Special surgery, and I'd like to thank Dr. Betty for allowing me to talk today and invite me here. So I'm gonna talk about, again, kind of to address the question of rotation, the first question. The first, it's also a dislocation inflection, but this one has a lot more rotational issues with it. So this is a patient who came to see me. She had actually had longstanding bilateral patellar instability, chronic. She was in her 30s, and she'd kind of lived with it for a long time. She'd had a surgery before on her right one. Her right knee was very chronic. That was the more chronic of the knees. It began at age 10, and I think as David pointed out, these patients where it begins much earlier, it's usually a much bigger problem. So instead of beginning at 12 with field hockey, this one is nine and 10 is usually more of a congenital and bony issue. The left one, chronic but obligatory. So this was more of the standard jumping J sign that I think Dr. Strickland talked about at one point. On her left, she extends her knee and it pops out every time. If she does an open chain knee extension, it pops out, and that's kind of the more routine. Still needs bony correction, but it wasn't as severe as the right one, which was dislocating inflection. So this is, again, when I saw her in the office, I will just be honest, I saw her on telehealth first, and her telehealth exam was not as remarkable, and the reason is because when I brought her into the office, because she lived in Maine, and so she came down to see me, when I brought her into the office and I was able to layer on her belly and rotate her hips, it was dramatic. I also, at that time, got a standing alignment film because it was such dramatic internal rotation, and the thing that I think is most, and probably could have seen it even on an AP, is that you're looking at different, you're looking at an AP of the tibia and an oblique of the femur, and I always think that that's a really strong indication to me, along with hip rotation, that there's aversion issue, there's a rotational problem here. So that's kind of what alerts me, and like I said, I wouldn't have seen that when I was seeing this patient on telehealth, it was really only when I brought her in the office and I was able to check her hips and understand maybe the problem was coming from further up. So for these patients, I do think I have a lower threshold when I see that in the office to do a rotational profile. So CT, axial cuts through the femur, through the knee, through the ankle, and then to get their aversion studies, and she had dramatic aversion. Interestingly, not that different between her right and her left, even though they were very different types of patella instability, and I think that's less common. Again, one was a dislocation and extension, the classic jumping J sign, the other one, which was her right one, which I'm gonna talk about, is the more, or less common, but dislocation and flexion. So this is, you know, I'm gonna go back to this for a second, because I think this is always the question. One of the things we talk about is what's the threshold? I think David said it before, anything above 30. There's some literature out there, and what we don't know is how does this affect instability? And I think one of the things that we're learning, and one of the things that we're doing, and sort of the title of this is, when is an MPFL not enough? Well, the flip of that is, when is an MPFL enough? And I think we have to figure out what we're treating before we understand that. Sometimes we're not just treating instability. For run-of-the-mill instability, an MPFL is gonna be enough most of the time. The question is, if we're making them stable, are we truly making them better just because they're not dislocating? And a lot of these patients, and to David's point about the trochleoplasties, some of them just have such terrible anatomy that even if you can keep their patella stable, they won't like the way it feels. I've actually sent before, I've now done a few trochleoplasties on my own in severe cases, and I do think there's a reason for it, but in my practice, it's a very narrow place where it fits. Somebody who's failed a well-done MPFL and TTO, because I always try to stay away from the joint if I can. But I think the question is, what is failure? Because instability isn't failing for a lot of these patients. They're not gonna fail by dislocating, but they may not like the way their knee feels, and they may feel that there are some abnormal fat forces on their knee, and they don't like it. They just don't like the way it feels. And I think that's one of the things that we're gonna start learning. The literature, AJSM actually published an article about six years ago looking at patients done with derotational osteotomies, which is what she ended up having, versus not, for over 30 degrees. They don't show a difference in terms of recurrent instability. What they show is a difference in terms of outcomes. And I think that's where we have to start to realize that if we're only looking at redislocation as a failure, maybe we're missing a whole subset of people who will feel better. And the question is, what is that number, and what's the so-called MCID, right? What's the minimally, clinically important difference to say this patient should have a much bigger operation, whether it's a varus-producing osteotomy or a derotational osteotomy? And I don't think we know that yet, but I do think in this particular case, it was obvious to me that she had a very large problem, dislocation, inflection, excessive rotation. And so this is a patient who ended up with a derotational osteotomy. And again, very similar to the difference between a TTO and a TTO with a distalization. In a DFO where you're doing a varus-producing DFO, you have a medial hinge, and once you do a rotation, you have no, it's a much less stable construct. And I do this with a partner of mine who's a limb-lengthening person. I've learned a lot about that rotational stuff through working with him. But that, to me, was the biggest issue, is to derotate that, and that does change where that tibial tubercle trochlear groove is. So to the question before of when I do it, I still did the TTO first, but I will go back and change it, and I do that just for purposes of getting the TTO done and then getting the DFO. And then the last thing, as David said, is the MPFL, because that, obviously, you have to fix at the end once your knee has new alignment. But I do think that there's some real issues here with not making sure we don't overcorrect these people, because you're moving their trochlea, you're actually medializing or lateralizing their trochlea when you do this a fair amount by rotating, by derotating it, and so that's closing the TTTG gap already. So if you start out with a TTTG of 25, and your plan is to move them 15, which is almost impossible, just from a real estate perspective, there's not that much real estate in there, you have to be really careful, because you really have to respect the fact that the derotational portion is going to reduce that TTTG by a fair amount as well. It's a very powerful tool. And in this particular case, as Jason talked about before, whenever you see a dislocation inflection, there's just not enough length in the system, so you have to be prepared, and in her, I did a quad lengthening as well. So I think that those are kind of the takeaways that I've learned, is that intraoperative TTTG in these cases is much more important to me than the number that I saw beforehand when I'm trying to figure out where to move that tibial tubercle, and the NPFL is the last thing that I fix. So, yeah? The question was, you know, I think the, nobody really, there's not hard and fast guidelines around how much rotation is too much rotation. So what was your target? Yeah, so the numbers that have been reported in that article that I was telling you about was looking at over 30 and under 30 as the cutoff. So we were essentially trying to get her down to around 20, 25, but probably closer to 25. And essentially, we did this at the same time so that I could check her tracking as the rotation. We preliminarily fixed the femur so that I could check the tracking before it was finally fixed with the plate and screws. And I think that's really important, because it is, it's a very powerful tool, and the question is, a little bit like when you're distalizing a tibia, are you trying to, or distalizing a tubercle, are you trying to get them to normal, or are you just trying to get them to an acceptable place where it's not gonna play into the instability? And I think in this case, that was the goal. The goal was to bring the trochlea into a neutral alignment so to get her to about 25, probably, is where we set her. And she started at 41. Do you tell this patient she's going to have to do it on the other side, because obviously, this doesn't affect her gait? So 100%, and the thing is, her other side, as I said, is a very different kind of instability. She still has the rotational alignment. You saw that the numbers are actually similar, and she did it on the other side. She loved this side, and she absolutely did it. A lot less, I didn't have to do a quad lengthening on the other side, so that was not part of the process, and so it was a much easier operation from that standpoint, but yes, she did this on both sides, because you're right, it definitely changes. And the other thing, you have to be really, really careful with the rotational, is in her case, she had antiversion and had in-toeing, but in a lot of these cases, they don't. And in fact, in some of them, they already have an external foot progression angle, and when you derotate them, you actually make that foot progression unacceptable, and so you have to think about swinging the foot back in, and that's a big, big deal. So you have to, those are things to think about, because you don't do this for a small problem, because in a lot of these cases, and she didn't, but the next one does, I think, that I'm showing, you end up with an externally rotated foot that you then have to turn back in, so that's a big deal. Oh, and then, actually, it is her, so there it is, yep. I will say that no longer are we using X-fixes for the distal portion, because my partner, who I told you about, the limb lengthening, my associate who's a limb lengthening guy, these patients, even though it's more predictable, and they can weight-bear on it right away, they don't like it at all, so now it's doing plate and screws for the distal portion. At what level are you doing the distal osteotomy? So you can see the level on the other side, so it's just above the, you can see, it's kind of diaphyseal, metaphyseal. Yeah, she had it done on the other side as well. Some people have done the rotation over a rod. Yep, so when you do it over a rod on the tibia, that's not easy when you're trying to do a tibial tubercle transfer, so that's one of the bigger issues, so you have to either, and so we've gone to using, he's gone to using a plate when we do this now because the X-Fix is, good patients, like patients have to be super compliant, obviously, and you guys know the non-compliant patients, and even compliant patients just don't like the frame, even though it's an easier choice, yeah? Yeah, I have a pretty high Amish population, so there's a lot of congenital differences there, so like the visible male alignment, so to speak, is like through the roof, and I've actually gone and I'm doing a HTO with like a step cut behind the tubercle, and as I rotate it, it's moving my tubercle with their foot, and it kind of keeps me in one surgical site, too, so I'm like just at their knee, right, so I'm like just doing their VFO and then the HTO. Yeah. It's a bit of a pain because you have to kind of whittle away a little bit of bone behind to get the rotation, but it's nice that you don't have to go down to their ankle anymore. And you can move the, and what did you say about the tubercle? How do you do the tubercle? It's like a proximal step cut on the back side of the tubercle. Yep. As you're rolling their tibia in, you're rolling that tubercle in with the tubercle, and because it's starting kind of poster lateral as you're rotating it, it's moving anterior medial. Yep. That was just. That's nice, yeah. You get to the. Yeah, and you're probably correcting it to deform it more where it is. Yeah. Yeah. Yep. It's a transverse ridge, you know, it's just transverse. Yeah. Yeah, and you gotta take, you gotta whittle away bone on the kind of back side. Yeah, so that you can actually rotate it. So you can actually rotate it. Yeah. What do you do with the fibula? I leave it, don't touch it. Seems like it'd be a precarious cut, but you don't really solve that one. It's not the most, yeah, it's a little fuckery. All right. All right. So this is another one, and this one, this one is a little bit different because it speaks to kind of what Jason said. Another patient who dislocates inflection, and this is a woman who has unilateral instability. So she dislocated at a very young age, had a soft tissue surgery back in her, so outside of this country, had a soft tissue surgery when she was 15, failed it pretty quickly, and very asymmetric x-rays, as you can see. So this is not a congenital problem. It's not like the previous patient where it exists on both sides. Obviously, there's some deformity on both sides, but this one is now, you know, terrible baja. And, you know, this is a different kind of problem. And even though there's, Jason was talking about it before, in an open growth plate, you know, that's a, or even in a young patient, again, different problem. And I think this is more the problem of how do you get length as well. And so for her, the, and I don't know if I dropped the vector, but she had asymmetric valgus, and you can see that on one side, right? The side that's affected has pretty significant valgus in addition to the baja and the TTTG. And you can see actually on her sagittal MRI, she clearly has a super trochlear spur. And as I said, I have a, I think David's indications are terrific for trochleoplasty, and he's done a lot more of them than I have, and I've done a few now. And I, but I really do try to do that as a salvage or a rescue, not as a primary. So for me, this was gonna be treated without a trochleoplasty, at least from, you know, to the best of my ability. These are her intraoperative images. And again, dislocating in flexion. So actually, this is, this kind of is the question. Again, there's just not enough length in the extensor mechanism. So I think in addition to getting the help from the varus-producing osteotomy, and this is a little bit of rotation in this one as well, because you can see it does go all the way through, and again, that oblique pin. So we did rotate a little bit as well to help. But what I did, and you can see below, is I proximalized her a fair amount. And there is some bone in the bottom there. I'm not sure if it's showing up. It seems to have resorbed a little bit, but she healed really well. And the one thing, and I don't know if you talked about this, Jason, is peeling off the extensor, when you need to proximalize, peeling off the extensor mechanism, you can get about a centimeter and a half, centimeter, centimeter and a half. So you can move it up a lot more without changing necessarily the joint line. So I think that's kind of thinking about how do you get the height. And then the other thing about these patients is getting their quad back, because if they can't get their quad back and actually Liza Arndt talked to me about this years ago, then whatever you do to get the height back in the system without that counter pull of the quad functioning and holding that patella up, they'll scar down and they'll still have a Baha after everything you've done. So I think that's really important is working on these patients and getting their quads back. So I think that's a really good point because you wanna really look at why they have Baha. So I've seen a few patients with severe Baha that had femoral nerve blocks and significant femoral nerve injury. That's not a patient you wanna address it because you're not gonna win. Right. If that quad doesn't come back, whatever you've done, they're still gonna scar down. And I think that's an important point with the Baha's. But again, getting the length in the system is critical because otherwise they just can't get, you'll never keep them stable. They don't have enough length in the system to get around the corner, so to speak, to stay in their trochlea. Yeah. One question maybe for you and the rest of the panel. There have been some recent papers, both on the hip side, but also at the teleformal instability, that when there's excessive anaversion or excessive external tibial torsion, there's abnormal geometry at the medial distal femur and this medial condylar angle that if you look at the relationship between the shaft and the medial condyle, is anybody using that or is there some predictive way to know beyond just 30 degrees of anaversion and an increased TTTG, a correlation of when you need to add the TFO? Yeah, I mean, it's a great question. Like I said, I think the answer right now is because we don't even know how much it plays into the instability. And always the question is, could we have gotten her stable without doing this? We might. We have a lot of powerful tools, right? The MPFL is a super powerful tool, especially with a TTO. And if you add a trochleoplasty, we have a lot of powerful tools. I think the question is not, will they be stable? It's how will their knee feel? And so I think that's the literature that's out there is just more on the outcomes, not on recurrent instability. So I think when we're doing these, we're doing them because we think the deformities are significant enough. And to Ashish's point, other than that number of 30 degrees, which has been the classic one for antiversion, and I think you said it, greater than six degrees of valgus or usually greater than six degrees of valgus. But those are, again, they're just parameters that we look at. And in isolation, I'm not sure what they mean without seeing the patient clinically and understanding what a big problem this is and how we're gonna try to correct it. I know I have one patient who I think had that exact problem and when she walked, she squinted her patellas almost like kissing each other and her feet were out like crazy. But when I did her CT scanogram, her femoral antiversion was only like 17. So it was more like a distal femoral antitorsion or like a kind of hypoplastic medial primal, I think. Then she had a real external torsion with it. So I think that sometimes it's where their hip is stationed relative to their knee. Because when we do our scanograms, there's always that protocol, right? They like tape the feet together and then you kind of shoot down. But when they're walking, you can kind of see like where does their hip sit relative to their knee. So a walking exam, I think, is useful for that. Yeah. Ashish, have you used that at all? Have you looked at that in terms of how it affects the patella instability or how their knee is affected by that medial condylar hypoplasia? Just interestingly, a little bit more of an academic interest. There was a paper in the Journal of Orthopedic Surgery and Research that looked at this and then a paper from Mike Salata at Case Western that used a old skeletal library in Cleveland. And it does appear that that angle can give you some insights into a sort of a surrogate of excessive anatorjunct. Now, I don't know that we know, and if you look at the hip literature, it's very difficult to know and define where the torsional abnormality is occurring. Is it proximal or is it distal? And we tend to correct it where we're focused, but they're clearly linked and related. And I know Jeff Knapple and others are here who are interested in this, but I still think it's the area least defined. Yeah, I think you're right. Yeah. Do I have a challenge in having a middle-aged person with this? A little bit early arthritis, maybe more. You've seen grandma, mom, and daughter in the same room with the same problem, two of which treated without surgery, and the others having surgery on it. And you can see the whole range. Then you pull the trigger and say, do the osteoarthritis, or the other procedures, MPFL, osteoarthritis, whatever, to help correct that, or just say, bear with it to the point that they need a knee replacement. Today, on Friday, I had three of them in my office, and one of them was so chronically subluxated that her patella was an L on sunrise yield. In meridian theory, you just store half of it without it. Yeah, I mean, I think what you're seeing is the natural history of malalignment, right? And that malalignment, and that's a vector issue, and David talks about this all the time, I think that's the part where we're missing, or we're not treating what we think we're treating right. Those are not just unstable patients. A lot of them are unstable, but we've all seen malalignment in patients who've never dislocated their patella. They just sit out like that and still get that. And I know Dr. Strickland sees this because we see it in the same place. The patient who comes in and both their kneecaps have exactly what you're talking about. They've just been wearing that side of their kneecap for so long that now they have bony erosion, right? They have almost an acetabularized patella because it's been sitting outside for so long. And so those patients, some of them have instability and some of them don't, but that's a problem of malalignment and trochlear dysplasia and sometimes it comes with instability. But then I think we have to be much more aggressive when they're younger about treating both problems early because that's where I think if you were to have realigned that patient or you do that for the daughter and you, she may still develop arthritis. She still has trochlear dysplasia, but you have taken off the loads on that part of her patella and so likely even if she gets the arthritis, it will be later and she won't have that kind of bony erosion. That's my feeling. Sabrina? I don't know if that's what the, as far as when to pull the trigger on an older patient, I mean, I've had patients that were sent to me from the arthroplasty service because they couldn't have a total knee because of their alignment. So the first step was to do the quad lengthening with a realignment, whether it involved both, because typically in those severe cases, both the DFO and a TTO, just to get them in the right ballpark. And you might lay a lot of crepe and say, listen, this is just for realignment. I don't think it's gonna make you feel any better, but my experience is even with fairly severe patellar femoral arthritis, they feel better with their patella. Well, this is a great example of that. She's 38. So we're doing this in a 38 year old, not because of how, she's coped with this for 25 years. She's had a knee like this, but to your point, she does have some arthritis. At some point she is gonna need a knee replacement and she cannot have a knee replacement with the current knee she has. And so this is, and she does feel much better. She does 100% still have arthritis. She has injections with my NP every six months, but she has a knee that functions for her much better now. And I do counsel them ahead of time a lot to say it may not feel better, but at least it gives you the option at some point to have a knee replacement. I think I'm looking at the time. We're about a minute short of closing up. So we'll skip the last cases. They're the most novice with me anyway. So if there's any other last minute questions for the faculty and panel, but otherwise it looks like we're at 8.30. Feel free to come up if you have any questions.

patellar instability

bilateral patellar instability

chronic instability

derotational osteotomy

unilateral instability

varus-producing osteotomy