Dr. Malhotra from the University of Pennsylvania is going to speak on navigation evolution and combinatorial strategies. Thank you for the opportunity to speak today. As navigation involved in my practice and in others, I think mostly we start with screws and that's really where the value is, placing screws in the operating room. I'm going to talk a little bit today about what you heard on both talks about using navigation for things other than screws, particularly in doing osteotomies. I have no pertinent disclosures. You could view these techniques as off-label. I'm not endorsing any of these techniques. It just illustrates what I'm doing. I have unrelated grant funding, nothing from any of the companies. So I'm going to use an index case to sort of talk about how these techniques have evolved for me and focusing specifically on cases of unblocked resection of different types of tumors. Just very briefly, speaking about chordoma or sarcoma, if you look at the data, there's clear advantage of surgical treatment over non-surgical treatment. If we can treat with negative margins or provide unblocked resections, patients do better than with positive margins. And so the language I'll be using is focused on the far right, wide or unblocked resections. Anything short of that is intralesional. Any time you cross the tumor boundary, you've put the patient fully into that category. And sort of what drives my interest in this, this is a patient with a chordoma that I treated, ultimately with a pretty reasonable resection, but of course not unblocked. It's at the skull base. Can't give these patients unblocked resections. At one year, the patient was found to have a one-year post-op despite getting proton therapy and a reasonable resection. At one year, had this recurrence in the neck, had to take the VRT, resect and reconstruct that. At three years, the patient has a drop mat here. So he's still working. We're at five or six years out now. He's still working, has a reasonable quality of life, but he's had to undergo three major interventions. So in the spine, if we can treat with unblocked interventions, there's an advantage to that. So here you see a patient with a lesion. This was discovered incidentally after a car accident. You see the bone defect in C2. And on MRI, if you're going to tackle this, I highly urge sort of a guarded biopsy or a stylet-based biopsy so you don't contaminate the tissue, but you have a diagnosis rather than putting a patient through a major surgery before you know whether it's positive or not. So this is a lesion that historically in our institution, about 15 years ago, we would have treated transoral purely intralesional. We would scoop it out. But if we can move this lesion sort of from that skull base type lesion of intralesional to unblocked, we give an advantage to the patient. Again, when I started, we used to treat patients this way with big resections that were challenging to recover from and somewhat disfiguring for the patient. When the University of Pennsylvania added a proton accelerator, despite the small figure on the bottom right that said that surgical treatment was better, patients, when given all the facts, would opt for, when they look at this, would opt for protons only and no surgical intervention. So slowly we've gone from intralesional grosser sections to developing our endoscopic approaches to intralesional, which is still intralesional but less destructive, to moving towards unblocked. And this is through big multidisciplinary groups, lots of people involved. I'll talk briefly about how to achieve this. So for us, there were a lot of learning curves. Obviously, learning the endoscopic approaches, developing better stabilization approaches, and most pertinent in today's talk, the osteotomy. So for odontoid fractures, we started navigating these, developing the techniques, getting very comfortable with how to attack this location with navigation. And so you can see, you know, deploying the screw. And now, so for C1-2 fusions, I almost never navigate anymore after sort of getting very comfortable with it. But for odontoid screws, I actually always navigate with, if you look at the bottom left, with intraoperative imaging. And you can just see screw deployment there. So now to focus a little bit on the osteotomy. So the osteotomy approach, the critical factors are the tools. So on the far left, the Midas Rex drill is essentially, you know, if there was one thing I could have on a desert island, it would be that. As you move to the right, you know, if you're performing osteotomies and you're doing it with an osteotome, it's unlikely that you're going to let a fellow or resident use that because it's such a high-risk maneuver. Whereas as you move further right, using ultrasonic bone-cutting devices, you can navigate these and potentially attack these tumors in a more effective way and reduce your transgression of the tumor. So here you see the way that we do this. This is application of the stealth fighter to the tool that you're using. A lot of people don't even use these trays. This gives you the chance to navigate basically any instrument. So case by case, we tinker with what we want to navigate, what we want to attach this to, and we've tried this on a variety of things, including metal osteotomes, but there's just too much movement. So you can see the process on the bottom right of selecting and connecting that instrument to the system. So in this case, we're using an ultrasonic bone cutter. And then it's easy to attach and then register, and then you can see the type of imaging that you get. This allows you to plan your cuts around this particular tumor, which won't require spinal reconstruction. So we're using navigation without use of screws purely for resection of a lesion, and you see that you can get a nice on-block resection of this type of lesion, cutting both the ribs and the medial pedicle and lateral vertebral body. So the way that this evolved for us, we thought of it as sort of wide-channel osteotomies and narrow-channel. Wide-channel being, I can see everything, I can make all my decisions anatomically, and narrow-channel being a more restricted field. So here's a wide-channel case. So you see the large, so this patient was initially thought to just have degenerative scoliosis, and then imaging workup demonstrated this lesion. And so you see, this is something that has high potential to be resected on-block because of the location of it, although there are some challenges. So here on the first portion of the case, we apply our instrumentation, but you can see on the bottom left, the second end, you can see that yellow cut, that's the osteotomy we've made. You can actually see the cut itself on that scan, the post-instrumentation scan. So I call that wide-channel because it's at a level where I can get around the fecal sac safely, I can see everything that I'm doing. Navigation helps dramatically in making sure that I can make the cut appropriately, but you heard me ask earlier about fusion, and being able to fuse the MRI with the CT scan with the intraoperative arm, which is something we can't do right now in our setup, and that's been frustrating. And here you can see the osteotomies. So there's the tumor, you can see the osteotomy that you've placed from the back, no tumor manipulation from the back, just making your cut, and then you can see the resection as we reflect the aorta, you'll see now the on-block tumor has been rolled out with the vertebral body, and you'll see the cut down, and you'll see the fecal sac in the bottom corner. So the osteotomy permits that. So that's sort of a wide-channel osteotomy, you can see what you're doing, but it gives you the advantage of navigated osteotomies. So then we want to move to sort of a narrow-channel approach, so what about when we can't see so well, so where navigation really helps. So we wouldn't want to tackle it, so this is a patient with a chondrosarcoma, we wouldn't want to tackle this with osteotomes, we want to maximize our chances at an on-block resection. So this is quite a challenging lesion, and will require an extensive reconstruction, where our years of experience with navigation will certainly help with the reconstruction, but we want to use navigation to make our osteotomies. And so you can see here, we're going to have to come around the fecal sac, of course, which you can retract here, but your visualization will be far more limited than on the prior case. On the upper left, upper right, and lower left, you can see the osteotomies placed using that navigated ultrasonic osteotomy device that I demonstrated earlier. So you can make all of your cuts, put in your instrumentation, and then roll out the lesion. I make it sound like it's a ten-minute procedure, but it takes a little longer. And then here, this is the reconstruction with the vascular isofibular grafts. So now we move back to the index patient, so we want to use, in this case, we're using a robotic approach to initiate our resection, but the osteotomies are performed the same way. So we developed a transoral corridor. Fortunately, ENTs are really interested in doing this kind of work, so it's not the neurosurgeons here aren't shouldering this alone. These guys developed these transoral robotic approaches that make all this possible, and we partnered with them rather than having to carry it all on our own. So you can see the same patient, the index patient I talked about at the beginning that we would have never tackled at that time point, but after our experience with narrow channel and wide channel osteotomies, we feel like this is something we can tackle. And here you see a brief video. The lesion, again, is demonstrated in C2, and you'll see on the MRI, it extends through the posterior wall. So this was something that, as I said, historically would have been a transoral intralesional approach. We discussed this case and thought that we could actually, we had the corridors necessary to do an on-block resection, and obviously discussed it with the patient after biopsy. You see the osteotomies there, and later in the video, there will be a little bit more clear. So that's the posterior instrumentation applied. The sucker is in the osteotomy. You can see the osteotomies there, left and right, so you can see how we'll be able to roll out C2. And then this is the transoral robotic approach, which I'm not going to talk much about today, but it's been an interesting development in what it permits us to do. And sort of as you work out to the right now, you can see the osteotomies we placed from the back. So no navigation in the front, but you know anatomically exactly where you are, because once you see those osteotomies, you know exactly, anatomically, what the location of the tumor is. And so we'll extend that resection out, and I think... And then roll out C2 and the tumor embedded within it. So this gives us an on-block resection, which gives us the opportunity to give this patient potentially a cure. The patient is two years out and was back at work. It's six months, I think, post-op. Thank you. what's the learning curve? The trans oral case? So that's what I try to get at with this talk is focusing on the osteotomy components of the learning curve. So, and I didn't, you know, this is a very short talk and I actually said it, I didn't say it at the beginning, I said, look, I ultra compress things to get this in. So quite honestly, the way that it really, it was a progressive course, I did things that were a bit time wasteful in the OR at times to develop the skill set. So for example, I'm quite facile with an osteotome for a T-lift, for a wiltsy approach T-lift, right? I can do that quickly and efficiently. What I started doing was navigating the osteotomy for that and doing, using the ultrasonic device. So I was doing those for a while, setting up the navigation on those, doing those for an MIS approach, getting more comfortable with it, putting the cage into that space and then working up where I could see everything using it that way. So it is, frankly the learning curve is not that steep. This stuff is reasonably easy to do, you know, our first speaker talked about once you sort of know the steps, the big concern is you don't want to tackle the case having no alternative option and getting stuck, right? So that's why I like it for the T-lifts because I have tons of alternatives, right? So I can tinker with it, make sure the instrumentation, the ultrasonic cutting works and go from there. Does that make sense? Thanks. So that's a da Vinci, yeah. So that is, again I can't emphasize how fortunate we are that our ENT colleagues invented the trans oral approach. They built the equipment, they worked with the da Vinci folks. So the tours, they're using it for neck tumors and then I said, well, why can't we use it for the spine as well? So we've sort of worked together on that. Yeah, so interesting, closure, we, so again I didn't touch on it, we have about four papers on this, just closure and managing the trans oral healing. So there appears to be less tissue manipulation because we do the closure robotically. So the exposure is robotic, the closure is robotic. That being said, the patient I described had a wound dehiscence at, you know, seven days post-op. We opened up, just put one stitch in and it healed great and he did great from there. But it's still a very challenging corridor. Thank you. Thanks, Neil.

navigation

osteotomies

unblocked resections

ultrasonic bone-cutting devices

transoral robotic approaches