So I have some disclosures, some of which are relevant. I am involved in some robotic stuff regarding osteotomy. So general indications for knee osteotomy, I think I'm sure most of you here are well aware of the indications regarding whether or not this is more for arthritis, chondral protection, instability. And certainly when I look at any sort of complex knee, this is sort of an algorithm that I often think about and something that we teach at Fowler Kennedy. And certainly realignment osteotomy is really at the top of the list here in terms of correcting biomechanics before you start getting into more complicated things such as biological interventions. Of course, the traditional concept has been in sort of this way. I was taught initially, was that you do a mechanical axis and you look and if it's a varus knee, we're gonna be doing a tibial correction and if it's a valgus knee, of course we do a femoral correction. And thankfully, that has started to change a little bit. And why is that? Because now if you do deformity analysis, and this is a great paper from Mathieu Olivier and colleagues really just showing that depending on if you have varus or a valgus knee, you will have different problems in different parts of the joint. So here in a varus knee, you're often gonna have, the tibia is predominant but you will often have some femoral disease and certainly on the valgus side, you may have also some tibial deformity, not just a femoral deformity. So that's the importance of doing deformity analysis planning. And of course, we all have PACS systems but if you do, if you can get your hands on more sort of digital planning software, you can really do this very relatively quickly and it does give you really quite a nice overview of what's going on with both tibia and femur. So this is an example of a guy who's a 22 year old, he had a ACL PCL medial sided injury. You can see here, he's got primarily issues really in his distal femur. And so we did a medial closing wedge distal femoral osteotomy. This is in a staged fashion around a multiligament reconstruction as a chronic injury. With a 23 year old medical student. So this is a guy who presents with lateral compartment degenerative change after a previous subtotal lateral meniscectomy. Here you can see his arthroscopic picture. He's got asymmetric valgus and I'm sure in the good old days, we would have just looked at that and said that's actually, we should be doing a distal femoral osteotomy. And if we actually do the deformity analysis, you can see most of his deformity is actually in his proximal tibia. He's got proximal tibia valga. And so medial closing wedge, proximal tibial osteotomy is the right call here because it really does unload both in extension as well as flexion. And there's some nice papers earlier in the week showing the impact of a tibial based correction to be able to unload throughout the flexion arc. And what if you don't have planning software? Well, you can still use your PACS system and you can draw all your lines as the 34 year old female bilateral valgus alignment if you get a mechanical axis. And I think as a general rule of thumb, if you see a mechanical axis that is outside of the joints, it's not even within the bone, you should be thinking maybe this is actually a deformity that's on two levels. And so in this scenario, I did a double level correction and got a fairly straight knee. Now you can see there's a little bit of a joint line obliquity. And I think this is where the challenge comes when you start doing double level corrections. It's a little bit harder to gauge an accurate correction. And I think this is where PSI might come in in the future as Neil was showing, where you can actually have a little bit more accuracy in your correction. So in terms of distal femoral osteotomy, so those are the sort of the principles in terms of correction, but what actually, how do we do it? Well, there's lots of different options. There's a lateral opening and that's probably the more classic approach that's been used in North America over the years. It's a relatively easy approach. It's one cut. You're able to titrate your correction. As long as you use stable locking implants, you should be on a winner. But unfortunately, there's a lot of issues with hardware issues, with ITB, irritation. A lot of patients need to have the plate taken out and there's always a risk of loss of correction when doing opening wedge cases. So medial closing wedge has really become very popular in Europe and certainly this is something that I've taken on. I really find this as my workhorse for distal femoral osteotomy. So you've got really good soft tissue coverage over the plate. It's a very stable fixation. You get an early range of motion, early weight bearing, and it probably is a little bit, certainly anecdotally, I think it's less painful than an opening wedge. But the approach can sometimes be a little bit more challenging, particularly in patients that are a little bit larger if you've got a very well-developed VMO. But of course, you can't just stick to one. Sometimes you need different combinations. So this is a young girl who had skeletal dysplasia. She's very short stature. And in this scenario, I really wanted to try and give her a little bit more length. And so we did combined DFO prox and tibial. So this is a lateral opening wedge as well as a medial closing wedge on the tibia. And this is another interesting case where we had single-level planning. This is a guy who had a KD3L knee dislocation and essentially was a significant varus. And if we just, we were planning to do an osteotomy, if I did this as a single-level correction just on the tibia, this guy's gonna end up with a significant joint line obliquity. And then coming back to this stage, multiligament knee reconstruction with joint line obliquity with increase in translation forces across the joint, I didn't think that would be a good plan. So I ended up doing double-level corrections. So this was a scenario of doing a medial, sorry, lateral closing wedge distal femoral osteotomy as well as a lateral closing wedge osteotomy because he was, tibial osteotomy because he was a smoker. And we wanted to get early healing and I wanted to be able to do the second stage ligament reconstruction in a fairly timely manner. So lots of different options depending on the individual patient that you're seeing and you wanna titrate accordingly. So this was a double-level osteotomy and then came back later, took the hardware out and did the reconstruction. So what about the evidence for various osteotomies? Well, it's fairly, the historic evidence is maybe not quite as good as the HTO evidence but certainly 64 to 82% survival at 10 years, 45% at 15 years and you get significantly improved in knee function and HSS scores. So it does work and it works very effectively. And planning-wise, okay, of course we're gonna use our mechanical axis, we're gonna do a deformity analysis. The simple planning tool, if you wanna just use it on your packs, you can draw basically your line, this is your correction. We wanna correct to a neutral position. We don't wanna go over into a varus knee. And then we draw our line, so this is our osteotomy plane. Okay, and then we can subtend that line to the correction and then just with simple trigonometry, we can end up with the blue line being the millimeters of correction that we need to do for the wedge resection. So this is the technique that I use. So it's a longitudinal incision based over a VMO and then we just do a subvastus approach. It's actually a really nice approach. You just elevate, lift the VMO off and then you're getting right directly onto the distal femur. And we're gonna divide the posterior into muscular septum. You can see that basically the vessels there. So you gotta cauterize those vessels and then we're going to subperiosteal dissection and then placing a retractor posteriorly. The guide wires are placed as per our templating. And so I tend to just use two pins. The two pins are measured off of, I just use a simple plastic ruler based on the correction that I'm planning for. And then we can measure that out with cautery and it has to be, you want obviously that cut to be perpendicular to the shaft of the femur. And then the osteotomy is completed with a very thin saw. You gotta think about the correction that you're obviously gonna take some bone away. So when you take the wedge out, it's gonna be actually smaller than the correction that you've planned for because you are resecting bone with your saw. Your retractor is sitting posteriorly. I often put a sponge behind that as well so the neurovascular structures are well away from here. I can put my finger all the way across the bone and I can feel that there's absolutely no issues with creating any problems with the neurovascular structures and then I'm gonna complete the osteotomy with osteotomes. Take the little wedge out. Of course, it always comes out just as easy as that. Okay, if you find that it doesn't, it's a simple thing to do is take a kerosene rongeur, put a kerosene rongeur back across the knee to resect some of that bone across to your hinge. And then you also wanna be thinking about doing this biplane cut. So this is a proximal extension of a biplane cut. That has to be done all the way to the level of the hinge. That allows you to basically control rotation and will stop the knee from rotating but also from flexing and extending. And then we close it down. You saw I just perforated the hinge. This is a controlled osteoclasis allowing the hinge to close down. Then we put the plate on and put the plate on in a compression mode. So we get locking screws distally and then a 3.2 millimeter drill to allow a 4-5 lag screw to be placed into the compression hole and that gives a really nice compression across the osteotomy site. And then we fill up the rest of the holes with locking screws and then the soft tissue goes back over the top and that's our end product. So a few tricks. So stand on the same side as your approach. So do that same thing for a medial opening wedge tibial osteotomy and bring your fluoroscopy in from the other side obviously using a radiolucent table. You use the vessels basically so this is the supermedial geniculates that basically you use these as a guide to your start position. Got to understand about how to manage the hinge and this is just some tips and tricks that I've learned over the years about your hinge. And so our correction point, our hinge point just wants to be slightly proximal to the posterior scar of the lateral femoral condyle. So that's my hinge point and that's my guide wire going in. Now if you put your guide wires in so they come exactly to that hinge point just think what happens when you put your osteotomes your saw on your osteotomes. Your osteotomes go either side of the wire and actually your hinge will be not at the hinge point that you want but it's a little bit more medial to it. That creates a fulcrum so that when you start to close it down the risk is that then the hinge will spring open. So actually when I put my pins in I want them slightly separated. So if they're separated then when I bring in my osteotomes I can bring my osteotomes to the hinge point that I want and that will get me a better resection of bone and it'll be easier to manage that hinge. Now the biplanar osteotomy this is just a saw bone example and this is what we're doing. We're just creating that anterior flange and that allows everything to rotate across that but also controls rotation. It gives a lot more stability to your osteotomy site controlling rotation as well as flexion extension. The curse and ronjure as I mentioned perforate the hinge to aid in closing. And then if you wish you can use a hinge pin or a screw for protection so you can basically put that wire across. I would just caution that when you do that just be very, very careful that when you take the wire out that you don't run into any problems. Then the biplanar osteotomy and really the management of the site. So take home points. You've got deformity analysis. You want to correct on the side of the deformity. Utilize closing and opening techniques. We're not a one trick pony. You've got to have all these tricks up your sleeve. Try to avoid excessive joint line obliquity. The biplanar osteotomy is a win and a management of the hinge is the key to success. And if you want to do a little bit more practical work around osteotomy, please join us in October for the AOSMS Across Osteotomy course. Thank you very much. Very nice. So can you tell us sort of what your maximum level of opening or closing is before you go on a double level? I think the threshold to go to double level may be different for everyone a little bit. Obviously, you talked to us about keeping the joint line essentially parallel to the floor. That's the key. But in addition, do you have any concerns about a certain number of opening before you think about your soft tissues and go bi-level? Yeah, I mean, if you look at most of the data regarding hinge fractures, particularly on the tibial side, 11 millimeters has been shown to be correlated with increased risk of hinge fracture. Once you're getting up over 14, 15 millimeters on the tibia, we used to do really quite large corrections. I mean, I've done 22 millimeter tibial corrections before. I'm sure if I look back at those x-rays and look at the joint line obliquity, it'd be crazy. So, you know, we certainly don't do that anymore. So anything sort of around about 14 millimeters, I'm starting to think I should be doing a double level. But, you know, every knee is different and, you know, we have different levels of deformity and sometimes you will have a big correction just because you have extremes of proximal tibia vera. So I think just recognizing that you don't want, you know, when we think about joint line obliquity on the tibial side, I think of more, I just, as a rule of thumb, I use MPTA as a way of gauging that and I'll accept up to probably about 93, 94 degrees of joint line of MPTA because otherwise you'd be doing far too many double levels because there is morbidity associated with operating in both bones. The femoral side, I think that's very rare. I do much more than an eight millimeter correction on the femur. It's very rare to have to do that. And remember, because it's more proximal based osteotomy, a smaller correction will give a, or a smaller angle will give a much greater angular correction on the distal limb. I prefer the medial closing wedge for the reasons you mentioned. Can you give me scenarios where you would go to a lateral opening wedge? Do you do a medial closing wedge if you do a lateral meniscus transplant or that unnecessary cartilage work that Anil mentioned? I still like to do a medial closing wedge just because, I mean, it's just so much more stable. The patients are, I find, much less painful. I think one thing with osteotomy, you gotta look at leg length. And if the leg length, if you wanna try and rebalance the leg length, then it's a great option to be able to, to do a lateral opening on occasion. So I think, you know, you gotta have that. You know, for patella instability cases, it's tempting to say, well, go on the lateral, you know, go on the lateral side, particularly if you're gonna do any sort of lateral retinocular lengthenings or anything. The problem is if you go on the lateral side, it'd be interesting to get David's thoughts on this. I find that when you do a lateral opening wedge with patella instability, you're actually tightening up the lateral side and the lateral soft tissue envelope. That can paradoxically make your patella instability worse. So again, I like to go on the medial side, close down, and then I'm right there to do my NPFL reconstruction. Give me a percentage of how many cases you put a hinge pin in prophylactically. Can you see that I'm percentage-wise? Currently, zero. I don't do it. It's an option there. It's there for you. I worry that if you put it in and you open it up, that when you take the pin out, basically all the stress is suddenly go. So that's a nice FEA study if anybody's interested in doing it, but. Give me your, I agree. Give me your thresholds when you lose the hinge, when you go and do an opposite-sided plate, staple, or anything. If I have, you know, the key with any hinge fractures, you'll often see propagation. You'll often see propagation on your fluoroscopy. And I think as long as you take your hardware out and have a look, and if there's no translation, then generally you've got a stable hinge. If you do medial closing wedge distal femoral osteotomies, you know your tension side is on the lateral side when you're walking. If you get an unstable hinge on the lateral side, it's a disaster. So if I see that, 100% get a staple just to help me sleep at night. Cool. Any questions? Thanks, Al. Thank you.

osteotomy procedures

knee alignment correction

deformity analysis

surgical approach

hinge management