 Now, let me just finish with a few other thoughts. This is Discoid Ladominescus, huge horizontal tear, mostly in Triminescal, and yes, there is a little radio component of the tear, and in the next session, we're going to talk about the different types of tears, but right now, I just want you to get a feel overall for how to address menisci, and review a little more anatomy before we quit. Some terms that you're going to hear us use, day in, day out, didactic, non-didactic, for patients. First, a term everybody uses, severe. You say severe, you mean, you think, this is horrible enough to warrant an intervention. Severe means something. Another word, incidental. Severe means, I see it, I'd like other radiologists to know I saw it, but that's all I care about. It's unrelated. It can't be fixed. It has nothing to do with the patient's clinical syndrome. Contralateral to the side of the patient's symptoms, same thing, means don't touch it. Chronic means it's been there a long time. If you want to touch it, you're taking a risk. Degenerative. If you want to say degenerative, there better be degeneration. There better be DJD. There better be flattening of the femur. Deformity of the tibia, chondromalacia. If you have high signal in the outer third of a 12-year-old, it's vascularity. It's not degeneration, as we discussed. Displacement. Displacement means simply that. One structure is displaced relative to another. It's a lead-in for other descriptors. Let's talk about maybe one or two of those descriptors. Let's talk about displacement. The meniscus should line up with the outer edge of the femur and the tibia on both sides and a healthy person lying on the back. What if they're lying on their back and the meniscus starts to do something like this? The meniscus starts to pooch out a little bit like that. Yeah, my lines are a little fat, but that's okay. Now the patient didn't have trauma. They're lying on their back. They're not even standing up. The hoop stresses that pushed the meniscus around are not in play, so they're lying on their back having a cup of coffee while the MR is going on. So what's going on here? From walking and from the change in shape of the femur and from running and from years and years of use and abuse, the attachments of the meniscus. These attachments here, the menisco tibial and femoral attachments or the root ligament attachments, which I can show you. Here they are. Here's a root ligament attachment right there. Put an arrow on it. Right here, there's the root ligament attachment. These stretch out. So I refer to this phenomenon personally as pseudo extrusion. Or you can say meniscocapsular laxity due to the wear and tear of activities of everyday living or if there's DJD associated with DJD. When do I use the term meniscal extrusion? When I define that one of those attachments is actually torn. Or the meniscus has decided to take a trip south towards Georgia. In other words, it goes down along the tibial gutter here or it goes up in the parafemoral gutter. Then I use the term true meniscal extrusion. Now if you have a meniscus that is ripped off and spit out or a meniscus that is ripped off and thrown into the center of the joint, that's true extrusion or another synonym for that is menisco capsular separation. Another term that is related to shape, although I'm not going to get into shapes today. That's for the next talk, is cleavage. I picked that one out because everybody knows what a cleavage is, right? It's a horizontal line. So if I see a nice horizontal line and it's not a 20 year old and I have DJD, cleavage is the lead in to tell you this is going to be a chronic tear that everybody has when they're 60 years old. Chronic, cleavage, trisonal, body tear, everybody's got that. Don't touch those tears. So cleavage can be a word used to downplay. Finally, the last thing I want to emphasize is the concept of meniscal failure. What does failure mean? Failure means the meniscus isn't doing its job anymore. All day long, failure after failure after failure we see here at PSI. People that are too heavy. The meniscus just couldn't hold up for 50 years under the onslaught of 280 pounds. And the meniscus gradually pseudo extrudes and displaces and displaces and displaces and it no longer supports the joint. And the joint develops arthritis and the bones misshapen and that pushes it out even further and you're not even doing a standing MRI. That is one type of failure. Another type of failure is the meniscus auto digests. There's not much left of it. In that case too, it is not supporting the knee. Now if you have a small meniscus, you've got to go through and we will go through this. The important laundry list of causes for why the meniscus is small. The most common cause far and away is resection. Another important cause is an old tear with a piece that got digested. Maybe an old bucket handle tear that got missed. Another important cause is simple auto digestion from arthritis. Yes, arthritis, especially rheumatoid, will with its enzymes destroy and dissolve the meniscus just like you can normally destroy and dissolve an extruded disc herniation in your back. Yes, your body can take it away. Another cause of a very small meniscus is one that has fragmented and separated. Not a classic bucket handle tear, but again one that has broken up into innumerable pieces. And finally, another cause of a small meniscus is pseudo extrusion where you're through the part of it that is just very thin. In other words, the whole meniscus is shifted and you think it's small. When you look at the coronal, you see the fat part, but the fat part isn't where it's supposed to be. It hits pseudo extruded out into the medial aspect of the knee. So go through your appropriate checklist of small menisci. Yes, there is such a thing as congenital absence of the meniscus. It's usually postural lateral. It's extremely rare. I've seen about five of them in my entire life, which is pretty long. So it's not a common thing. So that concludes our initial discussion of menisci for today. When we come back and review menisci in our next session, we're going to talk about meniscal anatomy. We're going to go through all the roots. This is obviously a meniscal cleavage tear in our discoyed meniscus. We're going to talk about all the root ligaments, all the individual attachments, the variations of the menisci, the displages of the menisci, and we're going to show the individual meniscal tear shapes. And we're going to drill again and again into meniscal extrusion, pseudo extrusion, failure, severity, unstable versus stable menisci, displacement, non-displacement, full thickness tears, partial thickness tears, chronic tears, acute tears, atraumatic, a very important word, versus traumatic, means you probably should fix it. Atraumatic, probably you shouldn't fix it. Cleavage in other shapes, incidental, non-incidental. Thanks, back to you shortly.