--- title: 'Transforaminal Endoscopic Fusion' type: 'lecture' url: 'https://doc.social/lectures/transforaminal-endoscopic-fusion' published: '2021-07-22' author: 'Dr. Paul Houle' specialty: 'Neurological Surgery' transcript: 'yes' --- # Transforaminal Endoscopic Fusion This lecture features Brown University Professor and neurosurgeon Dr. Albert Telfeian who will discuss the indications and techniques of outpatient, awake endoscopic spinal fusion. ## Summary Welcome to How I Do It. This series explores topics and techniques that will help us advance the field of endoscopic spine surgery. This lecture features Brown University Professor and neurosurgeon Dr. Albert Telfeian who will discuss the indications and techniques of outpatient, awake endoscopic spinal fusion. ## Transcript 3,235 words · 22 min · 3 speakers · automatically transcribed (aws-transcribe) and not checked by a person; it may contain errors, particularly in names, drugs and dosages. The recording is the source. [0:00] Speaker 1: Oh. [0:01] Speaker 2: Hi there, I'm Doctor Paul Hole, and welcome to How I Do It. In this week's episode, we're featuring Doctor Albert Telphian, and he's gonna speak about endoscopic fusion, where, what, how and why. [0:19] Speaker 2: Welcome, Doctor Talfan. How are you today? [0:22] Speaker 1: Great. Good morning, Paul. Thanks for doing this. [0:24] Speaker 2: Well, uh, you had, your last episode was so popular, I needed to have you back and talk about endoscopic Spine fusion, and you've been doing this for quite some time. Uh, that's right. And so you have extensive experience both doing open, uh, minimally invasive and endoscopic. So you have a unique perspective that I'm excited for you to share with us. [0:46] Speaker 2: So why don't you go ahead and uh let's get started with your presentation. [0:51] Speaker 1: So, [0:52] Speaker 1: We're talking about endoscopic Spine fusion and we're talking about the where, the what, the how and the why. The where is the anatomy, the what are the kind of. [1:04] Speaker 1: Implants we're using for an endoscopic T lift. The how is the procedure and the why is the indications. I used to talk about the D's with this, and what that really was was does it fit in through Camden's triangle? Do you get adequate decompression? Can you do an adequate disc prep and does it fuse? [1:30] Speaker 1: And so that first question there, the where or does it fit, is we're really looking at the anatomy of Camden's triangle here. And so the challenge is to get a static or expandable cage in through this narrow corridor. [1:49] Speaker 1: And it's not exactly like it looks on the left. It's more like it looks over here on the right, where we have the facet here. Now, you know, we know from our, you know, MIS T lift procedure that we remove this facet complex so that we can get in through Camden's triangle, so. [2:09] Speaker 1: I was interested in the anatomy for what were really the constraints for getting cages in through Camden's triangle. So I did this paper with Mitch Hardenbrook who had done a cadaver analysis of Camden's triangle. And so what we're looking at here is we were looking [2:33] Speaker 1: 10 cadavers, all the lumbar levels where we remove the facet and in this picture we have the L5-S1 foramen with the facet removed. We have the S1 pedicle, we have the L5 pedicle, we have the L5 exiting root, and we have the S1 traversing root. And what we did in this study is we measured the area of Camden's triangle here. [2:56] Speaker 1: But we also measured the distance from the medial wall of the pedicle to the exiting root and from the lateral wall of the pedicle to the exiting root and really wanted to know what these dimensions were that were constraining us. This is another example of L34, and this is what we described as really the safe zone for getting in a cage. [3:21] Speaker 1: And so you see here what our distances were really and so it was about, if you say conservatively about 17 millimeters and 10 millimeters and I'm just going to go back here. So the 17 millimeters is really if you look at the inferior pedicle, what's the distance between the medial wall of the pedicle here. [3:40] Speaker 1: And the exiting root and that 1 centimeter is the distance between the lateral wall to the exiting root, so you really have about 1.5 millimeters here, but you have much less as you Approach the superior pedicle. The smallest distance we saw here going through the Spine was about 4 millimeters. [4:03] Speaker 2: But going back to that, Albert, the last slide there, um, if you look at that safe zone right there, that defines, you get about a little, little more than 1 centimeter in diameter for, uh, but that's not the entirety because with the techniques that we use when we're doing endoscopic discectomies. [4:21] Speaker 2: We use the tubular retractor as a tool and we can get underneath that traversing root and elevate it slightly so we can actually create a little bit more space medially to get a slightly larger diameter tube in once we've done a bony decompression. Would you agree with that? [4:36] Speaker 1: Well, I think that is an amazing point here is that the constraints and the nuances of an endoscopic fusion are [4:46] Speaker 1: 1, you have to really remove as much of that superior articulating process of the facet as possible to open up the safe zone, and 2. [5:00] Speaker 1: What you're saying is you can expand the safe zone by medially retracting that traversing nerve root. I think you need to think about the exiting nerve root as a rigid construct. You don't want to go in without removing. [5:18] Speaker 1: Facet bone and try to get a cage in by retracting the exiting root because the exiting root is different than traversing root because the exiting root has the DRG and that's where we're going to see patients with chronic dysesthesia from overly manipulating that portion. [5:40] Speaker 1: So the [5:43] Speaker 1: What we're going to talk about the different kinds of implants. So we're going to talk about static and expandable cages. So this is my experience with using the static cage. So here's a patient with a significant L4-5 spondylisthesis and severe spinal stenosis, and this is an example of a titanium. [6:06] Speaker 1: Static cage. It has that nice 3D printed surface, and it's able to toggle on its way in and you can see how this retractor system, it's very similar to an MIS tubular retractor, but the idea here is that you're going to place a small dilating tube between the exiting and traversing roots and then expand it with sequential dilation. And for disc prep this system uses an expandable shaver. [6:37] Speaker 1: And you can see the bullet nose of this cage that you're able to use that also for retraction and distraction. [6:49] Speaker 1: And so here's a post-op film. This is an immediate post-op film from my case where you see you get a nice indirect decompression here which I'm locking down with the screws. This is one year later. This is one, this is one. [7:05] Speaker 1: The thing that's really novel about these 3D printed titanium cages, you look at these films a year later and you really can't, you don't see fusion bone because of the artifact, but it really looks like it's well seated in there. There's no screw loosening and the patient's asymptomatic. [7:25] Speaker 1: So expandable cages. [7:28] Speaker 1: So this is a patient that I followed for 5 years with L4-5 end plate changes, uh, lateral recess stenosis, and really this is at L4-5. He has L4 symptoms. [7:42] Speaker 1: And so what this is an expandable titanium cage where again we're using an expandable shaver system, a curette to be able to scrape the end plates here, and then I'll put in allograft and expand the cage [8:02] Speaker 2: here. I think. Can you go back to that, Albert? I think one of the important points there is that [8:07] Speaker 2: It appears that your tubular retractor is within the disc space, so you're able to move your instruments in and out of the disc space. [8:14] Speaker 2: Knowing that both your traversing and exiting roots are protected, is that correct? [8:19] Speaker 1: That's exactly right. So the way I do this procedure is I do an endoscopic discectomy and foraminotomy, which is directly visualized and I decompress the exiting and traversing nerve roots, and at that point I will switch. In that case, you know, I'm using a 7 millimeter. [8:39] Speaker 1: Um, uh, beveled cannula, and I'll switch it to an 8 millimeter and just put it in about 5 millimeters inside the disc space here. And then at that point, my visualization of the disc space can just be through fluoroscopy, um, while I do this portion of the procedure. [9:00] Speaker 1: And so this is what it looks like. This, this patient is actually awake with sedation, able to communicate to me. I'm using the, I do this prone, I'm using percutaneous screws in the expandable cage. [9:13] Speaker 2: I think that's an important point that shouldn't be overlooked is that you're doing this with the patient awake, so you're sparing them general anesthesia, and it certainly lends itself to an ambulatory Surgery center setting. [9:27] Speaker 1: Yes, this is an Outpatient Surgery, and you'll see that my setup here, it's, I'm using a Mayo stand and over here on the prep table, it will be the pedicle screws that I'll put in. [9:42] Speaker 2: And I also want to point out that you have to wear loops because you can no longer see when you are doing something up close because you're getting older. [9:52] Speaker 1: That's right. I use it for eye protection and then to put in the monochrome stitch at the end. [9:59] Speaker 2: I just, I had to throw that in there. I don't know who's older, me or you, but I know I can't see anything anymore. [10:04] Speaker 1: Well, I'm, I'm certain I'm older. [10:07] Speaker 1: You still look great, but this is, this is what the initial portion of the procedure looks like where I'm doing the endoscopic discectomy where I can directly uh uh visualize the nerves. I'm able to use the drill to do extensive framenotomy here at 3 o'clock. You can see the pedicle here, um, the fat from the foramen, um, and then the uh traversing nerve root going over the pedicle and. [10:33] Speaker 1: Then you see the expandable shavers and the curettes, placing the pedicle screws percutaneously, expanding the cage, and then I'm able to put the scope in at the end of the case, visualize the cage, and make sure that the nerves are well decompressed. [10:49] Speaker 2: And you can also see at that point whether there's any pressure on the nerve root, um, whether or not there is a dural tear, obviously, because that's the, the, the big question that people are going to ask when they see this is how do you avoid getting a dural tear, um, and so, you know, at the end of the case, you're able to directly visualize the neural structures and, and clearly determine whether or not there's been any injury. [11:12] Speaker 1: Yeah, exactly. Here we're able to communicate with the patient whether they have any leg symptoms. We're able to see the exiting, traversing roots well decompressed, and this is just the post-op CT scan that I do in the recovery room before they go home. I'm not doing this with navigation. I'm just doing this with fluoroscopy, so I do a confirmatory scan before they leave. [11:38] Speaker 1: And here is another kind of expandable cage case. Here's a patient. He has post laminectomy, spinal stenosis, and lumbar radicular symptoms and back Pain. He has collapse of his end plates here, and I'll use an expandable bone in a bag, allografted in a bag, and you can see again that point you made about the tubular retractor just being inside the disc here. [12:07] Speaker 1: Um, and this system has a drill, uh, a shaver for the discectomy, um, and you know, the percutaneous pedicle screws. I have, I put the wires in for the pedicle screws before I do the, uh, um. [12:22] Speaker 1: Uh, discectomy, and I do the discectomy. [12:27] Speaker 1: With uh um uh the drill. [12:33] Speaker 1: A wire brushes, paddle shavers, and this is what the post-op CT in the recovery room looks like. I've expanded the end plates here. You can see I've got a nice implant coverage here. This is the implant here on the axial, and this is comparing the pre-op MRI where you see the I have this disc here that I've removed endoscopically, and you see the height between the end plates here, and I've been able to crank this open and really get a good indirect decompression. [13:04] Speaker 2: Now do you ever, uh, you, you obviously have the ability with the endoscope to go in and check the Nplate prep. I know with the Optomesh system they have a little balloon that you can check the end plates, but do you find, uh, any utility in, in directly visualizing the Mplates endoscopically? [13:21] Speaker 1: You know, I, I, I do both. I do use the balloon to see the contours, and before I do my final implant, I do put the scope in and take a look. It's really very satisfying seeing the beautiful end plate preparation. [13:37] Speaker 1: Um, and again this is the post-op CT. You see how nicely open this framing is here on the axial, and on the sagittal you see it even better. I've really cranked open this framing and on the coronal images this is what it looks like. So very. [13:52] Speaker 1: Satisfying, um, and here's a patient that wouldn't have been a candidate for a lateral fusion because of his, uh, the anatomy of his POA, and so it really saves me from going in and skeletonizing his facets in a more open procedure. So, um, the why, or some of the indications, uh, I think I showed already, um, patients with degenerative disc disease, collapse, nerve root compression, failed laminectomy. [14:21] Speaker 1: This is sort of interesting to me that this is a patient who's had a two-level microdiscectomy, so he's had laminectomies. He has disc collapse here, and again I'm using the bone in a bag here, expanding those disc spaces and locking it in with the. [14:40] Speaker 1: A rods and screws, but if you look at the pre-op X-ray and versus the post-op X-ray, it really is amazing how we're able to get a deformity correction here. So these lines are indicating that the balance here on coronally, but on the post-op, I've really been able to level him out and get a bilateral nice foraminal decompression, which is a nice minimally invasive deformity correction. [15:07] Speaker 2: And I also think with some of the Other, with some of the expandable cages and being able to increase lower doses, we'll be able to restore some sagittal balance as well as the coronal balance. [15:18] Speaker 1: Yeah, you know, that would be the hope. That is always one of my struggles when using the bone in the bag is that it's not a lordotic implant. We get more of that when we use the expandable titanium cages, but that's why I try to do as much as I can with positioning the patient and the rod contouring. [15:41] Speaker 1: So another use for this type of endoscopic fusion is revision for pseudoarthrosis. So here's a case where this patient had first an L4-5 TLL and then extended to L3-4. And so he [16:02] Speaker 1: He comes with chronic back Pain and screw loosening of this right L3 screw. He has his peak implant here and some allograft, but he hasn't fused. But the problem with this gentleman is he has such severe heart disease he's not a candidate for general anesthesia, so. [16:25] Speaker 1: Um, what you can see here the haloing around that right L3 screw, and he has a pseudoarthrosis here. It's it's fused well here at L4-5. So what we do here is, again, you made that point here we have the tubular retractor just inside the disc space. I'm using an expandable shaver to open up here, and what I'm doing is I'm mirroring the trajectory. [16:50] Speaker 1: Of the T lift static cage with an expandable cage. So I go in with the endoscope. I see a ton of disc in there, clean that all out, prepare the end plates, and then crank open this expandable titanium T-lift cage after I pack in allograft and BMP, and I do it until I get a bending of that loose screw, so. [17:16] Speaker 1: I'm really applying Wolfe's law, but by putting pressure on that screw to get bone hardening, and this is what it looks like. I'm removing that disc. I'm using the endoscopic drill to do the frame anatomy, and that's what the cage looks like. [17:33] Speaker 1: And here's the final picture where I have the new T lift cage mirroring this, get this nice indirect decompression, and so this is a completely awake Outpatient procedure through a [17:51] Speaker 1: A 6 millimeter incision to rescue a failed T lift, and I think that's just an amazing application of endoscopic fusion. So I just see this as something that is just going to be more and more prevalent as a first line for fusion, but also it's a great rescue technique. [18:11] Speaker 2: That's [18:12] Speaker 2: a great point. I actually have a similar case where a patient came to me and has sort of been topped off. [18:19] Speaker 2: And they had failed at the level where there wasn't an inner body, and I was able to go in, uh, uh, not. [18:27] Speaker 2: Endoscopically percutaneously and apply an expandable cage to sort of provide some anterior column support and um you know, 3 years later it is solidly fused upfront and no no halos around your screws. [18:43] Speaker 1: Yeah, you want to, you're, you clearly love it as much as I do. It's just amazing when you can supplement somebody's fusion without putting them through a large Revision surgery, because typically we know our colleagues would be extending the fusion up superior levels. I mean we even forget about what. [19:08] Speaker 1: The Other treatments are for this because these are simple solutions to complex surgical problems, and I think that that is always the mantra that goes in with a lot of these endoscopic techniques is that they are simple solutions to complex problems and that's most of the revision cases that we're doing [19:26] Speaker 2: and I think there's a lot of these patients out there and to be honest, until you, I hadn't seen this presentation before and [19:33] Speaker 2: You know, I, I do have some people who have had TLLs that have failed and have a pseudoarthrosis, and I never thought about going in on the Other side and doing it endoscopically. And now this, you know, even, uh, though we have a fair amount of experience, so here's another population of patients that would benefit from a very small operation. [19:51] Speaker 1: Uh, you know, I, [19:52] Speaker 2: I, this is ingenious. It's out of the box thinking that, that we all, now that we have time to, to sit down and read and think, since we're not operating as much, this is, uh, God, this is fantastic. [20:03] Speaker 1: Yeah, you know, I had proposed to the Journal of Neurosurgery Focus, you know, to do an issue on a failed TLLIF because I think it's such a common clinical scenario that we see, and, you know, the, the solutions for them, you know, patients are getting stimulators, people are having, you know, thoracol lumbar fusions as, you know, solutions to their TLLIF. [20:29] Speaker 1: And I just love these more smaller ingenious solutions to TLL complications because, you know, we can, we can take the worst TLIft complication, do a revision decompression, revision discectomy, revision inner body, you know, it really is amazing. [20:52] Speaker 3: All right. [20:53] Speaker 2: Well, thank you so much Albert uh that was really uh thought provoking and uh really gives us another uh arrow in our quiver to uh treat some pretty complex problems, uh, endoscopically. [21:08] Speaker 2: So thank you very much for sharing with us and um hopefully you'll come back and teach us some Other things. [21:15] Speaker 1: Thank you. Thank you for the invitation. This is a subject that you and I are very excited about [21:22] Speaker 2: the future. Yes, I'm just going to close it out here with my plug. [21:29] Speaker 3: I spent so much time doing it. I have to [21:31] Speaker 2: show it every time. [21:32] Speaker 3: I love it.