Osteotomy. My disclosures are available online. My personal disclosure is that patellofemoral can be and is quite confusing. I think that's why we have a packed room of us surgeons here to try to figure this out together. What is clear is that these patients are seeing us in the clinic every week. But are we seeing them, the ones with apprehension into deep reflection, the ones with these larger J signs? Are we really evaluating them clinically standing up, looking for malalignment such as valgus or a scissoring-type gait? And are we turning them prone? And are we looking for rotational abnormalities every single time? We know that we can't use the MPFL to pull the patella anywhere. We need to correct that bony malalignment and then add soft tissue stabilization. We all know that isolated MPFC reconstructions are an absolute workhorse, even in the setting of trochlear dysplasia in certain instances. And so the question's when we need to do more. And I think the recurring theme that's helped me is looking for that jumping J sign and that apprehension into deep reflection. Those are big red flags for me in my practice. And the literature supports this. Here's a paper showing that increased version along with that high-grade J sign is associated with failure of those isolated MPFLs. What does do more mean? There's a lot of ways you could potentially get this right in isolation or in combination, and certainly derotation on the femur or tibia is one of them that we'll focus on. So what says one of our greats who's taught me a lot, Bob Taichi, about patella instability? Obviously, we have the soft tissue restraints and the trochlea, but really for him, it's all about that lateral vector of the quadriceps. And for that, the main contributors are valgus and rotation. And if you look at this, those are different gradations of valgus and how they influence the force vectors. And on the far right, you see 30 degrees of version and how that lateralized vector goes up exponentially, 120%. And that makes a huge difference for patella femoral maltracking. Similarly, our close friend and colleague with a ton of experience on this, Vicente Sanchez-Alfonso, thinks about this the same way, with that jumping J sign, that flexion apprehension, always thinking about the trochlea and always thinking about rotational malalignment. And so, when you go to the ESCA meeting I attended last year, and you think about how they approach patella femoral instability, it's a lot more about these factors and not as much about medialization, intermedialization. There's certainly some distalization. So we need all the tools in the toolbox and we need to think about limb alignment, not patella alignment. And I think if you look at the far right over there, you can really understand why this is important. The patella kind of stays where it is and the limb rotates kind of around it. And you can see this on some of our CTs and some of our MRIs. And this is not all patients, but when you see this in the right patients, you know that these are the main driving forces of their particular pathology. And so our prior dogma, I think, has dampened about TTTG above 20, equaling a TTO. I certainly use TTO as my bony workhorse in my practice in life, as taught by John. But I also really have to understand, as you do, that our measurements are not perfectly accurate, right? TTTG varies by age, by gender, by size, on CT, on MRI, in the presence of trochlear dysplasia, where is the groove center, by knee flexion angle in our different systems and coils. But more importantly, TTTG may be a surrogate measure for rotation in a lot of these cases. Clearly, it does measure lateralized tubercles, medialized groove centers in dysplasia, probably most realistically, a combination of all these factors. So I'm just painting a picture that is just not that simple. And so where do we all go from here? Chit Ranawat at HSS taught us that the eyes see what the mind knows, so at least let's see this. Let's turn people prone, let's look at them and recognize valgus and rotation as entities, like you'll see in many of these patients. Let's look for and be very astute in those patients with the jumping J signs. We're obviously going to accurately measure in all planes using multiple modalities, but then we're gonna take all of our threshold values with a grain of salt. So what is normal for rotational profile? This is from our friend and colleague in France, Matt Olivier, and just giving us some numbers to go off of, you can see femoral version and tibial torsion numbers in their paper, 15 and 31. For us at our center, and I'm sure all the panelists, we have our own protocols for MRI for patellofemoral. My MRI have spot imaging at the hip and the ankle to try to get surrogates for rotation. Our CTs are 2D and 3D and we can print and we're also measuring rotation and we can manipulate these models. And so we need our clinical acumen here. Do I need to do more than an MPFL? And then what does do more mean? So we need to make every one of these measurements every time with these complex patients. And there are so many other factors in the patients that we have to consider. This is ripe for machine learning and artificial intelligence. Luckily, we're collaborating with the Jupiter Consortium to do this at Stanford. And so we're getting all the imaging, we're getting all the patient values and we're trying to really make sense. We're doing some shape modeling. So I think a lot of excitement will come in the next two to five and 10 years in that space. So the bottom line is don't ignore extremes of femoral antiversion. There's literature support out there for these types of procedures. This is one of my patients. You can see the MRI in the middle. You see the severe trochlear dysplasia with that anterior prominence that Liza talked about, the jumping J sign. And for me, I've done most of the rare ones that I have started to tackle at the level of the distal femur. I find that I'm often combining that with my soft tissue balancing, of course, and in scenarios of severe trochlear dysplasia, a deepening trochleoplasty. And so here's kind of one of those cases. It's an extensile anterior approach. We're using chance pins to really guide the reduction of the femur. And these can be obviously quite challenging. This was one I did manually for one of the first times. And it is very hard to get that right in both planes for sure. And so I know John Lane may talk about, he does this over a nail. And so there's certainly ways that you can do this proximally at the femur. But because of the concomitant pathology that I'm dealing with, most of the time, I'm able to tackle this down distal. I would say that there's also evidence support, and this is what I've done the most of these biplane osteotomies for both valgus and version. So you can really kill two birds with one stone at the distal femur. And here's a series of only 13 patients showing that you can get successful subjective and objective outcomes with this type of comprehensive approach. There's also super tuberosity torsional osteotomies in our literature. And so in rare scenarios, you can affect change on the tibial side as well. And so I haven't really gone into that space yet. But what has helped me in my training wheels and in my own evolution is patient specific osteotomy. I did not learn any of this in my fellowship. And it's obviously hard just to watch people or watch videos and then to do it. But I'll tell you the planning on the 3D printed models helps me to create precise cutting guides to think about this preoperatively and then to execute in any and all planes. And this has really been a game changer for me, for valgus, for rotation, for combination and otherwise. And so I encourage you to check that out as well. It's still a personal evolution. I think it's starting to make more sense. I don't remember the exact numbers, John, but he pulled a bunch of us from the IPSG. And I've done certainly less than 10 of these lifetime. The combined derotations. So it's still new for me, but I was I think leading the pack of the Americans who actually are doing some of this work here. And I'm sure abroad, there's obviously a much more robust experience. And I don't know if Bob Taichi was included on that particular email because he obviously is leading the way for decades. So thank you very much for your attention. Look forward to discussion.

patellofemoral instability

malalignment

rotational abnormalities

soft tissue stabilization

jumping J sign