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TAPE STARTS – [00:00]
Troiano: What we're going to talk about is going to be kind of a review. And I like to just kind of point out some things which are important to practice.
Fixation of ankle fractures. Understanding the fixation of the ankle fracture means that we have to understand the anatomy. Now the anatomy, realistically, there's a lot of moving parts. It seems pretty simple like some of the pictures that Dr. Williams [phonetic] showed. Otherwise, screws are in great position; hardware is in great position. But when you think about it, the foot and ankle are very difficult to operate on. Because any other part that you operate on, you don't then put into a shoe on a 200-pound person and then say, “Now go carry me all around Las Vegas on the strip”, right? If you operate on someone's neck, they cannot use the neck. Even a hand or what have you, they cannot favor it. But in actuality, if you operate on the foot and ankle, it’s a very difficult thing because it’s ever evolving and changing with activity, with weight, with shoe gear, and any stretch of that person's lifestyle. So understanding the anatomy, not just the bones, but also the soft tissue and what's occurring, is paramount to fixing any broken ankle.
Third malleolus, a trimalleolar fracture; something that I want to point out for a second. This is the posterior malleolus. So when you think of medial malleolus, lateral malleolus, you have to really concentrate on that posterior malleolus. Why? Well posterior malleolus, we were all taught in school, if it's not broken by about a third, you don't have to fix it. Anything greater than a third, you should fix it. But I've seen ankle fractures even when a fifth of the ankle joint has been disturbed, that the talus can recess posteriorly and actually sublux. So posterior malleolus is in proportion to the ankle because of the sets [phonetic] [0:01:50] ligament, because of the posterior capsule, because of the FHL that runs there. So there's a lot of rethinking of when to fix the posterior malleolus, going forward.
But it's really the injury due to the pull of PITFL, posterior aspect of the syndesmosis. And if you have injury to the posterior aspect of the syndesmosis and you don't fix the posterior malleolus, then you can expect bad things to happen. In other words, what looks good on the table, if you don't fix that posterior malleolus, the rear portion of the syndesmosis opens and then you start to stress the deltoid ligament. You get some of that stress on the medial malleolus, and that's how you create your nonunion.
Here's another one. While the lateral collateral ligaments are injured frequently in ankle sprains, they are the least injured ligaments in an ankle fracture. So that's not to say that it doesn't happen. But by and large when you see someone with the fibular fracture, it's usually the bone or the ligaments. It's not both. So if a fibular fracture, probably not the ligament. If the ligament, probably not the fibular fracture. With the exception obviously of the Maisonneuve fracture which we're going to get into.
The syndesmotic ligaments will stabilize the ankle mortise, alright. And I'm going to give a lecture after this about the syndesmosis. It's a half an hour lecture, again, that we're going to try to condense, but syndesmosis is paramount to fixing an ankle fracture. For some reason what I'm seeing more and more in the younger generation of surgeons coming out, is the syndesmosis is not fixed so many times. In other words, they inspect the syndesmosis and if there's a little bit of spring or what have you, they usually leave it alone. But rupture of syndesmosis leads to diastasis. Diastasis is going to tax the repair of your ankle fracture.
Alright, so bone healing. Dr. Williams did a great job of going through the stages of bone healing, so I'm not going to belabor it. But what I usually tell patients is you get a clot within that first 1-3 days, very similar to a nosebleed clot. That clot at about three days starts to turn into the consistency of an Italian ice or water ice [phonetic] [0:04:04]. After that Italian ice phase which is the fibrocartilaginous phase, 10 days to six weeks, we start to get a paste before we get to the epoxy.
So the earliest that you want to really start weightbearing someone is that about the four-week to five-week period, because that paste is starting to develop and this is a good time to cyclically load or dynamize the fracture to get the bone a little bit harder. So I would not weight-bear before four weeks, if you can avoid it.
With that said, early range of motion is obviously one of tenets of AO which we will go into soon. But range of motion is paramount as early as possible. As soon as the sutures come out or the staples come out, I would start your range of motion. I usually tell patients to do the alphabet. I tell them if you are watching a television show, take your CAM Walker off and just start with capital letter A, capital letter B, capital letter C, all the way through any commercial break. And then next commercial break, do it again, non-weightbearing of course.
Types of osseous repair, it’s direct and indirect. So indirect goes through hematoma, cartilage and callus ossification, and usually happens when the fracture is unstably fixed. Direct is the preferred way because it's more predictable. There's a cutting cone, stable fixations imparted, and it's not faster. There's just less torus. So the torus is the big haymaker here. Torus is that kind of bone callus that has to remodel over time. How many of us have seen the second metatarsal fracture? That's a stress fracture. It goes on to heal unremarkably, and the person has this big swelling in the middle of their foot because the second metatarsal fracture starts to impede the nerves on both sides. They start to get neuropathy or painful neuroma. So when you're aiming for surgical stability, you're looking for direct healing, because it's more predictable.
So primary versus secondary bone healing, again, not to belabor the point. They're separate processes, one is not better than the other. It's just the more stable, or direct primary bone healing is a lot more predictable.
Here's a good picture of the cutting cone. You can see the advancing of the cutting cone, the osteoclasts come through an “A” forming resorption cavities. By the time you start to see “C”, you start to see deposition of the osteoblasts in the reversal zone. And then the closing cone is the maturation and remodeling of bone. And this wave of cutting cone will go right across your fixation and you can literally see it happen microscopically as time goes on. So again, bony union, full six to eight weeks for the cutting cone across the primary bone repair to migrate.
Secondary bone healing; again, you get a hematoma. There is chondroblastic and osteoblastic differentiation into cartilage. And this happens under low oxygen tension or high oxygen tension over bone. So what does this basically mean? Well, this is the principal part in a nonunion [OFF MIC] because low oxygen tension, right? I.e. smoker, i.e. someone with a catastrophic injury. You're going to get more favoring of cartilage as a post high-oxygen tension, somebody who's responding well and functioning on no-room-air leaders or what have you, nonsmoker or athlete that can highly accept the oxygenation through the lungs. So, people who are aged, people who smoke, people who have high volume injuries are going to favor this cartilage, low oxygen tension relationship. Here, as opposed to primary bone healing, what looks like with pluripotent cells and making the callus or torus here. And hopefully, as these two bones unite with the preparation of the callus here, this callus gets resorbed and flattened, doesn't always happen though.
Biomechanics of callus healing. Hard callus can only form where interfragmentary movement is sufficiently reduced. So now we get into the principles of AO. The more rigidly fixated something, the more imparted something, not necessarily on compression, the likelihood that you're going to get direct healing. However, that is not to say that in order to impart stability, one needs compression, you just need stability. It is a fact that usually the more compressed, the more stable, and that's why when we do our Lapidus, when we do our ankle fracture or what have you, we really want to see the bone kind of scream as we tighten those screws down, because we feel better, but it's not necessarily the compression. Compression is actually osteoclastic, right? It's actually going to necrose the fracture site. But stability is usually imparted by compression. That's why it's important.
Again, if you're recertifying your Boards, taking your Boards, the big difference between primary and secondary bone healing is the fibrocartilaginous phases bypassed in primary bone healing. Doesn't make it faster, just makes it more predictable. So again, compression is not osteogenic. Cyclical compression causes increased strength, when it's about four weeks that you're doing it. Lack of motion at the osseous junction, not compression, is osteogenic. And in fact, compression is not osteogenic, it's contradictory.
So now we're going to see ankle fractures. So, in order to create an ankle fracture, you’re going to have torsional load, bending load, or a compression load. Compression is going to cause impaction, bending is going to cause a transverse fracture, torsional load causing spiral fractures. I call it the breadstick fracture. If you take a breadstick and you kind of turn it on both sides or pencil, you'll see that torsional load causing spiral oblique fracture. Obviously, this is one of the most common that we're going to see in an ankle fracture. Compression is probably the least common, and then the bending load is somewhere in the middle, usually seen on a metatarsal fracture.
So if we look at those types of fractures, transverse is the more stable, comminuted is the decreased or least stable, oblique and spiral are somewhere in between. So if we see a transverse fracture, many of these are not going to be fixed unless it's something like a medial malleolus whereby the deltoid ligament has to hang on for stability. Most of the transverse fractures we can kind of favor conservative therapy. Comminuted fractures by and large need to be plated in some capacity.
AO Philosophy, arbeitsgemeinschaft für osteosynthesefragen. After I finished my residency, I did a fellowship. It was AO fellowship. And you'll see that a lot of the principles that we impart in our everyday practice, we don't even know that we're doing AO philosophy. It's just the way we do it kind of here in the United States, whereby this hand down of the teacher and the professor to the student, is already AO philosophy and we don't recognize it. AO was developed in 1960. The four components are anatomic reduction, stable fixation, atraumatic technique, and early mobilization. Again, this does not necessarily mean early weightbearing, this just means mobilization, range of motion to that particular fixated area.
Fundamental principles in AO fixation are buttressing, which can happen via plate or an external fixator; splintage; IM nailing and Kirschner wires; and then of course interfragmentary compression with lag screw or tension band principle.
Starting with cerclage. Cerclage wire is something that I use on an everyday basis. It’s is great for osteoporotic bone. There is no compression possible even with the heaviest gauge wire. So here in this example you can see cerclage wire around. You say, “Well if I tighten this, I'm going to get compression of the parts.” You're not going to. The wire is designed before you get compression, to break; so no compressions imparted with cerclage wire, great Board question going forward. You don't want to notch or bend the wire excessively. Why? Because it'll break. So where I use cerclage wire in ankle fractures, usually they kind of hunker down that butterfly fragment, and again, you just want to get it to lay into anatomical position. Butterfly fragment, okay to heal via indirect intention or secondary intention bone healing. Don't necessarily need a butterfly fragment rigidly fixated, right? You're just looking for the bone to increase its stability.
K-wires. Again, K wires are like cerclage wires. They cannot impart compression. The diamond trip wires cause less heat, but are less stable from the pullout because they're tipped into a recess. We talked about this yesterday. Wire diameter should not be greater than one third of the bone width. Any screw that you put in, any wire that you put in should not be greater than one third of the bone width, because after that it starts to disturb the blood supply to the bone.
The more perpendicular the wires are to one another, you can significantly improve stability. So if I'm doing an IPJ fusion of a phalanx or what have you, I barely use screws or anything. Two crossing state K-wires at 90 degrees I think are much more stable and will allow bony healing to take place. If the fracture is oblique, three parallel wire should be placed perpendicular to the fracture line. So in other words, as the fracture kind of rotates, you should pick three wires each being perpendicular to that fracture site independently to one another.
So here's an example of a fibular fracture. There was a high-level comminution here. So what I did was I used a neutralization plate, repaired the syndesmosis, and then whatever little pieces were left, I just kind of peppered in K-wires to hold the pieces into position. Obviously, the lion's share of the fracture I'm asking to heal via direct healing, indirect healing for the little pieces, understanding that these may need to come out at another point because they back out, but at least what you're doing here is you're making sure the collateral ligaments have a home to grow to if they are damaged. Again, not usually damaged, but if they are, and of course, the CFL and ATFL have little sets of ligament that comes off of it, and you're going to allow that to heal as well.
For it, K-wires are more stable and less likely to migrate but they're much weaker than smooth. Why? Because they're milled out for the threads. So they feel nice, they act like screws, they hold your pieces in the position, but they're going to break a whole heck of a lot easier. They're also difficult to get out if you plan to put them percutaneous, because you have to wait for the bone to reabsorb around the threaded portion before you pull it out. If an osteotomy is inherently unstable, K-wires will be unpredictable. So whether it be a fracture, if you're using comminuted pieces and you shoot your K-wires like I did in the prior example, there's no guarantee that that bones not going to die, and you're just going to have a floating K-wire. So, instability, K-wires look nice on the table, but they're very unpredictable. So that patient has to know, “Look, if I put some wires, then there's a very good chance that we're gonna have to take these out. But if the wires do their job, the bone will be more rigid, you'll have more bone stock and a more stable ankle conferred.”
Tension band wiring. This is a tricky one to look at. You know, everybody thinks it's pretty easy, but there is a right way and a wrong way to do tension band wiring, and a lot of it has to do with this. K-wires must be inserted parallel to one another. Alright? The reason being is what you're trying to do is you're trying to neutralize all tension forces acting on the fracture and create dynamic compression. Well, how do you create dynamic compression? You have to have eccentric forces placed on the fractured bone.
So in this example, this is a big example here in the hip, what you're looking for is, you're looking for two parallel K-wires, the wire going through the bone or your hanging screw here. And then as this person is walking, or as this person is going through range of motion, what's happening is the greater trochanteric pull is actually causing a reverse pull to the tension band wiring. So every step that this person takes, what it's doing is it's compressing on the tension side, the bone together. Where do you see that most commonly? Fifth metatarsal.
Everybody, if you're going to use tension band wiring, it's most likely going to be in the fifth metatarsal. I use it sometimes for smaller or more transverse pieces in the medial malleolus as well. The idea here that fifth metatarsal, its peroneus brevis is going to pull. As peroneus brevis pulls this fracture portion away, the tension band wire is going to fight the pull eccentrically and pull the fracture together. It is important to get even compression via parallel wires. If you don't have the parallel wires here, then what's going to happen is you're going to get one that's pulling away more than the other one. One's going to compress, one's going to distract, and you're now creating secondary healing, not the direct healing what you were hoping for in the first place.
So, here's an example of fifth metatarsal tension band wiring. Again. you can use a hanging screw here or you can drill through the bone. Fifth metatarsal, I usually try to drill through the bone. Medial malleolus and lateral malleolus, definitely try the hanging screw. So here's an example of hanging screw. Just a screw placed far away from the fracture site, my wires aren't perfectly parallel here, I had to kind of skew them in order to account for this transsyndesmotic screw. But here we are, you can see full compression at the fracture line here.
The other thing is, again, if you're going to use tension band wiring, this is a knotty mess here. There's a very good chance that this is going to have to come out at some point. You tell the patient it’s not a big deal, 10-day to 14-day recovery once the fracture healed. And you know at that same time, you can even scope the ankle if you want to, to kind of decrease in some of the impingement that's inevitably going to develop while they're in the cast for so long.
Now moving forward to screws. Fracture healing under absolute stability, primary bone compressions what you're looking for, there's direct healing without callus occurring. The weakest point is the run out of the screw. If you strip a screw, leave it in place, the bone will fill in and around the screw, alright. If you can still land another screw for your compression and leave the first screw in that stripped, fine. Wider screws are going to offer an increase resistance pull-out but again too wide you're going to break the cortex, so something to consider, again no greater than one third the radius of the bone.
Lag screws must be either partially threaded or over-drilled, so the threads only engage in the far cortex. If you're a resident in the room and you don't use a lot of screws, I would challenge you; go to Home Depot, go to Lowe’s, get two pieces of board and start to play around with under-drills, over-drills, and screws. Fully threaded and partially threaded. Why? Because you can really see, if you have screws on both sides of the osteotomy, there is no compression that occurs if you have threads on both sides. You either need a partially-threaded screw to grab the far cortex and pull it in, or you need to overdrive drill the close cortex or near cortex to allow a glide hole for those screws to slide.
So here's a typical AO picture. This is straight out of McGlamry’s. I use it because I really like it, I think it really shows very nicely how a lag screw compresses.
Again, under-drill here across the fracture site, you're going to counter-sink so that the screw pushes into the bone and you get nice imparted compression, over-drill the near cortex, measure, and then tap if you need to, and then your screw goes in. And as your screw grabs this far cortex, it literally sucks this piece right in and you get nice compression. So grab the cortex is the take home in this. If you cannot grab a cortex, then thankfully we have cancellous screws which will help increase your landing zone for compression. But whenever you can, I don't care if you go through the cortex a little bit, grab what you can, it's going to be much more stable.
And here's an example here with a posterior malleolus fracture. You can see it's got a long spike to it, back into position anatomically. And I'm throwing screws both ways to impart even compression really get tightly together.
Alright, “find a plate” sounds simple stupid. However, there's a right way and there’s a wrong way to apply a plate. The greater distance from the fracture line, the greater strength. You also at a minimum want to purchase three cortices on each side of the fracture. So many times I'll see put people put a plate on, they’ll capture a couple of cortices proximally, a couple distally and be done with it. You need at least three cortices. Now, locking technology counts as a cortex. If you lock a screw into a plate that counts as one cortex, the plate screw interface, then the second one is going to be the plate-bone interface. So right there, locking technology makes it more stable because it's harder for the plate to pull away from the bone.
With that said, a 10-hole plate with two screws on each side is similar to an eight-hole plate with four on each side. Meaning that the farther away from the fracture pattern you're going to get, the more stable. So a 10-hole plate, assuming that you're using the most proximal and the most distal plate holes, are going to be as strong as an eight-hole plate closer to the fracture osteotomy.
Of course, use lag screws whenever possible. You want to bend the plate a little bit away from the bone for axial compression, because as the screws bite into the plate, they'll push the fracture together if you bend the plate away. Why? Because the tension side of the fibula is the side that we're normally plating. The compression side is the more medial side. So when you think of a fibula, you have a compression side here and you have a tension side here. If you plate laterally which is the tension side, what happens is, it confers stability on the medial side. So for femur, for fibula, for fifth metatarsal, the sides differ. Femur laterally; fibula laterally; fifth metatarsal actually the undersurface is going to be the tension side, the compression side is going to be the dorsal.
Why do we do this then? Why do we plate second metatarsals dorsally? Anatomy, it's a whole heck of a lot easier to get. So although we would like to plate the tension side, we're not really going to dissect all the intrinsics away, and all the long flexors, the nerves and everything. Our cost benefit ratio is disturbed when we're talking about metatarsals. So, we usually get what we can get, and we plate the dorsal side, hopefully, although it's the compression side, we're not disturbing the anatomy.
Now, in order to understand plates, you have to understand why you're putting the plates in. So a fibular plate, a medial malleolar plate, oftentimes is a neutralization plate. Neutralization plate, what does that mean? That means the whole plate that you're inserting with all these screws, the whole purpose is to protect these two screws here. This whole plate, all the titanium, all the stainless steel, all the grabbing of the four cortices, all they're doing is protecting and neutralizing the bending forces from these two screws. That's the whole purpose of it.
So, you know, again, you don't necessarily need all these screws, you need three cortices proximally, three cortices distally, and that plate is going to stop the bending momentum and protect the screws. Here's an example of a neutralization plate. Again, neutralization plate is just protecting against the rotation of this fracture here. Again, another example.
Now buttress plate. Buttress plate is what I tell my residents, you know, when you're growing up and mom says, “Clean your room” and you're in a hurry, you take all the stuff in your room, you throw it in the closet, you slam the door, and you hope that door catches. Because if it doesn't, all the clothes are going to fall back out. That's what you're doing with a buttress plate. You're basically throwing everything against the wall and whatever sticks is great. And then once you get everything to alignment, you're going to put a plate on it. And by the grace of God, hopefully it's going to heal. Happens sometimes other times it doesn't.
But a buttress plate is not without its charm. Where do we use a lot of buttress plates? The calcaneus. Calcaneus is a buttress plate, what you're doing laterally is you're taking all these comminuted pieces, and you're just throwing hardware against the bone hoping that it doesn't push back out. And you know, if you're lucky enough and you use them locking technology, then the plate doesn't pull away from the bone, and the calcaneus will heal and you get an acceptable result. Sometimes you don't. So patient has to be aware of that as well.
A compression plate can generate interfragmentary compression. Again, it has to be on the tension side of the bone to do so, and the most proximal screws have to be away from the fracture site. The idea here is as this screw head comes in and hits the plate, the bone below it is going to start to push against this side. If we use another screw here that's pushing back, we're going to get imparted stability or compression here. And as you can see the screw had going from the most far portion of the plate is now centered in the plate. Why? Because the bone moved along the screw head and same side here. And then you have compression at your osteotomy or fracture site. So compression plates or something that I impart with the neutralization plate as well, to also protect those screws and offer a little bit of compression.
We're going to spend about two minutes on classifications, because it's important to ankle fractures. Weber A, B and C are the same as Lauge-Hansen, SAD to PER. So supination adduction mechanism of injury is the Danis-Weber type A. This only accounts for 10% to 20% of all ankle fractures, and oftentimes do not need to be fixated. Again, you're going to get a transverse fibular fracture because a transverse fracture is so stable, that we don't usually need to fix it. However, if the ring of the ankle fracture is broken, and you get now a medial malleolus fracture, this confers surgical fixation.
Nondisplaced, weightbearing talus or short leg walking boot with repeated x rays, displaced ORIF. So, obviously this is a prime example of where you would use screws, where you have a big enough piece or put your hanging screw here and use tension band wiring if you can. If you can use one of those hook plates that Dr. William showed, they’re great as well.
Now, supination external rotation ankle fracture; the injury begins at the level of the joint, it is the most common ankle fracture, 40% to 70%. However, again, I keep on seeing this new generation of surgeons come out and if the injury is starting anteriorly, like stage I here, they're breaking the syndesmosis. Stage II is the fibular fracture. Stage III is the posterior aspect of the joint. And then stage IV is the deltoid ligament or the medial malleolar fracture.
So if you've gotten stage I and stage II, you've already damaged the syndesmosis. People say do the hook test, do the cotton test, and they're all well and good, but boy are they positional. So, they are very dependent on how internally or externally rotated that person is on the table and what the C-Arm is doing at that particular time. So, you can get a lot of false positives and a lot of false negatives. When in doubt, fix the syndesmosis. It’s is crazy not to. Here you can see simple SER fracture, we see no medial malleolar fracture.
Weber B are pronation abduction injury, again stable fracture stage I, stage III. This is surgical fixation indicated. Mechanism of injury, pronation external rotation, 7% to 19% of all ankle fractures. However, these are the bad ones that correspond to the Weber C, this of course, any fracture above the level of the ankle joint known as the Maisonneuve fracture needs to be fixated. Have your residents, when someone comes in for simple ankle sprain, absolutely check and document that there's no Maisonneuve fracture by the knee.
I've been burned several times where patient will come in, resident on call, it’ll be two o'clock in the morning, how they sprained their ankle playing basketball, waited a little bit, pain got out of control. And you know, they're fine, they’d put them in a splint, told them they can weight-bear to tolerance in a couple days. The swelling goes down. They start to weight-bear and what happens is that proximal fracture, that no one checked for, now starts to impinge on the common peroneal nerve, where you get secondary type torus healing and that impinges on the nerve going forward where you get shortening of the fibula. So absolutely, absolutely get your high tib-fib films close to the knee in any sort of ankle sprain that shows any pathology when you palpate by the knee and make sure your residents are documenting lack of findings in that area.
Prime example of a Maisonneuve fracture. Now spend one second on this. This obviously you're not going to fix. Why too close to the common peroneal nerve? If you can get length, don't fix it. Mid shaft? What do you do when it’s mid shaft? Well the answer is, if you can't properly reduce it on the table, it is okay to open up and fixate mid shaft. There's a study out of Tokyo showing the absence and the fixation results of mid shaft and the answer is about the same, the outcomes are about the same, but you need to gain length. Anytime you fix a fracture of the ankle, you're looking for medial and lateral malleoli length, restore it back to normal. So if you cannot do that with a mid shaft fibular fracture, then go ahead and open it up and repair it as needed.
Again, the Volkmann fractures, we're all taught 25% to 30% of the articulator surface involved. It requires fixation. I'm down to about less than 20%. If it's greater than 20%, it needs to be fixed as far as I'm concerned. I fixed some with 10% if they’re too high displaced like this. If it's non-displaced, and it's just a little fracture, little chip fracture then I don't think you need to fix it if it’s around the 20% area, but certainly something as big as this needs to be fixed no doubt about it. How do you fix it? Well you can fix it from your lateral position, toggle it down with a dive punch, hold it together and then shoot a K-wire from posterior anterior, and then you can shoot the screw over the K-wire from anterior to posterior to grab this piece in and suck it down almost like a whirlybird.
Tillaux-Chaput fractures, again, pathognomonic for a child due to external forces causing avulsion of the anterior tib-fib ligament. These are syndesmotic injuries, in an adult. This is the reason why you have to fix this syndesmosis. The Wagstaffe or Le Forte fracture is avulsion fractures of the anterior margin of the distal fibula. So it's the same as the Tillaux-Chaput, right, except for one is off of the tibia, the others off of the fibula. That's the difference.
So avulsion fracture again indicates damage to the tib-fib ligament. Rarely is a bimalleolar fracture nondisplaced. By and large they need to be fixed. There are periods in an aged person, someone who's not active, that you cannot fix a bimalleolar fracture, but they are few and far between. So, if you see a bimalleolar fracture and you do not fix ankle fractures, at least refer it out, cover your butt, just to make sure you get somebody else's eyes on there. It is not standard of care to not fix a bimalleolar fracture without good reason.
Closed fractures should be treated within three weeks. After that you start to get bony healing. You should not cut through fracture blisters. If you do, you increase the infection rate, depending on who you read, up to 60%. Wait till the fracture blisters resolve. Hematoma block, conscious sedation to relocate the ankle.
Vassals principle is something that you should be comfortable with. The dominant fracture in any of those Lauge-Hansen classifications, once you fix that dominant fracture, the Vassals principal suggest that all the other smaller fractures are going to realign. What does that mean? It makes your fixation a whole lot easier. Doesn't mean that you don't need to fixate the minor fractures, just means that it makes him a lot more easily fixated because everything falls into line.
When do you fix clear space? 42% tibiotalar contact occurs with just one millimeter of lateral talar displacement. So if you see the talus is shifted from the medial position from a medial mortise, you're going to decrease tibiotalar contact 42%. What does that mean? That means greater than one millimeter of lateral talar displacement I fix in a healthy person; two millimeters, absolutely fix.
Lisfranc. If you're looking at Lisfranc’s, it's about two to three millimeters of displacement and that’s okay, less so in the ankle. It's the higher weightbearing joints, more complex. If we're going to look, again, four millimeters of displacement here, less than two millimeters here, two millimeters here. So our overlap, this is one that you look at first and you say, “Well I don't know that I need to fix it.” Right syndesmosis is a little bit sprung here, but you can see a four-millimeter displacement here. Here certainly bimalleolar fracture you're going to fix.
Finally, treatment parameters for talocrural angle. This is an important one, talocrural angle you're seeing more and more. It is the inferior colliculus [phonetic] [0:34:32] here with the tip of the fibular malleolus and tip of the medial malleolus drawn, and then it is a perpendicular line between the two; 83 degrees plus or minus means that you've restored your syndesmosis and your fibular medial malleolar angles together. As you see more shortening, these lines become more parallel. So if you're looking for a good way to gauge whether or not you fixed the ankle fracture, look at the talocrural angle. Again, 83 degrees plus or minus, compared to the other side.
So, surgeons’ goal for absolute stability or no motion through the fracture site, screw fixation alone can only tolerate minimal loading, which is why you need a plate. Plate version has been employed to help alleviate the shear and bending forces across the fracture site. We're not going to go into a million different ways of looking at ankle fractures.
Final thing that I'd like to talk about here is the Coonrad-Bugg trapping, which I've seen from time to time. If you do a lot of ankle fractures, and even if you don't, sometimes you never get the proper reduction. So like here, this person fixated. They did a nice job, the fibular length or outer length here, and they’re nicely compressing their syndesmosis here. Obviously, I would like another cortex here or another screw here. But if you have locking technology, assuming this screw is locking into the plate, which I'll give them the benefit of the doubt, that counts.
However, you see that this is not closed. The middle malleolus space is not closed here. Why? Because the Coonrad-Bugg trapping tells me that the posterior tibial tendon can be extra faceted [phonetic] right into this area. So oftentimes need to open up immediately, inspect, make sure there's nothing there and then manually take the talus and shift it over. Otherwise, again, what's going to happen is as this person starts to weight-bear, they're going to stress the syndesmosis. If there is a medial malleolar fracture that’s fixated here, you’re going to start to see these screws fail and you're going to start to see re-breakdown of the Maisonneuve fracture. So absolutely, absolutely, absolutely -- fix the syndesmosis and make sure that your overlap is adequate.
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