Okay, so I'll try to talk to you a little bit about my thoughts as I've gone through this journey myself. The history of trochleoplasties, there's two different kinds. Mostly we're talking about a deepening trochleoplasty. There's the trochlear osteotomy, which it's been more recently called, which is a thick flap approximately five millimeters, popularized mainly by Lyon School. And then the thin flap trochleoplasty, popularized or actually first initiated by Baradar of And they have both an open and now an arthroscopic technique. And the original thin flap was three millimeters, but if you do the arthroscopic technique, it gets pretty thin. So I'm going to talk a little bit about how do I consider, who do I consider for this, and I'm going to talk about patient selection and imaging criteria. I think that certainly when I first started, the most important thing was to have a big J sign. And we've talked a little bit about what this means, but it's really when you're reduced in, when you sublux in extension and you jump into the trochlear groove inflection. And there's no significant alta. And certainly in this country in particular, there's the thought because we sort of grew up with the TTO and then we talked about distalization, that if you have a supratrochlear spur and you have a deep groove below it, that you can bypass the supratrochlear spur by doing a distalizing osteotomy. And we'll try to talk a little bit more about that. I think that that's a really tough idea of when to do one or the other. And I would say most of us aren't crazy about going to do both bony procedures at once, although I think some patients do need it. And of course, all of these have high grade trochlear dysplasia. So here's that jumping J sign. We've seen a couple of situations like this. I like to call it hard when you can actually see it visibly and soft when you can't. I've got two people in front of me, Andy and Miho, that are trying to help all of us be a little bit more quantitative in regards to how we talk about J signs. So let's talk a little bit about trochlear dysplasia because I think that, you know, for me who's looked at this for a while now, I continue to learn. But if you can see on your right, that's a huge supratrochlear spur for sure. But once you get below that, you've got a pretty decent trochlear depth. And the length of this is a pretty decent groove. And so I think that we have to look at more than just the classification of A, B, C, and D. And the original, Henri Degere originally talked about, whoops, sorry, the depth of it. Okay. How do I go back? How do I go back? Okay. Yeah. So sorry. So sorry. So Henri Degere originally talked about the length of it, then he changed it and went to the supratrochlear spur. Now we talk about a couple of things that I wanted to pay attention to. One is a supratrochlear spur. And you can see that. And it's really this crossing sign, or it was a supratrochlear spur that's characterized by the crossing sign, which is where this cuts out superior to the anterior flange of the distal femur. And then this sign, which is a double contour sign, that's actually the medial trochlear facet. And we'll hopefully see that a little bit better. So if you combine those things, that's where that four classification comes. And this just is one grade D. I just thought that I would show this to you because it combines the crossing sign, which all trochlear dysplasia has, supratrochlear spur. And then you can see that you've got that medial hypoplasia. And the reason why you get medial hypoplasia is because what happens in trochlear dysplasia is this central area is elevated and the lateral trochlea ends up looking huge, but it's really huge because it's so wide, because it's a combination of the lateral and medial facets. And then you have this hypoplasia of the medial trochlea, and that's where you get that double contour sign. And then this other term that we call the cliff sign has come into our nomenclature, and that's really where you kind of fall off. And it's really a discontinuity of the articular surface between the medial and lateral facets of the trochlea. And here, that's a really nice demonstration. You're seeing that very wide lateral and central trochlea falling off, losing discontinuity of cartilage, and then that hypoplasia of the medial trochlear facet. So that would be a high-grade trochlear dysplasia. I just like to think about it this way. Everyone has a crossing sign. The double contour sign is in C and D, and the supatrochlear spur is in B and D. Now, I don't want to hang my hat on this classification. Certainly there's a lot of intra variability, intra and inter variability, but some people just group everything past A as high-grade trochlear dysplasia. When we do a trochleoplasty, we're really trying to go after that supatrochlear spur and trying to take, not necessarily a flat trochlea to being convex, I mean, I'm sorry, having a groove, but really taking the dome and trying to make it at least flat, if not trying to give yourself a groove. But I want you to try to see a little bit more on this lateral view. I don't want you to abandon the sagittal because the spectrum of trochlear dysplasia is great. Here we're seeing, you know, sort of a non-existent spur, a little bump. But you're seeing a positive crossing sign, but look at how short this trochlea is. And then a pretty decent depth of it when you come back. But it takes this kneecap all the way down here to get into the walls of the trochlea. And really it's the walls of the trochlea that give us our best stability. It's not really anything that we do soft tissue, although that helps. It helps guide it into it. Here we've got a huge supratrochlear spur, but, you know, pretty decent length and really good depth beyond it. Now if you look at this one, and that's why you really have to follow this intercontinular line, look at how shallow that groove is, all the way down. So you really never get much past two or three millimeters of depth. And this poor person, I mean, I can't even quite, it's not exactly interlateral, but it probably starts about here. And then it's really, this one is actually a dislocation inflection. And I think that you have to start to look at the depth. And I think that when you're thinking about distalizing and what you're doing, you have to think about depth and length of the trochlea, as Jack already inferred. So again, I don't have all the answers, but I think if you start to see the relationship of the patella to the groove, you're going to help make better decisions. The other thing that I've only recently come upon, again, is this concept that the real problem is that central area. So on your slice imaging, typically MRI, you should be looking at where the ACL is. And that's where you see that big supratrochlear spur, or the nose of it. And that's really very dramatic. And then we talk about the supratrochlear spur, but it's not all supratrochlea. And so this concept of a bosque has come into play. And that's where you make a line along the anterior shaft of the femur, and it's really the whole protuberance of that bosque elevation, combined with the supratrochlear spur. And there's not a real hard number, but I would say that, like Laura Hemstrom from Canada tends to do a trochleoplasty if it's past 5 millimeters. David Diederich and I are more like 7 or 8. What would you say? They have a jump in the middle, it's 5. Yeah. So, I mean, but you have to sort of look at this. And I think that that's kind of helpful. The interesting thing is when I tried to get the French to say, like, well, what do you call this? Like, what do you call that? Actually, Don Fithian's down there, you could probably tell us. They don't have a word for this, because it's this whole, you know, sort of equation of language. And my favorite story is, like, how do you define maltracking? And Philippe Nier said, mal, mal. Mal is bad. Who are we to say what's bad? Tracking. Who are we to say that? And so I think that some of this, there's so much that's embedded in the European literature, primarily French. And Don Fithian went to the source to try to find that. And I think that some of it's lost in translation. The French code, I don't get it. Yeah. I think I like, boom, better. So what about excessive TT and patella alta? We heard a little bit about it. But again, I don't pay quite as much attention to TTTG, and I might be a lone person in this regard. But you remember that you'd have a medialization of the sulcus. Sulcus is defined as the lowest portion. Because again, if you've got that elevation of that central area, it's pushing your low point of the sulcus medial. And so when you measure TTTG, it's going to be a more proximal measurement. The abnormality may be proximal and not distal. Hence you might go to the TT-PCL. But it's just something, again, to consider. And here you see that overlapping with the CT scan. And again, the TT-PCL might be better if you think you have trochodysplasia. And I thought that Jack had a really nice idea. Look at both of them. And if they're not sort of in congruence with each other, then kind of think, why might they be off? For me, patella alta, of course, is a measurement. But I always like to tell people a nice quantitative, I'm sorry, qualitative idea when you're sitting in clinic is just to look at the actual views on slice imaging and look at that first full cartilage coverage. So here you see the first full cartilage coverage. You look up, and you're not seeing the patella. And then they now have a measurement that if that patella tendon is sort of subluxed laterally, that that's probably subluxation combined with alta. But I think that that's a good quick sign to say, OK, I have some degree of alta here. Because in a way, that's not measuring engagement. But that's giving you a qualitative idea of what the engagement of the cartilage is. So I'm just going to go through two quick patients. So here, patella alta. I see the patella. I look down. I don't see the cartilage. Here in my first full cartilage coverage, I look up. I'm just seeing the very, very tip of the patella with the patella tendon. But you know what? Pretty decent cartilage, starting to be a groove. So you can look at the patella trochlear index. They do have overlap. But again, I'm working with a J sign. So I'm trying to say, what should my measurements be? You can see this was 2009. Here are my 30 degree axial views. I typically do 20. But they came in with 30, so I didn't repeat them. And here, I'm not sure what I would have done in 2017. But in this evaluation, I thought, OK, I'm going to bypass the supratrochlear bump. And I'm going to do a distalization. So I ended up doing a distalization. And this person reduced their J sign, or actually eliminated their J sign, and did not go on to dislocate. Now, this one, again, I think that this was a little bit higher ALTA by trochlear engagement measurements. But if you kind of look at what we were talking about before, here you're seeing that you're just beginning to see that this is where you have a bigger, you're starting with the lateral side. It's moving off to the medial side. Sorry that it's a little bit dark. But you're just beginning to see the cartilage on this view. But as you keep going, now you're definitely seeing that you have a bit of ALTA, or you do have ALTA, but you don't have any trochlear groove. And you're seeing that really severe hypoplasia. And so this person got a trochleoplasty with a stabilizing procedure of soft tissue. Now, I will say that when you do a trochleoplasty, I think you gain a little bit on the patella engagement index, because you take a hump and you sort of flatten it out. And so you do have a little bit better engagement than you did before you did the trochleoplasty. So again, kind of going through, like, who do I make this decision in? I do accept cartilage wear on the patella, and typically no cartilage wear on the femur. And these were just examples of ones that I accepted. I think that this may interfere with some of their patient-reported outcome scores, their quality of life, their crepitus. But it should not interfere with the ability to do it. And typically, since you're sort of changing the relationship of the patella to the groove, they seem to do well for a while, at least, in regards to not having any problems with this cartilage wear. I think that trochleoplasties done with grade 4 changes are difficult. I know we had a discussion about this in yesterday's ICL. But I do think that it's more difficult when you've got sort of problems with the cartilage. I don't do it if I have to lift up grade 4 changes, because there's no cartilage to lift up, although some make a very thin flap of bone and try to make that flexible. I think for some of these that you could try to take off the bump and do a form of groveplasty, which is actually what I did in all three of these. So for the arthrotomy, you know, there's still a debate, medial or lateral. I'm a total knee surgeon as well. So I will say a medial arthrotomy in my hands is the easiest, and that's what I typically do. I also typically do lateral-sided work. Of course, it's all individualized, but there is a negative aspect that you might have a reduction of blood supply issues. Lateral side, this is largely done in Germany. It's lateral-based pathology. It does not violate the VMO and what you might do medially on the medial side. But I will say that what I sometimes do is do my lateral lengthening, but I don't close it yet. And I see if I can sublux the patella medially. And with a high TTGG, or what I should say is a high lateralization of your tibial tubercle, it's difficult. And so then I might revert to doing the medial side. And I also think that when you're coming from the lateral side, you have a tendency to reduce the lateral wall. You don't want to reduce the lateral wall. You want to keep the lateral wall. So you really want to be coming from the top, and you want to kind of preserve that lateral wall. And I think it's a little harder to do that when you're coming from the lateral side. So here, you know, you have to mark out the new groove. You really do want to try to lateralize that groove. You start by gaining access to the subchondral bone. I typically do this by making a trough. And this is obviously a cadaver demonstration, and done with a little bit high speed. So you make a trough by making a little window, and you take out that piece of bone, and you save it for later if you might want to use it to backfill. You can undermine the cartilage surfaces. You can start with osteotomes where it's flat, use a high speed burr, which is how I started. And I do like the trochlear guide system. I think it's a little bit safer. And they do have both a 5 millimeter and a 3 millimeter depth. And so here, when you're thinking about like how would I do this, with the high speed burr, you could make individual sort of tunnels, channels, and then sort of connect them. And let's see if I can get this video working. And so this just sort of shows you, again, this is a cadaver in not the best bone. And so you're just making those troughs, and then you can connect them later. And then, or you can try to keep that area centrally and kind of move it back and forth, kind of like you're peeling an orange. And I sort of do a combination of both. But you can see on all of these, I'm trying to come from the top. So when I think that I don't have the flexibility, and this tends to happen in older people, for sure, but also some young kids that have, you know, a lot of subchondral bone and tightness, I can't get their flap thin enough for my comfort level. And so I do the flap. And I sort of make a decision at the time that I'm doing it. So in this picture, you lift it up and you make a groove. I've got to tell you, I don't always get this degree of flexibility of that distal segment. So we probably shouldn't show sort of our best when you do it. And so you can then, you know, recreate the groove and lay it down. The reason that I wanted to show this is that this is what I'm talking about. You want to remove the supratochlear spur. You want to get this flat part. But you can see that I'm retaining my lateral wall, maintaining my lateral wall. And then you backfill that with the cartilage that you've been taking off. And then you fix it with some form of a suture anchor with absorbable sutures. So this is cadaver. This is not absorbable suture. You put one down at the V, and then you take the two crossing and pull down. If you're doing the flap-type osteotomy, you would use two on the medial and lateral flaps. And if you're doing, if you are able to do a thin flap, then you might do three, keeping one in that central area where your new sulcus is. So a couple of housekeeping details. You have to remember to remove the supratrochlear spur. So you bring that level down. Keep the cartilage surfaces damp. So while I'm doing a lot of my work, I try to keep a sponge up there to try to keep my cartilage surfaces damp. Again, preserve the lateral wall. Really important. Backfill with the saved bone. So here's the pre and post. This would be one that I did the trochlear osteotomy type. You do want to improve the sulcus, but I've got to tell you, it's really variable. Again, in my first review of my first 54, I did improve the average range. You can see it was 9 degrees, but some of them were only 3 degrees, up to 24 degrees. You do want to reduce the supratrochlear spur. And again, my range pre-op was 2 to 12. And you can see that the two I did have some that were smaller, and I end up improving it. So I don't know what this should really be. Normal is about 3 millimeters, and I'm still trying to be reflective on what our postoperative actually should be, because if you look in the literature, all of the post-ops are based on function. It's not a bad thing, but I'm trying to say, how should these look radiographically postoperatively? So here's another pre and post. So thinking about the fact that you use observable sutures, here is second look arthroscopy. The six weeks one was because of stiffness, and the 14 and 12 months was because I did staged bilaterals. And you can see on the six weeks, you're seeing a little bit of this was a PDS suture, but they really don't have a negative effect on the cartilage, either because of the osteotomy or because of the sutures that you're using. So conclusion, surgical decision-making and patella stabilization demands a knowledge of anatomy and anatomic trochlea dysplasia. It is technically demanding, but for some, it's the best surgical solution. And I think for people who are patellofemoral surgeons, they have to have this in their armamentarium. And I think all people that are looking at patellofemoral pathology have to understand how to recognize trochlea dysplasia and when they might ask for a referral. Thank you for your attention. Thank you.

trochleoplasty

surgical procedure

trochlear dysplasia

deepening trochleoplasty

thin flap trochleoplasty