Name: External Fixator Placement
Uploaded: 2016-03-31T00:00:00Z
Duration: 8 min 1 s
Channel: Arthrex

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VID1-00742-EN | A | External Fixator Placement

Todd M. Oliver

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External Fixator Placement

Howdy. My name is Todd Oliver. I'm an orthopedic trauma surgeon from Columbia, Missouri. I wanted to briefly go over some external fixator principles with you today. Just some basic principles of external fixators. You need to understand what increases the stiffness and the rigidity of your construct. There are several ways that you can do so. The one that's been proven to be the most effective, which will be the least useful for you because most of your external fixators will be spanning external fixators for pylon and tibial plateau fractures. But the most important aspect is to try and get bone to bone contact. That works only for transverse fractures, so we'll skip that one. The next most efficacious way of doing it is to increase the diameter of the pins. The larger the diameter of the pin, the stiffer the pin. You can add additional pins. In other words, go from 2 to 3. You can place the rods closer to the skin. The closer the rod is to the skin, the stiffer the construct. You just have to be careful. You don't want to place them so close to the skin that either the clamps or the rod are impinging on the skin. You can vary the angle of your half pins. 45 degree. Difference in angle actually does increase the the stiffness of the construct quite a bit. You can increase the diameter of the rod for the set that you have. That's not possible. You can stack the rods. In other words, parallel rods as opposed to a single rod. You can increase the separation of the pins. Again, that's not overly relevant for what you'll be employing these for, for the most part, because we want to keep the pins out of the future plate site. And so your pins will typically be fairly close together. Yeah. I also want to talk a little bit about thermal necrosis. Pins can be inserted by power or by hand. There is some theory behind inserting them by power will cause some thermal necrosis of the bone. And not only decrease the strength of the fixation of the pin in the bone, but also lead to a higher infection rate. We'll talk first about doing a spanning external fixator for pylon fractures. In other words, intra-articular distal tibia fractures. Or they can be extra articular distal tibia fractures as well. If the skin requires it, the time when you would be employing such a construct is when the skin is just not amenable to surgical stabilization. Typically that's in the nastier injuries that you'll see. Not all pylon fractures require this if you can't get to them right away. Really, it's just for the grossly unstable fractures that either you just can't get an adequate reduction in a splint, or the talus is impacted up into the tibial plafond, and therefore you need some traction. As I stated, you want to keep the pins as far away from the planned surgical side as possible. That's more important in the tibia than it obviously is in the foot. The calcaneal pin. You have to be very careful of the medial and lateral plantar nerves. Typically, you're going to place this in the posterior tuberosity of the calcaneus. As you'll see in the video, some surgeons like to place a second calcaneal pin. But that does place these structures at increased risk. You can place a second pin in the neck of the talus in a cuneiform or the metatarsal. As far as fixation of the distal fibula, if your surgeon asks if you should if he should fix the fibula while he's in there, because typically these are fractures of both the fibula and the distal tibia that is controversial at this stage. Shouldn't be Shouldn't be your call on that. It should be the surgeon's call on that. Some people feel that if the skin is is amenable, you can go ahead and stabilize the fibula. And that gives you a little bit of extra stability with your spanning external fixator. The problem with that is, number one, you may not know where your Definitiv incision is going to be when you actually do go to fix the pylon fracture. And so therefore you may have compromised your ability to make that incision. And secondly, a lot of times someone placing the spanning external fixator isn't the surgeon who's going to be doing the formal fixation. And therefore you're better off just leaving things well enough alone and leaving the fibula alone. Typically you want to get a CT scan of these injuries, but you want to wait until after external fixator placement so that things are disinfected and you can get a better idea of the articular trauma. These are just some examples of instances where you might place a spanning external fixator. Obviously a severely comminuted and displaced injury. You can see the talus being pulled proximally and significant angulation and the top picture. And then that middle picture is after spanning external fixator placement, you can see how it brings everything down. And then the final picture is just after formal fixation. Here's just another example where the talus is shortening things quite a bit. Bottom left picture is in the spanning external fixator, and the right picture is obviously after fixation. This is a pretty neat 3D representation. This was a CT scan after placement of that previous case I just showed you. It's pretty cool. I just thought I'd throw that in for you to look at, but it does show very well where the pins and the delta frame construct exist. There are various constructs that you can employ at surgeon preference for a temporary spanning external fixator. Honestly stability. Long term stability isn't an issue. And so really, whatever the surgeon is most comfortable with and whatever the body habitus or the skin dictates. But you can do a box frame, which is easy. The problem with a box frame is that you have a proximal pin that's going directly medial hitting the other leg, and it's very uncomfortable for patients. You can do it just a unilateral medial frame, which I just don't find gives me the the stability and comfort for the patient that I prefer. And so typically I'm placing a delta frame. But again that's surgeon preference. Spanning external fixation for tibial plateau fractures. A little bit easier to employ. Not as much in the way neurovascular, but once again, a lot of the same principles apply. You don't want to place your Pin sites where you think you're going to be placing a plate later down the road. Typically you'll have you'll need to do this because the femur itself has been impacted down into the proximal tibia or the tibial plateau, and you can't reduce it just in a simple splint. The femur pins are usually placed in an anterolateral position and the tibia pins in an anteromedial position. You typically want to do this with mild knee flexion to allow the patient to sit more comfortably on a toilet in a chair, but not so flexed that they can't lie in bed. And once again, a CT scan is done after fixator placement. Here's just a couple of examples of when you would need to do this again. You can see the femur impacted down into that tibia that was irreducible by closed methods. And then you can see after spanning external fixator placement how that comes out to length. And then this is just that patient fixed. Another example of the femur impacting down into the tibial plateau. For when you place a fixator.