Dr. Bertrand Kaper shares tips and tricks when performing robotic-assisted UKA procedures.
Excellent. So uh we're gonna transition to the next talk. Uh moving from perhaps theory to practice uh when it comes to our union needs. Thank you for uh the two previous speakers, excellent presentations. And I'm gonna try to dovetail my talk uh from the tips and tricks standpoint uh for you. So, uh from a preoperative planning standpoint, patient selection uh is important, needless to say, um we have to have inclusion and exclusion criteria when it comes to our partial knees. Uh I think that's been well established. So I'm just gonna hit some of the highlights in terms of what I call choosing your patients wisely. Um I have a B M I cut off of 32 in my practice for my uni knees. But having said that um a patient who um is six ft seven and weighs £300 might still have a B M I less than 32 but that might not be your optimal, you need candidate. So, a weight and A B M I cut off is appropriate. Uh I do mandate that we have an intact AC L uh despite what the Oxford uh literature might suggest if you have fixed uh deformities, whether excessive er, or excessive valgus, uh that needs to be taken into consideration because this is not an operation that involves soft tissue releases as we'll also talk about. And then also understanding what our patient expectations are, what kind of demands that they're gonna be putting on their new knee, whether that's a unit or a total. So, uh choosing your implants wisely, I think uh is uh goes dovetails into our patient selection. My, my journey, so to speak in the uni world. I started with the M G back in the nineties, went to preservation and more recently to the journey uni uh we added robotics with May go about 10 years ago and then transitioned to the NAVIO system and now the core system which I use with the journey uni implant. So I've been kind of through a a different uh shifting landscape, so to speak, like many of us have uh when it comes to actually bringing the patient to the operating room from a surgical technique standpoint and approach. I use a mbas approach on the for the media unis and a standard to lateral pair Patel arthrotomy for the lateral uni knee. Uh I would caution uh the listeners not to try to do a mini approach on the lateral side. It's much harder to sub lux your Patel if you're doing it that way. If you get up into the quad tenant for a couple centimeters, your, your Patel and mobilization is dramatically improved. Um preoperative planning. Uh We'll talk about alignment and soft tissue management here. Um So this is not um a neutral alignment uh procedure. Uh There's much more talk in our community, of course about uh which alignment philosophy do we follow when it comes to our total knees. But really in the uni uh knee world, uh we're using the physiological alignment uh theory and what I say and teaches maintain limb concavity, meaning a knee that starts embarrass, finishes, embarrassing, that starts in August finishes in a uh you don't want to overcorrect these. You really don't even want to go to neutral. Uh The only way that happens, excuse me is if we are doing soft tissue releases, and again, this is not an operation that has soft tissue releases as part of that. Um So from the technique standpoint, a couple of retractors and instruments that I use, I use the short 90 placed in INCHCO or notch to help someone tell. And I use a self retaining gel type retractor uh especially in the robotic world where you need a sight line from your sensor uh to the sensors to the camera. You can't have an assistant on the opposite side of the table. The Gelpi takes the place of the uh assistant um from a surgical technique standpoint, I'm not gonna read the whole slide here. Um But uh you know, every point along the line of course is important. The ones I've highlighted in orange are just some uh tips I think will help you that when you're doing your exposure, you mark your tide mark. So you already know where that is. Um when you're doing your data collection and surgical decision making and you want to identify the tibial spine, this helps with your component positioning and sizing quite significantly. Um I mentioned the management of the collateral ligaments. Uh I would caution again against doing any type of release. Most of us will be doing primarily media units. Do not release any part of the D MC L. Uh Your risk of over correction significantly increases. If you do that, then you'll be back either putting a lateral union in uh or converting to a total in a, in a time frame that you don't want to be doing uh from the technique standpoint of instrumentation. Again, I mentioned I've been using robotics now for the past 10 years. Um But I, since we had an excellent coy talk already, I'm gonna actually shift backwards a little bit. Also understanding that a majority of our colleagues are still using standard instrumentation um to help facilitate that technique. So we'll talk about bone preparation first. Um Tibby is done first femur second in this uh in the workflow. The, this is the schematic from the uh product uh literature from Smith and nephew. So we're gonna just highlight a couple of the uh specific steps that I think merit some uh 10 when I secure my tibial cutting jig, um I only use one pin and I maintain the down rod uh secured at the ankle. I don't use the pin that's more uh towards the concave side of the deformity. Uh You'll reduce the risk of para prosthetic fracture if you don't put that second pin in. Uh When I start the cut, I use the stale saw and actually start it on the top of the tibial spine. Uh This is gonna allow you maximal M L uh exposure to get optimal um coverage of your tibi, osteotomy. We make the horizontal cut second. And then what I do is use two uh straight osteo toes at a 90 degree angle to one another, one down the sale cut, one down the, the horizontal cut and then make sure that there's a little bit of bone at the back corner that we are not gonna fracture that out. Uh We gently tap it back and, and then are able to remove the uh tibial plateau without difficulty. Use a rast to create a 90° angle again so that there's not bone debris uh or um can sells bone that will prevent you from positioning and getting maximal bone coverage. Um If you are between si sizes, uh the advice would be to downsize so that you don't have soft tissue uh irritation uh from oversizing. Um the when it comes to assessing soft tissue bound, you use the shims for flexion extension balancing. Uh And that will also determine uh which trial uh insert you put on the base of your uh thermal cutting block. I tend to use the 6.5 block uh rather than the 4.5 block. And then I set my osteotomy using the tide mark that I marked at the time of my exposure. Um And that will some will allow you to adjust your femoral flexion angle, uh one or two degrees, which is sometimes helpful. Um Depending on the, if uh also if the patient has a flexion deformity, uh we size the femur and then set the cutting block on the, on the distal thermal cut. But before you pin it, put a little chim or you can even use the seven millimeter flexion extension block so that it's the rotation of the thermal component is set based on your tibial cut. You don't have the visualization of the T E A or the PC A. So you need to make sure that your thermal rotation is appropriate. And the best way to do that is that is this with this technique? Um Before you uh drill the post, excuse me, post holes, verify that your, your thermal cutting jig is in the appropriate media to lateral position. And if you're gonna err on one side, push the that block and therefore your component slightly into the notch, there's less chance of edge loading um and overloading on the uh concave deformity side of the of the uh tibial component. Um There are occasionally still some post osteophytes that you need to get after as well. Some an inter collar osteophytes underneath the PC L. So I use a little pituitary retractor to pull those out, uh minimizing impingement and maximizing range of motion. And then finally, just to talk a little bit on some tips uh when using the robotic platform, the core platform. Now, um this system obviously gives us the ability to collect soft tissue data, not just at the static uh 0 90 degree uh poses but actually the full arc of motion. So I use a PC L Homan which matches up nicely to the convexity of the media, the condi um or the later thermo condal um and then take the knee through a cycle using the lever arm or the PC L. And that really helps you distract the soft tissues uh which is difficult to do manually beyond about 30 to 40 degrees. As I think most of us have uh will acknowledge when I'm looking for soft tissue laxity goals. Um It's 1 to 2 on the media side, 2 to 3 on the lateral side. And the nice thing about the core is that allows us to quantify this um when we have our trials and final component in and that helps with the uh assessment and determination of the final poly alene thickness. So again, I mentioned uh if you're gonna er on on positioning of the thermal component, move it into the notch. Same goes for the tibial component. You want to be as in as far away from the, the joint margin as you can. Um not to the point where you, you're starting to get uncovering of the component in the notch. But uh this uh help does help with where your contact point is on your tibial base play. And again, you want to optimize uh tibial sizing. So as the arrow and the star indicate, start your, your vertical osteon at the tip of the tibial spine. And that way you're not gonna have a mismatch between your M L uh dimension and your A P dimension. When it comes to sizing of your tibial component, the uh default on the quarry uh is, is a fairly, in my, at least my opinion, uh a deeper cut than I want to use. Um So I raise the tibial cut up one or 2 mm recognize that it's always easier to take a little extra bone or use a thinner piece of polyethylene. When it comes to the preparation, I actually will use the burr and make that vertical cut first and then come back and do my horizontal portion. Uh You get into the softer sub uh subchondral bone in the burring, it's easier from a technique standpoint. And when it comes to sizing of the femur. Again, you can put your trial in see where that transition is to the native cartilage at the interior aspect and make sure that it's not oversized. Uh And if you need to, uh the nice thing about the system is that you can downsize the thermal component to minimize that potential patella impingement. Um Make sure there are no residual osteophytes at the base of the AC L from chronic impingement. Uh And that'll help uh restore full extension for you when it comes to the actual component implantation. A little trick is to take a rate type sponge here, uh pack it into the back of the knee. Uh So that when you do uh place the cement, it actually will clear the cement from the back of the prosthesis in the back of the tibia and prevent from uh the cement from falling uh postea where it's very difficult to visualize. Um just some tips in terms of what a leg position I do when I'm implanting my uh tibial and thermal components. Uh the figure four position if you're doing a lateral, uh uni is very helpful uh to give you a little bit better access. And when it comes to the cement itself, I use a higher uh viscosity cement, uh keep it in its running state and basically just place it on the anterior lip of the, of the tibial osteotomy, let it run down the hill. Uh manually interdigitate it, dry it, uh and then place a thin layer on my components which I uh keep in one of the plastic boxes. I don't put it on the uh mayo stand back table. Uh In order not to let the components get contaminated with any uh thing that may have contaminated your uh trays and et cetera. And then hopefully, these are the type of x-rays that you'll see on a consistent basis when you're done. And that will lead to um maximizing our patient reported outcomes and uh and our own personal satisfaction in terms of how we did with our surgical techniques. So I hope uh this was helpful in terms of uh providing uh perhaps one or two trips, tips and tricks that you can incorporate into your next uni need. Thank you very much.