This is Dustin Keller. So, Dustin Keller, when he was playing briefly for the Dolphins, goes out in the flat for a pass here and gets obliterated at just the wrong time. So, he comes down, gets planted, and out goes his leg. So, he completely dislocated his knee too. So, we'll talk here about some, yeah, that's suboptimal. Never spar with the gym master. So, we'll touch on knee dislocations here. All right. This is a true orthopedic emergency. All right. So, I had always been taught that it was a disruption of three of the four major knee ligaments. It turns out that you really actually, by definition, only have to have disruption of two of those four ligaments, but you do have to have disarticulation of the tibia with the femur, right? The cruciate ligaments are typically affected, although there are some reports that show the ACL and the PCL weren't involved and the knee's still dislocated. Keep in mind that the posterior lateral corner can be involved as well. You've heard the phrase unhappy triad. I suspect it's bored and test fodder, and this is classically the ACL, MCL, and a meniscal tear all in one happens with knee dislocations. There are reports that it happens more frequently with lateral meniscus being involved than the medial meniscus, although there aren't great studies that validate it. 60% of the time the knee dislocates, there's an associated fracture, so keep that in mind. And the real critical part of knee dislocations, the ligamentous injuries are terrible and can be catastrophic, but the neuromuscular injuries are even more so, so you need to have a low index of suspicion for those. Made it all this way in the presentation, 50-something minutes, and having given you a classification, but I'm going to throw one at you a little bit because it describes the direction of the dislocation, which I think is helpful in understanding the risk for other injuries, so we'll stay classy here for a second. Up to 50% of the time the tibia translates anteriorly, and that's usually a hyperextension injury, and it's more likely to injure the peroneal nerve. Second most common is the posterior dislocation, and that's that dashboard mechanism I mentioned way back when. This one is actually more likely to shear or place traction on the popliteal artery and cause vascular injury. The rest of them are relatively uncommon. Both lateral and medial injuries require various or valgus stresses respectively. When it's a lateral mechanism, usually the PCL and the ACL are injured as well. In the sense of a medial dislocation, it's more often that the PCL and the posterior lateral arm are injured, so when you see the tibia in a certain position, you should have some underlying idea of what else could potentially be injured. This last type, rotational, is important to keep in mind because if it's a rotational dislocation, those are usually irreducible in a closed sense and will require a surgical intervention just to reduce the knee, let alone fix any of the other injuries. Overall, it's a rare event, and so that's probably why we all don't know more about it. It just doesn't happen that frequently, but when it does, it certainly gets everyone's attention quickly. Studies vary. I found one study that looked at patients between 2010 and 2014. This was from the U.S. and it looked at the National Trauma Data Bank, so that's probably about as good a number as we're going to come up with. The problem here is that it only reports dislocations that were diagnosed, and 50 percent of the time we miss them because the knee spontaneously reduces and we miss it. Again, your index of suspicion has to be appropriately calibrated so that we don't miss these. It happens way more commonly in men than women, four to one ratio. Don't get fooled by the mechanism, particularly in bigger people, whether that's truly obese people or big people with large muscle mass who would technically meet criteria for obesity according to some metrics. That by itself is an independent risk factor for knee dislocations, even in low injury. It doesn't have to be some spectacular hit. As you saw in many of the videos we played thus far, not all of those were huge hits. The scary part here is that with nerve or vascular involvement, amputation can result. The best study, I think, cites it, at least the National Trauma Data Bank study cited it at 3.8 percent. There are some studies that say the risk of amputation is up to 10 percent, and it can even cause death 2.8 percent of the time. Keep that in mind. These are serious things, and as previously mentioned, a true emergency. This one is a little bit much, so I'll admit that in advance. If you're a bit squeamish, I'd be very careful about watching Samantha Sierra from Auburn as she gives us our next example. I have a pretty strong stomach as an ER physician. That one was a little tough to watch. She dislocated both of her knees at the same time, but as was mentioned and will be mentioned multiple times moving forward, you have to consider a spontaneous reduction, okay? Even if it doesn't look grossly out of place, you can't miss this because the consequences can be dire. Make sure that you evaluate the common peroneal and tibial nerves, make sure that you evaluate the common peroneal and tibial nerves, right? Foot drop would be apparent if the common peroneal nerve is involved. That can be up to 25 percent of the times that nerve is far more likely to be injured than the tibial nerve, but both are possible. You also want to assess for vascular damage, right? Dorsalis pedis and posterior tibial pulses. If you have a Doppler available where you are, great. Ultrasound can help in this regard too, depending on your access to it, right? Up to 40 percent of the time in knee dislocations, the popliteal artery will be involved, and it can develop aneurysms or pseudoaneurysms as well, which can be quite problematic. Don't be fooled. If pulses are intact, sometimes there's enough collateral flow to present the appearance of a pulse, so if a knee dislocation is present, that doesn't clear you from the possibility of vascular damage, and even though we spent the first 10 minutes or so going over the knee exam ligamentus-wise, skip it when the knee is dislocated. You can be assured that there are at least a couple of ligaments that are damaged that will be focused on later and need to be addressed potentially surgically, but the vessels and the nerves need to be treated and addressed first. Ironically enough, this young gentleman injured his other knee this weekend while playing for the Cleveland Browns. This is Nick Chubb, but while in Georgia, he's breaking for the sideline. He breaks that tackle mostly, then gets hit again and plants that left leg, and it doesn't end well for Mr. Chubb. So you can see he dislocated his knee as well. First thing to do, whether you're in the training room, on the field, on the court, in the clinic, in the emergency department, wherever you're at, the first thing to do is reduce the knee, right? So make sure that it lines up, upward force often, I mean obviously it depends a bit on which direction the tibia is, but oftentimes upward force on the calf, downward on the femur, longitudinal traction, get things to line up, and then splint it, and it doesn't matter how you splint it, right? You can put them in an air splint, you can put them in a knee immobilizer, you can put two boards on the side of their leg and co-band or tape it up, doesn't matter. You just want to make sure that it's splinted and will not move. Try to make sure that the pulses are intact, do a pre and post reduction neurovascular exam. Those should improve if there's any issue ahead of time, okay? But the one thing you want to keep in mind is this dimple sign. So some people call it a pucker sign, but if you see this on physical examination, do not try to reduce the knee. So it actually is a contraindication to reducing the knee because these types of posterior lateral dislocations, which are admittedly rare, but if seen, trying to reduce them can cause skin necrosis and worsen the outcome significantly, so this is the one caveat. And if you were doubting, right, if the knee is dislocated, this is the time to call an orthopedic surgeon, right? So they need to be called emergently. If there's not one in the stands and you're covering a game, great. When they get to the hospital, they should be notified immediately. If you see this patient in the clinic for some reason or contacts, they need to be seen immediately because they will need their services, okay? This one is perhaps the most impressive one on a couple levels. So this is Todd Miller. He's tight end, former tight end for the Bears. So he's in New Orleans and he catches this pass and you'll see his left leg just buckle. Now a couple things to note. Kudos to him. He caught the ball and held onto it and the defender's arm was literally in between his arm and the ball. He still pulls it in and you can see his left leg just completely buckle. So he suffered a knee dislocation, was taken emergently to the local hospital, and had vascular injury, almost lost his leg. To hear him tell the story, he almost lost his leg, which is probably entirely true. Okay, so plain films for these patients are obviously part of the management, but again, if the knee is obviously disformed, get the pictures first, or excuse me, get the reduction done first and then get the pictures. You can't delay the reduction for imaging. It doesn't matter the type of imaging, okay? And this is always a question particularly for boards and for other discussion, right? So in terms of proceeding with their evaluation, it's often been argued that the gold standard is CT angiogram with runoff. And this will show with good detail vascular injury and to some extent whether or not there are any other fractures associated with the injury, okay? But you have to keep this in mind when you're talking about the popliteal artery. If the pulses are weak, asymmetric, or absent, then you need to call a vascular surgeon immediately, okay? Imaging is contraindicated. Don't waste time getting an ultrasound or a CT angiogram. If their pulses are abnormal or asymmetric, excuse me, please call vascular surgery or get them to a vascular surgeon immediately. If the pulses are intact, you can't assume that everything's normal. We mentioned collateral for previously, so you need to order a vascular study. Again, historically, that was a CT angiogram. It's still the gold standard if it surfaces on a board exam, but the data would suggest, recent studies in particular, that performing ABIs are just as valuable and you don't need a CT angiogram, contrast look, etc. to get it. So if you take the higher ankle pressure and the higher brachial pressure and you create the ratio as shown on the slide, you can get your answer. If their ankle brachial index is greater than 0.9, they still need cereovascular exams, but that has a 100% negative predictive value. By my math, it doesn't get much better than that. But if the ABI is less than 0.9, then you get the further imaging, right? That's, again, if their pulses are intact. Don't delay consultation if their pulses are asymmetric. And our last celebrity, right? This is Teddy Bridgewater, who dislocated his knee in a non-contact drill while playing for the Vikings. I would love to show you an image of that, but since it was a non-contact practice drill, I cannot. So in terms of disposition, right? These patients will need to be at the emergency department if they weren't already, and they will certainly be admitted. They're going to get surgery, the question is, is this for a vascular region? Is it for a neuro nerve region? Or will they tackle the ligamentous injuries right away? It's not usually the case that the ligamentous injuries get addressed right away, given the amount of swelling, okay? As mentioned, the order is kind of vessel, nerve, ligament. I've seen several patients in the clinic who have had knee dislocations and their vessels, whether it's aneurysm or otherwise, have been repaired. They've been treated for their nerve injury, and then they come back for the ligament part, okay? In terms of long-term prognosis, okay? 37% will have some semblance of instability moving forward, according to most studies. 50% get partial recovery if there's nerve involvement. It is not uncommon for ligament revision to be necessary. Sometimes that's due to instability. And the return to sport is a little grim. Now, it's variable, but some studies would suggest somewhere between a fifth and a third of athletes will return to their previous level of function. And while maybe a fifth to a third of athletes make it back, of the patients, athletes that we showed earlier in the presentation, right? Nick Chau, Louis McGahee, Sean Levingston, and Teddy Bridgewater have all come back, right? And so, the return to sport is a little grim. And while maybe a fifth to a third of athletes make it back, of the patients, athletes that we showed earlier in the presentation, right? And while maybe a fifth to a third of athletes make it back, of the patients, athletes that we showed earlier in the presentation, they all come back, right? And so, I know these aren't necessarily the gold standard for recovery,

2nd Edition, CASE 28

2nd Edition

Knee

knee dislocation

orthopedic emergency

vascular injuries

spontaneous reduction

athlete recovery