Michael J Trepal, DPM discusses the signs and symptoms of tarsal coalitions, non-surgical and surgical options, as well as the past and current literature to address the work-up and treatment of tarsal coalitions.
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Unidentified Male Speaker: In a room full of podiatrists such as this in the New York Metropolitan area, I hardly think our next speaker needs an introduction. Mike Trepal has been at the forefront of podiatric education for nearly 30 years. Yeah. He's Vice President for Academic Affairs at the New York School, Professor of Surgery, runs a residency program and I'm particularly grateful to him for coming and lecturing at this meeting since its inception. So please join me to warmly welcome Dr. Michael Trepal.
Michael Trepal: Thanks Allan. We're actually the same age so he's been around a long time too doing good stuff. Appreciate you being here, as you know on an August day, I'm sure people would rather be at the beach, but I'm not so sure today. It's a lot more comfortable inside than it is outside for sure. So I'm going to be talking quickly about tarsal coalitions. Tarsal coalitions is an area or a subject that podiatry should own and in fact does. It's a condition that occurs or occurs with some degree of frequency and to the untrained person is frequently if not more often than not misdiagnosed.
In terms of disclosures, I am a consultant for Vilex. What we want to do here today is describe the signs and symptoms of tarsal coalition, had to work up a patient, what the treatment options are and look at some of the outcomes. So let's start off with this. This is not an uncommon scenario. Let's assume it's your first day in practice and it's Monday morning, you just started, you signed that contract and you are ready to go and in pops a 10-year-old boy, his mother brings him in, complaint of pain in the foot, in the hind foot, had an ankle sprain, was out running in the school yard.
He tripped and fell and was initially thought to be an ankle sprain gone bad. But you examine him and you find a rigid right heel valgus, the forefoot is abducted, pain most pronounced over the posterior lateral aspect of the foot particularly the sinus tarsi. This is one of those scenarios that kind of almost parallels if I told you a 60-year-old hypertensive taken thiazide diuretics went out for dinner at Morton's and had a steak and a glass of wine and woke up at 3:00 in the morning with a big red swollen big toe joint pain. It doesn't take too much more for you to at least come to a presumptive diagnosis without even examining the patient of you know what?
No, that doesn't mean that it is and it doesn't mean you become complacent, but this was one of those clinical scenarios that are presented frequently in board exams, at all kinds of tests and most importantly, the most important test, real life. So tarsal coalition is an entity where two bones are connections where they shouldn't be connected resulting in restricted or absent motion. They can be and most often are congenital, meaning you're born with them or there are instances where they can be acquired, the acquired ones, which we're just going to briefly skip over, arthritis infections, status post trauma, neoplasm or iatrogenic and that's not the topic of today.
In terms of congenital, there were two theories out there. One has been discounted. The first one, you can see this has been around for a while since that there was an accessory ossicle that somehow wondered into the joint space. So here, you see an os trigonum in the back there of the talus and somehow that little particle would have migrated into the subtalar joint and caused a bridge behind it.
That theory has been pretty much discounted. Basically, what it is, it's a failure of differentiation. Think back to embryology, how diarthrodial joints develop that they start off with a collagenous unlike primitive mesenchymal tissue and that the joint develops. Well, as the joint develops, it doesn't fully develop and there's a little bridge that's left there in between so it's a failure to differentiate in terms of its development. And in fact, it's been shown at least in this study that post mortem examination of human fetuses that in ninth week of gestation, a little over a quarter of fetuses actually had a tarsal coalition as the foot develops through life by the time you get to the 21st week, that's down to about 5%.
[Leonard 0:04:54] showed that this is certainly a genetic tendency to this that it is really transmitted as a genetic mutation, autosomal dominant, with almost complete penetrance. And it's not new mutation, it's been around. Skeletons dating back to 1000 A.D. have shown tarsal coalitions. So it's been around for a long time. In fact, even early going as far back as 3600 B.C., tarsal coalitions had been identified in skeletons. Again, it's not a reportable incident. It's not something like if someone gets Zika virus where it has to be promoted, reported to the department of health.
But for the best retrospective review of insurance information, about 1% of the population have it. So that's a lot of feet out there walking around with tarsal coalition and it could be as high as 2% to 13% of the population. Again, since many of these are asymptomatic, the true prevalence is not known and about the half the patients who have them will have them bilateral and some study suggest slightly male to female predominance of it.
The most common as you know, talocalcaneal and calcaneonavicular will account for most of them. And when it involves the talocalcaneal joint, it will be the middle facet. The clinical presentation is generally a pain, deep aching in the area of the coalition and not uncommon, the onset occurs or the systems occur after some strenuous activity or trauma. Again, they seem to be somewhat age specific. TN coalitions in very young children, but we don't see too many of these. CN bars will generally first manifest or it becomes symptomatic at the 8-, to 12-year-old range and TC is a little bit older in the teenage years.
Again, we said this is frequently after strenuous activity. They have been likened to a sleeping giant that is there and is not until some traumatic event that they awaken, that they become symptomatic. And why? Because around the coalition, there is a plexus of nerve endings. There's a membranous periosteal if you will nerve endings around the coalition and if the coalition is injured in some type of trauma, that sets up the pain syndrome. It's the pain syndrome that creates the peroneal spasm or the splinting of a joint.
The peroneal spasm is reaction to a painful stimuli hereby being some irritation of the coalition. So when we see them, the peroneal spasm usually results in a valgus heel. Believe it or not, we tend to say that you know pronation is the big, bad daddy of all foot conditions, but actually a valgus heel has decreased intra-articular pressure as compared to a supinated heel. And some people have postulated that this was actually position of comfort.
I remember Henry Mankin when he was at the Hospital for Joint Diseases, which was right across the street from the New York School, I had the privilege as a student to go over there and sit in, in one of his talks one time and he was talking about, I don't know everybody puts varus wedges on heels and everything else. Really, we should be pronated and it will be a lot more comfortable in it, but that's for another topic another date. The clinical sciences, again valgus heel, abducted forefoot, depressed arch in adults is just the opposite.
They tend to present even for rectus or maybe even a varus heel splinting from the supinatus of the hind foot. Let me see that. The peroneal spasm, it is a tonic, not a clonic contracture usually related to the painful stimuli that's occurring. Peroneal spasm can be a whole panoply of causes. We think tarsal coalition when unsecured, but depending upon the age group, it could be just a general joint disease of the subtalar joint, a rheumatoid, it could be infection, neoplasm, any other time for the injuries or spastic neurologic in ideology.
But again, the first thing you think of specifically in a child would be that a tarsal coalition. Clinically, you're going to see restricted, a little range of motion of it and with the history with your suspicion of it, the next thing is to come to affirm diagnosis. Imaging will make the diagnosis in most cases for you. We're fortunate nowadays. We have all kinds of advanced imaging, MRIs and CTs. Bone scans are probably not terribly useful here.
Back in the day when these things were first identified, remember it was done without benefit of a CT scan or a valid benefit of an MRI. And in fact, tarsal coalitions were first identified in the early or the mid-1800s before Rankin even developed his x-ray tube and I've always like to relate that. When Rankin in London developed the x-ray tube, there was a whole public outcry about x-rays and the fear was that this x-ray unit would be used to invade people's privacy, not in taking body part, but you can x-ray through a hotel room, you could put one in your apartment and see what they're doing next door.
And there were several editorials in the London Times at the time condemning this new technology about where it would lead to in the invasion of privacy kind of puts today's technology in an interesting comparison. But anyway, we started off with standard x-rays in here. Here, the DP view is the best to identify a TN bar. They're not that common. Usually, they're asymptomatic. This was a patient who presented for bunion and just coincidentally, we noticed that there was also a TN. The more common oblique views to identify a CN bar if it's through osseous coalition, 90% to 100% of the time, you're going to be able to identify that on traditional oblique x-ray.
The lateral x-ray is a little bit less specific. It will show secondary adaptive changes and it could also help you in determining if you know you have a coalition that the proper treatment by giving you of some idea of degree of degenerative joint changes. On the lateral x-ray, we see the so-called C sign, which is actually the sustentacula, which is an oblique fashion from a valgus heel. You can see that in any valgus, the talar beaking, which some people say is pathognomonic.
Basically, talar beaking is pathognomonic of some restriction of motion just like first MTPJ dorsal beaking on the first metatarsal is a sign of hallux limitus. Talar beaking is a sign of equinus or restricted motion in the hind foot. Prominence of the anterior calcaneus refer to sometimes as the anti-design and certainly subtalar joint overlap from the pronated position of it. There, you see a good view of the so-called C sign. If we're looking at talocalcaneal coalitions, the calcaneal axial view is one you want to get. On the left there, you see that the middle facet and the posterior facet are parallel where you see those oblique.
As you see on the right hand side there is also thought to be pathognomonic for tarsal coalitions and greater than 25% is pretty much guaranteed that you have some degree of talocalcaneal coalition there. In the orthopedic literature, this has been referred to as the unstable weight design. Sometimes the oblique and the axial view will only show subtle signs there. You see that looks irregularity even though it's not oblique. It's certainly irregular and therefore advanced imaging is usually necessary to make the diagnosis. The hind foot alignment views can show the position of the entire lower extremity in the sagittal plane as well, which will be helpful.
Traditionally, the CT scan was considered to be the gold standard to image TC coalitions, which you see over there on the right-hand side and obviously it's still very useful for osseous coalitions. Here, you can see an incomplete coalition on the right hand screen there of a partial coalition in the middle facet there and likewise of a partial CN bar on the left hand side. CT can also evaluate degree of subtalar arthritis and help you determine whether resection or fusion is going to be your procedure of choice and here, we're seeing the CN.
CT though, if you're going to do it, you need to have narrow slices and you specifically have to order the examination to get slices as little as one millimeter because sometimes, you can miss it if you're taking a wide slice as it's frequently is done in CT scans, you can actually miss the entire coalition of it. MRI as compared to CT can better image the non-osseous components. Of course, the MRI has the advantage particularly if you're dealing with a young child of no exposure to radiation. Once you've made your diagnosis, we now have to enter some type of treatment plan in general because the surgery here for the most part is somewhat complex or a little more involved.
I think the literature will support that all patients should be given a trial of conservative treatment. What does that shoe modifications, orthosis, local injection of steroid, peroneal block to break the taut of the peroneal spasm. And then, BK inverted [KS] [15:08] for three weeks. And if you do that, about a quarter to a third of them will show clinical improvement. Coalition isn't going to go away, but it gets them into a comfortable position. Indications for surgery are persistence of symptoms following a trial of conservative therapy and that's generally considered to be at least two trials of inverted BK and KS.
If two trials of that isn't going to get the patient pain-free, then three or four or five attempts, that is not going to do no better and then they become a surgical candidate. The surgical options that we have to resect the coalition, we can salvage by arthrodesis or you can also do realignments to take a valgus heel and make it more rectus, either arthroereising or calcaneal osteotomies.
We'll start off quickly with the CN bar. First, the procedure first described by Badgely in 1927 where the bar was resected and the EDB muscle was interposed in between there, fairly standard Ollier's incision to expose the lateral hind foot starting about a centimeter distal to lateral malleolus and directed over towards the base of the second metatarsal. Be careful of the neurovascular structures in there, retract them. The EDB, you're going to be looking right down on it. You reflect the EDB off the anterior calcaneus and you're looking right down at the coalition then the bar is resected. You got a variety of ways to do it.
You can use a saw, you can use a curette, you can use a rongeur, you can use a burr, you can bite it out however you want to get it out. You mechanically need to resect that and you need to do it fairly aggressively because you want to have three quarters of a centimeter of space there unless you have recurrence of the coalition. Badgley then to prevent reattachment of the coalition inserted interpose the EDB muscle, threaded through down to the plantar aspect of the foot and tied the suture over a pad. The problem with this is that the EDB pads, the dorsal lateral aspect of the foot and that it became a painful bony prominence of the anterior calcaneus following this.
So most people now have abandoned using the EDB and in favor of some of the interposition such as bone wax in between the two surfaces and this seems to do pretty good in the retrospective studies I've seen to support that. I'm going to in the interest of time pass over some of those citations. If you want to get specific, just email at the college. I'd be happy to give you the citations, the closure, injection, post-operative care to put them through ranges of motion. There are a number of retrospective studies here showing this that this is an effective procedure.
And that the consensus of the outcome studies of the resection of the CN bar is better in younger patient, collagenous coalition whereas an incomplete coalition where you do a wide resection of the coalition and put some type of material into position in there to decrease the recurrence of the coalition and there's no preexisting degenerative joint disease. And if you do all these, anywhere the success rates, anywhere from 69% to 80% based upon recent studies that also tend to support this. And we'll jump into the TC coalition, the traditional approach always with fusion in all cases.
Recent study show excision of the coalition to be more effective. This time, we'll doing it from the medial side, or incision right over the sustentaculum tali, tibialis posterior and the FDL are reflected in opposite directions giving exposure to the sustentaculum. You can use to – with the help of fluoroscopic examination through pins, one distal, one proximal to the coalition and you can then start to resect a way. These have been John Hurst down in Maryland has – he hasn't published it, but talks about talar dominant, calcaneal dominant or in between of the coalitions.
Actually from a functional point of view, it doesn't make any difference. Intraoperatively, you see that the two pins or needles are used at one anterior and posterior to it using that as a guidance, the coalition is resected. Again, you can burr it, you can rongeur it. You just want to get adequate resection there. And then also interpose some material. Again, bone wax is cheap, it's effective and it's relatively inert. Here, we're coating the surfaces of the coalition. You can use autologous fat also if you want to use in closure and there has been several modifications of this.
Some people have used a split FHL tendon, which is right in the area. I did that once. I'll never do it again. It's all attempts at the same concept to try and put some material in there to prevent reattachment of the coalition. Again, physical therapy, range of motion is critical to the success of this and looking at the outcome studies, this shows to be most successful when the TC bars resected again in a younger patient where there's an incomplete coalition where you do wide resection of the coalition. You put some type of material in there.
There's no significant DJD and the general rule of thumb if the coalition is less than 50% of the joint surface, it's best to resect it rather than go on to fusion. Again, with this will – basically, what those outcome studies do is support what I just told you. In the absent of DJD and the absence of greater than 50% articular involvement, resection should be the first line. In cases where you have significant arthritis, fusion of the hind foot even as the subtalar joint or a complete triple arthrodesis is indicated and therefore you have the – always the dichotomy here, resection versus fusion, resection versus fusion.
And if you've used the criteria that were mentioned, I think at least the literature will show and my own personal experience that that's the way to go. Where you have valgus deformity over there, a variety of resection of a combination of resecting the coalition and realigning the hind foot has shown to be effective as well. So summary on here, the take home points, tarsal coalition is frequently the cause of a rigid heel valgus with peroneal spasm. There's a genetic predisposition to it affecting about 1% of the population.
CN and TC is the most common. They commonly present with pain. The best imaging studies we talked about, I'm not going to review it. Initially conservative surgery indicated in the failure of conservative therapy, options to resect the coalition or arthrodesis. And that's the whole story on tarsal coalition in a nutshell. Again, this is an area that podiatry should own, does own because as foot experts, I truly believe that this is something that we know the best. Thank you.
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