Next, I'd like to introduce Dr. Liza Arendt, who's going to be talking about trochleoplasty. Great. Those were great talks, Andy and Seth, we're going to try and talk a little bit about trochleoplasties and when to use it. The in vitro video is compliments of David DeJure, the Arthrex guide system is going to be shown. I don't have any financial affiliation with Arthrex. The history and types of trochleoplasties, I'll be brief. You can do a trochlear osteotomy, it's come to be known as, which is a thick flap trochleoplasty, typically 5 millimeters, popularized by the Lyon School and uses a central osteotomy cut and the thin flap trochleoplasty popularized by Barrett of Switzerland, Central Europe and it has started certainly as an open technique and if you're doing an arthroscopic technique, you are using a thin flap trochleoplasty. So when do I consider it as a surgical option? Patient selection and imaging criteria are essential. So for me, the biggest is the big J sign on physical exam, jumping J sign if you'd like, no significant patella alta and we'll talk a little bit about that, the thought that you could maybe bypass a supratrochlear bump and then of course one and two sort of suggest high grade trochlea dysplasia. We've seen some examples of the J sign, I like to show the red shoe lady because it's just so dramatic, compliments of Dan Green, but what I always call this sort of a hard J sign and sometimes it's associated with crepitus, which means that there's already some cartilage wear. The problem becomes is that we talk about that supratrochlear spur or boss and it's really the top of the, I guess I can't do that, here we go, the top of the spur that we're looking at, but I just wanted to point out that the original three classification of Henri de Jure, which was published only in French, really looked at the length of the trochlea. So the very first classification system didn't talk about the supratrochlear spur, but rather the length, like when did the trochlear end and that was based on the crossing sign as documented on the true lateral x-ray. His son David de Jure ended up having a four classification system which used the crossing sign plus the supratrochlear spur plus this double contour sign and this double contour sign is actually the hypoplasia of the medial trochlear facet. You could argue about the utility of it, about the four grade classification system, but I would say that the true lateral x-ray is still extremely helpful. What it doesn't do, however, it doesn't factor in trochlear length or trochlear depth, at least not in their four classification scheme. Now Roli Bidet did publish something that looked at the height of the trochlea. It's really fussy. It's not really in practice, but you can see on the short what he wants to do is he takes the mid-portion of the lateral tibial compartment and he looks for the height of the proximal trochlear and the posterior trochlear and the anterior trochlear should be higher than the posterior trochlea and if they're even or lower that's a short trochlea. So that's a little bit more of a qualitative, the numbers weren't really given. I think it does help. I will say I don't use it, but I look at it all the time in regards to the true lateral x-ray. So here's the spectrum of trochlea dysplasia. This is a very short trochlea. You have to have your kneecap travel all the way to about 60 degrees of flexion to even get into any kind of groove. And on your right you can see that you have a really decent groove, but a huge supratrochlear spur. And then I wanted to point out the utility of this lateral x-ray because in both of these you have an extremely shallow trochlea throughout. And on your left you can see why that patient is dislocated in flexion or why that kneecap is dislocated in flexion because they really do not have any groove. And so I think that you can see the depth of the groove and help use this in your analysis of what the patient might need. That supratrochlear spur is most notable in the central region. Here you see the cruciates, and I think that's important to recognize that it's really the elevation of that central trochlea that gives you that inability to nestle into the groove. When you're looking at that boss or that ventral prominence, we don't have really good numbers, but if you go back to Furman's initial radiographic gold standard where he used a lateral x-ray and tried to make MRI correlation, he feels that normal is 5, but the spectrum is large. The indications for surgery, I would say that most use 7 millimeters, 5 millimeters is often used by Laura Hemstrom in Canada, and she has some good information and outcome studies on that. David Diedrich and myself go closer to 7 millimeters when you're measuring that ventral prominence. So again, the main surgical indications are a jumping J sign, a ventral prominence greater than 7 millimeters, and the other thing that we like to talk about is a convex trochlea. So what you really, I mean everybody talks about wanting to deepen the groove, but in actuality if we get it back to a flat groove, I think that the soft tissue balancing might work, and what we're really wanting is to remove that ventral prominence in the most proximal area, and no significant patella alta. Now why does this make a difference? Well I think that this has become a little bit more popularized in the United States because as Seth has already pointed out, we all grew up with the TTO, and in Europe they pretty much grew up with looking at the trilateral x-ray and being more comfortable with trochleoplasties. But the thought is that if you have a proximal supratrochlear spur and your groove is rather deep, that you might be able to bypass the supratrochlear bump by moving your patella down. So if the groove is normal or near normal, which is the depth of it, in mid-arc flexion and alta is present, can we bypass it? Now we don't have good information on this. I actually just looked up my distal TTOs, and I have approximately 50 that had a jumping J sign, and only about half of them were actually helped by the distal TTO. These were really 210 to 215 group. And so I think that we have to analyze the trochlear better. I just don't have enough information on my group that failed that I can speak with authority at this time, but that's what we need. So this just shows you, I'm sure that you're aware that if we use the CD and the insulce of body, Kenton-Deschamps, could be different, and it really depends on the nose of your patella. I do think that using the patella trochlear index helps, but as you can appreciate that you need the patella, it's slice imaging, it's done looking at your cartilage surface on MRI, so that you need the patella in front of the groove. And with these high-grade trochlear dysplasias, it's not often there. You can try to superimpose two images, but that may not be where the patella is once it gets over the hump. I think qualitatively, you can look at what I like to say is the empty sulcus sign. So here you see a mid-sagittal image of the patella, and you look down and you see the proximal femur with no cartilage. And by the time you get that first full cartilage coverage, you look up and you see the patella. I'm sorry, you see the patella tendon. And you can also make a measurement of how much the patella is overlapping outside of the trochlear groove. So to me, this is a really nice qualitative image that you can just quickly see in your clinic without making measurements. That tells you that you have patella alta. The other thing is I think a quick interoperative check here. You have the clamp mimicking quadricep contraction. I try to look at where that groove starts. And for me, this person ended up getting, because I felt they had a decent groove, ended up getting a TTO with a soft tissue stabilization and not a trochlearplasty. Converse that with a different patient. So here we have a patella alta with a sort of borderline patella trochlear index and a supratrochlear spur. But when you're looking at axial cuts here, you see that they have this very big convexity approximately. And you see that sort of cliff sign where you have that really severe hypoplasia of the medial femoral condyle. And even as we get down to full cartilage coverage, you see that it's still quite flat. So we really don't have any engagement. So for me, this person got a trochlearplasty with a MPFL. One could argue that you could distillize it as well. I try not to do both. I'll be honest. I do sometimes, but I try not to do both. And if you're sort of flattening the groove a little bit, you do gain a little bit of height or a little bit of length on that trochlea. And you can see here that I thought that they had decent engagement. And that was a nice deepening of the groove. And so that is the way I sort of do an analysis. As you can see, no one up here to date has really talked about a really solid algorithm because I think that it really is patient-specific. So the step two for the arthroscopy, we can accept cartilage wear on the patella, but not the trochlear groove, in my opinion. Here we see where cartilage wear is often common and accepted. And you can see the groove looks pretty good. And oftentimes, you're relocating that patella. And so you're really shifting that wear pattern. And typically, it's a medial wear pattern. And you're loading the lateral side as it should be. The trochlear wear patterns that I found unacceptable is ones where you have high grade four. And these are ones that I chose not to do a trochleoplasty. So in terms of the arthrotomy, I think that a medial, I'm a total knee surgeon as well. It's certainly easiest in my hands if you get good visualization. However, if you're doing some kind of lateral lengthening, which is often common, you may have a negative effect on blood supply to the patella. I've never seen that, but certainly historically in the literature, particularly the total joint literature, that happens. Lateral is nice when it works. Because there is almost always lateral-based pathology, which Miho will talk about. It doesn't violate the VMO. But it's difficult with a high tibial tubercle offset, because you're trying to push against that. And then I think if you're entering from the lateral side, you may have a tendency to reduce the lateral trochlear wall, which is really not what we want to do. And I'll try to show that. I know that when I first started working with the French, they felt that, Philippe Millet in particular, felt that he didn't really know where to put his new groove. I think that the idea that you create a new groove doesn't always happen, and the goal really is to take away that convexity. But you do try to lateralize the groove, which is often medialized. And so you need to gain access to the subchondral bone, and you do that by starting to make a window. You do that with osteotomes. This is an example on a cadaver, of course. And you can make that window. This is a speeded-up film. And what you do is that you actually create a window so that you can gain access to underneath the trochlea. You have to go all the way down on the medial and lateral sides. People often say why, because the pathology is proximal. Well, the reason why you have to go down is because you won't get flexibility of your flap and you'll crack it. And so you undermine the cartilage surfaces. I do use a trochlear guide system. I use 5 millimeters on occasion, 3 millimeters way down distal. But you can use a combination. And so here we see the trochlea dysplasia. You can use a guide system to make your tunnels. And then you can also keep a central point and almost move it back and forth like you're peeling an orange. The guide system has the cutting surfaces around it, and the tip isn't so sharp. And so you really have to sort of move it back and forth. And here's just, again, in a cadaver, you can see that you can make the initial tunnels. David DeJure actually makes tunnels and then connects them with an osteotome. I try to do more with a burr. So then assessing the flap, we talked a little bit about, well, which one do you do? I actually do either. I think that if you have the flexibility of the flap, which I felt used to be in kids and not in adults, but I think that there's no such cutoff anymore, then you may be able to not get away without a central cut. But if it's stiff, as it often is, especially under that lateral side, you have to need that central cut. And so here we see one with the central cut that I needed to end up getting the flexibility with the central cut. And here's one that had enough flexibility. And you can see that I used a third suture to try to keep that central groove down where I felt my new groove would be. So some housekeeping details, you want to remove the supratrochlear spur. You want to keep the cartilage surfaces as voiced as you can while you're doing your open work. This just shows you how you can preserve that lateral wall, because what you're really doing is bringing that top, that most proximal piece down, and you can still preserve that lateral wall and backfill it with graft. This was the analysis of my first 53. They all had an improved sulcus angle, but you can see that it's not a lot. The average deepening was 9 degrees, but the range was 3 to 24. So the one that I showed you earlier was one of the ones that I had the deepest one at. But again, my goal is really to flatten it. I am trying to get rid of the supratrochlear bump, which, as you know, normal is about 3 millimeters. And sometimes I do go down to 0, but you see here that I was able to get rid of that ventral prominence. So here's an example of a pre- and post-osteotomy patient. I have done second look arthroscopy. Some of that is when I've done staged with the other side. Some of it is because I have had some stiffness. And you can see here that you don't really damage the cartilage surfaces. The first one at the six weeks post-op, you can still see a little bit of the absorbable suture. I use PDS, and it hasn't really had any negative effects. There are some controversies. Open growth plates, there's only one published study, as you see here, by Central Germany that he did a very small cohort, which he called closing femoral growth plates with no more than two years growth remaining. So they were really sort of early adolescents. He had an N of 18, excuse me, not 12. And then you can see the mean age was a bit old. I think this is important because I'm hearing people say in the United States now that you can do it in open growth plates. So you have to know that these were closing. And at a minimum of two-year follow-up, there was no growth disturbance. So I think that we can tiptoe into this. I have not yet, but know that that's still a controversy. So in conclusion, I would say that for me, the decision on who needs surgery is really the difficult one. It's as difficult as the surgery itself. I do think that surgical principles can be learned in a cadaver. I've heard so many people say, I don't have trochleidysplasia in my cadavers, therefore I can't do it. But the principles can be done in a cadaver. And if you crack the cartilage, you crack the cartilage. And these are often done in bone that's really hard because they're older people. But I do think the principles can be taught, as you can see in the cadaver that were on those films. So my final statement is don't abandon the true lateral x-ray. I still think you get a ton of information from it. Trochlear length, trochlear depth, and supratrochlear spur. Thank you for your attention. Thank you.

trochleoplasty

trochlea dysplasia

surgical techniques

patient selection

true lateral x-rays