Chapters Transcript Spinal Fusion: When and How do we Fuse? Course: Comprehensive Spine Course OK. So, I'm gonna go through some of the indications for why we might consider a spine fusion, and then I'll go through some of the techniques. Um, there's a lot of options. Um, so, I'm excited to get through this. OK. So, first note, this is the indications why we might recommend a fusion. So, if you have a lumbar disc herniation, which is gonna cause a lot of back pain and pain down the leg, um, most of the time we think about doing a microdiscectomy. Um, not a fusion, but sometimes we might think about doing a fusion, and that could be if it's a recurrent disc herniation, meaning that a herniation has come back in the same spot, um, a 2nd or a 3rd time, um, or if the location of the herniation makes it challenging to just remove the herniation, um, perhaps it's in the foramen and you'd have to remove a lot of the facet joint, so we might consider a, um, fusion in that case. As Doctor Goldstein was going over, sometimes you can have spinal stenosis, and you might think about doing a, a fusion for that. And, um, a lot of the pain with spinal stenosis, you can get some back achiness, and buttock pain, and then pain radiating down the legs. These symptoms can improve with leaning forwards or, or sitting and resting. And most of the time we think about doing a laminectomy, um, just taking out the, uh, lamina, so, and then the ligamentum flavum, removing some of the pressure on this, um, on the sack of nerves. Um, which you can do for different, uh, uh, through different techniques, either open, minimally invasive with a tube, super minimally invasive with, um, uh, endoscopic techniques that Doctor K Kazarian is gonna go over next, right? That's next? OK, OK. Um, but in some cases, you may need to fuse it, and that's if you have to remove a lot of the stabilizing structures of the spine in order to fully open up the space for the nerve roots. Um, you may consider, uh, doing a fusion and degenerative disc disease. So, you can get wear and tear of the disc spaces over time. Um, the disc heights decrease, you get all these bone spurs, and so the tunnel for the nerves to exit, the neuro foramen, might start to decrease. The pedicles are getting closer together, so the bony structures are getting closer together. And you can get some pinching of the nerves, as well as central stenosis. And it may be the best way to open up that space for the nerves to exit is going to be um restoring that disc height through a fusion. And then spondylolisthesis, that's a, you know, a micro instability in the spine. You can get some back pain, some hamstring tightness, um, some leg pain. Um, due to the shifting forwards of the, uh, vertebral segment, and then you're gonna get tightness on the nerve roots. And, um, sometimes this is due to just degeneration. Um, sometimes this is due to something called a Parge defect, a congenital condition, um, that leads to shifting forwards. And so you might think about doing a fusion for this, if there's a lot of movement, if the alignment is really abnormal, um, or it's really shifting forwards a lot, and you need to res uh bring that back, um, restore the, the slip. Another reason why you might need to consider a fusion, uh, would be degenerative scoliosis. Um, so you may have shifting, rotation, um, uh, curvatures greater than 30 degrees, and this may all contribute to, um, various types of pain in the patient. And if you go in and just do decompression, maybe that's not fully addressing things, or you destabilize further. Um, and so these are, these can be very tricky cases, and we try to avoid big fusions, but sometimes that's really, uh, the best way to address the, the scoliosis and the pain. Um, so I'm gonna go over some fusion techniques and kind of try and give a historical background, and then kind of talk to you, talk to you about what's coming up in the future. Um, so basically fusion used to be where the spine was opened, the, um, bone was decorticated and roughened, and bone graft was placed, and then the wound was closed up, and the patient was placed in a cast. Um, and this kind of came from the idea of getting bone to be your ultimate long term way of holding things together. Over time, this idea of externally stabilizing the spine turned to internal stabilization. So if we put screws and rods, we can internally hold everything together while the new bone forms, the mature fusion forms. Once the mature fusion forms, the instrumentation is kind of secondary, like rebar and concrete, but we don't go back and remove it because bone is a living, um, organism. It can remodel, and so we just leave in the rebar in the concrete. So, this type of surgery is a posterior lateral fusion where you're looking at the spine wide open. You can also get a fusion at the disc space. So you can take the disc out through different techniques, um, put a spacer to hold it open, and put bone graft in the disc space, and you can get the bottom of one vertebral body to fuse and form bone down to the top of another vertebral body. And that's in, um, inner body fusion. There's lots of ways to get to the disc space. It's almost like 360 way of getting to the disc space. You can go directly posterior, and that's called a cliff. You can go from the side, like an angle, not fully from the side, but like kind of like a 15 degree angle, take the facet joint off and put in a spacer, and that's called a T lift or transaminal lumbar in your body fusion. You can go directly from the side, that's an L lift, a lateral lumbar inner body fusion. You can go into the straight through the front called an a lift or anterior lumbar inner body fusion, and then there's the oblique kind of in between a lateral and an a lift, um, and that's called an Olift, an oblique lumbar inner body fusion. Um, so there's lots of ways of getting to the disc space, and the idea is just to stabilize that segment through additional bone growth between the vertebral bodies. Um, when you do, uh, a T-lift, or a pliff, or maybe an L lift or an E lift, all these inner body fusion techniques, you can you may also consider putting in screws and rods to hold everything together. As part of your fusion. Um, and so you can do that open, you can do that through X-ray and small incisions, you can do that robotic assisted, you can do that navigation assisted. So, um, there's lots of ways of putting in the instrumentation, um, but the idea is all stabilization, holding things together while the bone forms. Um. So this is just an example of using the, the robot to plan out where the screws are going to be, and making sure that they're in a good spot. So the nice thing about the robot is you can be really sure that if everything goes smoothly, those screws are gonna end up exactly where you planned them to be. Um, and then you can also find Nuances and differences about the patient that you might not have appreciated, um, if you weren't trying to plan a screw based off of the CT like maybe their pedicles are a little shorter in up, down height, maybe they're a little narrower and side to side width, and you make, make, you know, small adjustments based off of that. Um, and then you can also make adjustments based off of the technique, and so this is just a video showing how um I can scroll through and watch the path of the, the pedicle through, or the screw through the pedicle, and make sure I like it, and it feels safe. Then with the robot, we place these um little fiducial markers, because any sort of navigation and robotic system, it has to, the computer has to understand where the patient is in the room and on the table. So that's what these little fiducial markers, these little reflective balls here do. They kind of show the um the robot where the patient is. And then we do some X-rays and merging, uh, making sure the X-ray looks like the CT and then, um, we start placing the screws. And so this is just a little video. Um, showing all the screws are, uh, reachable by the robot, and you can really see that the robot doesn't do anything except tell us where to place our instruments, and that will get us to putting the pedicles, pedicle screws in the exact spot we want to. And so this is going through checking your anatomy to make sure the merge. Um, the navigation is telling you something that sounds reasonable. So if you go in and try to check your anatomy, and it's saying the right is on the left side and the left is on the right side, you know, there's something not quite right. And then this is the, the steps of the screw placement. So, um, the robotic arm says, I want you to do your work right here. So that's what we do. We just, we just do what the robot tells us to do. No, I'm kidding. Um, so, I, I like to make a little incision, um, to, uh, for placing the screws. Some people will just do a, uh, perk incision, and sometimes I do perks, sometimes I make a longer incision. It's really just based off of, um, My goals of that particular surgery, and sometimes little tiny incisions are just cool. So, um, that's kind of fun. So these, this is the steps, and you can see in real time how long it takes to place, um, a screw using the robot. So this is the step one, this is the burr, um, and then I take the drill. And I'm checking, I keep looking at the screen, A, to watch where my tool is on the screen, so that all makes sense with what I'm feeling, and to make sure that I have um green around the boxes. Green means the robot is still in the same spot, and we're still at at an understanding. Um, and so a lot of this, yes, I'm looking to make sure the technology is working, but I'm also feeling through the end of the instrument. This feels OK, this feels normal. It doesn't, this doesn't feel like I'm drilling into, this feels like I'm drilling into bone, this, or this feels like it kind of went down on some bone and then shifted off. That doesn't feel right. So different things like that. So there's a lot of um tactile, like uh haptic feedback coming through the system. Um, and then, uh, just with experience, trusting and knowing which steps are crucial, like once you've tapped the screw, putting in the screw, as long as you find the right path, then you can kind of go quickly through that, because it's gonna find the prior hole, you know, things like that. Um, and we use, uh, EMG, uh, stem to make sure that there aren't any breaches in the pedicle, so like the screw isn't like touching something it shouldn't. Um, and through electrical stimulation, it should be kind of slow if it goes to your bone. It should take a lot of stimulation to get muscle response. If it doesn't take a lot of stimulation to get some sort of muscle response, then there's probably a breach or an early connection. Um, and, and that helps us provide, helps provide us some sense of safety. Um, so that's just kind of like putting in screws, so you can do your inner body fusion, lots of ways. You can put screws in lots of ways, and that's just one way of putting your screws in, is, is with, um, robotic assisted. Um, and then going in through the front is called an anterior lumbar inner body fusion, and we're, um, what we're one of the centers in the city that do a lot of this, and because we have a lot of expertise in doing the anterior approach, um, And a lot of surgeons who have been doing this a very long time. And it's a really good option. If you have weak bone, like osteoporosis, maybe you want a wider cage, so it sits on the outside of the vertebral body, on the edges, and engages that more cortical ring, and you're not putting an implant in the middle where it's a little more cancelllous and soft. Um, or maybe someone has a really significant deformity, like a shift forwards, that requires a lot of biomechanic strength to bring it back, or someone's, um, sacral slope is pitched down. A lot so that I know gravity is gonna be working against me, so I want something really strong in that area. So, I'm going or I went through the back and it didn't heal properly in the disk space, so now I gotta go in through the front and, and do it better. So these are all reasons why you might want to go in through the front. Um, and you can see that there's some big vessels there, um, and that's why we have, uh, vascular surgeons come and do the approach. They are there for if there's a problem, and this doesn't happen often, but instead of me doing the approach, getting into uh a vessel issue, and then waiting to call for a vascular surgeon, it's safer to just have them there to begin with. Um, so I think it's uh really important that patients kind of understand why, you know, someone's doing the approach. It's for safety. Most of the time that person is superfluous, but when they're needed, they're really needed. Um, and it's also important, I think, for patients to understand kind of what we're doing. I had one patient asked me at his post op, I, I swear, he said, how does my liver look? He said, I don't know, we didn't look at your liver. He's like, Well, you didn't look at it before you put it back in, and I was like, whoa, whoa whoa whoa whoa. What do you think I did? And he's like, you went in, you took everything out. You did your work, and then you put it all back in, and I was like, oh my gosh, and you signed up for that? Like you literally agreed for me to do that? No. Um, so I feel bad when patients don't really understand. Um, but that approach through the front, you kind of move everything to the side. You're just retracting it. You're not taking out. I'm like, oh, I don't need this, don't do that, um, and because you're pushing to the side, you're not in the area where the bowels are, but still the bowels don't like to be bothered, so sometimes they kind of shut down when you go in through the front, so you can get like an ileus and things like that, um. So those are kind of the two issues with going through the front is the possible risk of a vessel injury, and then later they may develop an ileus, which uh anyone who's been nauseous, just imagine that times 10 for a few days and you can understand why that would be terrible. Um, and then you can go in through the side. You approach through the side is. The idea is to have a large spacer or cage in the disc space, but not going through the front. So avoid all that, what I just said. So, yes, you can do that through these small incisions, you can go kind of like through the POS or kind of in front of the POS and retract it, um, and yeah, you can get a really big implant in. The issue with this is that There's the lumbar plexus in the POS. And so we have to do a lot of testing of the nerves in the area just to make sure we're not kind of going through, um, a nerve plexus or anything like that. And there's ways to mitigate it, but this is, the idea is you can put a very large um cage in that, uh, in this approach. Another, uh, advantage for going in through the front and going through the side is curve correction. So, if you have a scoliosis, These large implants that go in and take up the space of the disc, if you shape them right and release right, then you can correct the scoliosis through that way. So there's a lot of advantages. It's just trying to get back to that area safely. And I'm gonna speed through this cause I didn't know you're talking about endoscopic spine surgery later, but it's another way to do fusions, um, and, uh, Doctor Kazarian is gonna go over in depth, but just so you know, you can do that whole posterior approach, taking the Facet off and everything, you can do that through um an endoscopic approach. And so there, you can still take the facet joint off, you can see your nerve roots, you can see your disc space, take the disc out. Do, um, a really good bone, uh, a really good prep of the disc space, cause you can see it directly, and, and then put your cage in. I could just watch this forever. I'd love it. Um, and then you can insert your cage. So uh it's all the same thing you can do through a tube or open, um, it just makes me happy to be able to do it through these tiny little incisions, which, again, incision size is not the end all be all, but it's just kind of cool, and if you really like this technique, then it's kind of neat to see these tiny little incisions, and knowing that I did a whole fusion through that. Um, coming back, so pretty underwater. You can see the capillaries on the fecal sac, um, and then this is what the X-ray, oh, coming up, this is what the X-ray would look like at the completion. Um, and then this is me just showing we can use all the technology in one case. Like, let's get like $5 million worth of tech in the OR and just use it all at the same time. So I can do. An endoscopic approach, uh, endoscopic T lift, navigate it with the robot, make sure I'm in the right spot, make sure I'm across the disc space, take the disc out, and then bring the robot in to, um, drop some screws, and it's like, um, a geek's guide to surgery. OK, so in summary, we talked about the indications for lumbar fusion, which are spondylosthesis or instability, degenerative disc disease, scoliosis, sometimes foraminal disc herniations, um, and then the fusion techniques are the traditional posterolateral fusion, and then an inner body, posterior inner body, um, posterior lumbar inner body fusion, transaminal lumbar inner body fusion. Those two can be open, MIS, endoscopic, anterior inner body fusion, and lateral inner body fusion. Published October 24, 2025 Created by
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