 Good day. I'm Dr. Steven Pomerance, and welcome to the Mentor Case Review series, and our concentration today will be the menisci with some unusual and obtuse manifestations of meniscal pathology that you might not think of. I'm here with my talented young colleague, Dr. Joseph Eugorgi, and we're going to go back and forth examining some of these unusual manifestations of meniscal pathology. Let's get started. And this first case is put up in the coronal projection. It is a 51-year-old woman who complains of right knee pain. The clinical concern was for a meniscal tear. So let's start scrolling, and we're scrolling in tandem. Now, in an adult, as we've mentioned on numerous occasions, when you're looking for meniscal pathology, you're more likely to find it in the body. So if you're trying to be efficient, which is a good idea if you want to keep your job, if you're trying to be efficient, you should go to the mid-coronal projection, and often you're going to see horizontal, cleavage, degenerative tears that run like this, inner third, right here, middle third where my rings are, and then outer third where my knuckles are. Those are nonsurgical meniscal tears. Almost everybody's got them as they advance in age. They're nonsurgical. We don't get too excited about them. But the ones that are more fresher are ones that are swollen, or edematous, or gapped, or have cysts, or have an effusion surrounding them, or the patient points to that specific locale as a site of pain. Unfortunately, though, in this case, we're in the mid-coronal plane, and we have what's known as window framing. The meniscus has a window frame of low signal around it on the water-weighted image. It has a window frame of low signal around it on the T1 fat-weighted image, and that's just peachy. That's normal. That is nothing you'd ever want to call a tear. The signal is a little brighter in the outer third. It fades in the inner third. It might slope gently downward. It might communicate with the capsular surface, but not with the inner articular surface, or upper or lower articular surfaces. It's not as bright as Highland Cartilage. In other words, it's a nothing muffin. And it has the rabbit ears that we've talked about. It does have those two little rabbit ears. The rabbit's lying on its side. The ears are sticking backwards right here, and then there's the little face of the rabbit. The rabbit doesn't have a body or any legs, or it looks like a Y lying on its side, and we'll make it a little brighter just so you can see it. Now, you can make just about any signal a tear. You notice if I bring up the window, there's a signal that goes all the way into the inner third. It does fade in the inner third. And what is that? That is progressive meniscal degeneration that's occurring in a 51-year-old from living. But that is not what is ailing her. There is no swelling or inflammation or cartilage disease there. But she does have a problem. Okay. Let's see if we can find it by scrolling, and we'll bring the size down to match pretty closely and start scrolling. And one thing that the water-weighted image does for you is it helps you find the hotspots. It's a detector sequence. So you're basically looking for anything that's bright. There's a little bit of an effusion. There might be a little swelling immediately. And as we move backwards, there's a little swelling right here at the back edge of the meniscus, which is also known as the meniscus root. In other words, the very tip of the meniscus has an attachment to the tibia. Now, let's see if we can make a drawing. So if we looked at the meniscus coronally, it might look something like this. It's a little thinner near the center. It's wider in the periphery. And then for it to be fixated or anchored, it has some attachments out here, which we'll call the menisco capsular attachments. And they go all the way around. They may be a little tighter on the medial side than the lateral side. But there are also ligamentous attachments that go down to the tibia. And I have this one drawn in green, but perhaps I should change my color. Maybe blue just because it's fun. So there is our root ligament. And it's the postural medial meniscus root ligament. So let's see if we can find the root ligament. So here's the meniscus. We work our way in. Let's blow it up a little bit. The meniscus looks like it's fanning out a little bit. There's a little piece right there. And then the ligament should be right here. There should be a robust, dark, straight or arcuate structure that goes right on down. I'm not seeing it. I'm not seeing it either. Looks like a little fuzzy bear right here. And then a little bit of interruption, maybe some tissue in there, maybe not. And then a little more squiggly, linear tissue. On the T1 weighted image, which is far less specific in terms of contrast resolution, all we see is a big gray blur. So perhaps it's time to turn our attention to the sagittal projection. What do you think you'd see in the sagittal projection? You know, I think it kind of looks radial-ish. So I would expect to see a gap or some kind of a disappearance. That's what I'm usually seeing when I have a radial or abrupt ending tear like that. Sure. So let's talk about that for a minute, because there are different types of root injuries. For instance, let's make a picture and let's make the medial meniscus. Axial. This is an axial view. So this can get pretty tricky. So let's assume that we had a radial tear of the root. So the radial tear, a radial tear over here, not in the root, would look a little bit like this, right? A radial tear in the root, right at the root attachment, would look like this. And if it went all the way through, it would be enter a third, middle third, post-tier third. And when you started performing your sagittal slices, what would you see? You'd see normal meniscus, normal meniscus, disappearing ghosted meniscus. And then you might even see a little sliver on the inside, depending upon how close that root tear was all the way to the free edge. In other words, if the root tear was over here, closer to the root, but not quite in it, you would see signal of the meniscus here, and then you'd lose the meniscus falling into this gap, and then you'd see a little meniscus again. So those are types of root injuries, one right up against the free tip, one a little more lateral to the free tip, sorry, a little more medial to the free tip, and then there is the actual root ligament tear. So those are all kind of the family of root injuries, and the root ligament tear is going to be a little bit different. Let's see if we can pick a different color to make it easier on us, we'll try purple. So here's our root ligament, and it is going anteriorly, but also down into the screen axially to attach on the tibia. So if this ligament ends up being transected, then you'll see the meniscus all the way out, this won't be here, we'll erase it. This tear won't be here. See if we can get our eraser to work. So we'll have a pretty good looking meniscus, and then when we get past the meniscus, we'll have a piece of ligament, a space with swelling or blood, and then another piece of ligament going down to the tibia, and that is exactly what has happened here. Let's scroll it one more time. This is a true root injury. So let's go right to it. There is the meniscus. There's the root ligament. There's the interrupted root ligament, and there's the rest of the root ligament. So this is a somewhat unusual and difficult case. Now, if we were cruising along the sagittal, which was my question to you, what would you see? And you said, well, you might see a big radial tear, which is true if the radial tear is right on the root, or you might get all the way through the meniscus. Let's do that. So you're through the meniscus, and then on the very next cut, you see swelling. And what is that swelling? It's swelling around the torn root ligament. So it's suddenly, and without warning, not only does it disappear, it disappears into a vat of inflammatory tissue. And let's see how the T1 looks as well. This is a T2. It's actually not that helpful. Let's see if we have a true T1. This looks like a true T1. Let's blow it up and get our drawing tool out of the way. And that's exactly what happens. Good looking meniscus, still pretty good. Bang. Gone. A big fluffy area of inflammatory tissue where the root would have attached. So these are kind of subtle. These are kind of subtle. I'm wondering, you know, just on a clinical level, how, I mean, how bad is this? Is this something that's going to get a surgery? Is this something that surgeons don't really know much about? Or what does this mean, I guess, for the patient? Sure. Well, I'd say it's an insightful question because it's not a common, it's not a common injury. A lot of general sports medicine people don't really know about this. The folks that focus on sports medicine only and or orthopedic surgeons that go in and look at these, they are familiar with this. And many times what will happen is the root will scar down. And so surgery is not required. However, if the meniscus has other problems, the other anchoring portions of the meniscus to the capsule are damaged and the meniscus at a young age is starting to slide peripherally, then you have to do something about it. Okay. You may have to sew the meniscus to the capsule and provide other stabilization techniques. Otherwise, the meniscus will become a non functioning structure. So the answer to your question is in the majority of isolated ones, they could be managed conservatively. But if it has other complexity to it, then each case is going to have to be taken on its own merit and the position of the meniscus and its stability based on physical examination, i.e. clicking or locking and the MR appearance.