possible. What I can do is take the foot that has a collapse in the midfoot like this with this association of the forefoot and rearfoot. I can reposition it and then beam it and then take the same foot which presents like this on the lateral, reposition it and then beam it and get a very stable foot. If you have a loss of cartilage and the destruction of joints, you don’t even have to open these feet, you can simply put compression across these joints with the inner thread screw and the beaming technique. If the joints are still well-formed, it does involve minimally invasive approaches to formally prepare the joint for fusion. Now using the butt joint suggest that I am able to correct the equinus with a posterior muscle group lengthening. If that is not the case, I’ll show you a technique that I use with the Taylor spatial frame. The beaming technique is very simple. We approach it from the distal metatarsal. The initial guide wire is started through the metatarsal. You have to look at this on orthogonal views in order to assure its position. Once you are sure of its position and we didn’t make a very small stab incision around the pin. We overdrill the entry point to make room for the head of the screw. If we’re using a 6.5 solid screw, we’ll use an 8-millimeter drill in order to make room for the head.

    [20:04]

    Then we’ll pound the wire back as far as possible. It is imperative that this wire go back into the body of the talus. That’s the strongest bone in the medial column and it needs to go back that far in order to gain the appropriate strength. It is introduced back into the body of the talus as you see here and then all the other appropriate metatarsals that you were going to beam and here you see the lateral column beaming back into the body of the calcaneus. The wire is then overdrilled. I only overdrill it pass the Lisfranc’s joint and then I introduce the beaming screws in order to support and share the load of the medial column. This provides a very nice construct, usually very strong. If you use solid screws, it is very appropriate for fusion of these joints. An alternative to that is a Synthes midfoot fusion bolt. This is a solid 6.5 fusion bolt which is non-cannulated and is used much the same way as a non-cannulated screw and it offers significant force in order to stabilize that medial column. I have also made use of pin-to-bar. If I have an acute Charcot that presents and I wish to stabilize, I treat it like it’s a fracture, like it’s a calcaneal fracture or a pilon. I put a pin-to-bar on, get it out to length. First, try to realign it as best I can and leave the pin-to-bar on without the use of a casting technique. I do this especially when the patient presents with an open ulcer that we have to address and be able to access and this allows that to occur very nicely. It’s a very simple way of preserving the length and alignment. Now here’s a case that presents to be a problem. I do a posterior muscle group lengthening. I then look at my dorsiflexion under C-arm and nothing is happening at the ankle. All the dorsiflexion is in the midfoot. In this particular case, I have a choice. I can go in and I can lengthen all those structures behind the ankle or I can stretch them out. The way I stretch them out is using a specific type of frame which is called a miter frame. Here you see two levels of involvement. The ring around the heel is used to correct the equinus in any varus valgus attitude of the heel and the ring around the forefoot is used to correct the forefoot to the hindfoot. This is what a miter frame looks like. My hospital is very happy that I don’t use these too often. That particular frame cost $24,000. Consequently, I use about one of these for every maybe 20 to 25 butt joints that I use. But in a particular patient, I think it very applicable because once again, I’m protecting the soft tissue envelope and I can usually reposition these feet without any massive invasive procedure. What about the Charcot ankle? I think the Charcot ankle presents significant problems and some that are unique from those of midfoot. The consensus panel once again pointed out that Charcot ankle may in fact be a primary indication for surgical intervention and I certainly don’t disagree with that at all because I find them very difficult to brace. At least in my tertiary care center, by the time I get to see them, everything has been tried. Consequently, the foot is disassociated from the tibia and it’s very difficult to imagine that any kind of bracing would have any effect whatsoever. When do I operate? I operate when there is osteomyelitis of the talus. I don’t hesitate to do a tibiocalcaneal fusion by removing the talus. When there’s AVN of the talus, usually, there’s collapse and some of these patients present as the consequence of malleolar fractures or tibialis posterior dysfunction which the treatment for which was not successful. They may have had a pilon fracture.

    [25:02]

    Basically, I think the bottom line is that they’re unbraceable for whatever reason they’re unbraceable and they need to be stabilized. As I look at that, I think there were only a number of options. You can do an ankle fusion. You can do a tibiotalocalcaneal fusion or you can do a tibiocalcaneal fusion and I approach them all the same way. It doesn’t matter to me which one I’m doing. All that matters is the size of the bone graft I have to use and the length of the nail that I have to use. You can again restore length by using a simple compressor distractor to get everything realigned to have this patient ready for your more definitive type of approach. These are the type of patients I see. Okay, where this was an interesting patient where I got a letter from the referring doctor that said that she’s had a two-year history of acute Charcot. That seems a little contradictory but okay, we’ll go at it. What do we do for these patients? Well I think a combination of an intramedullary nail supported by external fixation works very well in these particular people. Now have I used the nail without the internal fixation? Sure. I’ve also used external fixation without the nail. But in severe cases, I use both. This allows me to weightbear the patient rather quickly. I leave the external fixation on until I see bone formation at the proposed fusion sites and then I will remove the external fixation. You see a number of cases here. Some of which had talectomy but this goes to point out the complete disassociation between the foot and the tibia and the need for stability. Here you see the portions of the talus being removed. There’s always a question as to whether or not I should do a tibial calcaneal fusion and accept the shortening of whether I should put bone grafting. My answer to that is that if for some reason I can’t get enough autogenous bone to do this procedure, I’d rather accept the shortening and handle that in the postoperative bracing. If I can get autogenous bone then I will try and salvage that. These are not patients for lengthening by any means and I do not think that these patient do very well with cadaveric bone and I certainly don’t think they do well with femoral head allografts. I think that lengthens an already long healing process and is totally unpredictable. When I use a nail, my second recommendation to you is that I think it inappropriate to use a 150 and sometimes even a 200-millimeter nail although that’s even better. But a 150-millimeter nail means that you’re anchoring that nail in the zone of injury. I don’t think that’s appropriate. I tend to use 300-millieters nails in bigger individuals. I’ll use humeral and/or femoral nails and go up even farther. I think the nail has to pass or enter the isthmus of the tibia. If it does not, I still think it’s at risk. Here is a case with an intramedullary nail protected by an Ilizarov-type fixator and you can see the length of the nail here going up way above the isthmus of the tibia. I think that it’s appropriate. I do not want to rely on any bone around that ankle for stability. There was a tendency early on when people use nails not to lock it proximally, filling that. If in fact they ambulate that that motion that the unlock nail would provide with enhanced diffusion, and that may be true for non-Charcot patients. I don’t find it true for Charcot patients. I think rigidity is the answer in Charcot patients and therefore, I lock all these nails now appropriately. What used to be done was that they would wait for healing to occur, take the frame off and then at that time, lock it proximally. I don’t think that’s proved to be very effective. There are many ways to skin a cat. For those who can’t use an Ilizarov frame, this is a simple pin-to-bar where a foot plate was made and the positioning is maintained during the healing process.

    [30:07]

    It’s much less expensive frame. It’s not a weightbearing frame but it does serve a purpose in some cases. The treatment goals are limb perseveration leading to a community ambulator. The objectives are to mobilize or to do a way with any ankle contracture or varus to the calcaneus, reduce or eliminate rocker bottom of the foot, reduce forefoot supinatus because there’s always a forefoot deformity, be it supinatus or pronatus, reduce the forefoot abduction and medially translate the hindfoot. You want the calcaneus underneath the tibia. It always ends up lateral and unless you can get it under the weightbearing aspect of the tibia, even more medial than you normally would expect the normal relationship to be then you always have eccentric force on your fusion and it may have a tendency to break down. Having said that, I would like to make a few summary comments, this will be quick though. Whenever you embark on something like this, you need to protect the opposite extremity. Therefore, it is not unusual in our clinic for us to see Charcot reckon going on in one side and a brace and on the opposite side. Patient has to depend on that opposite foot and the last thing you want is to start a problem over there. Number two, know your patient. It is unlikely, even when I get a referral from two, three hours away that I would just book somebody for a reconstruction. I’ve got to get to know that patient. I’ve got to know that they want to save their limb as much as I want to save it for them. I have to know their home situation, I have to know their support system or lack of it. If I need a PT consult, I get it before surgery, not after surgery. You need to know what your patient is capable of. Thirdly, traditional musculoskeletal surgery is carpentry, carpentry with blood. This is not carpentry with blood, this is gardening. This requires nurturing, all through the postoperative period. This is not something that you just operate on and wait for them to heal. You’re going to be very busy with these patients during the postoperative period. Fourthly, I would say don’t embark on these reconstructions unless you can handle the complications. You have to be facile with both internal and external fixation. You have to know how to handle bone and soft tissue defects and infections. Fifthly, how many of these do you need to do to feel comfortable? I can’t answer that for you. I can tell you that in the last 15 years, I’ve done over 600 Charcot reconstructions. I’m still not comfortable. I get nervous every time I do one of these. Anything can happen at anytime and it usually does. Lastly, just because somebody has Charcot disease does not mean that they have good circulation. All of these patients require a very thorough vascular workup before you embark on the reconstruction. Thanks for your attention. Bob, it’s all yours.