All right. I'll be talking about coronoid fractures here. I'll go through some of the basics about this. The objectives here are to go over coronoid anatomy and we'll talk about some of the biomechanical data out there. We'll describe some of the pathoanatomy and injury mechanisms. We'll review some of the classification systems and then go over treatment indications, as well as review some fixation techniques with some examples. Most of this talk is coronoids are quite a broad topic. I'll focus on them in the setting of fracture dislocations from a PLRI perspective. When we look at the ulnar humeral articulation, it tends to be a fairly congruent joint. However, a small fracture can lead to quite a bit of instability that can be subtle without a CT scan. We're looking at both the bony anatomy afforded by the coronoid here as we're talking about this topic, the dynamic stabilizers of the form, as well as the static stabilizers, which are collateral ligaments. They all come together. When we specifically look at the coronoid, it's important to remember, number one, it's an anterior structure that's anterior. It serves as a buttress to prevent recurrent posterior dislocation. It's also a medial structure and it can provide both various stability from the actual bony component of the anterior medial facet, which is quite important, but also the sublime tubercle with the insertion of the medial ulnar collateral ligament can lead to some valgus instability. How much of the coronoid is required to maintain stability? Well, there's some biomechanical data that's over 20 years old now, but there's one study that showed that you needed more than 50% of the coronoid resected to lead to some posterior translation and to create various instability. However, another study by Schneeberger et al. showed that only 30% was needed to create a posterolateral rotatory instability type picture. When we think about the mechanism of injury, there's a rotational force as well as the compressive force that's seen particularly when we have conditions such as PLRI, but also there's a type of combined injury involving both the coronoid and the radial head, which is a little less commonly described as posterior impaction. If you look at the axial imaging here, you could see that the coronoid and radial head fractures are at the same level. When we think about PLRI, this is more of a capsular disruption that I think about it, that the injury occurs from lateral to medial and anteriorly, it can involve the capsule, the coronoid, or both. We'll talk about the implications of both of those in a bit. When we look at the classification systems of coronoid, there's two. The first is more simple. It's x-ray based. This is the Regan-Mori classification. We look at type 1s, which just involve the tip. Then they separated the type 2s and the type 3s. That coincides with that 50% data of when you have instability and not. These can be subclassified into those that with and without an elbow dislocation. Dr. O'Driscoll showed us that the coronoid fractures are actually much more complex. This requires a CT scan to really understand these different injury patterns. Looking at the schematic can be very difficult. Sometimes, it's nice to break it down. We can think of the O'Driscoll type 1s as just the tip fractures. Those can be subclassified based on the size. Two millimeters was what was decided in that classification. Then we look at the intermedial coronoid fractures. These are what we see in our posterior medial rotatory instability. These can be subclassified based on whether it's just the rim, the tip, or if the sublon tubercle is involved as well, leading to that valgus instability. Then you have your larger type 3 fractures, which can be subclassified into those with the transolecron dislocation and not. Another thing to think about here is the cartilage thickness that's at the tip of the coronoid. This group out of Canada showed that there's three millimeters of cartilage at the tip of the coronoid. This can affect both the stability that's afforded by the coronoid fracture, but also fixation techniques as what appears to be a large fragment when you get into the elbow intraoperatively might actually be a small bony piece that may not be able to be fixed with screws and such. We'll talk about that in a bit. What about accounting for other structures such as the radial head? Some biomechanical studies have shown that when you have a type 3 coronoid fracture, that is equivalent to having a type 2 coronoid fracture with a radial head. The valgus instability and rotational instability gets worse when you add a radial head component. This can account for some of the biomechanical studies that show differences. Also, we have to account for the collateral ligaments. In this study, we saw that both type 2 and type 3 coronoid fractures had increased varus to valgus instability, even when the LCL and MCL were repaired. Really, the coronoid probably has a larger component than we think. Then what about the tiny fleck fragments? We see this all the time. These type 1 fractures, biomechanically when this was studied, when they simulated just a 10% fracture, so a very small fracture, there was no difference between the native state, a type 1 fracture being created in the simulation, and the repaired fracture. This was irrespective of the ligament status. Essentially, a small fracture fragment does not really cause any significant instability. But this does not account for the capsule or injury. When we think about the clinical data, do these fractures, these small fractures, need any surgery? Well, there's two pretty good studies out there. One was looking at terrible triads treated non-operatively. Then one was looking at terrible triads where the coronoid was not fixed. When we break down the results of that data, you could say that select type 1 and type 2 coronoid fractures do not need to be treated with surgery, only if the radial head is stable, or it can be addressed to provide stability, whether with an open reduction internal fixation or radial head arthroplasty. You can create a stable arc of motion by fixing the ligaments and the radial head if necessary, and there's a concentric reduction. Now, the challenge with that is that when we think about our algorithm for treating most elbow fracture dislocations, the first step is to fix the coronoid because we're working inside out from the lateral side. That is very difficult to determine before surgery whether or not you're going to have to fix it. We have to think about the size and the location of the fracture indicating the need for a repair. What I think about this is when we get the elbow exposed, I tend to try to stick my index finger across the anterior aspect of the elbow. If I can get myself all the way to the medial edge of the trochlear, I think that there is a large capsular revulsion. For those tiny little flecks, I would suspect that we need to fix that because the capsular injury is what's really causing the instability, not that tiny bony component. Let's think about the size a little bit more. This is looking more at the otriscal type II, so our anterior medial coronoid fractures. This showed was that once you get to that subtype I, so just the rim, and you get to five millimeters, even with the LCL repaired, there is varus instability. Then when you get to the subtype II, so when you have the tip and the rim, now you're getting some valgus instability. You're getting probably towards that sublime tubercle or some medial ligamentous injury. There is this ability to say, you know what, maybe those earlier studies of looking at type at 50% versus 30% did not account for these special subtypes. This is a really nice study. How do I approach these injuries? Most commonly, I will fix coronoid fractures from the lateral side if I can using various techniques. If the radial head's fractured, you could work through it, or sometimes you resect the radial head with a plan to do an arthroplasty afterwards. Now, when do I go medial? In terrible triads, for me, that's fairly rare, but for large anterior medial coronoids, and I'm planning on plating that fracture, I will go through the medial side. I tend to try to work through the floor of the cubital tunnel if I can. But again, that's rare for more simple fractures that we'll talk about in the examples I'll show. Here's a couple of case examples. This is an older patient, 71 years old, had an elbow fracture dislocation, radial head fracture in a coronoid, and it's relatively common to displace this coronoid. It's about 30% when you measure it. By the Reagan-Warren classification, it's a type 2, an artristical type 1, and it's a subtype 2. This is that osteoporotic fragmented fracture that we can see all the time. If you look at that image on the left, you could see where this suture passer is passing through a drill hole that I've made. You could see the fracture bed is quite substantial, but the coronoid really wasn't there. This tends to be a capsular repair of the fracture. Here's a suture lasso being passed through. That's a suture that I've already passed through the capsule. I passed one limb through before, and here's a second limb being passed through, and I can see the good strength of that capsule. That's going to be the anterior buttress and help prevent that posterior translation. Then fix that first, maintain the sutures, don't tie it, address the radial head, the lateral ligament as complex, and then we can tie those at the end. Here's another example. This is a younger patient, so bare bone, 48-year-old. She's had multiple reductions in the emergency department, and the residents tell me there's extreme instability, cannot keep this fracture reduced. There's a relatively large coronoid fracture, about 40% to 50%. When you see this axial image again, this is that posterior impaction injury, where both fractures are at the same level. This is my approach to fix these bigger fragments that I don't think have enough bone to accept screws. I'll use your reduction forceps to maintain the reduction, visualize that reduction directly, and then I'll drill from posterior to anterior, and I'll drill two holes, and I'll pass a suture retriever through each hole. I'd use a separate retriever. These can then act as temporary K-wires, for instance, to maintain the reduction. I can take my clamp off, and then I make sure that, hey, can I see the fracture reduction being maintained? You can see it through this image, and we'll show another video in a bit where it shows it much clearer, but the fracture is well reduced. You can visualize the lesser sigmoid notch through the radial head resection that's there. Then I pass a suture limb through one of the holes that I have drilled, and then I try to make sure that the other suture retriever is still in both holes, still maintaining reduction of the coronoid. Sometimes having your assistant hold the arm in the appropriate rotation there can keep it out of the way. Then I'll use a free needle to grasp the capsule over the top of the coronoid fragment, which I've already done here, which was edited just because my head was in the way. Then we're going to pass the other limb there through the other drill hole, through the coronoid. You'll see here as we pull on this that that's going to give us ability to maintain that fracture reduction. Here's showing this lasso fixation technique. There's a schematic at the top there, and at the bottom here you can see now after everything's done, you can see the coronoid fracture and nicely reduced almost anatomically. Using that reduction forceps as a provisionary step, I think, helps make sure that your drill holes are in the correct position. How about whether or not this is the appropriate technique? Biomechanically, screws are better than sutures. That makes sense at time zero. When we look at clinical data in terms of fracture reduction being maintained, the suture lasso technique is quite stable, and screws tend to lead to almost a 60 percent implant complication rate. With these type 2s, these smaller fractures that I don't think I'm going to get great fixation and have a small medial to lateral dimension, I tend to try to avoid any metal fixation and use the suture lasso technique. Now, here's a much larger coronoid fracture. This is a type 3 in a relatively active male, has some degenerative disease at this point, but this is a one large fracture fragment, had quite a bit of instability. This was using a similar technique. This was a patient actually who could not achieve stability with closed reduction. You can see the external fixer holes that was sent from an outside facility to me. Then I tend to use cannulated screws here because I think it helps with getting your trajectory right, making sure things you can confirm on fluoroscopy. I usually put in three K wires and put in two screws. One acts as an anti-rotation screw. This is a nice other technique. You can use an ACL targeting guide, but I find it much easier to aim towards my own finger holding the reduction there. In some of my take-home messages here, coronoid fractures are usually associated with other injuries. More than 30% involves some instability. It varies based on any associated fractures or ligamentous injuries. In terrible triads, you'll usually see that small fleck, but it's really important to understand how much of a capsular injury truly has occurred during the fall and the trauma. The operative technique really is based on the fragment size and location, I would say. Always be aware of that intermedial coronoid fracture and having to go medial to put a plate on there. Ultimately, the goal is to restore stability, even if it's slightly non-anatomic, the way you reduce the coronoid. Getting that capsule down, I think, is very important in those smaller fragments. Getting the bony anterior buttress back there for the larger fragments would be critical. Thank you very much.

coronoid fractures

biomechanical data

fixation techniques

surgical techniques

stability restoration