 Okay, we're back. This is the most fun I've ever had without laughing. Drawing with all these colors is great. I used to be an artist, but I don't know what happened. But nothing good happened as time went on. I can assure you of that. So now I'm on to shoulder week, shark week, I'm on to depth. The concept of depth is a little bit confusing. Because when you're dealing with round tendons, the concept of depth doesn't really apply. You know, these round tendons can split. They can have intra-substance tears. The concept of length and width and depth is different. And we're going to discuss that for round tendons as a separate subject. So what we've been discussing about the shoulder really applies to flat broad tendons, which live inside the shoulder. So let's do it. Let's make another humeral head. We need another one. Another humeral head. And let's make ourselves a rotator cuff. And this time I am not going to draw all the sections of the cuff like the muscle section and the myotendonus unit and the cable and the crescent and the footprint. I'm just going to draw a simple yellow cuff. Because I want to introduce the concept of penetration, depth. Now you would think depth is a pretty simple thing, you know? This would be partial thickness. This would be full thickness all the way through from the articular surface all the way to the superficial surface. And that's pretty true because that's really what the clinician cares about. But they also care about, you know, retraction and length and some of the things we've been discussing. But there are a number of other modifiers that you can get into as you become more and more sophisticated in MRI. Earlier on we discussed the concept and we're going to have to make our arrow thinner now. We discussed the concept of hidden tears, concealed tears. And I'm going to use the color orange to illustrate this. So right here we showed you earlier in another section, in another session together, we showed you a concealed interstitial delamination tear that you couldn't see from the outside from a deltoid splitting procedure and you couldn't see from the arthroscopic view and so we call it concealed. There are other places you can have concealed tears too but it's so important to tell the clinician whether you think the tear is visible from approach A or from approach B or both. Well then it gets more complicated than that. Tears that are partial or full thickness, they can be vertical but like this, but they could also be horizontal from the medial footprint to the lateral footprint all the way through the footprint. But yet it doesn't retract. You used to do the arthrogram and you'd see a little pinhole go out from your arthrography and go out into the bursal space, it was a tiny little line. These are the tears that frequently did that. So they are communicating full thickness tears, but they're not articular surface tears. You can only see them from the outside if they communicate because there are still usually fibers of the foot plate or footprint that are attached medial to them. So you want to make very clear that this type of horizontal rather than vertical full thickness tear is a bursally communicating tear that goes from the humeral side to the bursal side, not from the articular side to the bursal side. This is critical and a lot of these don't retract. These are frequently referred to as foot plate or footprint avulsion tears. When you hear avulsion you think, okay, something came off. Yeah, something did come off, the tendon. But almost never does the bone come off. So they are avulsions without bone. You have to make that clear and educate your audience. Now are there tears where the bone comes off? Yes, but they are few and far between. Let's talk about some other types of tears. What if we had a little tear here, right next to the bare area? Along the articular surface. Let's pretend we're on the articular surface. My lines are a little bit thick. It looks like these two things are attached to each other, but they're not. There's a space there. So let's make the joint space something like green. So you can see where the joint space ends. The joint space ends right there. So hopefully my green line shows through. So I've got a little articular sided tear. It's a partial thickness tear. Again, it's articular sided, but it also has an eponym and has a name. It's called a staus lesion. A supraspinatus tendon articular sided tear for staus. Could you have an infraspinatus articular sided tear? Sure. It just has another eponym. But the one that's popular is the staus lesion. These are pretty darn common. Now what if your staus lesion does this? I said staus, I meant staus. What if it does this? I'd better get back to orange so it's not to confuse you and myself. What if it does this? Then we've got a partial thickness articular sided tear with interstitial extension, also known as partial p articular sided a interstitial int paint lesion. That's a paint. You've got to have a little bit of length to it. Let's keep going, shall we? What if we had a partial thickness tear that ran along the length of the tendon? Maybe something like this. And it retracted back to here. But the outer half of our pancake stayed intact. In other words, you delaminated the entire deep section of the tendon and it retracted. That's a pasta lesion. So that would be a partial thickness. A partial thickness supraspinatus tendon evulsion with retraction, a so-called pasta lesion. Could you have it on the outside? Could you have the upper surface do the same thing and spare the deep surface? In other words, this portion of the cuff tears and retracts, but the deeper portion stays intact. You absolutely could, and you do, and that's what's known as a reverse pasta lesion. Oh, but there's more. You thought, oh, just when you thought it was safe to go back in the water, no, here comes the tiger shark. So now we're going to go back to something that is pretty intuitive. Let's make our cuff yellow again. And this time we're going to take our tears, which are orange, and we've already discussed articular-sided ones, stoss and paint and interstitial ones, like the concealed interstitial delamination, and then we've got bursal-sided tears. Bursal-sided tears are often very saucerized. In fact, some people will even use that word, saucerized bursal-sided tear. If they look like little hairs and are very tiny and ill-defined, my lines are a little fat for it, then we'd call it bursal-sided fraying. But very often, when you have a partial bursal-sided tear, it is at the foot plate or footprint. That's the most common place. And it has a very distinct shape to it. It looks a little bit like a gullwing or a W. And that is called the gullwing sign. Some people say the bird sign. Some people say the W sign. But when you see that shape, and especially if you don't have high resolution, you know that you have a unique bursal-sided tear that is probably contained and doesn't go all the way through and allow fibers to retract. So it is a sign of a partial thickness tear. Now, let's finish with a flurry, but a really important thing when you are serving clinicians and therefore their patients. What happens when you have a tear and you just can't figure out whether it goes through or not, whether it comes out the bursal surface? That happens a lot. Especially if you have a lot of swelling or you have lower field and you don't have the spatial detail. Well, there are some indirect signs you can use, like if the fibers, the yellow fibers crimp, they micro-retract. They'll do this. They'll wave on you. Or you have macro-retraction where they just simply do this. Then you know. But another useful sign is if you can see what I call the spillage sign. The spillage sign is when you can see the signal going this way and then you see it spill on either end, going either medial or lateral into the bursal space. The mere presence of fluid is suggestive, but it's not diagnostic. But if you can connect the spillage to this hole, then you know you've got a full thickness tear. If you can't connect the spillage, if all you see is fluid on the outside and you have a deeper tear and you've got a decision to make, and a good term to use in that scenario is near full thickness tear. But when you say near full thickness tear, you want to always rectify it and clarify it by saying that it is a pinhole or it's diminutive or it's only one millimeter in diameter. A lot of those tears, which used to be surgical and sewed, are not surgerized anymore. So if you use too big a word, you know, near full thickness or high grade, a lot of you will use the term high grade out there. If you use high grade thought process for surgeon, high grade, knife. No, not a knife. It's deep, but it's tiny. So you've got to convey that message. You've got to separate in your head depth from length and retraction. They've all got to come together to sell the proper story of what should be done. So let's take a deep breath there and we'll have at it one more time for today, for shoulder week or shark week.