Thanks, Miho, and I just want to say it's great to see everybody's face without a mask on and thank you, Miho, for organizing this. It's really wonderful to work with everybody again. Jack has covered things extremely well, including most of my talk. So thanks, Jack. I appreciate that. But there's a lot of redundancy, and that's because these are important concepts. So I apologize for the redundancy, but lots of options on how to stabilize the patella. And we've all kind of evolved towards the idea that most patients can be successfully stabilized with an MPFL reconstruction or some sort of soft tissue procedure. And then the question that we're trying to discuss this morning is when to add these additional osteotomies on, how to identify those patients that need more than a medial soft tissue procedure. And if you look back on the trends in the popularity of patellar stabilization surgery, you can see that initially back in the 90s, the literature was all about tuberosity osteotomy. It doesn't mean it was the right thing to do. It just means that that's what we were studying. That's what we were writing about and reading about. And then this really huge interest in MPFL reconstruction starting in the late 1990s and early 2000s. And now the literature is reflecting an interest in trochleoplasty. To think about how to stabilize the patella, let's also think about the risk of recurrence following a first-time patella dislocation, because it's really the same risk factors that could lead to failure of an MPFL reconstruction. And in this study, the authors identified this patellar instability severity score and showed that if your score added up to four or greater than your odds ratio of recurrent dislocation was about five, and one of the items on that list was patella alta. Big picture, 30,000 feet. These are the things that stabilize the patella. And we know, especially in extension, the primary restraint is this medial soft tissue complex, the medial patelloformal complex made up of these different components. Here's that classic axial cut on an MRI following a patella dislocation with the classic bone bruise pattern and MPFL running from the medial patelloformal complex running there. So if those soft tissue restraints have failed, then you can have excessive laxity and you're predisposed to instability dislocation. So if your primary problem is insufficiency of those soft tissue structures, then an MPFL reconstruction or similar soft tissue procedure is used to restrain the patella. But like Jack said, not to realign the patellofemoral joint. And lots of different ways to do this, and you could argue which is the best way. Well, probably there isn't one single best way. What are the results of isolated MPFL reconstruction? If we're thinking about when to do more than an isolated MPFL reconstruction, we have to understand what works and which patients need more. So this is Beth Schubenstein's, I'd say, landmark article about treating instability with an isolated MPFL reconstruction regardless of bony abnormality. And she showed, at two years, really excellent results in terms of return to sports and recurrent instability. But it's important that we remember that there were a large number of patients that were excluded from this study that, for a variety of reasons, underwent concomitant tuberosity osteotomy and MPFL reconstruction. So this wasn't all patients. So in this prospective study, 42 patients who had borderline increased lateralized tuberosity, so here TTTG of 17 to 20, 18 underwent a combined MPFL reconstruction and osteotomy, and 24 isolated MPFL reconstruction. And in this study, there were better functional outcome scores and kinematics based on radiographic findings in the patients who underwent the concomitant osteotomy. So some suggestion that there may be a benefit to medializing the tuberosity in some patients. Well, how about failures? If we look at the failure of isolated MPFL reconstruction in this study, 239 patients, 10 of their patients failed and required revision surgery. And these were the risk factors. So the authors concluded that they'd still do an isolated MPFL reconstruction, but they'd consider an osteotomy, whether it's tuberosity osteotomy or trochleoplasty, for these risk factors, including patella alta. How about patients who fail isolated MPFL reconstruction? Going back and looking at them retrospectively, what have they found that may have caused that failure? So in this study of 26 patients who required revision MPFL reconstruction, 70% of these had non-traumatic recurrent instability. They identified these anatomic risk factors, and then they found a strong association between these anatomic risk factors and atraumatic instability, and there on the list is patella alta. So obviously, the purpose of my talk is to decide or to think about when is it worth addressing that anatomic abnormality, patella alta. As Jack pointed out, there are numerous anatomic abnormalities that predispose to maltracking and to instability. He showed us how you can measure the patellar height index and use that as one of your criteria for determining when is it time to distalize. Sagittal engagement is probably a little bit more important than patellar height index because you might have a high patella and a high trochlea, so you may not need to distalize if you've got excellent sagittal engagement despite a calculated patella alta. If we think about maltracking, it's really an imbalance of all of the forces acting on the patellofemoral joint. So Jack brought this up. Balance is incredibly important. These are those factors that contribute to that balance and clinically when we're examining a patient, we're visualizing balance with this simple concept of a J sign. So we're looking at that patellofemoral joint, we're asking our patient to extend their knee and we're trying to decide is this patellofemoral joint balanced or not and clearly there is not a normal balance. Doesn't mean that that knee is symptomatic. It may not be. But there's an imbalance if they're symptomatic, if they have recurrent instability, you need to think about all of those factors that may be contributing to that imbalance and we can't talk about this without mentioning John Fulkerson and he always says it's all about the balance. So what about the literature on patella alta? This early study by Chris Powers and his group compared 12 patients with alta to 13 control patients and they looked at these radiographic parameters, subluxation and tilt and contact area on axial MRIs during quad contraction and they showed that the alta group had more lateral displacement, more tilt and lower contact area and their conclusion was that the vertical position of the patella is an important structural variable. We've been using 4DCT scanning for about 15 years to try to understand the kinematics of patella movement and in our most recent study we used computational models of actual patients with recurrent instability and we compared a group of patients who had normal patellar height with recurrent instability and there were 8 patients in that group and then there was a group of patients who had alta and the CDI is listed here as between 1.21 and 1.78, 7 patients in that group. And then we looked at their tracking and tried to correlate their tracking with other anatomic parameters. In this case we found that in the non-alta group the patients had a normal patellar height, the tracking correlated closest with trochlear depth, so surrogate for trochlear dysplasia. So normal patellar height, recurrent instability patients, the degree of lateral tracking correlated with trochlear depth, trochlear dysplasia. But if you looked at the alta group, the degree of lateral tracking correlated more with tuberosity position than with trochlear dysplasia. And if you think about that, that's really an interesting and powerful thought. That means that you have to think about alta in conjunction with a lateralized tuberosity. You can't think about these as separate entities. You can't just look at a number and say, well, they've got a lateralized tuberosity, I need to do a medialization. Because if they have alta in conjunction with a lateralized tuberosity, it's a much more serious problem. And if you add that idea to Adam's work, which shows the difficulty in getting correct tensioning on an NPFL graft when you have alta, it really helps you understand how complicated this is and how many different factors are involved. So the influence of patellar tracking, I'm sorry, the influence of patellar tracking of the tuberosity position and trochlear depth varies with patellar height. So think about all of these factors together. So if you've got an anatomy problem, if your osteochondral geometry is a problem, then you consider an osteotomy not to stabilize the limb, but to realign it, different concept. Soft tissue procedure to stabilize, check brain, osteotomy to realign and correct. So this is one of many different ways of distalizing. In this case, the shingle is moved distally, a piece of bone from the proximal end is packed up in the top, and you can measure out how far you want to distalize. And Jack showed some images. But the question is, which osteotomy do you want to do? When do you combine a medialization, an anter medialization, and a distalization? And the answer is you want to customize that to the specific problems of each of your patients. And you can distalize eight millimeters, 10 millimeters, 12 millimeters, depending on your preoperative measurements. You can pick a slope of a flat osteotomy, you can go 30 degrees up to 60 degrees. Think about each patient and individualize. A couple of quick slides on my technique, just one of many ways to do it. I use two, five drill bits to create my shingle. And instead of converging towards the apex and leaving the shingle hinge intact distally for a medialization or anter medialization, I free the shingle and then cut the end of the shingle off based on the calculation of how much I want to distalize. Like Jack said, I use three of these, three, five screws. I think I get better fixation. The head is, a screw head is smaller. It's very unusual to need to remove these screws. If you lack that little piece of bone in the defect, you can add some additional bone graft. So what about the results of combined MPFL and tuberosity osteotomy? This systematic review, which was just published, is of 786 athletes, 10% of them had concomitant osteotomy, 93% returned to sports, only 70% at the same level. And it was about seven months. These authors found no statistically significant difference in patients returning to sport following isolated MPFL versus combined osteotomy. In this study, 100 patients, 71 of them had isolated MPFL reconstruction and 29 combined. There was no difference in return to sports between the two groups, but return to sport at the same level was statistically different and it took substantially longer for the combined osteotomy patients to return to sport. We've got to remember this because these are real. These complications can and do happen. You can have complications with MPFL reconstruction too, but these complications here are more devastating. And Jack pointed out the potential for delayed healing, non-union, and even fracture following a distalizing osteotomy that's done with a step cut. So don't be surprised if you still see that healing osteotomy at six months. And I would urge you to follow these patients closely, repeat x-rays probably at three months, probably at six months before you let them get back to cutting and pivoting sports. You want to make sure that the shingles heal. There are other ways to distalize. This is the step cut, but you can converge towards the apex and do a little slide. That works well. You can use bone graft approximately, allograft as well. We looked back at complications of tuberosity osteotomy and they are real. They do happen and they happen more frequently in distalizing osteotomies than they do in non-distalizing osteotomies. And here's that little point about using the 3-5 screw, three of the 3-5 screws, the risks of complications is lower in that study. So to summarize, MPFL reconstruction to stabilize, osteotomy to realign, consider adding a distalization if you've got ALTA, think about sagittal engagement in addition to your patellar height index, and then of course other osteotomies are indicated in selected cases too. Thank you.

patella stabilization

MPFL reconstruction

trochleoplasty

recurrent dislocation

patella alta