All right, for sake of time, we'll keep moving forward. Next, we're going to have a video technique demonstration. Dr. Frisch is going to show us varus and valgus correct osteotomy indications and tips and tricks to get these right. Thanks. Yeah, thank you. It's a pleasure to be here. I'm Brett Frisch from Sydney, Australia. And some tips and tricks on HTO. These are my declarations. A successful HTO, you need the right patient. You need it planned well in three dimensions. You need to deliver it accurately. Don't break the hinge. And use rigid fixation. Indications for an osteotomy are essentially anything that you want to shift the load from one part of the knee to another. The commonest indication is the isolated arthrosis, unicompartmental arthrosis in the young active patient, but also chondral or meniscal deficiency in a malaligned or overloaded compartment. Instability, chronic post-lateral corner injuries, or recurrent ACL ruptures with excessive slope, or overload syndromes are all common indications. The contraindications are relative. Essentially, they're factors which indicate more diffuse disease, disease in the target compartment where you're going to shift the load, or excessive load. And those papers represent those well. Planning is key. Precise understanding of the starting and desired final condition, and then intraoperative data that can use to actually deliver that are the key to a great outcome. Classic planning is a long leg x-ray combined with trigonometry, of which there's several techniques. Just remember, these are all two-dimensional techniques, essentially in a single plane. And what you're dealing with in reality is a 3D problem in three planes. So we use a 3D planning system where you can do a virtual type surgery. You can assess the deformity in three planes. You can plan the correction in those three planes. And a good issue to think about is slope. Make sure you understand the slope. Because your pivot point's not directly medial or lateral, you're going to change the slope if you don't know how to plan it properly. Opening wedge HTO has a tendency to increase the slope, because the pivot point's posterolateral. And closing wedge is the opposite, with a tendency to decrease the slope. Of course, you plan it properly, that won't happen. So with an opening wedge osteotomy, if you want to maintain the slope, the gap posteriorly needs to be twice the height of the gap anteriorly, not equal. And then if you want to change the slope, which you can easily do, you need to think in three dimensions and plan that out. So we use an EOS scan combined with a CT. We use a system where the surgeon does the planning, but the software does the calculating. So the surgeon simply selects where they want the weight-bearing axis to be in the coronal plane and similarly what they want the final slope to be. And then it generates the plan. So screw position, plate position, screw depth, some information for your saw for safety, the size of your wedge, et cetera. Translating that into surgery itself, you can simply take the plan and deliver it freehand. Use intraoperative checks if you like. Precision navigation is an excellent tool. Or a combination of accuracy and efficiency is a patient-specific guide, which is what I now use predominantly. Don't break the hinge. The hinge is the mother of HTO complications. You get an intact lateral hinge, you are going to get a good outcome. If you crack it, you might get intraarticular injury, nonunion, implant failure, or loss of correction. How to avoid cracking the hinge? Get it in the right place. The ideal point is the proximal level of the tib-fib joint, about 10 millimetres from the lateral cortex and 15 millimetres below the articular surface. The key point is that you want to be closer to the lateral cortex than you are to the articular surface. You want to sufficiently release the MCL. Multiple papers show that insufficient release of the MCL not only increases your chance of failure of your hinge, but it negates the effect of the osteotomy by overloading the medial compartment. You might change the alignment, but the pressure doesn't improve. So we do an anterior to posterior subperiosteal release, all the way down to the post-remedial corner, and then tee it proximally. The deep MCL remains intact. You have no change in stability, but it gives you great access to the back. And I like to make sure I can get my finger all the way across to the proximal tib-fib joint on the posterior surface of the cortex of the tibia. If you can't get your finger in there, it's insufficiently released. You want to avoid hinge fracture by completing the osteotomy. You want to complete it posteriorly with the osteotome. Similarly, you want to complete the anterior cortex underneath the patella tendon, and then the central aspect of the osteotomy out to the hinge point. I start with a saw, but I complete it with an osteotome. This is the hard part to get to, the very posterolateral corner of the posterior tibia. My technique for making sure I do that is to use my finger as the retractor and feel the edge of the osteotome. Simply place the finger across the back, as described, to the tib-fib joint, insert the osteotome, and you can just, a millimeter or two is all you need to really feel the sharp edge. And as you go from medial to lateral, wiggle it anterior to posterior, just bouncing it off your finger, making sure you've got a clean, complete release of the posterior cortex. Everything's protected behind your finger. You can de-tension the pivot point. So I pass a second wire. The first glide wire is the line of the intended osteotomy. The second wire crosses that at the pivot point. Has two roles. One, it dictates the depth of the osteotomy, but more importantly, it acts as a load-sharing device. It's a pretty extreme example. I will say that's a cadaver where I was trying to crack the lateral cortex, testing out the load-sharing capabilities of that wire, but you can see the wire bends and the cortex is intact. I found that a really useful tool. Finally, the way you open the osteotomy, I think, is important. There's multiple devices. I use a spreader, either a laminar spreader or a broad spreader, and not that wedge-type device. The wedge-type device looks exactly like the blockbuster I was made to split wood with as a kid, or as a stonemason will use to split stone. And because as you insert it in, it not spreads it, it actually puts a distraction force and lifts them apart, and that'll crack the lateral cortex. So I've used a laminar, a broad spreader. I'll put that over to the pivot point after completion of the osteotomy, and as you carefully wind it, it actually hinges on that pivot point and plastically deforms the lateral cortex rather than breaking it. It's not spreading it apart, it's hinging it open. You can then convert that to a low-profile laminar spreader. It's now a pretty flexible osteotomy. Easily open it up to get access. For the last stage of the last tip is that you wanna use solid fixation, a low-profile but strong locking plate, and a cortico-cancellous allograft. It's both osteoconductive and inductive, but the cortical margin gives some structural stability for a very stable construct. So if you choose the right patient, if you think in three dimensions rather than two, if you deliver it accurately, if you don't break the hinge, and you use rigid fixation, you're gonna get an excellent outcome from your osteotomy. Thank you.

osteotomy

indications

planning

hinge

fixation