Just a little housekeeping before we get started. This is meant to be and will be kind of a small group session. And it'll be very much interaction with our esteemed faculty that we'll meet in a moment. And so in order to do that, anyone who's kind of over here, please make your way to one of the round tables and we have likely one to two faculty at each table. We'll make sure of that. Also make sure that you'll be able to see the screens because we're gonna be going through cases and discussing cases. So it's better to have more people at the small tables together. Thank you. Looks like we made that work effortlessly. That's excellent. All right. Well, I'm Seth Sherman from Stanford University. And the goal here is to take a tour through patellofemoral joint preservation, really doing this in a small group and case-based approach. I'm fortunate to have Miho Tanaka with me to help moderate and to move us along. We're going to do this as case presentations with three of our faculty. So I've asked Adam Yanke, Christian Latterman, and David Deduck to present cases. These will be open-ended cases, and then we'll discuss them. And then we'll come back as a larger group. We have, what could be said, one of the highest authorities in all of the world of patellofemoral sitting in this room. So we have a real great faculty, Liza Arendt, Beth Schubenstein, John Fulkerson, Andreas Gamal, Sabrina Strickland. Really world experts in the field of patellofemoral joint preservation. So for each one of these cases, we're going to present it for about five minutes. We're going to discuss, which is the most important part, for about 10 minutes. We're going to come back to the big group, and one person from each table, preferably non-faculty, can give your thoughts going through the problem list and what you'll do. And then we'll bring it back to the case presenter to say what they did, and then we can have questions and answers. So we'll keep to time, and we'll see how that goes. If it's too fast and we need more time, or too slow and we need less time, we'll adjust accordingly. I just have a few slides to level set here before we get started with Adam's first case. While patellofemoral chondrosis is common, the majority of these patients that we see every day are asymptomatic. So while we're talking surgical here, it's very important that we must not over-treat these patients. The cartilage repair landscape can be very confusing. We're going to go through the easier, cheaper, one-stage procedures. We're also going to talk about the more difficult, expensive, and two-stage procedures. We're going to see how some of the procedures may lead to fibrous tissue, and others of the procedures will lead to hyaline or hyaline-like repairs. We did a consensus statement several years ago, and the reassuring aspects are that if we stick to principles, there's actually a lot of concordance amongst the faculty in this room and around the world. However, when we're talking about differences in ACI versus OCA, in the location of the defects, like a central trochlea, median patella ridge, multifocal lesions, things that we'll get to today, there is some discord. And so there's both science and surgeon preference that comes into our selection of the cartilage procedures of choice. Bettina Hinkle put together this nice systematic review, 59 articles, and the good news is that if we do stick to these principles of alignment, stability, and cartilage, really whichever you select, you can get improved outcomes, low rates of minor or major complications, with really no major differences. We've seen this throughout the meeting and throughout other discussions on patellofemoral joint preservation. We think about the joint as an organ system. And when you go through in your small groups, really think about all of these aspects. So really don't laser focus or jump right to the cartilage problem. Go to that one last, and perhaps think about the patient, the joint as an organ system, the alignment, the stability, and then the cartilage. And these are kind of the most common things we'll likely discuss as concomitant procedures, whether you're going to add TTOs, MPFLs, lateral lengthenings. You can see there are other things we may add at certain times, and we can get to those, but I think those will be our workhorses. This is just looking at cartilage mapping. This is John's famous work. Basically, if you have distal and lateral lesions, you can offload them typically without cartilage restoration. And so think about when you can do that. Whereas if you have lesions that are central, medial, or panpatella, you really can't do that, and you need to add cartilage restoration to your balancing or alignment to get a good outcome. And so lastly, this was just a database study, 1,000 patients, looking at cartilage restoration with or without osteotomy. And when you add that osteotomy in these cases, you can reduce the risk of reoperation, similar complications, and similar overall costs. And so the reason we're all assembled here early is for lifelong learning and for passion about the patellofemoral joint. So we're grateful that you're attending, and we look forward to a lively session and a very interactive session. So we'll transition over to Adam, and we'll get going with case number one. OK, perfect. Thanks again, Seth. And thanks for having me. Again, my name's Adam Yanke from Chicago, and we're going to start out with a case that I actually just treated recently. And one of my fellows challenged me on what we ended up doing on this case, and I still look back at it and scratch my head about what I did. So I'll be interested to see what everybody says. This is a 12-year-old female who came in for primarily retropatellar pain, and she also had patellar instability. She did have documented patellar dislocations with MRIs that showed bone bruise patterns, so that part was very legitimate. She said the pain had been going on for about the last 18 months. It's mainly medial inferior to the patella with higher-level activities, but also she really had pain with daily life. These were semi-tearful visits of trying to get her through different treatment options for this, which we'll be able to discuss. But it really was shutting down her life. She really wasn't doing anything that she wanted to do, wasn't going out, hanging out with friends, and she was becoming pretty sedentary, which for a 12-year-old, obviously, there can be other factors at play there, too. So I think that makes some of these decisions a little bit harder. So she says now she gets frequent subluxations, even when she doesn't dislocate, and very clearly for her, she has pain outside of dislocations. So she has pain with the events, but she also has pain without that. So I'll move on to the exam. If there's any questions or clarifications before we get to the discussion, just let me know. So she had no effusion. She had a little bit of hyperextension, but she was able to actively get there, too, so no limitations in motion. She really had a pretty normal exam, except for patellar translations. So she had almost three quadrants of lateral translation with no firm endpoint with apprehension. She did describe some mild medial apprehension, but she said it made her much more nervous when we moved her laterally. She actually did not have any pain or crepitation with patellofemoral grind, and her hip range of motion was normal. Her tracking was what I call a C sign. I don't know what everybody else sees with these, but sometimes the patella just goes straight up and down when you flex and extend the knee. Sometimes it's a J. This one just comes over and back a little bit. So I don't know what that means. I still don't know why some do that, but I feel like 5% of them kind of do that. And then otherwise, ligamentously stable throughout. On her imaging, here is her lateral X-ray. And I guess I'll let some of you discuss at the table how you view the amount of dysplasia on this X-ray. But you can see that I calculated the CDI ratio, or canton to champs ratio for you there. It's 1.5. The rest of the X-rays were normal. And then these are her MRIs. So we'll scroll through this axial one. Let me see if I can control it. There's probably a good slice. And then, so you can see the TTTG flashed up there. It's nine. And we'll run through this sagittal. Should go through there. So there's a view of the patellofemoral cartilage. A little bit of dysplasia. I'm purposely not saying too much now so that you guys can discuss it. But this is really what I have for the setup. So, you know, if there's questions that you want to ask me now to help clarify the case or the situation, we can do that. And, you know, the... Go ahead, Andreas. I would say closed. Yeah, that's a good question. And the, you know, I think that also at the tables, if you want to discuss what you would do non-operatively as well as operatively, probably good to know. So if you're going to talk about bracing, therapy, injections, just I think it'd be good to hear a consensus around those things too. Yes? Sorry, but can you use the mic because these sessions are recorded? So... Thank you. And for those who just came in, maybe join one of the, sorry, for you guys in the back, maybe join the tables when we break and that way we can be part of the active discussion. Andy? So Adam, just quickly on the sagittals, if you could just let us know because it went through fairly quickly. No edema in the patella on the sagittals, is that correct? Correct. Yeah, no bony changes. Maybe like a little bit of increased sclerosis there at the center, but really no bony changes. Patella trochlear index and knee hyperextension. Hyperextension minus 5 degrees. Patellar trochlear index I didn't measure, but the overlap here you can kind of see. I would say that it's actually fairly normal, even though the CDI was high. So a little bit of a long trochlea. Her BITEN score was 3. Sorry, I didn't include that. How about the rotational profile? Was it assessed? And is there a poor mechanical axis assessment of her? Yeah, great question. Yeah, all the MRIs I get go from hip to ankle and with mechanical axis. They were all normal for her. So normal thigh foot progression angle, normal femoral anteversion, tibial torsion, and her knee rotation angle was actually normal, too. Great, so let's break and discuss and then we'll come back in a few minutes. Thanks. All right, let's bring it back together to the larger group. And we'll start with this table over here. So we do need to grab the microphone so that they can have this recorded. But maybe whoever wants to be the ambassador from that table, just give us your thoughts. And then we'll go down the line and have a discussion. You can also ask clarifications from Adam and whatever you want to do. So our discussion centered around the fact that we think this is a structural problem, that first of all, we would probably offer non-operative measures first off, but didn't really think that that was going to be the solution. And so we discussed the fact that we would likely do a diagnostic arthroscopy and then ultimately lead to doing a distalization osteotomy, a tibial tubercle osteotomy, distalization, antramedalization, and MPFL reconstruction. We didn't really get into details about what we were actually going to do with the cartilage. I think that would be dependent upon what we found at the time of initial diagnostic arthroscopy. Personally, I would want to, the main reason I would, one of the main reasons I would want to do the diagnostic arthroscopy was potentially to harvest for a potential MACE at the second stage procedure. And wanting to do that, I would probably set it up as if I was going to do a chondroplasty and hope that maybe that provided benefit to the patient, but ultimately be talking to the family about the fact that I'd be moving to a cartilage procedure with the concomitant procedures at the same time. Would you definitively plan to go back, meaning do the small surgery, big surgery, or is this one where you're going to perhaps debride, wait and see, and come back only if symptomatic? And that's not just for you, anyone from the group. You can answer it if you want. So personally, I would want to try and see if she did OK with the chondroplasty. I think ultimately it wouldn't. But I have a hard time convincing patients to jump into a big surgery where I'm talking to them about cutting the bone and shifting things. And I've had a few patients that just do a chondroplasty, and they do OK, and then they never come back. Gives me the option. I would actually very much agree with that. I've had probably most patients with a patella lesion here, medial side of the patella, instability's involved. You fix the instability, fix the alta, they did great. I'd be very optimistic that'd be all this girl would need. But you could have the biopsy there just in case. But I think I tend to undertreat chondro lesions most times, and I'm very pleased with the results I get. Even sometimes big lesions on the medial side once you correct the instability. So just to clarify, you would advocate for a single-stage solution, is that what you're saying? Yes. Perhaps cartilage later. Correct. Yep. OK, that makes sense. And I guess on that, does the cartilage mapping, like the location of the defect matter here? Because this one's what? Would you say it's central? It's medial and distal? I would consider this medial. Medial and distal. We discussed that when you're talking about what to do with cartilage, you've got to first understand how it got there. Because if the forces at play remain, you're going to continue to have the problem. So I think this came from instability from the relocation. So then you fix that. That doesn't happen anymore. Those do fantastic with the rebate alone. That's my approach to this. And if you've got a revision situation, that's different. So maybe others, but I think you could easily overtreat cartilage lesions that you're going to otherwise do well. Yeah, so fundamentally, I would agree. But in my experience, I don't have such a great track record of these medial-sided lesions. In my experience, they tend to go bad. And then the discussion always comes, are you going for too big surgeries and too big rehabs or not? Now, in a 12-year-old, they have a lot of resilience, usually. And depending on who they are, I mean, some don't. But they have also time. So you could maybe make that argument. But if this was, let's say, a 20-year-old who was in the middle of trying to basically build their careers, I don't think they have the luxury to potentially go through too big surgeries. And to do a cartilage case here, yes, it does cost money. But it is a very, very small effort to add that. And I think my consideration would kind of play around with that a little bit. And I would certainly discuss that with a patient. Now, a 12-year-old is a little bit different. Excellent. We can give the microphone to group two. And then maybe Andreas can make his comment. And then whoever wants to summarize your discussion. So I think both of you have really good points. And it's interesting how we can have different views, technically, about the same lesion. So when you look at that lesion, I think it really matters if we get a sense, and no one can answer that fully conclusively, but whether this is a lesion who comes, like David said, from the relocation after dislocation. And those tend to be maybe a little bit more distal and maybe a little bit more, you know, Those tend to be maybe a little bit more distal and maybe a little bit more medial. It's a little bit more peripheral, even. And I agree. Those pure dislocation distal medial lesions do great as long as you fix the instability. Or if this is a lesion that developed over time from her having pretty extreme alter. And I think the ones that come from having extreme alter, unless they're totally distal, which this one isn't, they don't do so great with just unloading. So spending more time on the MRI scan, figuring out which one of those two personalities that lesion is would help. And then to Christian's point, doing a TTO with an MPFL is a pretty long rehab. When you do your MPFL, you're essentially looking at the medial facet. It's just a capsule between you and that. So to add either what's been mentioned, Macy or a single stage particular juvenile cartilage allograft, I don't think that would change her treatment's rehab very much. So it may be worthwhile. I hate this word, oh, let's just throw it in. But that might be one where I would just throw that in. Even in the setting of that amount of alter? No, no, no. I would do a TTO and MPFL. And the throw it in just means, why don't they also do the cartilage? Anyone want to summarize some other thoughts from the group? OK. So I'm John. I'm a St. Luke's resident. So we talked about first starting off pretty conservative physical therapy and kind of throwing the gauntlet at addressing her pain, kind of trying to find out if it's coming from the chondral effect or the instability, and then trying to focus on strengthening the posterior chain and core. And then we're assuming that she's going to surgery without physical therapy. Can I just clarify one thing, John, and maybe with Adam? Was this recurrent documented dislocations or a one-time dislocation with longstanding pain and some instability? She did have a start with dislocations prior to the constant pain. Dislocations, plural? She has had multiple full dislocations. Per her report, she has one that had an MRI after it that showed the bone bruise pattern. But she didn't have multiple MRIs for multiple dislocations. I bring that up just to ask your group. I mean, if it's a recurrent dislocator, are you guys going probably to operation sooner? I would imagine you are, right? But if it's a one dislocation and then continued pain, that might be a different kind of case vignette. Yeah, I would just say that we were talking about just the pain, pure pain part of it. I think that's the question is, why does she have pain? To David's point, why does she have pain? She clearly has instability. That's a whole separate issue. And she's going to need surgery for her instability because she's a recurrent dislocator. So there's no debate on that. And I think all of us would agree some type of medial-sided reconstruction is the answer. The question is, in this setting, if you believe that this cartilage lesion is from her instability, then you've solved the problem by just treating the instability. If you don't believe that, and again, she doesn't have edema. So I do fall on the side that this is likely from her instability. I always think you have to look for the upstream problem, right? What's the reason why she has the lesion, as David said? So I think that's what we were really debating on, whether or not to treat the lesion or not treat the lesion. Excellent. That's a great point. One quick comment on that. We talked briefly, and then we didn't get to finish the conversation. But by distalizing a CDI of 1.5, and maybe I just raised this as a question too, if we distalize, can we unload that lesion? Is that enough in itself just to do that, maybe meet a stabilization? Yeah, that's a great point, because I think that Baja gets a real bad name. But in reality, the two biggest predictors developing patellofemoral cartilage disease outside of instability structurally is trochlear dysplasia and ALTA. So it just spends too much time out of the groove and too much time entering it, and then you get this type of appearance. Other John, maybe just briefly say what the group thought to do. Yeah, so we definitely talked about an obvious stabilization procedure immediately. We were kind of back and forth on osteotomy in a 12-year-old. And then we did agree with table number one on getting a Macy biopsy for the cartilage defect, but not addressing it at that time. And then we didn't get to finish our discussion on addressing the patella ALTA, but considering some kind of distal anteriorization. Great, and we'll go to the last group, and then we'll see what Adam did. Just because it sounded like multiple dislocations, we briefly touched NONOP. But went right to operative management, and we're like, yeah, no-brainer, NPFL for sure. Cartilage, we just discussed chondroplasty. And then we kind of ran out of time, but we decided not, real briefly, decided not to do anything, no TTO. The more I thought about this, just myself, if I had this, I would not do a TTO. If it was an older patient, I would. Something about her age, for some reason, is telling me not to do a TTO. Just do an isolated MPFL and chondroplasty. Less is more. I just kind of wanted to make a comment that I do think that there is increasing evidence that if you have ALTA, that it does put load on the inferior part of the patella. We do not have a lot of evidence in the literature about how long you have to spend in ALTA. And I would highly doubt that at age 12, that this lesion is from ALTA. And even though she's got a CD of 1.5, you know, Adam, you already said it, she's got a half, she has a semi-normal patella trochlear index. So I think the only thing that would make me want to distillize her is if she had significant hyperextension. But I just, I don't want people to leave, think, I don't know, at least that's my opinion, that as soon as you have ALTA, you're going to have a distal lesion. If you have a medial-sided lesion that you get from a dislocation, that might be aggravated by having ALTA. But at 12-year-old, that we have evidence that just having patella ALTA changes the cartilage on the inferior patella, does anybody have that evidence? I think the evidence is there for it to be there later. The question is, what stage are we catching it at here? Well, she's painful. So the. So two questions, though, on that. No, is she painful on that medial facet? Is all her pain inframedial? She has inframedial and just retropatellar pain. And did you measure sagittal TTTG? As much as I love it, I did not, just because I don't know what to do with it yet. But I academically measure it, but not clinically. So the other thing that, anybody see the movie 10 Cloverfield Lane? John Goodman, ever see that? This is going to be a major spoiler alert. But in that movie, he's a psychopath that finds a woman outside of his, like, fallout shelter. He brings her downstairs and says, the world's ending. She thinks he's just crazy. And then she's trying to escape the entire movie. She gets out, and there's aliens out there, and she dies. So, like, it's an amazing movie. But the point is, they're not mutually exclusive. She's not crazy. She was made crazy by her disease. Like, you can have, well, you can have both things going on. So you can have medial defects from dislocations, and you can have cartilage damage because of other abnormalities. So I feel like she fit in that category, where it's, like, maybe a little confusing, because I think it's actually a little bit of both. Last comment from Christian, and then Adam. Yeah, so this is kind of like a comment to Lisa. So I agree with you. This is not, I don't think this lesion is from the alter. This lesion was originally likely caused by the dislocation. But the problem is, if that keeps on happening, then you're starting to turn that into a chronic lesion. And that is something that then becomes a completely different animal, and may, you know, this is why the value of the arthroscopy here is really high, because I wouldn't be surprised when you actually go in there, that lesion is a lot larger than what it originally looked on the MRI. Can I ask just a quick question? So we keep talking about the cartilage issue with the, tuberculosity, her main problem is instability. So why are we not talking about improving the instability with the distalization? We keep talking about the cartilage issue, but the main problem is instability, and a distalization may help that. So why are we not talking about correcting, doing the TTO for instability or for the cartilage issue? I understand for the cartilage issue, she's got it. But that will also help her instability, correct? Doing the distalization, someone's got an alter. Right, I think that's something in this setting. So first of all, for her, the main issues are both. She would be unhappy with a stable knee that's still painful. And so maybe let me get to some of the treatment, and maybe it'll help. So, you know, 12-year-olds, I think the youngest paternal instability I've treated is 8 years old. I see more like 10 and like this age. And I think we all know that the dynamic between you and the patient, the patient and their parents in this setting, it's all really important how much eye contact they're making, how much pain do they actually have. Are their parents just trying to make them play a sport they have no interest in, and they're just, you know, it's a family psychosocial issue. So I think there is a lot there with 12-year-olds that, you know, you have to be a little bit careful. It's different than a 25-year-old. So I personally wanted to, like, be as sure as possible that I was going to have a good outcome with whatever I did. So I put her through a lot. She was pretty annoyed with me, honestly. But I did physical therapy because she just, she wasn't the strongest person. Like, she didn't need it to solve her problem. But I thought she'd just, you know, put money in the bank because you're going to need to withdraw it after surgery. So we tried to strengthen her up as much as we could. I put her in two different braces. I used a patellar stabilizing brace as well as a patellar offloading brace to see if she got some diagnostic benefits with that. If she wore that patellar stabilization brace, I wanted to know if she had less pain in that situation. She said it made me feel very confident and stable, but I still had the baseline pain all the time. We used a patellar femoral offloading brace. She said my pain got better when I used that, but I still had sensations of instability when I would come out of it. And then prior to seeing me, she had a cortisone injection, and she said that flared her pain, which that is always hard for me to figure out. I do think that there's patients that have no intraarticular pain source, and you cause a new sensation to them by injecting their knee. And that's, those are the people that have these flares and no improvement. So I had some concerns there. She was recommended for an isolated MPFL reconstruction, and this is what you guys were asking for. So, you know, she had that flap. That was a fissure that had a little bit of delamination next to it that we were able to debride. But the total defect size for that, like, grade three, grade four lesion was maybe 10 by 12 millimeters. But most of it was this soft central cartilage that really went across the patella. So does that, I guess at this stage, I guess who would do more than a TTO MPFL? So I think this part's helpful. You know, go ahead. I think it would be helpful to find out who would still not do a TTO. Great. I think we only had one. I'd like to, I mean, I would just love to see who would just do an MPFL. Even with that, an MPFL contraplasty and just see who would like to do that. Yeah. And we didn't even, because there's a lot of different rabbit holes we could go down here, but we really didn't even go down the rabbit hole of what if there was no cartilage damage in this patient, no pain, you know, would you also osteotomize them? But I think your guys' table was the one that was isolated MPFL. So do you feel like this would be any different for you at this point? Still the same. Okay. Just to make it clear about the contraplasty, we're just talking about taking that little flap off, not doing anything with the soft thing. Correct. Okay. I'd lose my lunch if I started touching that soft stuff. I just want to show this as another example. This was another patient with retropatellar pain, and this is what her cartilage looked like. You know, this patient presented with almost mechanical symptoms. You know, and this is just one I like to show, because this is after debridement. It's just very smooth. Her pain was gone in the, actually, I hate saying this, but this was a very specific situation. It was gone in the PACU. Like, she could just tell. She had lived with this popping and cracking. And, you know, it was mentioned, and most cartilage lesions don't need to be treated in patients with patellar instability, and I think a lot of us would agree with that. We looked at my patients and Brian Cole's patients that had Macy biopsies, and this is a non-instability cohort. So, this is just cartilage pain, retropatellar cartilage damage, and we found that we weren't always going back to do the ACI at the time, and it turns out that when we looked at it, just two-thirds of the patients just had done better and said they didn't feel like they needed to have anything else done. So, we tried to look at this then prospectively in about 100 patients, 120 patients, and followed them to see when they would ever convert to having a cartilage transplantation, and the patellofemoral joint actually was less likely to convert than the tibiofemoral joint, and then you can see the overall conversion. And, we looked at what could help predict them need a later transplantation after the chondroplasty, and so there were two different PROs that correlated with that. One of them was Kuh's quality of life, and you can see that in the orange are patients that eventually converted to having a cartilage transplant after the debridement, and the blue did not. And, so the ones that did not started out actually in a better spot, but what I thought was pretty amazing, because we don't usually collect PROs this fast, but even at two and six weeks, those patients would not be better, which you might say, well, they need more time, need more therapy, but at two and six weeks, the people that responded and thrived, they actually were already getting there that fast, and so that difference really widened out to as wide as it would ever get at six weeks, which I thought was pretty interesting. And, so Mario Havezzi was one of our fellows who's over at Mayo now and helped us put this together, and this was a calculator to try to figure out, you know, what factors lead to a higher likelihood of a patient converting or electing to have a cartilage transplant based on their pain within six months of a debridement, and patellofemoral defects were much less likely to do that because there is something different about their mechanical nature and how they engage. Kuh's VR-12 score is an Amadeus score, which is a combination cartilage score that includes bone and defect size on MRI, but in a lot of these patients, the chance of converting is three or maybe a third of people, so a 3% or 33%, but the vast majority of people will do well, and you can certainly overtreat people if you do a little too much, and this is just one other food for thought slide. We looked at cytokines associated with chondroplasty, the time of chondroplasty, and they associated with patients' current pain levels better than any structural aspect whatsoever. And so, you know, that's where I think injections can sometimes play a role, but that's basically what I have. I can skip this next one, so I'm happy to answer any questions if we need to move on. That's fine. Yeah, what did you do? Oh, yeah, I didn't say that. Are you serious? I got so excited. I got so excited about the debridement and the cytokines. I did a 60-degree cut with five millimeters of distillation. Ten millimeters of translation along the 60 degrees, an MPFL, and a chondroplasty. Single stage. Single stage. She's, this was Tuesday. And sorry, you had that planned the whole time. Let's say. But I've done it before, and it works. If that defect looked much more impressive than this, would you have done it differently? Yes. Or it actually looked fairly underwhelming, so did that maybe even make you think that you should do less? I mean, it really could diverge in both ways. Yeah, I had, that's what I'm saying. Like, when I was in this case, the fellow was like, why are we doing this to this 12-year-old? I was like, don't tell me that right now. It's like, I got the saw in my hand, and. A touch, yeah, as opposed to a straight anteriorization or distillization, I guess. Yeah. Yeah, so I. Yeah, there's a lot there. I would just say that the, I would just say why I did what I did, and maybe that'll answer the question. Yes. Correct. Yes, that is correct. And if I have somebody that, she also had to tell her instability, so I didn't mind medializing her a little bit, even though her TTTG was like very normal. The other thing that I think is like a little tricky with these is that you are not, when you do this surgery this way, you are not medializing them, you're centralizing them. And I think it's an important differentiation, you know. You're taking somebody that's, and she's not the best example, like, but a lot of times you can have people that have medial defects that are more lateral than her, and when you do a medialization you're bringing them to normal, not over medializing them and loading it. So actually when you go from lateral to central, even though you technically medialized, you're actually offloading it biomechanically. But that's assuming abnormal initial values, right? Yeah, yeah. Otherwise force vector. That's why I didn't do a flat cut on this. Adam, did you take a biopsy here? It's a good question. I did not. I did not. And I did tell the family that this could become a staging scope. Things looked worse when we were in there. Yeah, but I do have like, it's a very small number, less than five kids that are like teenagers that had no instability, but they have that same cartilage on MRI. It's only on the patella. They have a little bit of ulta. It's like black cartilage on MRI. You get in, the whole thing is soft. I've done isolated TTOs for them, and they actually seemed to be doing well. I do a preoperative diagnostic patella-femoral offloading brace to also help convince myself as well as the patient. But I feel like that that was like playing into my decision. That's an observation that I've had, too, during my time in Kentucky when I was taking care of Shriners Hospital. Kids that age have a tremendous recovery ability in their articular cartilage. If she was 24, would you have taken a biopsy? That's a good question. You know, I guess I just don't know what this soft cartilage, if it ever turns into a transplantable lesion. My threshold to take the biopsy is pretty low, but I don't know what this turns into, to be honest with you. And to Liza's point, I think this might be part of early stages of stuff, but I certainly don't know. I don't have evidence to say that's true. Okay, well I think we need to move forward. Thank you so much, Adam. Next up, we have Christian Laderman presenting his case. All right, good morning, everybody. My name is Christian Laderman. I'm from Boston, and I was asked to provide the second case here, and I always hate following Adam, because then usually I look a lot more aggressive, and he's a hard act to follow. But this is a case. 23-year-old female, currently a student. Recreational activities. She likes to do some gym workouts. She can't, currently. She has recurrent left knee pain with swelling, crepitus at the initial presentation. This has been going on for over a year. She has had some sort of a cartilage surgery on the right knee. That's where I leave this right now. Three years ago. She has pain with active daily activities. Doesn't wake up with a swollen knee, but at the end of the day, she has a swollen knee. She has done, I think, 40 some sessions of physical therapy without much success, and half of that in our center, so I know that they did a reasonable job doing that. She failed NSAIDs. She had one intra-articular cortisone injection with relatively little relief, short term, couple of weeks. On physical exam, she has a relatively mobile patella in extension, about three to four out of four. She becomes stable if you do the same thing at 30 degrees. She has a smaller fusion when I see her, free range of motion otherwise. She has a J sign. It's not super impressive, but it's present. Pain around the rim of the patella and, she tells you, deep inside. The VMO musculature is atrophic. It's not horrible, but it's atrophic. She has normal alignment otherwise. These are her x-rays. The AP is usually non-contributory. I actually, frankly, don't know why we keep showing it. The lateral, you can see this here, and the patellofemoral view. This is done at slightly more than 30 degrees of flexion, but I can't educate my people to do this better. What I see here, if you measure her caton, the caton is about 1.3 and a half, so it's a little high. Not horrible. I didn't feel she has much dysplasia. If you're looking at the Dijon classification here, she doesn't seem to have much of a bump. The patella looks reasonably well located on the sunrise view here, but then you get the MRI. I go through that slowly. These are the axial cuts, obviously. You see there's a significant cartilage lesion, medial overriding to this lateral, and then the patella appears laterally subluxed. This is basically the lesion. If you do some measurements on the MRI, on the sagittal, her patellofemoral engagement index is about 16%, and her TTTG is 11, 10.6. Caton, I wrote down here 1.2, 1.3, somewhere, so it's not really a dramatic patella alta on the radiographic measurements. The caton difference, this is something that I always look at if I'm thinking about moving anything on the bony side, is 8 millimeters. That means basically the difference between the two limbs on the caton measurement. This is her scope. I apologize, I don't have a nice video. My facility doesn't let me routinely collect these. This is a 20 by 25 millimeter defect, overriding the midline, involving a large portion of the medial facet. It is isolated, technically, and it has some loose chondrofragments. The central fragment that you see on the top right is actually relatively loose. The trochlea, however, is pristine. So we have a 23-year-old, symptomatic from a chondro defect with pain and swelling, no dislocations, but a functional patella alta, if you're looking at the PFEI, positive J sign, TTTG of 11, PFEI of 16, caton distance 8, isolated chondro defect of patella with large loose chondrofragment measuring about 20 by 25 millimeters. Assume that all non-op management is exhausted here for the discussion. The patient is compliant, motivated, and at this point wants surgery to fix a problem, which is partially because she had a similar surgery where that was needed on the other side, where she was reasonably happy with, and partially because she feels she has exhausted everything else that she needed to do. So what I would like to think the tables about is what technique to address a patella defect, if you want to address it. Would you do a TTO or not? If the TTO, what parameters? Medialization, enterization, distalization, think about those things, and then pros and cons of different technology approaches. Christian, could I ask you to go back to the AP that you think is non-significant? I knew this was coming. Caught that too. The one that I said we don't really want? Yeah, that's the one. I don't think it's as, like, major, but if you look at that, you have to suspect version, because you see that the tibial spine is butting into the lateral femoral condyle, and you should see the two arms of the intercondylar notch pretty symmetric or pretty clearly, and you can see. So I think that there is some rotation in that particular, and you have to ask yourself the question, why does she have an isolated lesion? So, you know, I don't want to overplay antiversion either, but I think that when you have an atraumatic lesion and you have this kind of an x-ray, I think there's a lot you can learn from an AP. So you bring up a very good point, and this is an important thing when you're talking about chronic, but mostly true instabilities, which she really has not had any truly dislocated or truly documented dislocations. What I do in those cases is I put them prone and basically test rotation in the hip, and that in her is completely symmetric, so I'm not worried about an antiversion issue, and you know, I think this is not a bad idea to measure the distal femoral rotation. I didn't think that she had much of there. She didn't have squinting patella at all. She had actually had a fairly straight gait, but she did have a function. When you test her for extension, she did have a functional J sign, so you could see that the patella clearly was coming, you know, above and out. So I did not believe, did not think that rotation is much of an issue here, but your point is well taken. Do you have anything on the sagittal? Sorry? Do you have anything on the sagittal, TTDG? So how far forward versus posterior is her tibial tubicle relative to the trochanter? Sorry, can you speak more into the microphone? The sagittal TTDG. Do you have any information on that in her? No, so she is not, I don't routinely measure that. I look at it for interest, but I frankly, I'm not exactly sure what to do with it, because if I do any kind of cartilage-based procedure, or even in instabilities, I by default actually anteriorize. So I'm not really kind of, that wouldn't change anything in my surgical indications for me. I know that, you know, you are looking at that, but I simply don't know what to do with it on a kind of interventional perspective. Well, maybe Miho and Adam can talk a little bit more about that, because you've done research, but it would help me if TTDG is normal, if patella-alter were normal, which this one isn't, and I just can't explain why they have a big cartilage defect. If I see that they're really posterior, I may consider just a pure anteriorization TTL. Okay, can you show those cartilage lesions again? It looked to me like there was still some pretty good cartilage on the medial facet. Lesion looks like it was almost entirely lateral and central, but still a preserved medial facet. Is that true? Yeah, so that's a good question, and this is something that, you know, when you are, so I come into the patellofemoral field from the cartilage side, as you guys know, and these lesions have a tendency to grow, right? They start somewhere, and initially this may have just been a central lesion, and then depending on what happens, these lesions expand, and this has been going on for several years here, so I think at that point, basically, it becomes impossible to really determine what the original mechanical problem was here, and you are now dealing with a pan patella lesion that goes from medial to lateral, and in those cases, I'm not 100% sure that I know whether this is originally an issue because of the outer, or it may have been an issue because of, you know, changed loading patterns. The other thing, and you'll see that later on in the resolution of the case, and this is something that I can show you here on the MRI. Yeah, so if you look at the patella, the medial facet actually starts here. It's a very short medial facet, and when you see the solution, I'll get back to that for you because she's actually, she has somewhat of a dysplastic portion there, right? Now, what I don't know is if this is because of progressive wear. This has been going on for multiple years, and, you know, if this is truly a dysplasia, but you'll see that when I resolve the case, what the issue was there when you see the intraoperative pictures. Christian, before we go to the breakouts, can you just quickly, did you say what she had previously done? So on that side, she hadn't had any surgery? No surgery on that side. Okay, I think it's time to go to the disc. Can you just show the sagittal MRI just so we can look at the integrity of the bone? Here it looks okay, but I'm just trying to determine the subcondylar, subcondylar bone, and I think on the sagittal that you showed before, I thought I saw some irregularity. Yeah, relatively little, relatively good. So, at this point, she was no longer loose on that side. The other side was taken care of, not taken care of by me, and she was happy with that. But she had a very similar picture from what I could gather and what was done on that side. Yeah. Okay. We're going to... Sorry. We're going to go to the breakouts. Maybe we can go into the discussion now? Okay. We're going to get started with the discussion. And I think we'll start on your end, Liza, or at your table, if you have a designated person who's going to talk to us about your plan. So we looked over the case. We decided this is mainly a cartilage problem, would need a cartilage treatment. I think we'd all settle mainly on Macy, as far as which treatment technology, just because of the ease of matching contours. OCA would also be an option, but it might be more difficult to match appropriately. Second thing would be an osteotomy, TTO, mainly a steep osteotomy for anteriorization. All right. You want me to resolve it? No. Everyone's going to... Keep going? Good. Can you talk a little bit about how much you want to anteriorize, whether you would consider any medialization or distalization in your osteotomy? The distalization, she's a borderline alta, right? What was her? 1.25, I think. 1.2. So the distance was eight millimeters. Can you clarify that difference, eight millimeters? That is basically the difference between the limbs, right? So that would bring you to a caton of one, which is slightly lower than one to one, two is normal, right? Christian, are you talking about how much you would astectomize, like the amount of bone we needed to remove to bring her to normal? Come again? You're talking about the amount of bone that you would remove to bring her to normal? No, that's not amount of bone that I remove, that's just how far distalized, how much I would slide down the bone block on the osteotomy. So that's eight millimeters, to bring her to normal. I can't hear that. He said it's not an instability case, so why distalize? Since this is not an instability case, why distalize? So that's a good question. That's a question that I actually throw right back at you. Why would you distalize if you're doing a cartilage repair? I would up the danger. You want to optimize your biomechanical environment when you are going through the effort of repairing the articular cartilage, right? And if you are looking at a tubercle osteotomy, you have the luxury that you can correct in all three planes, right? So why would you not? Don't give it away yet. Let's go through the tables and then maybe come back to it. All right. Good. I'll show you then at the end what we did. Actually, to that point, I think what we talked about is doing a steep TTO and getting as much anteriorization as possible. We would not distalize. And the reason not to distalize is because then we just erase what we got with our anteriorization in terms of the increase in contact forces of the overall joint. So in order to maximize the unloading or decreased contact forces, anteriorization, steep anteriorization, and then a single-stage cartilage restoration with cell-based cartilage. Excellent. Next table. Do you mind passing the mic over? I think we said steep anteriorization, potentially a 90-degree cut. I think we debated between MACI and patellar osteochondral allograft. I still feel a little weird about this whole instability thing. I was saying I don't want to be doing NPFLs for patients that aren't dislocating, but just something about that part of the story I don't fully understand. Can I throw this out there? Does the choice of a cell-based versus a structural osteochondral graft, does that influence in this kind of a case whether you're going to or not do your tubercle osteotomy? Maybe someone wants to comment on that. Sabrina. I also thought that lateral might be in a little more flexion than a standard lateral, which could underestimate the ALTA because the PTI was looking worse, right? Go ahead. We discussed doing either cartilage procedure with either a Macy versus an allograft, and then doing a tibial-tubal transfer focused on anteriorization, maybe a little bit distalization. That's what we talked about. Okay. All right. And these are all good points. And for full disclosure, so she had a very similar picture on the other side. And on the other side, she had a TTO and a Macy. And she was overall happy, but she still had some pain. And so when I started discussing this with her, I had exactly the same discussions that you mentioned. Basically, we can do this with a Macy, or we can do that with an osteochondral allograft. And she was apprehensive with a Macy. And so I said, okay, we can do this with an osteochondral allograft. And in the end, I was happy that that is the way that we chose. And part of the reason is because when I got in there, that medial facet was actually practically – it was so steep and worn out that when I was putting the osteochondral allograft in, you see here, there's a little bit of an edge. And I was getting really worried because I was thinking, well, maybe I just didn't fit it correctly. And I kept going back and forth, testing it out in the trochlea. And it turned out that that actually fit perfectly into the trochlea. And so my suspicion was here that she had a little bit more bony changes on that medial side, and I actually left it that way. But I was a little bit concerned about that and had a couple of sleeplet nights after that. So as you can see here, we did a slight distillation. I try to aim for a 1.0 ratio, so I distillized about 8 millimeters, probably a little bit less. Typically, I dial it in, and then I take it back a millimeter or two, because the one thing I absolutely don't want to do, obviously, is a Baja. And this is a very steep cut that I did here, about 75, 80 degrees, so more than 60. And this is her. And can you play the audio? Or can I play the audio? So, Alyssa, tell me again. So this is, what, six months now after your left knee surgery, and how long after your right knee surgery? Over three years. And tell me what was done to your left knee, you know, six months ago. You did, oh, I forget the name of it already. What did you do? Sorry. An osteochondral anaglyft. You did that. You did that. And then there's realignment of my patella as well. Exactly. Yeah. Tibiotubal colosteotomy. And, you know, show me how you move that knee. Yeah? You can do a full extension and flex it down. So you see, the j-sign is gone at this point? But you're not totally comfortable with the extension yet, right? No, not yet. Okay, good. And, but what do you feel in that knee when you move it compared to the other knee? It's just very smooth. It's very smooth, right? Yeah. And did, you know, if you remember what happened with the other knee around this time point, would you say that this one is, moves easier? Mm-hmm. And, you know, if you compare it at this point, what would you say the biggest problem is with your right knee? It's just super crunchy. It's very crunchy. And it just doesn't move very well. It's not smooth. It just feels like it catches more. Okay. But pain-wise, you don't have much pain in either? I don't have any pain in the left. The right I have a little bit. Okay. All right. Do you have a lot of swelling in the knees? Nope. Good. All right. So overall, but you would, would that? All right. So, so the reason why I chose this case is because this is a beautiful kind of comparison between the two techniques. Actually, they work, right, on both sides and both solutions here. I, I would consider good solutions, but the one thing that I have noticed is the osteochondral allograft solution recovers quicker. You know, they feel smoother. They recover quicker. In the end run, that probably doesn't make much of a difference. You know, but you also heard her basically, she's three years after a well-done Macy. On the right side, there's still some issues, but she's overall very happy. She doesn't swell and she has practically no pain. You know, so that was a point that I was going to make. Thank you guys. I think that's an excellent case. We have, yeah, great job. Dave, I think in the interest of time and because your teaching points are so excellent, let's run through your case and then if anyone has questions throughout it, we, we have 12 minutes and otherwise we'll go through the case and then we can discuss it at the end. Maybe while you're pulling that up, I wanted to comment on the APTTTG or the sagittal TTTTG because we've discussed it a few times. You know, the normal is zero. So in the coronal plane, the deepest point of the trochlea and the tubercle are kind of in the same plane. So I always measure this on my patients because that's what I try to correct too. The same way that we try to bring the TTTTG down to 12 to 15, I try to correct that to zero and so it gives me a sense of how much they are in need of angiorization or not. Great. Thanks. So I'm going to run through this. So 14-year-old recurrent patella instability, failed a prior MPFL. And after that MPFL, she was better but never really felt normal, had trouble getting back to activities and has had several instability events post that MPFL reconstruction and still young. She effuses, which I think is a very important indicator that things are going on with cartilage, crepitus, apprehension, soft J sign, so not a jumping J sign, just that little bit of lateralization and terminal extension, and has a moving apprehension test. This is the name I give to this test. Maybe somebody has another name for this test. I find this test incredibly useful. So watch this video. So quads relaxed, translating laterally, just like you do an apprehension test. When does it lock in and you can't push it laterally anymore? What degree of flexion? And compare that side to side. Very useful assessing your MPFL reconstruction. Very useful flushing out, is this pain-related buckling or is this instability? Incredibly useful in the office. You all have those patients. They describe their events. Somebody's told them that they dislocate. You don't think they're dislocating. You think they just need more therapy, maybe bracing. So the moving apprehension test I think is very useful in side to side comparison. She was unstable up to 90 degrees of flexion. Radiographically, you see that she's got two fragments. This one is intra-articular. This one is an avulsion that's embedded in the tissues medially. That's not going to be intra-articular. That tends to be distal and medial, and you often don't even see it when you do your MPFL reconstruction because it's so distal. So here's her chondral lesion, medial patella facet, inferior, large. It gets pretty disrupted, and you see that actual loose body is embedded. It's tethered by the synovium there in the front of the knee. And that chondral defect measures at least 1.2 by 1.3 centimeters, but again it does not cross the keel of the patella. It's just the medial facet. So her measurements. So I've got to understand, okay, what are the mechanics at play here? And I really try to understand the vectors that are affecting the patella for each patient. Her TTTG is high normal, but not abnormal. So her PTLTR, and I'm going to explain that if you're not familiar with that measurement, is 16.4. That is definitely high. But yet she doesn't have a high TTTG. So the position of the tubercle does not explain everything with a bad vector in the coronal plane. And often if you have valgus and patella alta, you can have a really abnormal vector, but yet a normal TTTG. So the PTLTR is the amount of patella tendon measured in millimeters that sits lateral to the apex of the lateral trochlear ridge. So you do a perpendicular, the apex here, how much tendon measured in this plane, not straight side, straight laterally, but how many millimeters sits lateral to the apex of the lateral trochlear ridge. So if you look at that MRI cut, that tendon is draped over the condyle. That vector is terrible. You're not going to solve that problem by pulling on the patella harder with an MPFL graft. So the solution for this patient is not a bigger MPFL pulling it harder. Then you're going to create posterior force and chondrosis. So understand that the TTTG does not explain everything. So this patient, the tendon is sitting lateral, is draped over the edge, but yet has a normal TTTG. Okay, so why is that? Well, here's another. The same group that gave us the PTLTR measurement also gave us this measurement. I don't think this is quite caught on yet. This is a group from CHOP in Philadelphia. So they describe an on-track, off-track. So here, if you look at the center of your tibial tubercle and the tendon attachment, whether that sits medial or lateral to the apex of the lateral trochlear ridge, on-track, off-track. So they call this a tibial tubercle lateral trochlear ridge. And if you're sitting lateral, so minus one would be on the medial side. So if you're on the positive side, so lateral, 72 percent risk of recurrent dislocation. Very prognostic. More useful than an elevated TTTG. I think we probably ought to spend more time thinking about it this way, because this really, in my mind, sums the different anatomic risk factors. We spend a lot of time thinking about individual anatomic risk factors, but they're all working together. Case in point for her, she's got moderate patella alta. Her CD ratio is 1.35. Normal is less than 1.2. So she's got some patella alta, not crazy high, not 1.5, but certainly some going on. Patella alta makes everything else worse, because it takes a long time before the patella engages whatever the groove is. She's got some valgus, too. I've gone to getting long-standing x-rays on every single patient. I used to think I could eyeball it and decide who needs it. I can't. So I get them every time. She's got five degrees of mechanical excessive valgus. That's important. So now we've got alta, and we've got valgus, and we've got a slightly lateral tibial tubercle. All that comes into play, and I think that PTLTR is one of the ways it kind of sums it up. Does she have some dysplasia? Yes. So here at the very top, the proximal cut, she's got a little bit of convexity. But then it quickly becomes flat, and she's got a groove. This is not enough dysplasia to correct. And she has slight prominence there, five millimeters or less. So it's playing a role, but it is not the primary driver. So if you look at the people who fail an isolated MPFL, they're the ones with two or more anatomic risk factors. And that's the interplay, where they all affect each other. And so in this case, she's got four. She's got alta, malalignment, valgus, and dysplasia. So that's why she failed. And it's that interplay. So then the considerations are what do you do with a revision MPFL and this chondral lesion on the medial side? How are you going to navigate those two? You've got to think about femoral tunnel position, the telotunnels, how you fix it, what kind of chondral procedures you do, same time staged. Prior fixation. And then on the patella side, how are you going to fix it? Transosseous tunnels, anchors, bigger anchors, different anchors. Do you put a limb through the quad? Great option. And then adjacent cartilage work. So this is where we pause for discussion. I'll just pause for any questions before I go on to what I did. Do you guys understand the PTLTR concept? I think I just find that more and more useful. Yeah. Do you think that the PTLTR is influenced by the lateralization of the patella in addition to the vector? Like the more displaced and it's sitting outwards, you know, the tendon is going to be more lateral. And how do you account for that? I would say yes. But then in response to that, I'd say, well, why does the patella sit lateral? So if they have a convex trochlea, it's going to sit lateral. That's your jumping J sign. But that's important. If you have extreme patella alta, it's up beyond the groove. There's no engagement, which is important. So I think it's really telling us at a moment in time, this is where the patella starts. And it doesn't take much as you twist your leg to dislocate. So I do think a really large effusion may abnormally influence that. But otherwise, I think it's probably important. Yeah. And by the way, over 5.5 was what their threshold was for abnormal, yeah. The question for you is, do you find that PTLTRs do measure instability, or is it a measure of instability in the setting? The latter. The latter, yeah. It's telling me what the vector is. It's not really a measurement of instability, but there are so many patients who have a PTLTR that's normal, that have instability. Pure instability does not need a high PTLTR. It's instability in the setting of malalignment. Would you agree with that? Yes, yes. But I'm thinking vectors, and it's telling me the vector is bad. And I'm thinking, so, yeah. Just a quick comment, too, along that line. I think it's a great measurement. I love it. A lot of our thinking now, looking at 3D, is that the whole goal for us is to get the patella from where it's sitting in extension on that lateral side, which this indicates very nicely. It's pulling it over that way. And so just getting it inched over a little bit doesn't have to be moved that far most times to make that patella stable and get it so it drops down into the trochlea where it needs to go. So that is a great indicator, I think, for that. Awesome. So here, just to sum up her anatomic growth vectors, 5 degrees of valgus, slight alta, high normal TTTG, abnormal PTLTR, moderate dysplasia. So my plan was to do a tubercle osteotomy. That's my workhorse. I can correct so many things with that. And I'm going to medialize enough to get the PTLTR in the normal range. That's my target. Six or less. And also the TTTG, I'm shooting generally for around 10 or less. But in this case, I was going to medialize 12. And I'm going to also correct her alta by distalizing with a goal of a CD ratio of 1.1. That's my target. If you do a two-limb MPFL reconstruction, that will inherently distalize your patella 0.1. So I would expect when I'm done to have a CD ratio of 1.0. Okay? So that's how I calculate how far to move it medial and distal. You had a question, Beth? Yeah, I just wanted to reiterate. So you would set the CD to 1.1? Yes. You want to finish with 1.1? I think that's a really important comment to make for everybody. When you're distalizing, you really want to make sure you don't set them at lower because the risk of a Baja is so significant in that case. But understand, you're going to get inherently with a double-limb MPFL a little more. So I don't want to be below 1. Correct. Yep. And in this case, I chose nosocon or allograft, a pre-cut 10-millimeter plug, and then did an MPFL reconstruction. And I'll talk about that here, too. So here you can see I've distalized the shingle slightly and also medialized it. I use three screws now. I find that really helps with healing. And I put that middle screw off-axis because occasionally as you distalize and you get the overlapping shingle and you tighten that screw down, you can crack the shingle at the bottom. It's brittle, and sometimes that crack will propagate like a block of wood approximately to that second screw. If that third screw is off-axis, it's not going to do this. So it gives me that security. So I use three screws now all the time. So this cartilage lesion is sizable, but it's all medial. So a 1-centimeter allograft plug would fill most of it, but not all of it in a single stage. So here you can see the other option I'm going to do is oblique tunnels transosseous for the patella. So I learned this from Liza. And if you go as steep as you can to stay in bone with a 3.2 drill bit, the same drill bit I use for my TTO screws, for large fragment screws, you can make tunnels that will accept the gracilis every time. If it's really tight, add a little sterile mineral oil. And two parallel tunnels like this, in most cases, are going to avoid your cartilage, which you can see. Here's my cartilage plug. And the tunnels avoid that, so that's not a concern. You could also have put a limb through the distal quad, which would have been a great option here. You could do one limb in the bone, one limb in the quad as well. So I use this routinely, and I save the cost of anchors, and they're never going to pull out. And can you get a fracture? Yes. We've tracked them. We have over 600 knees. We have one fracture. Okay, somebody fell directly on it. So this is different than what got a bad wrap originally, which are completely across the patella in 4.5 millimeter tunnels. This is different than this. So this is very safe, and it saves you the cost of anchors. And I just don't worry about an anchor pullout, which can be an issue for the patella. And then here I'm getting the shuttle's point and going to do the NPFL with that double limb graft. And she did fantastic. She's very happy with this and that single stage. So just a couple of quick points. Why not anterize at all? I did. It was an oblique cut. I'm sorry I didn't mention that. And do you put a proximal buttress when you distalize? Only if I'm going more than a centimeter down. Then I'll do a step cut and take the block and put it up top. I just want to mention a few technical points about your cartilage. So microfracture is not a great option for the patella from a compartment. You tend to get intralesional osteophytes that form, especially in the trochlea. Macy is certainly a very good option, longer rehab. If you're going to do osteochondral allograft, you need a drill because the patella is hard as a rock. And then when you implant it, you want to keep the inserter device there until it's all the way down. Because as soon as you take that off and you try to mallet it down further, the top, the mushroom cap is going to want to expand and it won't fit inside your hole. So keep that tube there to contain it until you're fully down. So the cartilage thickness difference matters. And I try to match the bone height. I don't want to leave the bone proud because that's going to be excessive pressure on the cartilage graft. So I'm going to trim it down for depth because the graft pre-cut comes from a femoral condyle and the patella cartilage is thicker. So if it looks like it's flush on the surface, your bone is proud. And that, I think, is detrimental to the success of your graft. So I'm slightly recessing the cartilage graft to get the bone flush. And that's what I'm shooting for with this. That's just a couple technical tips. I think that's all we have time for. Any questions? Or maybe you can catch us afterwards if we have to vacate the room. Yeah, Elizabeth? I'm not. I don't know what to do with it either. But maybe we'll learn from our faculty colleagues. Yeah? They did. Five degrees. Yes. Sure. I definitely think so. It definitely plays a role. I think all of those are playing together, and that's reflected in the PTLTR vector. I could correct most easily by moving the tubercle over and down. If the valgus is seven or more, I'm thinking about correcting the valgus. I don't, but I think it's an important contributor. I would also go after valgus primarily if there's a lateral-based lesion as well. So if there's a secondary lesion in the lateral compartment. Good. Good, good, good. Well, thanks, everyone. This was a great discussion. I hope we all learned from each other, and have a great meeting.

patellofemoral joint

cartilage lesions

patellar instability

tibial tubercle osteotomy

MPFL reconstruction

chondral defects

PTLTR measurement

surgical intervention

case studies

clinical outcomes

joint preservation