Thank you so much, Seth. That was fantastic. Next, I'd like to introduce Dr. Andy Pasgaria from Johns Hopkins. He'll be speaking about patella alta and distillizing tuberosity osteotomy. Thanks, Miho. Seth, that was a great talk. I'm gonna have to sit and think some more about what you just taught me. But let's not just assume we've gotta get rid of tuberosity because tuberosity osteotomy can be very powerful in a lot of ways. And as Seth pointed out, there are times when it's useful and indicated. So I've got no disclosures. I wanna start with a case presentation here. I'm gonna talk about distillizing osteotomy. So I'm not gonna mention a soft tissue distillizing procedure. There is data coming out that suggests, in some cases, a soft tissue patellar tendon shortening is a reasonable option. But I'm gonna talk about using a tuberosity osteotomy. Most of us are comfortable with the idea of a tuberosity osteotomy for medializing, distillizing, enterizing, and sometimes even moving the single proximal. It's a 16-year-old recreational athlete. She had a contralateral intermedialization a year ago and came back for this side. And here's her exam. So she's got the typical sort of exam with some irritation under her patella when you load her patella. Here are her plain films. And it's not a perfect lateral. We really do need to get perfect laterals. But the main finding on her plain film here is that she's got a patella alta with this CDI of almost one and a half. She had an MRI. She had a CT scan. So here's a summary of her radiographic findings. Some mild dysplasia. There's no chondral lesions on the MRI. And her TTTG distance is listed here at 15. So what's her problem? Her main problem is soft tissue insufficiency. That's her primary problem. But she's also got a pretty substantial alta. So how are we gonna address this? Well, we're gonna do an MPFL reconstruction or MPFC. In my case, it's MPFL. MPFC is sort of the general soft tissue envelope medially. And distalizing osteotomy. So moving the tuberosity distally, but also realizing that it's not pure distal. And you can address more than just patella height by moving your shingle. Also remember that when you cut the shingle and move it, you lose some of your change. You lose some of your medialization, some of your enterization when you put screws in. So this is the piece of the distal shingle that is removed from the end of the shingle and packed proximally. You calculate out how much distalization you need to sort of correct your patellar height index. And some intraoperative photographs here. This shingle is released distally. Instead of hinging distally, staying attached, you have to release it, remove a piece off of the end. I like to use three of these bicortical screws. And then you can pack that piece of bone proximally and it fits in nicely. And then put some additional bone graft in. And so you can calculate out what you're trying to do, what your goal is to try to improve the normal indices, try to improve the capture of the patella and the trochlea. So here's some postoperative images. There's the proximal part of the shingle, the distal part. And this is crucial because you're going through the anterior cortex. Lots of ways, as Seth just shared with us, to address recurrent instability. And the workhorse of the osteotomy, the osteotomy that most of us are most comfortable with is the tuberosity osteotomy. Of course, there are times when you need to do other osteotomies, but the most common osteotomy, the one we're most comfortable with is the tuberosity osteotomy. And you can modify your tuberosity osteotomy if you need to distalize your shingle, if you need to improve your patellofemoral engagement. So what's the justification? And the question here is, when is NPFL reconstruction enough? When do we need to add an osteotomy? That's why we're all here today. So let's look at the literature, the clinical literature here. We know if you dislocate your patella once, there's a pretty high risk of recurrence, and that risk is based on risk factors. And studies like this show that these anatomic abnormalities, these risk factors, things like patella alta, increase your odds or your risk of having additional dislocation after a primary dislocation. We know that there are three main factors, thinking sort of globally here from 30,000 feet, that contribute to stabilizing the patella. So the dynamic muscle action, the soft tissue restraints, and then the osteocondal geometry. And so from the soft tissue restraints point of view, you have a medial patella formal complex, and if this is your primary problem, and you can address your instability with a soft tissue procedure, and most of the times you can, then a soft tissue reconstruction like an NPFL reconstruction is the best way to go. And there are a bunch of different ways to do this, and I encourage you all to find a way that you're most comfortable with, master it, make sure that you don't over-constrain it, but also learn how your medial soft tissue reconstruction affects anatomy, because it turns out if you do a two-strand NPFL reconstruction, you actually decrease your CDI by anywhere between .22 and say .8. So you distalize by four to 10 millimeters when you do a two-strand NPFL reconstruction. If you do a one-strand NPFL reconstruction, you don't distalize at all. We looked at that at three or four different centers, and we're about to publish this, so realize that an NPFL reconstruction results in distalization, but it depends on how you do your NPFL reconstruction. We know that NPFL reconstruction surgery is excellent for most patients, but even this outstanding study, which is very frequently quoted, the authors didn't do NPFL reconstructions on all of their patients. Some of their patients underwent an osteotomy. So the real question is when? When is it time to add an osteotomy? Which osteotomies are you comfortable with? And I think the key is to be comfortable with whatever your resources allow. And if you're Seth at Stanford and you've got the ability to do those phenomenal osteotomies, that's great. If you don't have those sorts of resources available or you're not comfortable with those cases, figure out what you're comfortable with, use it, and refer on patients that you think you can't successfully stabilize. So here's some information about the patient who has borderline lateralized tuberosity, so the TTTG in the 17 to 20 millimeter range. And in this study, the authors found better outcome scores than what they described as patellar kinematics when you combine the NPFL reconstruction with a tuberosity osteotomy. This would be a medialization or antimedialization, just an example of how the data sometimes supports a combined osteotomy. What about the results of isolated NPFL reconstruction? Pretty good results here. In this study of 239 isolated reconstructions, there were only 10 failures that required revision. And those failures had these anatomic risk factors, including patella ALTA. So this study, 26 patients who underwent revision NPFL reconstruction, 70% of them had atraumatic recurrent instability. They identified these anatomic risk factors that predisposed to instability, so here's ALTA. So what I'm saying here is that try to identify those patients who you think are at higher risk for failing in isolated NPFL reconstruction, and pick an osteotomy that you think you're able to do successfully, minimal additional morbidity to the patient that's gonna decrease the risk of recurrent instability. We do need numbers. We have to be careful with the numbers. Seth pointed out how difficult it can be to measure something like TTTG. And I would encourage you all to do your own measurements. So here's an example of trying to understand sagittal engagement. At what flexion angle does the patella become engaged in the trochlea? And that's really what we care about, because it's that lateral ridge that gives us some resistance to instability laterally. So we could try to measure that by using this index here. And if you eyeball this, it looks like, well, that patella's not really very much engaged. And you can do the measurement, it's about 0.2. Anything less than that, you really have to worry about how well that patella is engaged, especially if you have a lateralized tuberosity. If you don't have a lateralized tuberosity, the rest of your anatomic factors are fairly normal, this isn't such a big deal. But if your tuberosity is lateralized, the combination of ALTA, trochlear dysplasia, and lateralized tuberosity is a big problem. So this is the way that we typically try to quantify, we've gotta use numbers, we need to measure, we need to measure before, we need to measure after, we have to have a sense of what's normal, what's not normal, and then incorporate that into our own individualized treatment algorithm. What works for us with the resources that we have? And thinking, again, globally, maltracking, and Seth pointed out multiple times that jumping J sign, it's imbalance of these factors. There's the J sign, that's what it looks like. And as John has focused and has taught us, it's all about the balance of all of these factors. So how about some basic science data about ALTA? This is a study from a while ago from Chris Power's lab, and he compared 12 patients with ALTA to 13 controls, and they found that the ALTA group had more displacement laterally, tilt, and less contact area, and they concluded that the vertical position of patella is an important structural variable associated with malalignment and reduced contact area. It plays into instability, it plays into cardiosis and arthritis. This is a biomechanical study, computational analysis, John Elias, and what we did in this study is we took two groups of patients, a group with ALTA and a group, a control group without ALTA. These are all actual instability patients. Each of these models is made from a patient with instability, and compared the two, doing simulated range of motion, trying to determine tracking, the non-ALTA group, the ones with the patellar, normal patellar height, the amount of maltracking, the lateral tracking, correlated with trochlear depth. So in these patients, trochlear dysplasia was the primary factor, but in the ALTA group, the lateral tracking correlated with the tuberosity position. Now, tuberosity position is affected by lots of things, not just the TTTG distance, but the idea here is that ALTA affects how factors like trochlear dysplasia, lateralized tuberosity, tibial torsion, thermal anaversion, influences tracking. It's all incredibly complicated. Just starting to get our heads around this concept, I think computer learning is gonna help us figure this out. But if we simplify it, and we try to think this through, if malalignment is a substantial part of what you think is leading to recurrent instability, then have some osteotomies in mind that may be able to address that malalignment. And we've got a bunch of osteotomies. The workhorse here is the tuberosity osteotomy. You can medialize, you can antimedialize, you can distalize, a combination of those. You can even transfer the tuberosity proximally if you need to. And here's just one example, one way to do it. This is a step cut distally. So there's the shingle. The distal cut in the cortex is something you have to keep an eye on. But you take the piece, pack it proximally, put a little bit of bone graft in there, and you can calculate out how far you want to go distally. You can incorporate a slope on your osteotomy to get some anterization, some medialization, whatever you feel is necessary. And you can individualize your outcome here based on what the patient's problems are. This is just an example of how I do a tuberosity osteotomy. In this case, there's a step cut distally. The piece is removed. I use three bicortical screws, pack that piece there, and then use a little bit of the bone graft from a local area. So what about outcomes and return to sport? There's information from this clinical study here. Return to sport, 93% and 71% at the same level. This is NPFL reconstruction with tuberosity osteotomy with approximately seven months and a low recurrence rate. And interestingly, the return to sport was similar in patients with an additional osteotomy. So yes, it's bigger surgery, bigger incisions, takes longer to heal, higher risk of complications, but you can still expect a return to sport at a pretty high rate. So yes, complications. And we have to respect these complications. You can see all of these happen, including the wound healing in the bottom. The one that's most common, though, with distalizing osteotomies, particularly with that step cut distally, is delayed healing. Nonunion is very rare, but it can happen. So just remember, this is almost the equivalent of that dreaded black line, a tibial stress fracture, because it can be on the tension side of the tibia. And in this case, it's not unusual for it to take six months or longer for it to fully heal radiographically. Clinically, it heals quicker than that. Keep an eye on it. Keep your patients away from jumping sports, contact sports, until you're convinced that it begins to heal. There are other ways to do these distalizing osteotomies. This is the one that I'm talking about. We looked back several years ago and compared distalizing to non-distalizing tuberosity osteotomies, looking at complication rate. We found in these osteotomies, there was a 2% risk of nonunion. Delayed union, radiographic delayed union, was more like 23%. And comparing the non-distalizing to the distalizing osteotomies, it was the distalizing osteotomies that took longer to heal. It all makes sense. We also found, though, that if you use three bicortical screws and you get excellent compression, rather than two 4.5s, if you use three 3.5s, that's much less likely to happen. You can countersink and you have a very, very low risk of needing to go back and remove hardware. So I encourage you to think about the three 5 bicortical screws, countersink them. It's really rare to have to remove them for tenderness. Finally, a brief case here. A 30-year-old homemaker, she first came to me after having her first child. And she's got Charcot-Marie-Tooth. She's had five dislocations on the right side, one on the left. And here's her exam. You can see the expected lower extremity weakness and the sort of typical instability-type findings. Here are her playing films. Little calcification there. And this very substantially increased patellar height ratio. Here's her MRI. You look closely at the inferior pole of the patella. There's the signal change in that articular cartilage. And then you try to calculate out the amount of engagement. And this MRI, she's not even fully extended here. And so her PTI is 0.15. Here's a 3D CT, part of the dynamic CT study that we do routinely. And you can see she's barely, if at all, engaged here, at least in terms of the bony anatomy. Here's her TTTG distance, which is in the normal range. And her bisect offset is 100%. So to summarize her radiographic findings, she's got normal TTTG distance, patella alta, poor engagement, high bisect offset, and then this chondral irregularity in the inferior pole of the patella. What's her primary problem? Her primary problem is soft tissue insufficiency because she's had recurrent instability. But she's also got patella alta with poor trochlear engagement and then a chondral lesion at the inferior pole of the patella. On top of that, she's got this neuromuscular disease with lower extremity weakness. So how do we address the problem? Soft tissue reconstruction after doing the osteotomy. Of course, you start with the osteotomy and then you do your soft tissue reconstruction. I agree with Seth. It's extremely unusual to do an isolated osteotomy. I recently had a patient who performed just a distalizing osteotomy on. She had no, he had no instability. It was more of a arthritis procedure. So here's a summary of the procedure. There's the fragment placed proximally, a correction of the CDI down to the normal range. This is the location of the MPFL reconstruction. I use a single-strand reconstruction. I get no distalizing effect with a single-strand MPFL reconstruction. If you do a double-strand, you can get five to 10 millimeters, five to 10 millimeters of distalizing effect from your MPFL reconstruction. Okay, here's the good part of the case. Two weeks post-op. Two months post-op, she falls down. There's her shingle. She's a little tender on the shingle. It's displaced. The screws are intact. They're not loose. We're patient. At four months, she's no longer tender. She hasn't healed, but she's probably healing. And if you look proximally, you can see that that graft is becoming incorporated. She came back two years later to have her other side distalized, and she's healed. So caution, be careful, respect the healing, and keep an eye out for that potential complication. So if the primary problem's soft tissue insufficiency, and most of the time it's the primary problem, do your MPFL reconstruction however you do it. But if you have substantial malalignment, have a treatment algorithm in mind so that you know what works for you, and consider adding a distalizing osteotomy if you've got a very substantial ALTA with poor engagement. Thanks very much. Thank you.

patella alta

distalizing tuberosity osteotomy

soft tissue insufficiency

MPFL reconstruction

malalignment

return to sport rates