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Board Review Foot Conditions

Cavus Foot Deformities

Ryan Fitzgerald, DPM

Ryan Fitzgerald, DPM gives a succinct lecture on cavus foot deformities. Dr Fitzgerald reviews common etiology and different classifications as well as an informative look at surgical options according to the Green classification system.

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Goals and Objectives
  1. List the different types of cavus deformities
  2. Describe the classification of cavus deformities and the progression of the condition
  3. Discuss the green classification for surgical correction
  4. Describe appropriate surgical options for both rigid and flexible deformities
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  • CPME (Credits: 0.5)

    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
  • Ryan Fitzgerald, DPM

    PRESENT RI Associate Editor
    Clinical Assistant Professor of Surgery
    USC GHS Center for Amputation Prevention
    Greenville, SC

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    Ryan Fitzgerald none

  • Lecture Transcript
  • Male Speaker 1: Dr. Overley [phonetic] gave a great talk on that. That is a challenging kind of fracture to get and you'll see it and you'll learn from it. You'll do it and then you'll look back and like, oh my gosh, why did I do that. That's one of the things we were talking about, some ankles that I have fixed that I have then watched go on to Charcot. So it's out there and you will definitely see it. So I'm going to be talking about cavus foot deformities. Again, it's kind of a broad topic to do in 15 minutes. So we're going to skip through a fair amount, but just bear with me here.

    So as you know, a cavus foot is a high-arched foot. Everybody knows that. And it can be described in a variety of ways based on the location and the apex of the deformity, whether it's more anterior or more on the hindfoot. And you could see that there could be a metatarsal cavus, a lesser tarsal cavus, a generalized forefoot cavus or some combination of all of those things. And then ultimately, a rearfoot cavus is going to be something obviously for the rear foot. So a metatarsus cavus is going to be more at Lisfranc’s joint. You kind of see this here as compared to a lesser tarsus cavus, which is going to be further back, kind of in the midtarsal joint. A forefoot cavus is going to be [indecipherable] [00:01:03]. So you can see kind of the apex of deformities, the consequence of that.

    In contrast, a rearfoot cavus use a really high calcaneal inclination angle here. And that is something to note. And then ultimately, there are combined groupings, ones that are both forefoot and rearfoot and that's pretty common overall. It's important to understand the ideology of cavus foot. Commonly, it is a neuromuscular problem. So when you see a cavus foot, you need to be thinking neuromuscular problems. About 66 percent of cases, we can see this. Another 33 are idiopathic, either from trauma or from infection or some other problem. And then there's some congenital issues, spina bifida among them, clubfoot, congenital syphilis. Things like that. So the take-home point for this is, if you see cavus, think neuromuscular until you're kind of proven otherwise.

    There are variety of ways to classify it. The most common which is to think in terms of flexibility, either it is flexible or rigid or it is somewhere in between. Flexible deformities are more noticeable when they're non-weight bearing and you step down and the arch kind of gets back in the position that you want. As they become more rigid, the cavus deformity maintains itself throughout the gait cycle. As they become more severe, you can see that there's limit to joint motion and the fixed adaptation starts to occur. And it's a commonly progressive disorder, not unlike we talked about this morning with the hallux limitus.

    So as you see, as it progresses, it often starts out flexible and then it becomes more rigid. You can see here, this is a hindfoot varus in conjunction with the cavus foot side [phonetic], also very common. So there are a number of associated conditions, largely associated with the forefoot, forefoot varus and valgus ultimately. Plantarflexed first ray, metatarsus adductus, pseudoequinus and also that hindfoot cavus that we noticed. And you can see here, this is just a forefoot valgus. When you load the lateral column, the first ray is plantarflexed.

    Often, these are seen with digital deformities and this slide just kind of talks about that. This is the extensive substitution sensor and flexor substitution that we talked about when we're talking about hammertoe corrections. You can essentially what happens is, is there's tensing of the extensor tendons as you have the cavus. And the only way to get around that is for the tendon to be lengthened. Of course, it can't lengthen, so the toe draws [phonetic] up as a consequence of that. This is a great picture that shows the dorsiflexion of the digits and contractures as the ankle is dorsiflexed in extensive substitution.

    You also have paralysis of the intrinsic musculature, which can cause a claw toe deformity. So again, it's sort of not necessarily germane to the topic, but you can see, these are common deformities that you have to address in conjunction when you're dealing with a cavus foot type. So at pre-operative evaluation, you're thinking you have these patients and you're thinking you're going to take me to surgery. You have to think of a number of things. Again, neurology consult. I can't stress it enough. You have to think some sort of a neurological problem until proven, otherwise. So you, definitely, want to get that worked up. EMGs, nerve conduction studies. Dr. Overley talked about making friends with your local vascular surgeon. You want to know a good neurologist as well because it's going to come in handy for this and for your diabetics and other people.

    You do want to do a gait analysis. See if they have a steppage gait. That's a common indication if they have a drop foot neuromuscular issue often seen in patients with CMT who can commonly have high-arched feet. You want to do a thorough weight-bearing and non-weight bearing exam because again, you're looking for that cavus foot type that may reduce with weight-bearing. So you really want to figure that out.

    And then you want to get radiographs. Most commonly, the lateral radiograph is valuable. And this is kind of a busy slide, but it shows all the things that you're looking for, increased Meary's angle. This bullet hole sinus tarsi, you can see sort of the postural location of the fibula, kind of an indication of a supinated foot position and an increased calcaneal inclination angle. There's a posterior displacement of the cyma line and it's helpful to get a long leg axial tube to see if you have a structure varus in the calcaneus as well. Is it positional or is it the actual curve or the bump. And that's going to give you some indications as to what to do. A gait analysis can sometimes be helpful to see where the pressure points are because often, this is where you're going to have these concomitant deformities, development of calluses, complaints of pain.

    [00:05:03]

    And you could see here very high, in kind of a tripod position, the heel and then under the first and lesser mets. Particularity on this foot, you can see there's more of a cavus foot type. One of the greatest tests and I think it's underutilized is the Coleman Block Test. And I know it's kind of rudimentary and there's a lot of ways to do it. We know it, but I don't know that how often we're actually doing it in our practice. That's why I challenge you to, as you're going back to your residency programs and in your practices, to actually do this. You don't actually need the block. You can use a book, a PDR, a stack of notecards. But ultimately, what you're testing here is to determine whether this is rigid or not by removing the influence of the first ray. And so you can see here, this is a rear hindfoot cavus. And then in with the first ray hanging off the block here, you could see that that reduces. This would be a flexible deformity. Here, the rearfoot doesn't reduce, which would suggest a nonflexible deformity. And essentially, that's what you're looking for, is the hindfoot reducible or not.

    This is the actual clinical photo. You can see bilateral cavus deformities. Here is in rearfoot varus and then in the block test, you could see that that hindfoot realigns. So that suggests that the rearfoot is mobile. And if you can remove the deformity forces of the forefoot, you'll be able to address this condition. So it gives you an idea where you're going to go surgically. So in terms of surgical and conservative management, you know, the nonsurgical stuff is the same stuff that we talked about before, bracing, orthotics, anti-inflammatories, therapy. You're just trying to accommodate for the foot and the position that it's in. These are modestly effective and it depends on how aggressive the deformity is. A flexible deformity is, obviously, going to be far more reducible and it's going to do better with conservative care. The more rigid it becomes, the more aggressive you're going to have to be.

    In terms of orthotics, I think it's another thing that we don't necessarily utilize enough or at least we don't utilize it in the right way. I always tell my patients, the orthotics are like eyeglasses. They do you no good in the drawer and they correct your foot function without changing your feet in the same way that eyeglasses improve your vision without actually changing your eyes. So they work when you're wearing them. And that's an important thing. Now, a orthotic for a cavus foot is going to be very different than a flatfoot orthotic and you have to kind of know the nuances of that. But it's important to try, particularly in the flexible types. Physical therapy can sometimes be helpful, sugar modification, all the things that we've talked about. And you could see here, there's an orthotic with a -- this orthotic is not really doing the job. You can see that it still has a fair amount of space here for the medial arch. And the heel is kind of coming up off the medial flare. So this could be modified and be a little more effective for this patient.

    So in terms of surgical judgement, what are you thinking about? Particularly in a context of neurological disease, and I know I'm hitting on this a lot, but it's important because it's 66 percent of these cases. You have to really consider this is an option. In the context of neurological disorders, many of them are progressive, so you want to think in terms of what are you going to do. If you're going to do one intervention today, how is that going to look in ten years particular if this is a progressive deformity. So you want to think ahead of what's going to happen. You also want to know, are you having sort of spastic neuromuscular issue or paralysis. Is the muscle tight or is it loose? Is it going to get more tight or be more loose? These are all factors that you need to address. And then is it flexible or rigid. You also want to consider the patient's age. When you're working on kids with spina bifida, you're going to do something very different than, you know, a 60-year-old with CMT. So you have to kind of think that through as well.

    In terms of surgical reconstruction, you have to think when to operate. When you have failed conservative care, that's obviously an indication. And when does it work for the patient. There are some social issues particularly when you're dealing with kids. If you're at a program that does a lot of pediatric surgery and you're dealing with, you know, kids with clubfoot or things like that, you have to kind of work into that sort of mindset. And you have to have clear goals for the surgery. This is not a bunion surgery or hammertoe surgery that you're looking for a functional and anesthetic outpoint. You know, you want to have a braceable foot that is pain free and it functions in a shoe. And you have to have very, very good clear expectations going into it with the patient because if not, they're going to be disappointed and that's going to be a problem.

    So Green came up with a classification system for surgical correction. And essentially, he breaks this down into type 1, 2 and 3, and type 3 is the most common. Essentially, it's a function of how flexible the deformity is and where the location of the deformity is. In type 1, they talked about a forefoot deformity that is largely flexible, and all the surgical procedures described are ones that are addressing that forefoot deformity. As you progress down, type 2 is more rigid in presentation and you're moving more towards a global cavus. That's more in the midfoot with multiplanar components, possibly a rearfoot varus as well. Type 3 is the most common and it's essentially an advanced multiplanars. It's three-dimensionally a problem. And as you progress, this is going to be something that's going to require more of like a triple or some sort of combination deformity correction.

    So when we think of soft tissue procedures, these are more likely geared towards the use of flexible deformity. So obviously, things like Steindler stripping, medial releases where you go through and you kind of release everything on the medial side to let the foot kind of relax out. And that's an option as well. But again, more likely a flexible deformity. If it's rigid, it's not going to move once you reduce the deformity forces.

    [00:10:00]

    In terms of other soft tissue procedures, there are variety of tendon transfers that can be utilized. And these are interesting to do. They're more effective when you get over about ten years of age. So you have to kind of, again, conider the patient population and the age of the people going into it. Certainly, Jones tendon suspension, the Heyman procedure, Hibbs procedure, split tibialis procedure, peroneus longus, posterior tibial. Depending on the muscle strength that you have and it's important to consider what kind of deformity you have. A patient with CMT is going to get a very different transfer than a patient who has a clubfoot, largely because of the muscle weakness that they demonstrate. So you have to really know what muscles are firing. It's important to also remember that when you transfer a muscle, you're weakening it. So you want to make sure you have muscles that are strong enough for transfer because they are going to be weakened.

    So here is a good picture of the Jones tendon suspension and everybody knows this. It's good for a hypermobile first ray that's plantarflexed, but does have mobility. And you're going to just do IPJ fusion and do an EHL transfer to the first metatarsal. I had to bring that up, to reduce that deformity of the forefoot. You then can basically leave the rest alone. Sometimes you can do, if you have combined procedures, you know, calcaneal osteotomy, cotton. Whatever you need to do to get that foot where you want it to be.

    In contrast, a Hibbs is kind of a more global cavus. It's where the whole forefoot is mobile. And you're going to take the EDL, section it, reattach it to sort of the cuneiforms on top here and then anastomose the remaining stumps with the EDB tendons. The stab [phonetic] procedure is a good one as well, but you have to remember what kind of motion you have and where the level of flexibility is but also the strength in the tendons. But essentially, it's just split in the tendon and you're going to anastomose it over through the sort of the distal slip of the peroneus tertius.

    Peroneus longus tendon transfers, again, it's sort of variations on the fame [phonetic]. You're talking something from the one side and moving it to the other to reduce that cavus deformity. Largely, it's something from the inside and moving it to the outside. Posterior tibial transfer, obviously, you're going to take it around through the back, pass it through the interosseous membrane and insert it in the midfoot.

    So those are your soft tissues options, more of a flexible deformity. As the deformity becomes increasingly rigid, you have to start thinking in terms of osseous procedures. What are you going to do to the bones to make them get the position you want. Obviously, things like the Cole, the Japas, dorsiflexory osteotomies. Things that are going to reduce that and there are a lot of different names and they're described in a variety of ways in literature. But you have to consider how much correction you need and just the technical difficulties of some of these cases.

    A Cole procedure gets a lot of correction, but it's kind of hard to assess how much you're going to get and you do end up with kind of a short wide thick foot. So you have to kind of think what you want the end result to look like. Calcaneal osteotomies are an option. If you have that sort of structural varus deformity at the calcaneus. And ultimately, you can progress to an arthrodesis to the hindfoot if you have that sort of in stage kind of deformity. So the Cole procedure as you know is sort of a V osteotomy in the midfoot. And essentially, you're removing this closing wedge to come up with something that looks more like that. So you can see that well there. I can tell you, I've done a few and they're always a challenge. And it looks great on the table, but getting it fixated is really tough to get a really good, strong, stable construct, but it works out okay.

    The Japas procedure is a similar idea, but it's more of a V cut. It's a little more reproducible. The key is you have to perform the ancillary procedures. You have to lengthen the plantar flexion to allow that structures to relax a little bit. A truncated wedge osteotomy, frankly, I do more of these simply because it's a little more reproducible. I feel I can get a better correction, essentially to variational lapidus and then do a Lisfranc fusion. By removing the wedge, you can get what you want. You could see here that this is more into there and then on the lesser digits, in the metatarsals to kind of realign on Meary's angle to get you more of an appropriate position of the foot. And now, obviously, calcaneal osteotomies, closing wedge osteotomies. They're also describing opening wedge osteotomies for the medial side. Those are, I feel, kind of necessarily hard. It's much easier to do a closing osteotomy. You can see here, we just take out a wedge of the calcaneus and then close it down, put a couple of screws through it and you're done.

    Progressing ultimately to hindfoot arthrodesis, which is going to be kind of the in stage procedure for these. And as we discussed, this is sort of the end of it and these patients are likely to have compensatory arthritis elsewhere moving down the line commonly in the ankle among other places. But you do have a lot of flexibility in terms of what you can do because with wedging of the bones, you can end up the foot in the position you want, ultimately. Obviously, you do kind of a closing wedge, truncated wedge to swing the foot out of adduction and then you can reduce the varus component as well.

    Depending on how you position the talus on the calcaneus, you can either flatten the arch or make it higher. And so you can kind of, you know, sort of anteriorly and posteriorly slide the piece before you fix it to get whatever position you want. So it's important to think about that. It's not just enough to hold it in sort of the frontal plane correction that you want, but think in terms of sagittal plane, how far forward or back you want the talus to be located on the calcaneus. And then this shows just kind of how that works with the removal of the bone.

    [00:15:00]

    Now, this is certainly an aggressive correction not necessarily what I would recommend doing, but you get the idea. So here's a patient of mine. You can see that we did a subtalar and did a TN. We actually didn't do CC. We just let it sort of be opened. We took out a wedge and then we also did a closing wedge osteotomy, dorsiflexory wedge osteotomy at the first metatarsal-cuneiform joint. This is a different patient with the triple that we did to reduce that. We did some staples on the outside at the CC joint and the cross screws through the rest of the configuration.

    Anytime you're going to get involved in these reconstructive cases, you have to think in terms of complications and I challenge you to start thinking in terms of complications, you know. Start with that and work backwards because ultimately, that's where you're going to be your sleepless nights. It's going to be trying to deal with this kind of stuff. So commonly, for this sort of reconstructive surgery, the biggest complication and the reason for complication is the wrong procedure, you know. You're trying a tendon transfer on somebody who is obviously rigid or more rigid than can tolerate the transfer and they're unhappy or they have a problem. So it's not really one size fits all. You really have to tailor each correction to the patient themselves. And over-correction or under-correction. If you get too much cavus correction, you're going to end up with the flatfoot, which has its own host of problems. Except now you've done this big corrections, so it's going to be much harder to fix or you just don't get enough of it and the patients are still complaining. So that's an issue. Obviously, now a union, non-union or things you want to address.

    And one of the things that I'll check, you know, Dr. Overley gave a great sort of summary about the medical management of these patients, but you have to think in terms of that. You know, if you're going to be fusing somebody, you want to know that they have the capacity to heal a bone. So you know, I check the vitamin D levels and anybody is getting a fusion, you know. All of the factors that you learned that were important for wound healing, you know, total lymphocyte counts, the protein levels, albumin. All that stuff is still important, perhaps even more so in the healing of bones. So you want to check those levels and really take that to heart. And if you do have a complication, you just got to manage it aggressively. You got to get on it and just see it all the way through.

    It helps to have clear objectives and we talked about that before. The more objectives you have and the more clear you are at the beginning, the less likely you are at the end to have somebody who's unhappy with you because if you start out saying, you know, we're going to give you a foot that works and that you can put a shoe on and you're going to be able to walk and you come up with that even if it's not pretty, they're going to be happy. My residency director always told us, you know, you want to under-promise and over-deliver. And that's how you want to, you know, come through with your correction. If you have any questions.

    Male Speaker 2: No.

    Male Speaker 1: Okay.