Learning to use a modern surgical navigation system improves efficiency, accuracy and care quality, says orthopedic surgeon and spine specialist Shane Burch, MD. Offering tips from his own experience in both complex and minimally invasive procedures, he explains navigation’s benefits – which include reducing radiation exposure, highlighting individual anatomy and supporting tasks such as screw placement – as well as how to avoid common user errors.
Thanks. Thanks Lionel thanks to um Kyle and and leave for inviting me. Um. Great chorus. So we're gonna talk about navigation and uh do a brief overview of navigation, the applications of it interior and post early and then some tips and tricks that I've learned over the years. Um And navigation really kind of fits into this overarching um computer assisted surgery paradigm. And really what we're trying to do is improve the accuracy of surgical technique and we can kind of break it out into, you know, ease of the surgery for the surgeon and obviously benefit to the patient. And ultimately we want to improve the outcomes and quality of care and decrease the cost of care. And I think navigation does is a tool that that allows us to do that. But it's amazing how this is still very low hanging fruit and there's still a huge segment of the of the sector that doesn't actually embrace this. Um And you know, one of the things that I've learned um about navigation is that, you know, it's a tool, it's not just a machine to turn it on and it does something for you. It's a tool. And like any tool, whether it's a lengthy probe or screw, you have to learn how to use that tool and you have to know how that tool um responds in your hands. And the number one thing that I like about navigation is that it's predictable. So none of the papers really tell us um you know that we talked about accuracy of medical screw placement for example. But there isn't any paper that says, how long or how many times did it um that it took you to get that screw into the pentacle. So once, twice, three times. Whereas with navigation, I think you can hit the medical um predictably on the first shot. And navigation really uh is about obtaining registration and maintaining registration. And if you can obtain and maintain registration, that's kind of the that that encapsulates the the the the the technique. So um again, the predictability. Nobody likes to get punched in the face and we've all been there and it's a bad day in the operating room when we get punched in the face. Um And I think navigation can prevent us uh from from getting punched in the face. So why do I use navigation apart from the predictability? Well, if the anatomies challenging, then for me it becomes very efficient, it's accurate. And again, it's predictable. We heard earlier about how it's important to have improved medical fill. And so at the time you can look at the pentacle because you have that cross sectional imaging and you can say how big should the screw B we can improve our construct. So we can um, you know, easily do four constructs. S ai screws. Um things like that for minimally invasive surgery. Guide wireless perks crews are very easy to do. So you drop a projection. You actually don't need a guide wire. It makes the procedure safer for the surgeon. We avoid radiation and I'm going to talk a little bit about osteo to me planning and precision medicine um and customer implants. And then this is kind of off label but you can actually uh M. R. Emerge. Um the CT scan onto an M. R. I. And actually navigate off of an M. R. I. Inter operatively. So in my hands if I just tried to freehand this, it would be a very long day. But if you learn how to use navigation, this case becomes as simple as a as a degenerative case because you can identify the bony landmarks and you can um appropriately place the screws and have good medical screws. So the point here is that you don't start with this case. You start with an easy case. And when you learn how to use the easy cases, this case becomes actually easy and if you think well, you know, I don't use image guidance. Um I think I would push back a little bit and say it's we're really kind of in an evolution whether you use an X ray to make sure your your screws are fine or whether use fluoroscope to make sure your screws are fine. It's all image guidance and it's time to evolve. So what is what is sort of the the the essence of of navigation. And it's really about as I said obtaining and maintaining registration and when this first registration first came out it was about putting a a frame onto somebody's anatomy, bolting it to their head and registering and and then you can navigate off that frame. And but we've actually, you know evolved in a frame less registration. And you have to think about aligning three different spaces. The physical space, the image space and the tracker space. And that alignment is what registration is. And there's a transformation, mathematical transformation that occurs in these systems that allows us to align these uh these coordinates. So you have the image coordinates. Um you have the physical space coordinates. And that could be uh whether you're talking about a robotic arm or whether you're talking about uh sort of an optic system. It's the same thing. And then you have either a mark, earless registration thing, which is like surface registration or whether you're going to mount a tracker to the patient. And that's a marker based para point registration. And then as I said, there's this other class which is image to image registration, which I'll touch on briefly. So how does it work interactively. Um there's the the the camera system that looks at the financials on the on the image system. It also looks at the tracker. And so we now have the image space and we have the patient space and then there's a transformation and there's a rotational and a linear translation. That's in this transformation algorithm. But inherent in any system. No, no system is perfect. So there's gonna be a localization errors. So in other words, the optics are never gonna be perfect, right? We can't invent a system that's perfect. So there's gonna be some era there there's gonna be some registration error. In other words, when you do a scan and the and the scan kind of moves up and down, there's gonna be some scan distortion. So you're gonna get an error there. And then when you're moving a track around in space, there's gonna be a little bit of error there that's inherent in any system. And you have to know what that error is in the system. And essentially it's small, it's, you know, between a half a millimeter and two millimeters, depending on the system, you have to know that there's gonna be some error. But where the errors come in, it's us, it's the surgeons, it's the people who are using the tool that don't know how to use the tool. And there's eight common errors that we make patient positioning, but the two big ones um which kind of lead to these bigger errors are really line of sight. So where you put the reference frame and reference frame stability. So if you kind of put it in and don't sink it very well and it's an osteo product bone and the frame moves. You're gonna bump the frame, the frame is gonna go off. The registration process goes off and then guess who gets blamed Not the surgeon, the system gets blamed. But it's actually the surgeon. So I think we have to own the fact that when we're using navigation, we actually have to understand these common extrinsic errors or the surgeon errors when we're doing it. Um So what about surgical and imaging workflow? Well, there's all kinds of different tools and based on the tools that you're using, it kind of changes your work flow a little bit. Um There's, you know, drill guides, drills, taps, osteo Tums, um dis prepped sets which are great and then um cage, you know, cages. But one of the big things when you're using a system and this is something that's not talked about a lot either with robotics or navigation is the burden of technology in the operating room. And when we bring in these big sort of sophisticated uh systems and equipment, we can't run at all. Like you can't be like concentrating on the surgery and trying to run that system. So you have to you have to have a co pilot, you have to build a team that team has to be there all the time and you have to get good at it. And when you build a team then it's it's smooth sailing. So here's some examples of why, you know, it's like it's hard to it's hard to prove this, but just looking at it, you can see that cross sectional image allows you to put that pedestal screw in the first time ideally every time. And um you know doing S Ai screws. Makes S. Ai screws date easy. This is kind of dropping a projection down so you can kind of follow um You know that the pathway uh dr theologians and I published on cervical um pentacle screws. And as these tools become more refined, the accuracy uh in this uh in the navigation realm becomes more and more accurate. So we published on sub axial cervical medical screws a few years ago um and had a very high high accuracy and success rate. But you don't just necessarily have to use a navigation for putting in screws. You can use it to look around at the anatomy and say oh is that frame and tight. Um Couldn't use a little bit more decompression. You can put in cages as an example of uplift cage, bilateral cliff cage. Then dien chau and I kind of published on our anterior experience um using uh answer to the sos technique and have 95% accuracy rate of placing screws. Now again when you're dealing with this simple degenerative spine, it's easy to do. But once you start to have really rotational deformity and you're trying to fit that Cajun direct lateral in something that's rotated 30 or 40 degrees. Navigation becomes pretty sweet but it becomes it's as easy as doing it um in a in a straight spine. Uh If you learn how to use the technique, this is kind of the the surface uh merged um are um uh M. R. Two C. T. Merge that we can do again off label but we have the arms, can we have the M. R. I. Scan and Jason stroh who's in the back of the room there uh you know kind of taught me how to do this and we kind of match the match the bony anatomy to the EMR anatomy. And then now you can actually navigate a tumor. And I've used this technique finding some very very difficult tumors buried kind of under iliac vessels and things like that. And it's been a real game changer. So again it's it's allowed me to not get punched in the face um during certain procedures. Well what about M. I. S. Again um straightforward. This is the this is kind of the picture that we all want. We want to cross sectional image. We know where everything is depth and alignment. Again dropping a projection and being able to uh to reproduce that. So I'm gonna talk a little bit about osteo autumn ease And this is kind of uh you know getting into you know where to go from theoretical. We have all this machine machine learning and predictive analytics. Now we have a theory about how are osteo to me should go. But at this on the other hand we have to actually get our technique to be precise. And again I think this is where navigation can really um can help. So dr Metz and I published this paper back in 2000 and eight where we actually did a complex case used the mimics software for materialize and um osteo itemized this this this patient and proved that we could use navigation to um to plan out complex um uh procedures. Um This we published this as a case report in in in spine. But here's an example of I think um more of a routine use in a medical subtraction osteo to me. And again we have these uh these these algorithms now that are becoming more and more robust, that kind of predict what we need to do for a patient, whether that's uh distribution between 4 to 1 or trying to prevent a proximal junction infosys through reciprocal chi infosys. We get these plans. And now if we have this like sophisticated plan, we should have a technique that allows us to accurately reproduce that plan uh in the in the uh in the operating room. So here's a patient who's got um some some saddle mal alignment. I wanted to do a pentacle uh subtraction osteo to me And I used the stealth navigation system to drop the wedge that I had pre calculated onto the the patient's anatomy at the time of surgery. And that allows me to determine exactly where my cuts are going to be. So in that case I or in this case I had predicted um that we needed 20° of Um correction. I dropped the 20° wedge. And now all I have to do is use a tool to cut that 20° out of the out of the spine and you know, things working in parallel. So this is the my sonics. And now we have a tool that allows me to cut the spine very, very accurately. And the image on the, on the left there just shows that I haven't actually cut All the bone away to get to that 20° wedge and I still have some more work to do. And then a pedestal subtraction, Osteo to me becomes like cut by numbers. We just know where the cuts are. That's the wedge kind of looking from a dorsal eventual view and I know where it's going to be. Um we can harvest a lot of bone with that, you know, with the my sonics and removing the wedge and reproducible. E um get that 20° correction. So I think this is just an example of how we can use navigation, not only just for putting in screws but also for osteo autumn ease and hopefully that will translate into improved improved outcomes. There are limitations to navigation. Uh I've talked about the intrinsic errors, the extrinsic errors which are the things that we all need to think about every time we use it segmental motion where if the spine moves when we're, when we're actually navigating it requires an additional scan and that's a technological thing that needs to be solved or improved upon as time goes on. And then when you're, when you're embracing navigation, there are workflow changes. And again, you need a co pilot in the operating room and a team that that knows how to run this stuff. You can't just do it all on yourself on your own. So again, build a consistent team. Um, I think in at least in my hands, um, I've enjoyed the reduction in radiation and the improved accuracy and predictability, both using navigation and your and post really. Um, and again, it's a tool and I think this is a tool that will augment the skills of any surgeon, but you have to learn how to use it. Thanks. Mm hmm.
