All right, patella dislocations in general, sometimes they're non-contact, we'll see some examples of that. Other times you can be struck, oftentimes it's a heel blow. The patella can dislocate a mealy, but most of the time, the vast majority, in fact, it's a lateral dislocation. These account for two to 3% of all knee injuries, at least according to epidemiologic data. It's not thought to affect one gender more than another. Classically it occurs in the second to third decades of life, but there are several sources that say it's the most common knee injury in children. Now, I couldn't find numbers to validate this, and it was more of a statement in passing in several different references or resources, so that's why I put the question mark there. But somewhere in the neighborhood of 15% to 60%, and oftentimes it's said 50% of the time, recurrence will happen. So if it happens once, there's a fairly good chance that it can happen again. There are certain risk factors, risky business as it were, that contribute at baseline to patella dislocations. I've listed them here. Keep in mind, there may be an underlying kind of connective tissue disorder, such as Ehlers-Danlos, that can contribute to this. A high-riding patella in general can also be a cause. If the patella groove or notch is flattened, otherwise known as trochlea dysplasia, you can be predisposed to a dislocation of the patella. Having dysplastic musculature, so an insufficient vastus medialis, or overactivity of the vastus lateralis, for instance, can contribute to patella dislocations as well. So you may only be able to pick this up in hindsight, but if you're doing pre-participation physical examinations or evaluating patients who are saying they have anterior knee pain, you may look at these things and consider their risk of patella dislocation. On the note of patella dislocation, famous NBA player, played alongside Kobe, straight from high school, this is Andrew Bynum. So he had a fairly innocuous appearing injury. He just goes up for a rebound, and all of a sudden, he plants his leg, and it completely gives out on him. Now, he had a career riddled with knee injuries, and in this instance, this certainly didn't help. But you'll see he lands on someone's foot, he creates that valgus moment, and he dislocated this patella in this instance. The exam's pretty straightforward for patella dislocation, right? If the patella's out of place, probably dislocated, most often laterally, as we discussed earlier. You want to make sure you evaluate for hemarthrosis. This will often be present. Many, many, many clinic patients that I've seen have had patella dislocations, have come in days later, and still have a significant hemarthrosis. Look for tenderness along the medial patella femoral ligament, excuse me, which is helping to hold the patella in place, along with a couple other muscular components. On physical exam, try the apprehension test. As the patient is lying supine with the knee extended, try to take that patella and force it laterally. The patient may note pain, they may tense up their quadriceps in an attempt to prevent you from moving that patella. That's a positive apprehension test and suggestive of likelihood or previous dislocation or subluxation of the patella. You can also look for a J sign. So this patient is showing it to us as he extends his knee, you can see it slide. It's being held into place, so it's subluxing at this point and trying to dislocate. With enough force, and it may not require much, that patella can slide right out of place. The other thing you want to make sure is, in the setting of a patella dislocation, make sure that the neurovascular structures are intact. Far less likely to injure those structures than with a true knee dislocation, but you want to make sure that you have evaluated those and documented them accordingly. I don't know that too many folks out there in AMSSN land or YouTube world are going to know this one. It's a little tricky, but this is Ryder Jones. Ryder Jones just taking a swing, watch his face. Hello. Yeah, he just completely buckles and no one really knows why. In this case, it was because his patella dislocated, and that's what gave out. No significant history of this happening repeatedly in the past. In terms of imaging, a couple of pearls for patella dislocation imaging. Should you image the patella before you reduce it, after you reduce it, or both? For the most part, barring a significant trauma. You can get post-reduction films. I think it's safe to put the patella back into place and then look for your fracture otherwise. If there's a significant mechanism of injury, so struck at a high rate of speed, for me at times in the emergency department, if it was a motor vehicle incident, those types of things, then I might get imaging beforehand. But typically, post-reduction is sufficient. Give you one caveat to this though, particularly post-reduction, if you look carefully at these films, which are from an athlete that I took care of, you look carefully and these films are unremarked. But if you get the sunrise or merchant view, skyline view, you can see that the patient clearly has a patella fracture. It was not seen on the AP or lateral views. Take-home point here, make sure you get that additional third view. I always like to tell the residents and fellows, the knee has three compartments, medial, lateral, and the interior. You should get three views of the knee at least, AP, lateral, and merchant or skyline. The other thing you might see on plain films, particularly the merchant view or skyline view or sunrise view that I just mentioned, you may see this trochlear dysplasia. There's not really much of a notch there and it's flattening out the undersurface of the patella as well, but that's clearly going to predispose someone to a patellar subluxation. Next up on our hit list, that's Baron Davis. So you'll see Baron Davis bearing down on the rim here. He's headed right for a bucket and all of a sudden his knee just collapses on him when he plants and you can see a big divot there. His knee went laterally. He put his hand right in the divot. So again, non-contact patellar dislocation, LeBron, not impressed. All right, so it's out. How do you relocate it? Well, that's pretty straightforward. Just do what this young gal did. You want to roll over and you want to hit it really hard multiple times and probably just go in closed fist usually works best. All right. I'm kidding. I'm kidding. Don't do that. All right. Do what Patrick Mahomes did last year when he dislocated his patella. So he heads up the middle for a QB sneak and he just gets piled on and he's clearly in pain and it later came out that he dislocated his patella, but you can see what happens here is they just straighten it out and there's a clunk all of a sudden, life is well, and he walks off the field. So really patellar dislocations are that easy, right? So put pressure on the patella toward the midline. Most of the time that's going to be a medially directed force. Straighten out the knee and the vast majority of the time, voila, back into place and then you can straighten it out and go from there. Sometimes occasionally the patient will need medications to make them more relaxed, et cetera. But with the exception rather than the rule, these usually go into place pretty easily. As I said earlier, I think post-reduction plain films are a solid plan. At that point in time, barring any fracture, you want to protect the knee. Now sometimes this requires a knee immobilizer to keep it in place, particularly if that's all that you have available to you. A Shields brace or a J brace, depending on where you're practicing, is useful as well. Now that typically has a padded component within the brace that goes laterally on the patella that helps to keep it shifting out. Obviously if it was a medial dislocation, you'll need to reverse the orientation of that brace, but works pretty well and is functional unlike the knee immobilizer. Just like Patrick Mahomes walked off the field, you can let them wait there as tolerated. You want to protect that and make sure they don't do anything that could cause a subsequent dislocation of the patella. A set of insets for pain control is needed if necessary. And then, again, you may also want to consider, as was previously mentioned, aspirate the knee, particularly if it's tense. There can be a significant hemarthrosis associated with this, and drawing out the blood is not necessarily a bad thing. In fact, it can be quite helpful. I've taken more than 100 milliliters of blood out of patients' knees following such injuries. You can imagine how much tension that places on the knee and minimizes range of motion. Also, keep in mind, studies have shown blood is generally toxic to cartilage, so letting it sit in there is probably not doing a ton of favors to the intrareticular surface of the knee. I like to bring things full circle. Remember, we mentioned our One Direction buddy, Niall Heron, on the loose? Well, I didn't just do that because he had the song on the loose. He's actually suffered from patellar dislocations bilaterally. He had surgery on one. I believe he had surgery on the other. I couldn't independently verify that, but he suffered from patellar dislocations over the course of time. One surgery, I believe, was on his left knee, and that was about 2014, give or take. He's afflicted as well. Overall, look for the patellar dislocation patients. You can pretty much guarantee physical therapy is on the way, and they're going to work on strengthening the quad, hip, and core. Careful, closed-chain, short-arc exercises of the quad will generally be implemented and can help to really stabilize it and keep it in place. Many will need patellar bracing, not always for the rest of their life, but it's often the case that it'll be needed for some period of time, and again, that J-Brace or Shield Brace is usually pretty effective in that regard. The return activity, for Patrick Mahomes, it was in six weeks. That's commonly cited as the length of time to rehab and keep that ECAP tracking appropriately before turning it loose to planting and pivoting activities. That, again, mileage may vary, but that's the current guideline recommendation that I could find best cited. Keep in mind, 15% to 50% will dislocate again in two to five years, and if that first dislocation happened before the age of 20, it's highly likely that it could happen again. From a surgery perspective, if there's an associated loose body or a fracture or this keeps happening repeatedly, then concern for reconstruction of the medial patellofemoral ligament or different other surgeries that we won't get into that improve alignment may need to be considered.

2nd Edition, CASE 47

2nd Edition

Rheumatology

patellar dislocation

knee injuries

connective tissue disorders

physical therapy

surgical intervention