In that vein, my disclosures are in the My Academy app. I think my probably best disclosures, I do a lot of osteotomies. It's funny, I've got a couple of former fellows in the audience, and they're from a decade ago. And if you ask them how many osteotomies I did a decade ago, it was probably, you know, single digits a year, maybe 10 or 12, and now it's closer to 50 or 60 HTOs or DFOs, and that doesn't include another probably 30 or 40 TTOs. So I do a lot. I'm still learning a lot. In fact, one of the cases I have here I haven't executed yet, and I wanted to ping some of my friends about how they would approach it and how they assess some of these really difficult concepts. So as you guys heard from Seth, he did a really good job of capturing how we do this assessment, how we do our preoperative planning. But the ideal, as you know, is about 87 degrees on the medial proximal tibial angle and on the lateral distal femoral angle. And the goal ideally is a straight leg, you know, with a 180 degree or zero degree hip to knee angle. And again, the goal is a joint line that is parallel to the ground. I think this is something that doesn't get a lot of attention. I think as we continue to discuss osteotomy and hopefully in the next five or 10 years, we're going to be talking about slope in the coronal plane as well as in the sagittal plane. Whoops, not quite sure what happened there. So this is my first case. This is a 44-year-old male. To further complicate this issue, he's an orthopedic surgeon. So he had a tibial plateau fracture skiing. He was complicated by a post-operative infection. This was all done elsewhere. He developed sepsis. He was in the ICU. He had adrenal shutdown. He had DIC. He was really sick for a long time. Overcame that, got back into practice, went on to nonunion, had a revision, had no RAF, and that went on to union, and this is where he healed. So he is constitutionally in neutral on his unaffected side, and he's in significant valgus. Amazingly, his joint is pristine, so his infection was extra articular. He's got a really healthy-looking joint. He is in significant asymmetry. He functionally is compromised in his ability to bike, ski, hike. His leg hits the crossbar on his bike. He can't ski because his leg is so far out from where the other leg is, but he's obviously apprehensive about pursuing it and further intervention given his previous surgical history. So these are his numbers. So he's got about 12 degrees of valgus. His mechanical axis is deviated about 43 millimeters into the lateral compartment. Lateral distal femoral angle, as you would expect, is fairly normal, but most of the deformity is on the tibia. So he's got 12 degrees, so he's about 10 degrees, I'd say, on the tibia, maybe 2 degrees on the femoral side. So Anil, what do you think? You got a challenge, right? You got most of the deformity on the tibia, but you got a really compromised bed for surgery. He's had infection. He's had revision. He's had two. So, I mean, you know, I would, in my earlier days, just go for the femur and, you know, potentially overcorrect the femur, potentially violate, do not violate the joint line to stay away from the tibia. But you could also attack the tibia as well. That would be, to me, the debauchery. Al? Yeah, I'd probably fix him at the end. Sorry, on the tibia. On the tibia. Yeah. What'd you do, Seth? It's a double level talk, Seth. Yeah, you know where I'm going to go. It's fair. He's very situationally aware, that guy. So this is a challenge for what Anil said, like it's the deformities on the tibia. You know, I think you got a compromised bed. This guy's had previous infection and infection's been ruled out, you know, and this is the discussion we had. Now, would you guys do, if you do it on the tibia, would you do closing wedge or opening wedge? Closing. Al? Closing. Yeah. That's my thought process, too. Is, right, you've already got a bed that's going to be a little bit challenging to heal. It's been operated on twice. It's been devascularized. I want bone-to-bone contact. So this is his deformity analysis. You know, for disclosure, I do, I'm almost 95% CAD osteotomies now. I do a lot of, I do talks for BodyCAD, but I have no financial interest in their products. So this is, so my concept on this guy was, let's do it on the tibial side, right? I was very tempted to do it on the femoral side. He sought multiple opinions across the country, all differing opinion. Just do it on the tibia. Do opening wedge. Do closing wedge. Just do it on the femur. Do both. And so we, I really thought he needed a pretty thoughtful deformity analysis. So here's the challenge, I think. So we planned him on the tibia, and this is where I think that there's benefit to doing computer-aided planning. I don't necessarily think you need to do it all computer-aided execution, but if you notice Stephen and Al's talk, a lot of it is done with computer-aided, you know, the planning itself has got a CAD component or a computer component to it. And I think that that's probably more important than how you actually execute it. So this would bring him into neutral mechanical axis, but he's got, I had the, and this is where I still struggle, is trying to figure out what that joint line's going to do. And I've got some concepts on it, but I'm curious how the rest of the panel assesses joint line obliquity. But this gives him a joint line that's about five degrees off of parallel. Do you guys have any hesitation, you know, as you plan it? Like, do you have a, do you look at joint line obliquity? Do you have a threshold where you start saying, man, this could be a problem? Al? Yeah. I mean, in some ways I think the whole concept of joint line obliquity has gone a little bit too far. You know, you're doing double-level osteotomies to get an absolutely perfect parallel joint line. There's morbidity associated with that. For sure. I think we've got to be a little bit more, you know, a bit more pragmatic. I'm usually thinking if it's going to be over 93 degrees of approximate tibial angle, then I'm probably looking at a double-level. So I'm going to accept some obliquity for sure. Yeah. That makes sense. I think you've got to, it's nuanced, right? Seth, do you have a threshold? I don't have much to add to that. Yeah. So I start getting anxious, and I've got a reason. So in this particular case, he's got five degrees, and I said, you know what, I don't want to do as much surgery on that tibia. I want to be nice to that tibia. This is a tibia that's got some challenges. He's pretty normal on the femoral side, but he's probably low normal. So I thought I could potentially, in this case, do a dual-level osteotomy, do less work on the tibia, close it, because I don't want to open it, because I don't want to create a non-union issue, give him a joint line that's a little bit more parallel to the ground. So what's the issue with joint line obliquity? Well, and again, this is a concept that I continue to try to understand. I don't really fully understand it, because I think it's a dynamic process too, right? You can look at all your measurements and say that joint line's going to be flapped. As they change their adduction angle, when you realign them, that changes the obliquity of the joint line as well. So it's not purely static, and there are ways to try to predict what it's going to do, but it is a dynamic feature to a certain extent. So if you look at joint line obliquity, understandably, in the coronal plane, again, we've talked about the sagittal plane. You can see the shear on the articular cartilage on the plateau with increasing tibial slope. We've talked a lot about its influence on ACL and PCL, but it has an influence on articular cartilage and on where loading occurs in that tibia. It shifts toward the down-sloping meniscus, which makes sense. The femur is sliding down, just like it does in the sagittal plane, and on the upslope of that tibial spine. And this occurs at about four degrees of coronal plane slope. So I'm not saying that's necessarily the threshold, but that's where it starts getting my attention. It's interesting, because on the clinical data, it's less clear its impact on clinical outcomes. So in this series, they looked at a series of 100 essentially opening wedge high tibial osteotomies. It was about six degrees where they started seeing some radiographic change, but clinical outcomes begin to deteriorate at about four degrees of joint line obliquity, or what I would say coronal plane slope. But I would say there's other data suggesting that this may not influence clinical outcomes to the same degree. This is an interesting concept of how do you predict joint line obliquity after surgery. So this is a South Korean group. And so you see A is the initial state, B would be your planned osteotomy. And you can see that kind of shadowed area, just the inside, is if that leg comes back into its natural position, that's the adduction angle, right? So that leg's going to go out as you kick into valgus. He's going to bring his foot, he or she's going to bring their foot back into a neutral position. And that gives you an idea. You can add that to the initial joint line obliquity to predict where your ultimate joint line obliquity is. Meaning, if they're at two degrees, and then they bring their leg in another three degrees, and now that you've changed their alignment, that ultimate joint line obliquity is going to be five. I think there's nuance to this. I don't think it's as straightforward or as linear as they would illustrate. But there are ways to try to predict what that joint line's going to do as you change your alignment. And this is, again, I don't think this, I agree with Al, I think you can over-focus on this at times. And I think still relying on your medial proximal tibial angle or your lateral distal femoral angle is your best bet. But I'm always mindful of what my operation is potentially going to do to their joint line, especially in cases of arthrosis or articular cartilage preservation, which is probably my most common application. So it's interesting, if you look at dual-level osteotomies, and this is very aligned with what Al just said. So they took this study, looked at it in Japan, they looked at 68 patients, half of which had opening wedge high tibial osteotomies, all for varus, 34 of which had distal dual-level osteotomies. And their indication, similar to what Dr. Gekko just said, is if the medial proximal tibial angle was over 95, so even a higher threshold after the correction with HTO alone, and they had an abnormal lateral distal femoral angle, these patients got dual-level osteotomies. So just to give you some guidelines as to when you should start considering a dual-level osteotomy, at least specifically in the case of a varus knee. And what they found is, in those cases, with the HTO alone, probably because of that adduction moment, they increased slope pretty significantly from about 1 degree to 6 degrees, right? And now we're getting to a threshold where maybe that's going to impact radiographic and clinical outcomes, and when you got to these numbers, a dual-level osteotomy kept that joint line flat. So again, just reinforcing the concept is know where your deformity is, know where you're going to end up after your osteotomy, and if you're getting to these non-anatomic, non-physiologic numbers, consider dual-level osteotomy, one, you know, to keep that joint line not necessarily flat but close to flat to the ground. But again, interestingly enough, they didn't see any huge difference in their patient-reported outcomes. So to me, I'm still learning. I do 50 to 60 of these a year, and I've certainly had my share of complications, none of which I'm presenting today, actually. But I think this is just, for me, an evolving concept. Do I need to worry about it? Do I not need to worry about it? Is it going to be like sagittal slope, where we didn't even talk about it 10 years ago, barely talked about it? Are we going to be talking about this in more frequency as we refine, as osteotomy becomes more popular and we refine our indications in our techniques? So this is that same case. This is that same orthopedic surgeon. This is how we plan them with a dual-level osteotomy. So smaller resection on the tibia, so a little bit more forgiving, with a very small 7-millimeter DFO biplanar cut, not biplanar correction. And for me, that small correction on the distal femoral side, he was apprehensive, understandably, about me operating on his femur because it was pristine, but I felt that this gave me an operation that gave me a joint line that was flat to the ground. Particularly challenging case, retained hardware, planning, everything is really tough. So this is our surgical execution, taking the hardware out actually was probably the hardest part. It's not illustrated here, he had a huge ball of callus in the back of his tibia. I like to get all the way around the back of the tibia. I want to put my finger on the tib-fib joint from behind, so I know I've got a plane that is safe. So that's just, I don't use alignment rods other than for illustrative purposes, frankly. So the alignment rods, to me, are the most imprecise measurement in all of orthopedics. It is subject to parallax, surgeon bias. I mean, we will move that line to wherever we want to make our X-rays look good. But I think it's illustrated for a case like this. So this is a closing wedge medial tibial osteotomy, relatively small correction. You can see us closing it down there, probably overkill. I think you could fix this with staples. I still like plates, especially this guy had a lot at stake. You can see how that line begins to shift. So if I'm doing a dual level, I'll at least, between the two osteotomies, check where my alignment is. Maybe that's an overkill. Maybe I should rely on my template more. But that's what I did in this case. And then we did a small correction DFO. This is him after correction. It's always nice to show your home runs. He's done remarkably well. In fact, I just... What was that? No, no, no. So this is... He asked how your feet are, to Gene's point, you know, how they're symmetrically opposed and then they're more adducted on the other X-ray. Oh, yeah, yeah. Part of it is that his foot can't get adducted on that right X-ray, right, like on the left X-ray. So that's our preoperative plan. But this is his clinical picture. I actually emailed him yesterday. I was like, can you just show me? I know you've got... So the problem is you can't get these feet together when a knee is that valgus, right? So like this is him just hanging out with his son in the left picture. And this is him after his correction last week. So he's about eight weeks out. So I'd still... You know, clinically doing well, obviously, there's still a lot to, you know, in terms of his outcome. But I do think the goal, again, is to try to focus on where the deformity is and be mindful and aware of what you're doing to that joint line over time. So I'm going to skip... Case two is actually a similar failed osteotomy. I'm just going to skip forward because this was... We ended up doing her on one level, but fairly complex failed osteotomy. I think when the hinge fails, if you don't have adequate software, adequate hardware, they tend to fail into varus, is my experience. I don't know if you guys have had the same experience. So for an opening wedge osteotomy, on the femoral side, if the hinge fails and you don't have good stable fixation, they will overcorrect. And on the tibial side, they will lose correction. That's been my experience seeing several of these. So she overcorrected in an old DFO, and then we revised it. So this last case, just in the interest of time, I think this is... I think we're kind of over time. I haven't done this case yet. So actually, I'm kind of opening it up because I'm curious how you guys would handle it, and I'm not sure what the right answer is. And I'm very curious how you guys, Chris, how you guys manage or, you know, conceptualize these concepts. So this is similar to the case you presented, I think Aaron's case. So he's a 46-year-old male. He's active. He's still a soccer player. He had a partial meniscectomy in 2002. He's got medial knee pain and instability. His mechanical axis essentially is outside of his joint. Deformity appears to be principally just by looking at it on the tibial side. And he's got a true, you know, triple varus knee, you know. He's got, he walks with a big varus thrust. He's got, you know, significant instability on exam, and that's what he feels. He feels that varus thrust. Double varus, yes, sorry, double varus. But he is passively correctable on exam. So the question is, how do you guys, I can make all the measurements on the femur and the tibia. I think that's pretty easy. I think we've beaten that dead horse. How do you guys compensate for the joint line of obliquity in cases with chronic collateral insufficiency? Al, what do you do? I tend to go, well, there's a number of different things you can do. First, which we don't make films. Yeah. We can do a push view, so you can actually reduce that lateral gapping, and then retake your x-rays, so you don't have a stress radiograph. And then do your standard planning. The other thing is you can leave it as it was, and then you're just going to measure the difference between the gaps on the affected side and the contralateral side. And then you're going to do a push view, so you can actually reduce that lateral gapping, and then retake your x-rays, so you don't have a stress radiograph. And then do your standard planning. The other thing is you can leave it as it was, and then you're just going to measure the difference between the gaps on the affected side and the contralateral side. If it's a three millimetre difference, I take three millimetres off my correction. That's pretty basic. Yeah. You know? That works, right? Alternatively, then you can do your digital planning. And you can do it on the correction for the joint line obliquity, and build that into your planning. And that's where I think some of the software packages are really, really helpful to take all this stuff into consideration. So if you were doing it on the software, he's got eight and a half degrees of joint line congruence angle. How much, if you were just planning it without doing a stress radiograph or anything, how would you compensate? I've heard guys say, measure the other side. But he's varus on the other side. He's got some gapping. I've heard some people say, take half. Right? Take half. Right? And then you're going to measure the other side. If you were doing it here, how would you, what would you tell them to model it from eight to four? Would you tell them to go to three, or pick a normal standard? How would you do that? I mean, I think, because you've got your double level, you've got your CT from the other side. So I think it would be good to actually look at the other side and see what it's sitting at. Yep. The French guys came up with a funky formula, which I can never remember. Right. Yeah. Right? You know, it's something minus something, and minus something, and then triplet. It's way too early. I didn't realize there'd be math involved today. So that's kind of, I'm very, I keep it very simple from that perspective, and really just go with the difference. I mean, I think, because you've got your double level, you've got your CT from the other side. So I think it would be good to actually look at the other side and see what it's sitting at. Yeah. I mean, I think, because you've got your double level, you've got your CT from the other side. So I think, because you've got your double level, you've got your CT from the other side. And Chris, do you have other thoughts? Well, as a general rule, I mean, so one thing that interested me is, Pat, you mentioned not being too concerned about joint plantar fluidity, but as I'm doing, it's hard to believe this, but I'm aging, and as I'm doing more and more total joints, as a sports surgeon, it's interesting that, you know, sports surgeons don't like doing complex joint replacement, and joint replacement surgeons don't like doing complex joint replacement, and one of the problems is, when you're doing total knees, it has totally changed my perspective on my osteotomy practice, particularly as I go down the path of doing my patient-specific anatomic and kinematic axis knees, where in the post-osteotomy knee, you can either have normal soft tissue balance, or you can correct the deformity, choose one, and so I'm deferring way more now towards exactly what you guys are all saying, really thinking about the anatomy. When you say that, you know, joint parallel to the ground, I would add joint parallel to the ground in a stance. Correct. And trying to, in this guy, for instance, Knowing that every osteotomy patient is someday a total knee replacement patient. Yeah, I think that's fair. So this was how, just since we're over time. So if you plant them traditionally, just drop the, you know, just drop that, you know, measure your, you would end up with a 20 millimeter opening, which is kind of the upper limit of what I would do. And when that lateral, you're going to end up with a ton of joint line obliquity, and that lateral side clamps down and stance, as you just indicated, Chris, he's going to be way overcorrected, right, because you didn't compensate for that. You could do the same thing if you plant it without compensating for the joint line obliquity. So I did what, Al, what you suggested. So I took, I did a stress x-ray, but not like you would do if you were testing for ligament insufficiency, but rather to close down the lateral side to see if I have an optimal lateral soft tissue envelope and I'm balanced, what happens to that joint line, and then superimpose that. I didn't necessarily do the whole scanogram with the stress, I just did the knee, but they were able to superimpose that digitally. Also just reinforcing, I think, the strength of some of these computer-aided design planning software. You can see how that teal line shifts over, so now I'm going to plant it based on his anatomic measurements and where that is. And you can see just how our plan changed as a result of that. So again, just focusing for me on the anatomy and on trying to get a joint line, and I don't know if this is the right or wrong answer, I'm just trying to get a joint line that ultimately is flat to the ground. Just picking up from Chris's point, there's joint line obliquity when you're dealing with ulcerative arthritis, and there's joint line obliquity with ligament dysloxia. So I will accept some joint line obliquity in a way, but for ligament dysloxia, typically if I'm going to end up having to do multiple ligament reconstruction, forget it. I want it anatomically. Which is the content of the failing varus knee. Single, double, triple varus is for instability. The failing varus knee away is a totally different paradigm, right? It's loss of needle compartment, stretching of the lateral side, failure of ACL, and then posterior medial wear. They're completely different failure mechanisms of the varus knee, and that's why you can't think of noise as triple varus to the failed arthritic triple varus. It's a different mode of failure. So this was our most recent iteration. So the nice thing too is that you can continue to iterate these plans as you understand the deformity better. So if we just did an osteotomy now compensating for the joint line congruence angle and lateral insufficiency based on the stress x-rays, you can get a straight leg but you still get numbers that are both abnormal in the femoral and tibial side. So I have not refined this plan. I put this case in here because I had an opportunity to pick the brains of some of my friends who are smarter than I am about how to handle this. But to me, this is a case that ends up with a dual level osteotomy with a smaller correction in the tibia, a small correction in the femur. And then I think you can make an argument about do you do a lateral collateral ligament at the same time or do you do that in a staged fashion if necessary. And I think probably beyond the scope of today's talk. But I think, again, planning is key, right? If there's a summary of all the talks today is planning is key and knowing how to assess deformity and where the deformity is. I think you should be mindful of joint line obliquity. I think we're still evolving in that concept of how much can you accept and how do you plan for it, how do you figure out what that's going to end up with at the end of your surgery. I think you need to be situationally aware. And that first case illustrates that, right? You've got a tibia that's compromised. Do you have to do it all in the tibia in cases like that where you've got some concerns about healing, infection, wound complications, et cetera? For me, from a technical standpoint, if I'm doing a dual level, I typically will do the bigger correction first if there's a discrepancy between the two. If they're relatively similar, I usually do the closing wedge first because it's more stable and I can do my opening wedge. I think that's just personal preference. I'm not sure if you guys have a different advice. And I like to assess my correction after each step just to ensure that I know what I'm doing as I progress. But, again, I'm going to rely on my templates more often than I'm going to rely on any Bovey cord or alignment rod. So, Seth, you know this place. Thanks, guys. Thanks. So I'm just trying to resolve the issue of the joint line stuff in these lateral instability cases. Traditionally, if you just drop your plumb line and try to correct for that and assume the varus is in the tibia, then, yeah, I think you've got to certainly take into account that joint line gapping or whatever, so I decided to correct for it. If you strictly stuck to proximal tibial and distal femoral angles and just assume you may leave the lateral side lax, but when you're making the leg straight, it needs to be as big an issue, does that sort of negate all this other mental math to correct for this gapping or not? Yeah, I think that's what Al was getting at with his comment, which is if you're starting to get to, if you do it all on the tibial side, your medial proximal tibial angle is getting up pretty high, like, you know, mid-90s, you know, you can use whatever threshold. Some people use 90 as a threshold. You need to start thinking about doing it on the femoral side because you're going to create that joint line obliquity. So I think if you just, if I understand your question correctly, yeah, I think if you just rely on those measurements, the LDFA and the medial proximal to help guide that, I think that's very helpful and simpler than trying to predict. Totally. I mean, I think that's very reasonable. So I'm generally a minimalist when it comes to that, so I think, and I'm a big stager for a lot of things anyway because I think it's a lot of surgery and now I'm going to have a plate on the femoral side because I'm going to, right, so now I've got some, I've got to figure out where my tunnels are going to be and am I going to intersect with my plate? So in my hands, I'm probably going to stage this guy. And I think you can make the argument, too, if you look at, like, Leprod's data for HTO with chronic collateral ligament insufficiency, I think it was like 40% of their patients never went on to a ligament reconstruction because they felt better with osteotomy alone. So I think, but you can make the argument, like, you're there, you've already got the collateral side filleted open, just do it. So I don't think there is a right or wrong answer, but I'm a stager. I like those odds that I may not have to come back and I know I'm going to have compromise now because I'm going to put a big metal plate on the femur and I've got to work around that potentially. So I personally would stage it, but I'm sure that you guys may feel differently. Than one huge correction. So, and then you have an opportunity because, especially if you put a plate on the lateral side of the femur, if you think you have a high removal hardware on the medial side of the femur, the lateral femur is 10 times higher. And if you want, that's the best IT band or sites we'll ever get. And then you have an opportunity to take the plate out and do your work. I will say one elegant thing, too, and I didn't do it in this case because it was a previously infected bed, is you could take the wedge out of the closing wedge and move it to the opening wedge, right? And you can use it as your autograft and you can flip it around. The other advantage of doing the closing wedge first. I didn't do it in this case because I didn't want to use that bone. Cartilage patient with malalignment, I'll do the malalignment first, correct the two points in that, and then come back for the inter-articular work all at once. Chris, I'm a stager in the same sense. I do a lot of staging arthroscopies. But if the question is, do I stage my osteotomy from my cartilage work, I think it depends on the context and I'm pretty evenly split. So, like I'm not afraid to HTO, ocealograft, you know, meniscal root repair. So like oftentimes I'm doing all that together. And the nice thing about some of the CAD stuff, you can move screws around to accommodate root tunnels, meniscal transplant tunnels. So I like to stage to look at it, but I don't necessarily stage the one big procedure at the end. It depends. If it's more of an arthritic process where I'm thinking I'm going to get away with an extra-articular operation alone and just wait and see if they need cartilage, then that will do an osteotomy. Like, they're 40-something and I'm like, gosh, the outcomes of osteotomy alone are pretty favorable and there may not be a huge advantage to having cartilage. I may just do an osteotomy and wait and see without planning the other stage. If I'm already planning on doing everything, there are 20, I want a more biologic solution that's going to last longer. I'll probably do it all in one setting. I've had timescale failures of ACLs. You have tunnel widening and you have a couple of unknowns. Yeah. Imaging. Yeah. Osteotomy, bone graft. Osteotomy, osteotomy, bone grafting. Understanding, you know, that you don't want to put a meniscus transplant in a hostile environment, so you need to know what the cartilage status is. Yeah. Knowing if this is truly more than one compartment early away, you know, just changes your... It's the one or two failed versus the three or four failed. The younger patients, I go for them. Yeah. But I think Al's point is well taken, which is maybe we should be doing some of these slope correcting osteotomies earlier, because they don't do amazing, right? So maybe we've waited too long. I don't know the answer. It's just that you and I have talked about it. The fact that James went and pushed off the corner, I think if the biceps is off, then I'll kind of fix it. If it's an intrasubstance strain, maybe that we're tight and they're just gapping, you can do an advancing of the large compartment. You can just pull it up and then you can actually fix that with your DFO plate. Yeah. I've done that a bunch of times. It actually works really, really well. That's a good thought, actually. Yeah. It's easy. Yeah, and that doesn't burn any bridges. If you had to come back and do a recon, that's pretty easy. Yeah. And to me, it's more common and interstitial than the true blown out corner. It's just interstitial. It's very stretched. Yeah. Awesome. Thank you, guys. Thank you very much, everybody. Thanks again.

osteotomy

joint line obliquity

surgical planning

anatomy and deformity

parallel joint line

dual-level osteotomy