Welcome to the American Journal of Sports Medicine's webinar. Thank you for joining us. I'm Christine Watt, Publishing Manager at AOSSM, and I will be the operator for the webinar today. Before we get started, I would like to take a moment to acquaint you with a few features. There are options for how you can listen to this webinar. If you have any technical difficulties hearing the audio properly, please try clicking the phone call option and calling in for the audio, or switching the speakers that are being utilized. At any time, you may adjust your audio using your computer volume settings. To send a question, use the Q&A feature at the bottom of the screen. When finished, click the Send button. Additionally, you can indicate your interest in a question by upvoting it. Just click on the thumbs-up icon located to the left of the question. Questions you submit are seen by today's presenters and will be addressed at the end, so please send those questions as you watch. There is CME available for this online activity. Here are the learning objectives and the disclosures for our faculty and organizers. At the conclusion of today's program, we ask that you complete a brief evaluation to collect CME for this activity. Details will be given at the end of the program and in an email to attendees. At this time, I would like to introduce our moderator, Dr. Miho Tanaka. Dr. Tanaka is Director of the Women's Sports Medicine Program at the Massachusetts General Hospital and Associate Professor of Orthopedic Surgery at Harvard Medical School. She is an Associate Editor for the American Journal of Sports Medicine for Electronic Media and Women's Sports Medicine. And with that, I'll turn the program over to Dr. Tanaka. Thanks very much, Christine. Thank you, everybody, for being here. I'm just going to share my slides so that we can get this going here. So hopefully everyone can see these slides. So I am very honored to be introducing this new webinar series called From Bench to Bedside and Beyond. And today's topic is on the medial patella femoral complex. It is a tremendous honor to have these experts on this topic here with us today. We have Dr. Peter Fabrikam from HSS, Dr. Beth Schubenstein also from HSS, and Dr. Elizabeth Dennis from Mount Sinai, as well as Dr. David DuJour from the Leon Ortho Clinic. So thank you, everybody, for being here. A little bit about this topic, as you know, we're talking about the medial patella femoral complex today. So I just want to introduce the topic for those who aren't necessarily familiar with this as to why we're discussing this today. As you may know, the medial patella femoral complex is the primary stabilizer to lateral patellar translation, with fibers attaching to the patella and to the quadriceps tendon. And this can be variable in its attachment sites. And even though the original description was going from the femur to the medial patella, we now know from other studies anatomically that this attaches not just to the proximal patella, but also to the quadriceps tendon, as can be seen in this intra-articular-sided photo here. And so, of course, John Fulkerson has called these fibers the MQTFL and has described a reconstruction technique to avoid patellar fixation and avoid the risk of patella fracture, which is one of the biggest, most catastrophic complications after an MPFL reconstruction. But additional studies have shown that this is actually just one ligament with a common origin on the femur attaching to both the patella and to the quadriceps tendon, and that this varies. And some knees have an attachment only to the patella, while others have an attachment only to the quadriceps tendon. And so, this is kind of where the term, the medial patella femoral complex, was born to allow for the variability in its attachment site to the quadriceps and the patella. And we also know that the midpoint is fairly consistently at the junction of the medial border of the quadriceps tendon and the patella, meaning that the fixation can be on either structure. And so, this is where a lot of this conversation comes into play. Do we fix it on the patella? Do we fix it on the quadriceps tendon? Do we do a double bundle fixation? And I think a lot of our authors today have different thoughts on this. And of course, when we're talking about patellar stabilization procedures, it's critical to identify and address the individualized pathoanatomy. So in addition to the MPFC reconstruction, whichever you choose, whether it's patellar fixation, quadriceps tendon fixation, we have to also consider the other factors. Do we need a tibial tubercle osteotomy to assess bony malalignment or patella alta? Do we need a trochleoplasty to address severe trochlear dysplasia? Do we need a DFO to address rotational or coronal plane deformities? And so, we're going to put this all together today. Dr. Peter Fabrikant is going to talk about the basic science and his study on the effects of different MPFC reconstruction techniques on contact pressures and kinematics, followed by a clinical study by Dr. Schubenstein and Dr. Dennis talking about isolated MPFL reconstruction regardless of TTTG distance and patellar height. And lastly, we have a long-term outcome study by Dr. Dejour on MPFL reconstruction when performed in conjunction with trochleoplasty. So I think this is a really nice way to look at from bench to bedside and beyond on this topic, and we'll have a nice discussion at the end. So, without further ado, I'd like to introduce Dr. Fabrikant, if you want to pull up your slides to talk about your paper. Yeah, for sure. Let me share my screen here, and we're going to go full screen. Okay. How's that? Can you see me and hear me okay? Perfect. All right. Great. So, thanks, Dr. Tanaka. Thanks to the AOSSM for hosting this and for the invitation to speak. Our study was designed to biomechanically look at the effect of medial patellofemoral complex reconstruction techniques on various measures of patellofemoral contact pressures and kinematics. I want to obviously acknowledge my co-authors. We have no relevant disclosures to this presentation, but they're listed on our AOSS disclosures website. So, quick background. We know that the MPFL reconstruction is a workhorse for patellofemoral instability and multiple reports of this and different techniques have been described, but like Dr. Tanaka mentioned, some authors have advocated for an isolated MQTFL reconstruction, and others have advocated for more of a hybrid reconstruction, reconstructing both of the MPFL and MQTFL limbs. However, and there's been lots of reports on the clinical outcomes of these, however, this study has really compared them head to head, looking at the biomechanics of the patellofemoral joint contact forces and kinematics. So the purpose of our study was to compare these three, looking at the following variables. So lateral patellar tilt, lateral patellar translation, patellofemoral contact area, and patellofemoral contact forces through a range of motion of the knee. And we hypothesized that, or at least we tested the null hypothesis, that there would be no difference in the patellofemoral contact areas, forces, or kinematics among all the three reconstruction states and the intact state. And so the way that we did this was we used 10 cadaveric knees, and then we tested each knee in five conditions. So the first was always the intact state. We did the testing, which I'll show on the next slide, and then we transected the entire medial patellofemoral complex, and we tested that second. Sorry, I'm getting a note here. Okay. Then the third, fourth, and fifth was randomized between MPFL reconstruction, MQTFL reconstruction, and hybrid reconstruction. So these were done in a random order as number three, four, and five. And after the reconstructions, each reconstruction was done, or each situation was established, we loaded the knee in a servohydraulic load frame as diagrammed there. We had an actuated quadriceps force attached to the quadriceps tendon in order to bring the knee through a range of motion. We had pressure sensors and motion markers in order to test all of the different variables that we were evaluating. So we had a cortex motion capture system, which allowed us to precisely track patellar tilt and translation. And then we used tech scans for pressure sensor measurements in the patellofemoral joint. And so the results were that the intact state was no different than the MPFL reconstruction, the MQTFL reconstruction, or the hybrid reconstruction in all of the four variables. So that's the lateral patellar tilt, translation, the patellofemoral contact forces, or the patellofemoral contact areas. We did note, however, that the transected state actually had increased forces in the lateral patellofemoral joint once the knee went past 60 degrees, which we thought was interesting, that as the knee approached deep reflection, there was greater lateral patellofemoral compartment overload in the transected state compared to the other reconstructed states. And in that amount of flexion, there were no differences in the patellofemoral contact forces between the intact state and the reconstructed states. So in conclusion from this study, we noted that all three of those reconstructed states had no differences in lateral patellar tilt or translation or patellofemoral contact forces or contact areas. All three of the reconstruction states were no different than the intact state for all measured variables, and that there was no evidence of over-constraint of all three of the reconstructed states. And that's really what we were looking to determine was, were any of these over-constraining the knee and potentially putting patients at risk in the future of osteoarthritis? And so we then reported that from a biomechanical standpoint, at least, that all three of these were viable treatment options. As Dr. Tanaka mentioned, we all kind of may have a different practice variability as far as how we treat these. So in my practice, my skeletally immature patients, I do a combined MPFL and QTFL with onlay fixation as described by Minh Coker and his team. And then my skeletally mature patients, I do a two-limbed MPFL reconstruction with allograft, with onlay fixation at the superior part of the patella, and then interference fixation and tunnel at the medial distal femur. So thanks again for the invitation to present. This study was published in detail in AGSM in 2024, so I'd invite you to read it if you have any further interest. I'm happy to answer any questions during the Q&A. Thank you very much. Fantastic. Thanks for that. That's, you know, a great paper. I think for the audience, if you have any questions for Dr. Fabrikant or anything on this topic, please enter your questions into the Q&A. At this point, we'll continue through the talks, but we will have time for questions from the panelists and a discussion at the end. So please feel free to enter your questions as they come up. So next up, we have Dr. Beth Schubenstein and Dr. Elizabeth Dennis talking about their clinical paper. Who's, oh, here we go. Okay. So Liz, you're sharing your- Liz is sharing, but I'm actually presenting because we had some glitches before. Okay. So team effort. Yeah, we're going to do a team effort for this. So we're going to start, first of all, a huge thank you to Dr. Schubenstein and Dr. Dennis. We'll go over the results as well, but we did want to talk about the background for why we thought about this study as well, which was important. So this is a study that we began. It's isolated MPFL. We have, I'm sorry, we have no relevant disclosures in the ones we do have on the website. So the background for this study in terms of doing a study on when is an MPFL really necessary or is it enough, right? When do we have to add bony procedures? When can we just use an isolated MPFL reconstruction? And just because Dr. Fabrikant just finished, I'll say my technique for an MPFL is a two-limbed reconstruction fixed on the patella, on the upper third of the patella. So I do it that way, but it looks like all of the ways are acceptable. So the answer is MPFL reconstruction is usually enough except, of course, in those cases that all of us have seen when it isn't. We'll keep going and I'll give some background. So some patients come in and they have fairly normal anatomy. They have a little bit of valgus, maybe a little bit of alta. The merchant looks okay. You can keep going, Liz. A little avulsion fracture that we almost always see in these first time dislocators and sometimes it's still there after the second or it's ossified. But in most of these cases, that's enough. Then you have the other side of the spectrum like this where you clearly know an MPFL is not enough, right? You can look at this person walking in the door and know that what they did was going to fail. This is somebody who had severe valgus and they tried to use the ligament to pull it over and clearly it stretched out and failed because it couldn't overcome that pathoanatomy. So those are the polar opposite ends of the cases. But what do we do with that 80% that lives in the middle where it's not an easy decision? Next slide. So this is another example of one that you're just not going to try an isolated MPFL, right? This is a very unique type of dislocation. You can see this is a young open growth plate kid who dislocates inflection and that's one of those. It's very obvious that's not going to be enough. Next slide. This is actually the same, next slide. This is the same child that we just showed in the video and because she was open growth plate, we did a large lateral lengthening and we staged the procedure. So we did the MPFL reconstruction, but this is the intra-op vision of the TTTG essentially that you can keep going. Yeah. So you can see the vector on that, right? That's the tubercle. There's the patella now that it's located once we've done the large lateral lengthening and you can see that that, those forces are likely going to overwhelm this type of soft tissue reconstruction. So we staged it in her and about a year and a half later, once her growth plates were closed, I did go back in and move the tubercle and luckily her MPFL was still really solid at that point. Next slide. So really the big questions in the world of patellar instability that we ask still are, what do we do with the first time dislocator? That first time dislocator, should they be having surgery? The standard of care currently is non-operative. PRISM actually just published a consensus statement in January that said the current standard of care should be maintained as non-operative. I think we all know that there's literature that is aiming us in the direction of maybe finding that subset that's a high risk group of first time dislocators that maybe we should be fixing. So over the next five years, we'll see answers to that question and more direction. But what we're talking about is really the recurrent dislocator. We know they need surgery. Every patient who has more than one dislocation who walks in my office, I always say you're not getting out the door without something to stabilize your patella. They all need an MPFL or an MPFC reconstruction. They need some type of medial construct to help them. The question is who needs more than just a soft tissue reconstruction? Who needs some type of bony augmentation? Whether it's a TTO, a DFO, a trochleoplasty, or guided growth if we're lucky enough to find them when they have open growth plates. Next question. Next slide. So what we do know is we know that that MPFL or MPFC really plays a large role. 60% of the resistance restraint to lateral translation is offered by it. And we know that it's isometric through most of the range of motion, but it loosens in deep flexion. We also know that we've gotten much better at doing this operation over the years since it was established in 2016 out of Cincinnati. Schneider published a systematic review showing we have a very good high rate return to sport and we have a very low rate of redislocation across all studies. So we know it's a good operation. Where we have gaps in the literature, we do not have any clinical studies that demonstrate what combination of risk factors predicts failure of an isolated ligament. If you're not doing a bony reconstruction, can we predict that group ahead of time? Can we look at their ALTA? Can we look at their TTTG, the trochlear dysplasia, figure out how they interplay with each other and find that patient ahead of time so that we don't wait for them to fail that ligament? So again, the big question, is an isolated soft tissue reconstruction enough? And when do we really need to add some type of bony procedure to help us to unload that ligament reconstruction? So what we really need is a patella instability severity index score or an ISIS. And Pascal Boulod did this for the shoulder in 2007, published it on an ISIS on the shoulder, looking at a predictive instability score that would allow them to determine which patients would be best served with an isolated Bankart soft tissue reconstruction versus a bony Latter-Jay or Bristow. And we're trying to do the same thing in the patella. We want to try to find out and identify the group of patients that have an unacceptably high risk of having another dislocation after an isolated MPFL and failing that surgery so that we can get it right the first time. So we started this study. Next slide. We started this study in 2014. Dr. Dennis just published the midterm outcomes on this in AJSM for us last year in 2024, looking at isolated MPFL reconstructions regardless of bony anatomy. And so we really enrolled a consecutive series of patients. Next slide. There were several exceptions or exclusions. The study is often misinterpreted. It is not meant to imply that we should be doing isolated MPFLs in everyone. That's not what it was meant to do. It is intended to establish this ISIS so that we can see which patients should have the bony reconstruction and tell them ahead of time without guessing or making educated guesses as most of us really do based on what we know in our experience. So the exclusion criteria are an unloadable lateral lesion, as you can see on the left. That's something that you can treat very effectively with a TTO and it should be treated, or a jumping J sign, as you can see here. So if the patient comes in with that kind of mechanics, that just a ligament's not going to be enough to control that. So we excluded that as well. Patients who have previous surgery, as well as patients who have pain as an equal to or greater proportion than their instability. This is an example of somebody who has a jumping J sign on the left, but has a regular J sign on the right. And so again, even though they have the same anatomy, it is something where you can decide. And so their right knee would have been included in this study and their left knee would have been excluded again, just because of the factors, even though they have symmetric and mirror image trochlea dysplasia. Next slide. And I'll let Dr. Dennis take it from here. Okay. So I'm just going to talk about some of the specifics of the study, which was recently published in AJSM in 2024. These were the midterm outcomes that were the continuation of the study published by Dr. Erickson and Dr. Schubenstein in 2019. Just make sure this is working. Okay. Perfect. So as Dr. Schubenstein discussed, the point of the study was really to understand the best way to address patients who have recurrent patellofemoral instability, to understand when an isolated MPFL procedure should be enough and when a bony procedure needs to be added. And at the end of this, we're just going to touch briefly on the Jupiter cohort, which is the multicenter expansion of this hypothesis. We know from the literature that clinical studies in patients who have TTO have demonstrated good patient reported outcomes. They have high return to support rates and they have low recurrent instability. And we know that a TTO from this research and from all of our clinical experience is a powerful tool that we can use to destabilize, medialize, combinations of that to address patients that need offloading or realignment. And it's a powerful tool that has safe and reliable outcomes but it's not without its risk. If you do enough of these procedures, you're gonna see patients can have a fracture. They have a longer recovery. They require a period of protected weight bearing that comes with a risk of DBT. We also know from the literature that they have a longer return to support rate. So it's not, there's things you need to think about when you're adding this to your armamentarian for treating these patients. We also know that we don't understand yet the definitive measurements or cutoffs of trochlear dysplasia, patellar alta, or TTDG that indicate when to add this. And so that is really what's driving the hypothesis here is when can we do an isolated soft tissue procedure that's sufficient to prevent post-op recurrent instability? So the hypothesis, the question that we keep talking about here is when can we do an isolated MPFL reconstruction and when do we need to add more? So the exclusion criteria for the study, Dr. Schubenstein mentioned, we excluded revision patients. We excluded patients who we knew we could offload an inferior lateral grade four lesion with a TTO because ethically that was indicated for those patients. If they had anterior knee pain greater than 50% of their chief complaint, those patients were excluded in the pilot study and patients with a jumping J sign as previously seen. All patients who met the inclusion criteria underwent an isolated MPFL reconstruction regardless of their bony anatomy for treatment of recurrent patellar instability. And early outcomes were published in AJSM in 2019 that showed effective treatment for patellar instability with low rates of recurrent instability, high return to support rates, and significant improvement in patient reported outcomes. The paper we're discussing today is the midterm outcomes data for these patients that supported the previously published results, low recurrent instability rates, high return to support rates, and significant improvement in patient reported outcomes that were maintained at five years. We did note an increase in the recurrent dislocation rate from 2% to 6% with this midterm follow-up. Of the 138 patients that were included in the analysis, there were six instability events that were reported with five-year follow-up period. The two-year survival rate seen here in this Kaplan-Meier survival curve was 98%. And at five-year follow-up, adjusting for the patients who had not yet met that follow-up time point, the survival rate was reported at 94%. There was statistically significant improvement in all patient reported outcomes and satisfaction scores over time. And this was achieved at one year and sustained through five-year follow-up. And these are just reporting the mean radiographic measurements for the patients included in this cohort. Notably, there were 44% of patients had a TTTG less than 15. 43% had a TTTG between 15 and 19, and 13% had a TTTG over 20. For the measurements of patella alta, we utilized a cutoff of 1.2, and 32% of patients in this cohort had patella alta. And trochlear dysplasia, as measured by the trochlear depth index of less than three millimeters, 63% of patients in the cohort had that. These are the demographics of the six patients who experienced recurrent instability. Notably, two patients experienced a frank redislocation while four patients experienced recurrent subluxations. Activities that occurred during failure included jumping on a trampoline, dancing, and playing lacrosse. The mean time to this recurrent event was approximately three years with a range of two to four years. These are the radiographic measurements for the six patients who experienced recurrent instability. And it's important to note that it's not just one factor that was consistent among these patients, but an interaction of several bony parameters, including alta, TTTG, trochlear dysplasia, as well as other measurements. The return to sport rates, we looked at 100 patients who participated in sports or physical activity, and of the 98 patients who responded postoperatively, we found 89% were able to return to sport and 84% were able to return at the same or higher level. All patients did so within two years, and their average return to sport time was 9.1 months. Additionally, there were five patients who were not playing sports prior to surgery who were able to participate in sports postoperatively. So putting this all together, the role of this work is to try and develop the prediction model for how to best treat patellofemoral instability, when to add a bony procedure, as Dr. Schubenstein mentioned, similar to that ISIS score that was developed for the shoulder. We know that there's no hard cutoff for TTTG or patella alta or trochlear dysplasia that dictate when to perform an additional bony procedure. And one hypothesis we have is that perhaps the exclusion criteria for these studies may give us a hint as to who needs additional intervention, that jumping J sign, those unloadable cartilage lesions or revision patients. The entire cohort for this study is closed. There's 208 patients that are included that have at now a minimum of two-year follow-up. So stay tuned for the reports on that that will be coming in the next year. And so now Dr. Schubenstein is just gonna talk briefly about the JUPITER study. Thanks, Liz. So the JUPITER study was really started in 2017. It was about three to four years after I'd started collecting patients for the NPFL study that we just went over. And it was started by myself and Chantal Parikh out of Cincinnati. And it's a multicenter study. We ran the first cohort and we now have over 2,000 knees and this was closed in 2021. And we are following up on those patients. We've already published, I think about seven studies from this one cohort and we will have more as our follow-up gets more robust and we expect to see a lot of interesting things. We've already learned some things about osteochondral fracture, skeletal immature patients. So we expect to do way more and see much more based on this cohort that we originally enrolled. Next slide. We were lucky enough to receive the multicenter award from AOSSM and OREF to further the study that you just heard about. So as Liz said, this was a pilot study that we did at a single institution. We are now doing the same study that we published on at a multicenter scale. We have 23 surgeons from 14, 16 different centers. You can put up the next slide, Liz. And our target for our power analysis to do the same study with the number of surgeons and the centers that we just spoke about is 850 knees. So consecutive enrollment of isolated NPFL regardless of bony anatomy, as long as they do not meet that exclusion criteria. And as of, oh, it's actually not 432, I just got an update, it's now 471. So we now have 471 knees as of this month in the study. And I think now that all centers are enrolling, we're targeted to meet the 850 by the end of this year or the beginning of next year. So we'll hopefully have a lot more to publish on this topic with a much more diverse group of surgeons and also a diverse group of patients. So hopefully much more applicable to all orthopedic surgeons. Thank you. That's excellent. Thank you so much. Last but not least, we have Dr. David DeJure. He's going to be talking about his long-term outcomes. Thank you very much for giving me the opportunity to speak about trochleoplasty, NPFL and the very long-term results of this surgery. I will go through different articles that we did recently. And I need to speak a little bit about the rationale for the trochleoplasty, probably to change the knee architecture and also to look at the auto-biologic and to look at the cartilage. The rationale for deepening trochleoplasty was the bump, the bump over five millimeter. And this was the studies done in 1987. And this was really important because the bump has to be removed to prevent from abnormal tracking and patient dislocation. Nobody really understood how to check and to see the bump on X-rays because nobody has a good X-rays or good CT. So we moved to the MRI and the full MRI analysis. But if you use the MRI, you need to standardize the MRI as we did for the X-rays. And you need to reorient your MRI and to look the NPR mode just to align the condyles. And then you will be able to see perfectly the bump and measure the bump and be able to be, to have the right indication for the trochleoplasty. So that's why we moved to this new classification, which is a linear classification from zero to three. And it is probably much more simple using only one tool, the MRI that you can use in every country everywhere. So the trochleoplasty is indicated for the type three where you have a bump and where you have no sulcus and no LTI. This is the right indication for trochleoplasty. What's new about trochlear dysplasia? We recently have this article published where the orientation of your groove is mostly medial when you have high-grade trochlear dysplasia. And in the type three, the angle of your trochlea goes medial 12 degrees compared to the control, which is four degrees, aligned with the anatomical axis. So that's very important because it also show you that you need, when you do a trochleoplasty, you need to realign the groove and diminish and decrease the TTTG. The other measurement, which is the cranial trochlear orientation, really shows how much the trochlea can push the patella on the lateral side. And you have seen some beautiful videos showing the abnormal tracking and jumping J-sign. This is abnormal tracking. And this is probably because your trochlea is oriented on the lateral side. And this is what we have published recently. So in conclusion, we need to remove the supra-trochlea, the overhanging of your trochlea in type B or D or three with the MRI classification to decrease the PF pressure, decrease the dislocation pattern. And definitely you will never accept that on a total knee arthroplasty. So how to do, you can look at this video. And the first is to remove the bump. And the bump is definitely the patellar tramping. It leads to the maltracking and it will definitely lead to increase the PF pressure. So this is the first goal. The second goal is to realign the trochlear groove. And you have seen that it goes medially 12 degrees. You have to bring it back to four to six degrees and to be in line with the anatomical axis. And then of course, the third step will be to deepen the groove and to make it more congruent with the patella. So looking to this, we follow our patients since ever and we have all those different publications from 2010 to 2024. And what we have seen, the very first series, it's a very short number of patients. My first trochlear prosthesis, 23 to 30 years of follow-up. It's very interesting to see that most of them, 64% had previous surgery. And on those patients at that time, I was not doing any MPFL reconstruction because I didn't know about that. I didn't know about what was a MPFL and we were doing VMO plastic. And about the results, we see that the satisfaction rate is really high because all those patients were really in trouble with their knee. And on the osteoarthritis rate, 22% had a stage three or four E1O classification. This is definitely what we call isolated patellofemoral arthritis. So this is 22%. And if you look to the other side, you will see that we have also 22%. So the trochlear prosthesis that we did at that time, and I remember you that 63% have previous surgery, did not increase the patellofemoral arthritis. It did not prevent, but it increased a lot, the satisfaction of those patients. So this is an example. You see that this patient has a E1O stage four patellofemoral arthritis. He still has no total knee arthroplasty. None of them had a new surgery since the trochlear plastic. So this is interesting. The second study that we have published recently in AGSM, it's a 48 knees, so it's much better. 10 to 20 years, the mean follow-up was 15 years. And here again, 62% had previous surgery. So those patients had a lot of history before the trochlear plastic. And on those patients, we also did 100% of MPFL. So we probably improved the technique by doing the MPFL because definitely it helps in preventing new dislocation. But I would say that it gives mostly more confidence to your patient. And if we look to the results, none of them had recurrence. The satisfaction was really high. And here we had no stage three or four E1O arthritis. We had stage one or two, which is on mostly remodeling of the patellofemoral joint. And this is very interesting. And if you look to the contralateral side, you will see that this is exactly the same. We did not increase arthritis on those patients. So maybe it's due to the technique and we do the thick flap technique and we leave five millimeter of osteochondral bone to be able to do this type of surgery, even if your cartilage is not so perfect and try to preserve the cartilage viability. So in conclusion, what we may say, what we can say is that 10 to 20 years of follow-up, one on 48 re-dislocation, satisfaction rate very high, no re-operation and no stage three or four E1O isolated patellofemoral arthritis. So the goal was really good and the results were really interesting. On the very long term follow-up, the arthritis rate increased 22% stage three and four, satisfaction rate is also very high and we have no re-dislocation. So those results are more than encouraging because it's a so long, long term follow-up. So in conclusion, we probably should say that proclopasty is not a salvage procedure and should be considered as primary if you have a spur or bump over five millimeter. The goal is to preserve the cartilage layer using a thick flap technique, remove the bump, correct the trochlear angle to four to six degrees, deepen the trochlea of course, and sometimes elevate a little bit the lateral facet and increase the congruence. So definitely I am in favor of doing NPFL plus in some patients as you have seen previously. So see you very soon in US or in Europe. Thanks for your invitation. Thank you. That's fantastic. Thank you so much to all of the speakers and authors. Just as a reminder, these are all papers that have been published within the last year within AJSM. So it's pretty exciting to see how all of these come together, especially surrounding this topic. So for the listeners, feel free to enter your questions in the Q&A. I see that one was posted already and I know Pete, you already answered it, but I think maybe just for the audience who might not be reading along, I'm gonna read this out to you and maybe you can just kind of go over what you had said and elaborate on that. So the question was, why do you do a hybrid MQTFL and NPFL in the skeletally immature patients? Yeah, it's a great question. I think there's a couple of reasons. So it's, you know, like many of us, it's kind of how I was trained. So I did a fellowship at Boston Children's Hospital and this was how we did it in our skeletally immature patients. I think from a technical standpoint, when I do skeletally mature patients, I like to tension the free ends of the graft in the tunnel at the MPFL origin at the medial distal femur and tension it across to the other side. Someone holds tension and we put in the screw. I tend not to wanna do that if there's an open growth plate there. And then I know many folks are really successful at kind of trimming the graft and dunking it in and getting the tension that way, but just in my hands, I'm just not able to do that as reproducibly. And I like the online fixation there in kids who tend to have very robust periosteum. It heals pretty reliably in that location. And then I think like Dr. Schubenstein was mentioning when she was talking about those 80% of patients kind of in the middle, you know, who you might be considering for a soft tissue only procedure or soft tissue plus bony, you know, in pediatric patients, they can't get a tibial tubercle osteotomy. So if you do elect to go for a soft tissue only reconstruction, and for whatever reason they do need a revision as, you know, later on as part of like a TTO NPFL revision, you haven't drilled any tunnels. You're not working around kind of, you know, tunnel implants and screws. It's just kind of a little anchor. And so the revision, if you need to do it, it's easier. And then the last thing would be, especially in the smaller patellas, you only have to put one implant in the patella that way. And, you know, we always consider patella fractures as a potential complication. And it's demonstrated good outcomes, I think would be another reason. So that's kind of why I did that. And then that was one of the reasons that spurred our study was, you know, I have these two different techniques. And if I found a reason that one was better than the other, I would probably, at least biomechanically, I would probably switch to that both for young and older patients, but they were no different. So I've kind of stuck with the two approaches. Great. So we have some additional questions. One of them actually is asking Dr. DuJour to put up the QR code slide about your technique again, if you don't mind. Thank you. So maybe while you're doing that, I will pose the next question that has also come up. And the question was, is there any role for the quadriceps turndown in lieu of a formal MPFL reconstruction? So I think this is a good opportunity maybe to go through. I think, Pete, we just heard about your techniques, but maybe Beth and Liz and David, if you all wanted to talk about your specific techniques in terms of what graft you're using, what construct, what your fixation is on both sides, that would be great just to give the audience some flavor of what you guys do. So when I do the MPFL, I use the gracilis and I use two tunnels on the cortical side of my patella, because I'm not super confident on the middle part of my patella, because the middle part of my patella is, you have the bony allusion sometimes, and I feel that the bone is a little bit soft or weak. So I prefer to go on the cortical side. I would say that I don't like to use any anchors on the patella. I don't like to use hardware on that side. So if I have to make a choice, I would also do the MPFL, which is good to me, of course, because you don't do any, you don't put anything on the patella. On the femoral side, I use a bone tunnel. I use a fluoroscopy all the time to be really accurate in my positioning. But here again, I may say that if you don't have a fluoroscopy or you're not confident with that, it's very good to go over the third adductor, because you will not over-constrain your MPFL, because the big issue with MPFL is to over-constrain the MPFL. I always tell the resident that a good MPFL is a little bit of a loose MPFL. Excellent. Beth? So I have similar techniques. I do use anchors. I started using anchors about probably 10 years ago for the first, I don't know, 15, 10 years or so that I was doing them, something like that. I was using a short blind tunnel, about a 20 millimeter tunnel, five millimeters. And then I would do divergent tunnels and just pull it across and tie it on the outside. So there was no fixation, no implants. I started doing it because I end up doing a lot of cartilage surgery, and I didn't want that tunnel to converge with some of the cartilage, the OCA's or anything else I was doing on the patella. So I started using anchors. I didn't have any fractures with my tunnel, at least that I know of, and it was a short tunnel, but I think the anchors are definitely safer for me. I use all suture anchors now, and they're 1.6 millimeters, so they're very small. And I try to get about an eight to 10 millimeter bridge in between, so I like that nice broad attachment on the medial patella side. I haven't had any problems. The type of anchor I use expands behind the cortex, and so it does get good cortical fixation. I know what David's talking about with the avulsion fractures, and so sometimes that can be an issue, and in those patients, I will opt for a pronged metal anchor if it does pull out, but I do use two anchors and small anchors on the patella. I use the semitendinosus autograft for anyone who I'm doing an isolated MPFL in. So if I'm not adding bone, I'm using their tissue, and my rationale is there's absolutely no difference shown in the literature between allograft and autograft. We don't have big numbers. We will start to see big numbers when we get follow-up from the Jupiter cohort and really tell if that's true or not, but I do not think it's an extra articular ligament, so I don't see it being like an ACL. I think you will be able to choose. My rationale for using autograft is in patients where I'm doing an isolated MPFL, we're leaving them with their ALTA. We're leaving them with their trochleidysplasia, and we're leaving them with their TTTG vector, PTLTR. So for me, my goal is to get them to heal as fast as possible, and autograft heals faster than allograft, and that way we don't have to worry about stretch during the healing phase that you could see if it takes a longer time. So that's my rationale. If I'm doing a bony procedure, TTO, DFO, anything like that, I'll use allograft because I think at that point you're realigning them. You're taking away the bony risk factors, and so I think an allograft is fine, and then I do a single limb, so two limbs that goes to one limb. I think they call that a C. I can't remember if it's a C or a Y, but either way, it's two on the patella, one on the femur. Like David, I look at the image, but I actually check. I use anatomy first. I try to make sure it's isometric or anatomometric, as Jack Farr always said, where it loosens after about 60 or 70 degrees, but it remains fairly isometric through the first 60 or 70 degrees, and then I always use image to confirm that we're kind of in that area that we want to be in on a lateral, and I use a screw, and I use a blind short tunnel, and the reason I do that is because I can go north and go up if I want a deeper tunnel for adults where I don't have to worry about the growth plate, but I can easily go underneath the growth plate in my skeletally immature patients, and I don't have to change my fixation, so I use a blind socket with a adhesive screw. Perfect, and Liz. So as Dr. Fabrikant said, you're a product of where you trained, so everything Beth said is pretty much similar to how I do it, and I was fortunate to scrub a few cases with Dr. Fabrikant when I was a fellow as well, so I do it pretty similar to how Beth does it. I will say the thing probably to point out in this webinar, and maybe you guys can comment on some of this too, is the balancing, so you can't be afraid to utilize an open lateral lengthening. I've really shifted to that when needing to realign stuff. I don't do it arthroscopically anymore. If I need to balance the patient, I'm doing that open because I just think you get so much more control with an open lateral lengthening than you do with an arthroscopic release, so I'm using an open lateral lengthening in patients where I'm moving the tubercle, or if I feel like they need to be balanced, or if I'm doing cartilagin, they need to be balanced. That's my preference, just to add something with respect to that. That's a great point, Liz, and I think that's probably not talked about enough. I think the concept, most people who do a lot of patellofemoral surgery really have gone to doing them open because you can titrate it and doing a lengthening rather than a release. I think that's a really good point to make. Great. This is a perfect segue into one of the next questions, which is what role does lateral release have with these patients? I would probably expand that to say what role does lateral release or lengthening have? How do you assess these knees? When are you indicating it, and how do you add this on? Maybe we can just quickly go through the panel. Liz, you kind of commented on that. Pete, you came off mute. Go ahead. Oh, yeah. I just was getting ready. I didn't want to be the guy who was still on mute and talking. Yeah. I think for me, it's largely kids who you can't tilt the patella to neutral with it reduced in the groove. Otherwise, I would say I'm almost universally doing it for patients who need a tibial tubercle osteotomy just because I find that medializing the tubercle seems to really over-constrain laterally if you don't lengthen. I think those are my two big ones. Okay. Yeah. I would say for me, again, I evert them to neutral. I try to get them parallel to the floor. If they do, then I'm less likely to do it. I also check in figure of four. When I'm doing a scope, I bend them into figure of four. In deep flexion, if they're concentric, then they don't need a lateral release in my hands or a lateral lengthening. Then I watch them track. If they're tilting in flexion in figure of four, to me, they're booking open on that side. To me, that's something that their lateral tissues are tensioning them. Then I want to loosen those or lengthen them because I do lengthenings. For myself, I use the clinical test and I look at the mediality test. If I'm able to reduce the clinical tilt, I will not do a lateral release or lengthening. Most of the time, I do a lateral release or lengthening. It's quite often. Yeah. I think maybe for perspective, really quickly, we can go around the panel again. Could you just estimate what percent of your patellofemoral cases, instability cases? I know, obviously, there's a variety and everybody has different practices, but just so people know, or maybe what percent get a lateral release or lengthening and then what percent of isolated MPFL reconstructions would get some sort of lateral procedure also? Pete, can you start? Yeah. I think it's pretty rare for me in the setting of an isolated MPFL or MQTFL. I would say definitely less than 5%. I don't know exactly how I'd quantify it, but low single digits. Then I would say it's greater than 80% for those who have bony procedure done as well, or like a TTO done as well. When I do an isolated MPFL, it means that the anatomical abnormalities are very low. Most of the time, I don't do a lateral release for isolated MPFL. For all the other procedures, TTO, trochlobes, most of the time, I do it. I'm probably in the camp of, if it's a patellar malalignment with arthritis, not an instability. Malalignment with OA, I'm doing it 80% or 90% of the time in those patients. It's probably almost exactly the opposite for instability cases. So many of my instability cases are loose medially and laterally, and so I really worry about that. I would say I really use those tests that we all talked about to really decide. I think I probably do it in 20% to 30% of instability cases. It doesn't matter to me if I'm doing an MPFL or not. I'm just going to an MPFL or again, because I do the MPFL even in patients with bony malalignment that maybe someone else might do a TTO or a DFO in because of this study. But it doesn't matter to me what surgery it is. If they're unstable, I use the two tests. And if they are tight on that lateral side, I will lengthen them. And if they're not, I won't. But it ends up being about 20% to 30% of my instability cases. Yeah, I think that's pretty concurrent for me. And I would say, you know, to Dr. DeNora's point, like if they're not exhibiting things that need to be addressed from a bony anatomy perspective, they probably are ligamentously lax or have some contribution of soft tissue component to their instability. And those patients don't need to be further released, at least what I've experienced thus far. Yeah, great points. I think, you know, we know that it has a posteriorizing vector. So we don't want to release it if we don't have to, because it can increase the instability. We've got one more question on MPFL. And then a couple questions on trochleoplasty. So really quickly, in terms of the risks and benefits of patellar inlay versus onlay fixation for the MPFL. I know clinically, we haven't seen much difference from a systematic review from I think it was Aaron Critch's study. But biomechanically, I think, Pete, this is kind of what you looked at. I know that you didn't actually compare the fixation in terms of how they do and heal. But do you have any comments on this from your study? Yeah, I think, you know, it probably does biomechanically, it probably doesn't matter what you use, because the pullout strength of either of those implants is far greater than the tensile strength of the MPFL or of any other part of the system. So it's definitely not the weak link in the chain, no matter what you use. I think, you know, for me, I like to use them universally in the patella, like Beth said, mentioned, because you don't have to worry about either converging tunnels with cartilage work, you don't have to, you're much less concerned about patellar fracture, you know, the smaller implant, like 1.6 or 1.8 millimeter implants, you're not worried about it kind of breaching out, you know, dorsally or towards the cartilage side. So those are kind of the considerations for me. Yeah, I agree. I mean, I think it's more important that it's anatomic and not too distal on the patella, not too proximal on the quad, more than, you know, the being inlay versus onlay. And again, clinically, outcomes wise, it appears that they're the same in terms of recurrence rates, in terms of how they do, and then maybe a little more risk of fracture with bone tunnels. But onlay, I think, is a good option for the patella. So getting into the trochlea, we have a question specifically for Dr. Dujour, any tips on how you weigh the benefits of trochleoplasty against the risks of post-operative stiffness or arthrofibrosis, particularly in young patients? Definitely, when you do a trochleoplasty, the knee is stiff. And for the first 45 days, I always tell the patient that they will be 90 degrees of flexion at 45 days, because it's of the surgery, but because of why we did a trochleoplasty. And most of the time, it's a high-grade trochlear dysplasia, you have to move the TTO. So it's big surgery. And I told you that almost 65% at the previous surgery. So this is the reason for the stiffness. But if you go slowly, and if you are able to wait, you will see that after one month and a half, two, three, four, the knee gets much better. And the rate of arthroplasty after trochleoplasty is very, very low. I would say it's probably two or 3%, but no more than that. Excellent. And then we have, oh, a cameo appearance by Dr. John Fulkerson, who is submitting some comments. He says, great webinar. So congrats, everybody. And he would like to know what percent of your patients get a trochleoplasty for each panel member. So maybe you can say a number and then kind of a little bit of a rationale. So we'll start with Dr. Dujour. I think you'll have the highest number here. Yeah, the highest number, but finally, I don't do so much. And I would say that I do between 30 and 40 per year. And I have a very, very special recruitment for those, because most of them are sent to me by orthopedic surgeons. Yeah. Pete, any experience with trochleoplasty? Yeah. Yeah, I haven't had any experience with it. It's not really part of my armamentarium. I'm particularly worried about, you know, the distal femoral physis in kids, and I treat a lot of skeletally immature patients. So it just hasn't made its way into my practice. How about you, Beth? Super judicious. Sorry, I'm sitting in a room with auto lights. So you went into the, into the nighttime mode. I didn't move quick enough, but I, it's a, I'm very judicious about it. I would tell you, I do think it's a really good tool to have, but it's extremely rarely needed for me. I really have had, I mean, I've been doing this now for more than 20 years and I've probably done, I started doing them about three years ago and I've done three. So that's one a year. And, and before that, I was actually just saying to Dr. Dennis, the reason I started doing them is because I had a cohort of about three patients over the, who had, who I had done a long time ago with TTO MPFLs and they came back, not because they failed their MPFL. They actually just didn't like that feeling of escape and extension. They didn't like the J sign feeling. So it was more of a sense and, and a quality or quality of life, not re-dislocation. And I had sent a couple of those. I had actually sent them to Dave Dedick, who does them in UVA, and then I learned the technique. And so I've done them, but it's, I mean, I do hundreds of instability cases every year and I, I've done one a year or less for the last three years. So it's, it's not something I do often. I think it is a great tool, but it's just really rarely needed in our, in my practice and the group of patients I see. So I'm still early in practice, so I've done, I've done one and I think really excited to see more of the work that Dr. DuJour is doing with the MRI classification. So we can learn more about the morphology and what Dr. Fulkerson's group is doing with the 3D anatomy. Because I think for me personally, like I just want to understand more about the morphology of the trochlea because I want to understand and be able to correct it appropriately. And I just think personally, you know, I'm so impressed by Dr. DuJour and Dr. Dedick specifically, you know, sort of 3D understanding of the anatomy and the correction, et cetera. And I'm still learning that. So I think looking to learn more from all of the data that we're getting so that we can make sure that we're surgically correcting it appropriately, but, you know, agree judiciously, I think for, you know, revisions or patients who have jumping J signs, or, you know, that, you know, that, that convex trochlea is, is just not going to have the patella track well. But yeah. Great points, Liz. I think, you know, two big take-home points kind of on trochleoplasty with this discussion is one, even, you know, the Dr. David DuJour is still talking about his numbers, not being trochleoplasty on everybody, right? So even a high volume trochleoplasty surgeon is still, you know, not, we're not talking hundreds here. So I think that, and then the other point, Liz, that you touched on is that our understanding of the anatomy and how to address it is still, you know, limited and hopefully some of these new classifications, novel, you know, imaging techniques might help with this, but it's not just, we're not just treating a flat trochlea and trying to deepen it. So I think that's a really important message. So I think we're in our final minute here. I know that our AOSSM and AJSM staff have some final closeout slides. So I'd like to thank everybody for joining us and thank you to our panelists for an excellent discussion. Thank you. Thank you. Thank you very much. I'd like to give a big thanks to our panelists and presenters for their work on tonight's webinar and thank you attendees for your participation. On behalf of AJSM and AOSSM, we hope you enjoyed this webinar. 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patellar instability

medial patella femoral complex

MPFL reconstruction

biomechanical study

cadaveric models

trochleoplasty

anatomical differences

tibial tubercle osteotomy

lateral release

patient-specific treatment