Chapters Transcript Video Planning a Revision TKA Using LEGION™ RK System Dr. Jaime Carvajal delivers an in-depth overview of the LEGION? Revision Knee System. Hello. Uh This is Jaime Carbajal. I'm coming to you from Miami at the Department of Orthopedics at the University of Miami. I want to give a thanks to uh Smith and nephew for allowing me to share the material with you. I hope it's very helpful. And let's start uh talking about legion uh revision system and what you need to know when you're thinking about doing the coy and using the revision system. So, one of the things about uh the revision system that you need to know is that it is usually the same A P box uh cuts uh from the CR to the PS, from the PS to the revision and to the revision to the Hinch. That's something that remains constant and that allows us to give freedom to move from, from those different inputs. Um going from the revision to the Hinch is only three additional stray uh steps and that actually is gonna help you um doing a quick change from revision to Hinch if needed. One thing that you need to know though is that there's a bailout uh with a primary implants. And one of the things is when you have a PS, you can us usually use a PS constraint liner on a primary PS thermal component because the box is the same size as the regular PS box. So that's something that you can use. If you have some instability. When you're um uh doing a primary knee or vision knee, and you're using a, a primary thermal component, you can usually use a constraint liner as well. Um Because of that reason, the other thing that is useful is if you have uh the need to use augments on the femur, including this augments or posterior augments, you can use a uh that in a primary thermal component. So those are little things or bailouts that you can use in um using primary feral components. Now, as we all know, revisions are very important in fixation in revisions. Uh is very important and we have to think about the three zones like zone one being the joint surface and the bone in uh metal interface join uh zone two, which will be the meta area and uh zone three, which is the diaphysis. And with the legion system, we have the option of using uh grade fixation in those three areas. Let's start talking about zone one. So the bone implant interface. So it's important to know the implants and know how uh they fit the bone and what the the measurements are. So all the components of the thermal components have the same distal width. So it's 9.5 except for the seven and eights, those uh become 11.5 as you can see in the screen. Um the distal, the posterior cut is always the same is 9.5 millimeters. And that's something that you need to take into consideration. Um One other thing is that the, the taper on the femur is about 18 millimeters. So in order to introduce a revision thermal component into the bone, it has to be 18 millimeters at least. So you can fit this. Um and uh there is a six degree uh tilt on the taper on the on the coronal view. Um The distal implant thickness is always the same including in the Hinch uh system which is 9.5 millimeters except for sizes seven and eight. As I said, this is key. Um what's the difference between the TV base plate in a primary setting compared to the revision setting? So in the primary setting, it has a three degrees built-in slope as you can see here. And then the thickness is 2.3 millimeters. When you're thinking about a revision base plate, a revision plate base plate is supposed to have no slope because it has to accommodate for the taper and the stem and the thickness is 5.5. So when you're planning for a revision uh uh surgery, you have to take that into consideration those 3.2 millimeters. Um um in the in the final cut because if you're not, if you don't, then you're just going to overstuff the joint and it's gonna have, you're gonna have difficulties trying to get this name in full extension. So 3.2 millimeters difference between the thickness of the baseplate and important to um try to not use a slope on the TV, base plate as well. Um So we do have augments so we can use TV, augments and thermal augments, you know, have hemi and full stepped augments on the TV. They are all titanium and then you have uh thermal augments on for distal and posterior augmentation. And you can do L witch combinations as well as you can see the numbers in the screen for the Hinch system. As you can see the posterior cut is 19.3 millimeters compared to the A 9.5 that was in the past. Um So this is important because you have to accommodate for that posterior Conal when you're actually creating your um augmentation for the uh uh Hinch uh uh component. Now, the distal thickness is still 9.5 millimeters and the taper still has to be six M already has six degree built in angulation in the coronal set for um the TV base plate. We know it's an asymmetric design that is being done to improve the coverage on the tibia. And uh you know, in uh improve the the surface of the bone that is in contact with the metal, the um medialized paper that is being made anatomically for that uh uh tibial intra modular canal and the screw holes that we can see from the uh surface of the tray for the augments to be used. As I said in the past, it's very important to know that there's no uh a slope on the uh tray. Um So we have to make sure when we're planning for that, we have to take the three degrees off the TV lope and make it zero in order to accommodate for the taper on the stem compared to the primary setting that has uh three degrees. So as you can see in this image, you want to make sure that you're at 90 degrees and completely serious lope. So you can accommodate for the taper. Now, when talking about meta Pix, we do have the option of using uh uh cones and the cones are very important to improve our fixation uh in the meta region. So is minimal instrumentation. Usually you have an ion guided alignment uh tool that you can ask, you know, help for the position of the cone and uh it's pretty uh user friendly um easy to put and improve your uh fixation in the metaphysis. Um It is compatible with both the legion and the Hinch, the revision system and the Hinch system and you can be, it can be used with cement or press feed steps. Um It has some freedom uh uh with the flash of the femur as well as with the um uh TV, um uh base plate and it gives you about 20 degrees on the femur and 25 degrees of the uh degrees of freedom on the TV as well. Um The cones are stick tight, uh pores, Ingrid surface. Uh They're very um adhesive and um it allows definitely to improve fixation. Um They have the largest uh possible inner diameter to allow, you know, bigger stems to uh fit in. Um And they tried the smallest possible outer diameter. So you reduce the amount of bone that you're taking. We actually uh using this type of cones. Uh There are different sizes, you can get uh cones that are short or long. They come by two millimeter increments and they go from 18 to 30. Um and thermal cones go left and right. So it's, it's uh you have to, you know, make sure you're putting it on the right um in the correct uh uh side and then two millimeter increments, it goes from 18 and 30 millimeters um as well. Um It has a greed blasted interior surface, uh which could be easily cemented and that's the, that's the purpose of it. And then the outside uh surface is stick which allows for um bone in growth. Now, let's talk about this, the pix. So there's in the, in, in the lesion revision system, you have all these options including the cemented stems that are um coop premium. You have the press feed stamps in different sizes and even curve stems. Um When using quarry is very important uh to use short cemented stems because the plan that you create with the quarry system, it's based on the uh bone cuts on the TV, on, on the femur. So you don't want the stem to dictate where these uh implants are gonna go. You wanna make sure that you have some freedom and that's when cementing a short stem makes more sense. Um And you do have an, an option of a short stem extension on a, on a primary base plate that is 80 millimeters and it 12 millimeters in diameter for complex primary cases as well. It's very important to know that the length of the stem is not the true length of the stem. So when the box says you have a 1 20 millimeter stem that doesn't see that doesn't mean that the stem is 1 2100 and 20 millimeters of length. It does take into consideration that this subportion of the femur and the taper. So when you're preparing for 1 20 you know that it has to be 1 20 from the uh surface of the uh thermal component, not from the bone surface. Um And same thing happens with the tibia. So the tibial stems 10, take into consideration the uh thickness of the base plate. And for example, a 1 20 millimeter stem. Um It's actually uh 90 it's, it's smaller and that includes the taper as well. So it's 90 millimeters from the surface of the bone to the tip of the stamp. Why is that important? Because when you're planning for a uh revision case and you plan to use short cemented stamps which usually are 1 20 millimeters. You don't have to prepare to 1 20 you have to prepare to 90 from the surface of the ball, maybe a little bit more. So you can get more cement sly, but it is not 1 20 millimeters. And that's very important to keep in mind. And this is just to again, going back to the numbers and saying if you need a 1 20 stem is not really 1 20 on the femur on the va and you have the calculations um there finally, when you're using short cemented stamps, um that allows you to use not all the the stamps available. So for example, if you want to plan for a revision case and you want to reduce the amount of traits that you, you can, you need to use in, in in these cases, you can basically use, use 12 and 14 stamps on the uh uh va and then 14 and 16 stamps on the on the femur. And that takes all these Remmers out that that takes all the weight from those trays to minim minimize the amount of trays that you're using. So remember that you're cementing the canal and you're putting the stem in. So you don't have to actually fill the canal with a big air stem. So that actually minimize and makes things more efficient. Um So in my practice, I usually, you just only use these uh uh red stems or tial stems and green green boxes are the thermal stems and then I don't have to use additional stamps because everything is filled with cement. Um And this concludes my talk. Thank you so much. Published August 1, 2023 Created by
