What I'm going to do now, next half an hour, is try to give you an overview of the lateral axis to the spine, specifically the minimally invasive axis to the spine, and see a little bit of applications, but more than anything, the technique aspect of the procedure. You saw Rusty was talking about patients with x-lifts and they revise them because they need laminectomy, this and that, but that's a problem with the indication, not with the technique. Unfortunately, we don't have time today to show you what patient is the ideal candidate and why not, but I'm more than happy to answer questions at the end or through the day in the lab. So these are my conflicts that I have to live with them, but in general, the approach lateral to the spine as it is, it's lateral as the name goes, it's through the retroperitoneum through the psoas into the spine, and there is some modification later on trying to decrease the most common complication that we see later on, and the approach was definitely popularized by Pimenta, lateral axis to the spine has been forever, but Pimenta pretty much put it together as we're doing it today, and all the modifications that are around it. It's very important to know and master the anatomy of the retroperitoneum and all the structures that are inside, because if we don't know where we're going, then the complication is going to happen, and there is not going to be reproducible, the procedure. And this part is very important, because unfortunately, in our training, in your training on med school, and right now not because you're living with the lateral axis, but for us that we're outside the faculty, we didn't know what happened in the retroperitoneum, we didn't know what the lumbar plexus was, we didn't know any absolute, any branch, why? Because we don't do any surgeries there. Only the GU surgeons maybe, they were doing something with the kidneys in the retroperitoneum. And the OB-GYN taking tumors of the pelvis, dealing with the femoral nerve and the obturator nerves, and otherwise general surgeons with abscesses in the psoas. Otherwise, for us, we had nothing to do. There was a single question on the boards about the lumbar plexus. Everything is brachial plexus, you name it, but the lumbar plexus, not even asking. So we were kind of ignorant, and then we started doing a surgery that we were absolutely going through every structure of the retroperitoneum, and then we started having complications, and we were already doing the procedure. And this one was a big problem on this access to the spine, that actually we started doing the cases, we didn't know what we were doing, and the procedure was getting popularized through everywhere, and then we were seeing horrible complications, and I would say nowadays the procedure as it is, is more reproducible, it's just because we're improving the knowledge. The other point that is critical is this. If you're trying to do this procedure as it is, minimally invasive, through four centimeters incision, working deep, at least 10 to 12 to 15 centimeter depth, through all the fat of the retroperitoneum, where it's very hard to visualize, you have to rely on something to identify where are the main nerve structures of the lumbar plexus, so that's why the EMG is so important. It's the equivalent of the fluoroscopy images trying to put a pedicle screw, you know, you can do it freehand, but you're playing hard, unless you have a huge exposure of the anatomy. So if you want to do it without the EMG monitoring, fine, open, split the patient in half, like Dan showed you yesterday, go through everything, dissect the entire retroperitoneum, find the entire lumbar plexus, and then you get safe there. But if you want to do it minimally invasive, you have to rely on indirect ways to show you where the nerve structures are. And then, obviously, it has complications, and very interesting, this procedure comes with a new set of complications. For example, you will never have, with a T-leaf, a quadriceps, I mean, a femoral nerve injury. You will very hard to have a vascular injury with a T-leaf. You can have it, but you have to be pretty much like an animal to have it. But then, for example, with the lateral axis, you will never have a CSF leak. So you see, each procedure comes with its own set of complications. So you have to know how you avoid one of each one of them. And then, very important is, if you are dealing with patients without sagittal balance, patients that need lordosis, you have to be careful when you're using the lateral axis, because this procedure doesn't give you automatically a lot of lordosis. It's not a kyphoric procedure, unless you do something else that we're not talking today, but you can release the anterior column, cutting the ALL, and putting hyperlordotic cages, and you can provide some lordosis. But in general, the procedure, if you're trying to do some sagittal balance correction, you have to do something else, or do some osteotomy from the back. And then, this procedure is also very unique, that works by indirect decompression. And I will show you a little bit how the indirect decompression works. You see in this case, for example, you don't do nothing posteriorly, but just by doing ligamentotaxis, and increasing this height, and putting it back to where it was, then you get the decompression. So you see, without laminectomy, in this case for example as well, without laminectomy, just by doing ligamentotaxis, increasing the disk space, you get the decompression as you see for example in here, without the need to manipulate any of the posterior structures. So you don't need to do laminectomies on that. Another case for example, you see that just by doing the ligamentotaxis, regaining the disk height, how you actually get, not only for aminal decompression, but also central decompression. So the question is, what is the right patient for this? Some patients, you have too much stenosis, or there is too much alpha-set degeneration that actually is not a good candidate for indirect decompression. So that's when it becomes very interesting, because you have to recognize what patient can respond to this, what patient cannot. That way, we avoid what Crusty was telling us today. A lot of ex-lift patients, that they need to have a laminectomy. So these patients, do you think they need a laminectomy? They don't. The decompression is well documented, even with an MRI post-op. So now we're going to see how we get there. So first, start your work, start in the clinic. So in the clinic, you have to start looking at the anatomy. As spine surgeons, we like to look at the paraspinal muscle, the facet, the size of the canal, and we kind of, this is the line where we work as spine surgeons, doing everything for posterior. Now with the lateral axis, we have to check more things when the patient is at the clinic. Which one? You want to see the morphology of the psoas. Make sure that the psoas is escorting the vertebrae completely. There are some patients that, for example, when the anatomy is transitional, that they have like a L5, L6, the psoas is already taken off into the pelvis, and it looks like a Mickey Mouse type of ears where the muscles are located, like right here. In that patient, for example, they're not a really good candidate for lateral axis, because in that patient, actually most of the time, the vessels are very bifurcated, so you will see that the vessels are too much lateral in your way, or even worse, the lumbar plexus is not anymore the lumbar plexus, now it's the lumbosacral plexus. So that's the classic patient, they do the lateral axis, and we come with a foot drop. That is a very unlikely situation to happen. So in this patient, for example, this is a case actually that I decided not to do a lateral. So you pay attention when I draw the video, when this one goes to where it is supposedly L4, L5, you will see how these vessels are going to move. So keep an eye on the vessels in here, and you see, once you get to L4, L5, that is around here, see how lateral are the vessels. So if you do the axis in here, there's a very good chance that you may hit these vessels going through it. So in the clinic, you have to check for these. Where are the vessels? How do the muscles look like? So that one is going to help you a lot to prevent complications. And also, you have to look at this. Unfortunately, not all the MRIs and not all the centers that we have, they do coronal series on the MRIs routinely. And in this case, take a look at this complication. This is a contralateral psoas hematoma. So as you can see here, in this patient, the axis was from the left, and you see how big hematoma the patient ended up having. Why having that? Because if you look at these two fellows in here, the segmentary arteries were very good in here, but in this level, actually, the segmentaries were not exactly where they should be. They were running, actually, you're looking here with detail, there is two flood voids in here. They were running at the level of the disk space. This is something else that also you have to check in your clinic. Not only you look at where the big vessels are, make sure that the patient has not anatomical variation on the location of the segmentary vessels. So I could avoid this complication by looking at the pre-op MRI, and I would say, well, this is going to be complicated. If I go from the right and dissect it, I will do something else, a T-leaf or something else. So you see how important it is to have a good pre-operative evaluation of the patient for that. So the patient goes in lateral position. This is the classic position, how you put it for the lateral axis. And then, this is very important because, so what I'm going to do, I'm going to show you a lot of parts of the procedure, but at the same time I'll show you complications and how to avoid it. So that way we put the two talks that we have today together. So why is it so important to have the patient in a perfect AP and lateral position? First is because if you're relying on working almost percutaneous through a very small incision, you want to be exactly, if I'm putting my retractor right here, I want to be right here. I don't want to be here or here. So if the patient is rotated and a little oblique, you end up, or too posterior, too anterior. And then, not only that, if you don't have the end plates parallel, then what you do is you violate the end plates, and don't forget this procedure works with indirect decompression. So if I violate the end plates, put the cage, looks great immediately post-op, but five, six weeks after, it will subside, it will collapse, the patient will show up again with radiculopathy, with all the pain, and then you lose all the indirect decompression. See for example, this is for example immediately pre-op images inside the OR. So you want to have the spinal process there on the center, and the pedicles in a really nice distance. And as well, on the lateral aspect, one single image of the pedicles, one single image of the posterior aspect of the vertebra. Why that? Because this is the complication. Actually, this case is a real case of a vascular injury. This is, unfortunately, we're losing a little bit of definition, but in here, this is where the CAVA is. Unfortunately, we don't see it on the quality of the projector, but this is the CAVA. Actually, this patient is from a nearby institution. The patient had a catastrophic CAVA injury through the procedure. But I'm going to tell you what happened here. That's why it's so important to have the patient in a perfect AP and lateral. If you have a patient that the vessel is right here, actually the procedure is not contraindicated because you're working through lateral. But what happened on this patient? You keep attention to this cut on the CT, this spinal process is a little bit deviated to one side. So you're trying to make your AP view, relying only on the spinal process. In that case, if you want to see a spinal process perfect, you have to rotate a little bit the patient. So that's why it's so important to make sure that not only the spinal process in the middle, but the pedicles are also equally in the same distance. Like in this level that you see there is no spinal process, you rely on the pedicles. Why is it so important? Because this is what happened to this surgeon. This surgeon got tricked by, got fooled by the spinal process. Because when he was trying, if you do the access like that, you're safe. You don't hit the vein in here. But watch what happened when the surgeon tried to correct the figure. What he did is he killed himself. He just pretty much moved the cava into his axis, trying to put this spinal process where we should look perfectly beyond the x-ray. So the message is what? Make sure that the pedicles also look very equidistant. And this is very important when you have a patient with a scoliosis and rotational deformity. So you have to pay attention to all these new things that are happening. This patient, for example, from another institution as well, very interesting. In this case, they didn't have a vascular injury. But this surgeon violated the anterior longitudinal ligament without knowing. See he came in here and put the cage, looks fine. Then he was thinking that by using pedicle screws, he will protect this cage from migrating to the peritoneum. And see what happened later on. You see here? Looking inside, this is a horrible situation. Revise this patient, I can't imagine what a nightmare. You have all the big vessels in front of you. Taking this cage out of here is going to be like a nightmare. So again, very important, the positioning of the patient. As Mike mentioned also on the percutaneous pedicle screws, all these minimally invasive techniques rely on a perfect preoperative evaluation. For example, when you're doing, let's say, one single level lateral axis, the procedure takes 60-70% of the procedure is positioning the patient and setting up the entire room. 30% is actually the procedure itself. So for example, a 730 case, single level, let's say, stand-alone L3, L4. By 8.15am, we're cutting the skin while all the other colleagues are doing the ACDF, deep localizing and start taking care of the disc. But then, by 9.00am, I will be done with the lateral and they will still be dealing with the axis of the laminectomy, the open surgeons on the other side. So that's why it's so important to spend a lot of time doing the positioning. Watch this. Bad carpentry, didn't have a good preparation of the end plates, too aggressive. Price is a subsidence and then you lose all your indirect decompression. This patient, if you're lucky, he will be able to function, otherwise you have to come back and do a laminectomy for aminoramines and the whole procedure of decompression. So very important to have a good preservation of the end plates. Then now we go to, I would say, the most important part of the procedure. That is, you have to recognize and know exactly about the anatomy of the lumbar plexus. So I'm going to give you a little overview fast of the lumbar plexus. The lumbar plexus goes from T12 to L4. We believe that most of the lumbar plexus lives inside of the psoas muscle, but that's the first mistake. Actually, most of the nerve lives inside the psoas itself, but then as you see here, there's two, three or four nerves that actually live outside and those nerves are what we show on Josh. I'm just asking my resident because he should know. Speak loud, my friend. They don't listen. I'm like a little shy guy. Come on. Allow it. Okay. The ilioinguine and iliohypogastric and the subcostal nerves, they tend to live on the abdominal wall and they're very susceptible to injury if you don't do a nice dilation of the muscles during the initial parts of the approach as I show you later on when you are dilating through the abdominal muscles. So you see here, at every level of the axis, you can injure nerves and not only at the beginning of the procedure, but also when you get through the psoas. So if you look in here, this is the way that the lumbar plexus actually looks from the lateral view. As you see here, there is a lot of nerves in different stages. So your game is how can you get through one of these nerves, mobilize them until you get to the stage that you need to do the job. And then, not only dissect it right, but also you have to flow. You have to be very efficient doing your job. So in other words, to make this example easy, and this is actually an example that I always take from David Ocampo, if I put my fingers in my eyes for 10 seconds, I'm okay. But if I keep it for two minutes, I'm going to be blind. So the nerves, even if you retract the nerves correct, you have some time to do your job. In general, we just finish like a multi-centric, trying to find out the question, and it seems like 20 minutes, half an hour of femoral nerve retraction is what it can take the most. After half an hour, we start seeing all these different complications from tight pain to sensory deficit to the full-blown femoral nerve injury. So you have to recognize what is that. And then, I want you to look at this, because this is actually one of the big differences between the lateral axis and any posterior approach to the spine. So you're looking here, let's say we're going to L4, L5. Yes, correct, we have to negotiate three, four nerves, and obviously the most important nerve that can be injured is the femoral nerve. And the femoral nerve, even if it goes at L2, L3, L4, what is more critical to injury is at L4, L5. Why? Because it's already out, and usually it runs in the posterior third of the D space. So your game is, how can I get right here, retract the nerve from anterior to posterior, and do it in a very efficient manner? So you compare this one to the T-leaf, this is what the difference is. When we're doing a T-leaf, we are only dealing with the exiting root and the traversing root. And not only that, but we're dealing with a pre-ganglionic nerve structure. So how many times are you doing a T-leaf, and you hit this root hard, and actually the patient doesn't show up with an injury? The question is because, and why when we're doing a lateral axis, you retract this nerve for half an hour, and then you have a big deficit? Why is that? It's because this structure right here is post-ganglionic, and here we're dealing with a peripheral nerve structure. So in other words, if I injure the femoral nerve right here, it's the equivalent if I do three level T-leafs, and I injure at every level, I injure the exiting root, at L2, L3, and L4. That's why it's so noisy and so complicated when you have the complication. That's why you have to be so meticulous and so technically successful in order to have a good outcome through this. And this is the complication. You see this patient, it's a full-blown femoral nerve injury. You see how bad is the atrophy of the quadriceps. And then if we look in here, take a look at this video, the different deficits when you have, and this patient was a little bit more than a femoral nerve injury, he has a little bit of obturator injury as well. I want you to check in here how devastating is the complication, and this is a patient in great shape. So you see he can have a flexion hip, but then if you look in here, the good side, how nice he can extend the knee, and you see here it's absolutely nothing. Then there is also obturator, there is absolutely no obturator on the right side. So this patient, this is a horrible complication. I can trade this complication to a foot drop any time. So as you can see, if you don't do this right, the price that you pay is a very expensive price and the complication is bad. But this one doesn't mean that you don't do the procedure, because the point is that in our institution, for example, almost every week we ask for a file and ask you, Joe, how many times we have a full-blown femoral nerve injury? I mean, why? It's not because, oh, this one, no, it's because we take it very seriously and we're trying to flow as it is. We don't treat this thing, this procedure has a lot of control in terms of timing, how you retract it, how you position. But you control these levels, I promise you, it's going to be a great procedure, because the blood loss is minimal, the fusion rates are great, the overtime is very minimal, and believe it or not, you can send patients very soon home. So let's go to the details. So the access, we divide it in three main stages. The first stage is the access to the retroperitoneum. What is that? Cutting the skin, dissecting the abdominal muscles, get where all the retroperitoneum is. The second stage is dissecting the retroperitoneum itself. This is a very easy part of the procedure, you just go with your finger to the retroperitoneum, you feel where the psoas is, and then you find the entrance into the muscle. And then the third part is just the psoas, the muscle itself, the passage through the muscle. And this is when the EMG actually starts making its big contribution. So let's see each step and we go from there. So this is the traditional size of the incision I'm using here, it's one and a half inch, you know, it's three, four centimeters. And then, looking here, you can do it with two incisions or one incision, I personally do one incision, but the important thing is you have to know how to dilate these abdominal muscles. So let's see it in here, step by step. So if you're doing BP shunts, for us as neurosurgeons, it's very easy. Remember when you do the BP shunt, how you go with the two hemostats into the peritoneum. You do the same technique, but on the side, to get to the rectoperitoneum. And I'm going to show you in a couple of pictures in here. So you put the patient in a perfect position, you mark where your entry point will be, and this is very important, as we see in the lab. And then, once you open the skin, you get into the fascia. This is on the microscope, just to show you a little bit of detail. You open the fascia, then you have the external oblique, then you start dilating the fiber, you start the internal oblique, and then finally you see fat again, that's the rectoperitoneum. But take a look, this was an L4-L5 axis, and I think this is a case that we did with Vigel. It's not Vigel that we did it, I think Vigel was with us and we did it, and you see here, how one of these nerves was in the middle of the exposure, and this one could be the ilio-hypogastric nerve. So you find them, what you do is just dissect it a little bit, you can mobilize them very easily, and you can keep going straight with the approach. What is the difference, how do you get the complication in here? For example, you go with the bovie all the way through. The way that you see the general surgeon doing the approach for us, they just go with this bovie and burn everything. So you get one of these little nerves, then you have the complication. I'm going to ask Patel, Achal, is in here? Achal, Patel, Achal? Okay, so if I'm doing the approach, let's say L4-L5, I'm doing L4-L5, and I get this one, I found this nerve, and I actually cut this nerve, what should I expect on this patient? How is he going to wake up? What kind of deficit of nothing, or what do you think will be the deficit? I'm going to go back to my dressing. Numbness and pain in the groin area, which one is that? The genitofemoral. And that one, where is the genitofemoral located? Any volunteer in here? So genitofemoral is deep, and it's actually in the psoas. It's not even on the abdominal wall. So what nerve is the one that I'm injuring here? I need a volunteer so I don't hit right and left in everybody here. Well, and what's the complication? Okay, so this is the classic complication. Remember, Don was showing yesterday, when you injure these nerves, actually the function of these nerves is the motor innervation of the abdominal wall. If you cut them, the patient shows up with what we call the pseudohernias, or the abdominal wall hernias. This is like a bulge in here of the abdomen. Actually, it's a really bad complication, where we did it especially with women. They hate it because they say, oh, Dr. Rio did this surgery, and I look like a little chub in this side, kind of. So that's a minor complication, but actually it's a complication that shouldn't happen. And it's very easy to avoid it, just by doing a good dilation of these muscles without cutting this. And very interestingly, these nerves are coming from L1 and L2, and you can injure at L4 and L5. So they're susceptible to injury at every level. And by the fact, there is a nice paper from a general surgeon from Germany, correcting inguinal hernias with a trocar, where actually they can have the complication. And the answer is why. Because if there is three nerves that do that, the subcostal, the ilioinguinal, the iliohypogastric, usually one takes all over the function. And if you have such a bad luck, and you hit that one, then you have the complication. So the message is, every time you see a nerve like this, you just dissect it, and you go through it, around it, and then you keep with your approach. So once we do this, then this is the complication that you see here. This is the classic complication. You see that? This patient probably has an injury of the ilioinguinal, the iliohypogastric, and this is the classic complication, like an abdominal pseudohernia. So now we're going to dissect it to a retroperitoneum. So this part is easy, and this part, the nerves that you can actually injure, are again these two fellows. The ilioinguinal, the iliohypogastric. Why? Because they're coming from L1, L2, as we're going to see later on in here. And then they run in the posterior wall of the retroperitoneum. If we look in this specimen, we took the entire abdominal wall out. We're looking from the front. This is the quadrilumbar muscle. This is the psoas. Let's take the CT from here. So if we look in here, if this is the iliac crest and the L4, L5 levels in here, take a look at these two nerves. So this is the ilioinguinal and the iliohypogastric. You see how they go in the front of the quadrilumbar. That is actually the posterior wall of the retroperitoneum. They ascend and they travel inside the internal oblique and the transversary muscles, trying to innervate those abdominal muscles. So you see here, for example, if I'm doing L4, L5, I can injure one of these nerves and then have the complication. Or if I go with my finger, dissecting the retroperitoneum too aggressively, I can actually abolish these nerves. And I remember when we started doing these cases, we were like, put your finger and release the adhesions. I wanted to know how many adhesions actually were these nerves that we were abolishing then. So you have to be careful when you get through it. You have to put your finger through the posterior wall, feel the transverse process, and then get through the psoas. And then, finally, we go through the trans-psoas part of the procedure. At this stage, that's when finally the EMG starts doing its magic. And this is another very critical, important point. Because a lot of the complications that we have is because the surgeon doesn't have the right system to do EMG monitoring, and he doesn't understand and doesn't pay attention to this. So at this level is when we injure the most frequent and fatal complication of the procedure, that is the femoral nerve. So most of the systems, they are very sensitive in terms of identifying where the nerves are. But the problem is you need a system that is able to tell you not only where the nerve is, but also where is my relation, the dilator, the relation with the nerve. If I'm behind the nerve or in front of the femoral nerve. And then, not only that, but also tell me how close I am to the nerve. Because, to be honest, you want to be very close to the nerve. Because the closer you are to the nerve, the less you have to retract it. And one of the mistakes that is outside, in some surgeons, they think that if you dock your retractor very anterior, and you leave a lot of muscles in front of the nerve, you're safe. But the problem is by the time you move the retractor, all this muscle actually is going to act as a mass effect on the nerve, and then you're going to have the deficit with a perfect EMG readings. Because you were too much anterior. So let's see, for example, on this case. This is an L45 case. We put the dilator. We are using the EMG readings. And in here, I'm stimulated anterior. You see I have 60 milliamps to get the quadriceps work. And as I rotate the dilation posteriorly, you see how the numbers are getting lower and lower. So you see here, when I'm stimulating posteriorly, you see I'm rotating the tube. The numbers are very low to obtain the response of the muscle. But when I come in all the way front, the numbers are high. So what is telling me this? That I need a lot of energy to have response of the quadriceps muscles when I'm stimulated anterior on the recto-peritoneal. But when I was going posteriorly, I only needed like 4 or 5 milliamps to get the same response. So if we translate that one to a calaveric specimen, we were pretty much like this. So you pay attention a little bit in here. This is the specimen with the right side up. So this is the quadrilateral lumbarus muscle. The transverse process should be around here. This is the L4 nerve root coming out. This is actually a femoral nerve passing through it. And this is the L4 5D space. So in that case, probably that's what happened. And when I was stimulated anteriorly, I was having these big numbers. But when I was stimulated posteriorly, I was having the lower numbers. Actually, probably I was located right here. This is actually a really good place to place a retractor. Because these nerves, they like to be retracted from anterior to posterior. What you don't want is to put the nerve somewhere in here. So I'm going to show you another case. This case is exactly the other figure. So in the numbers, we're actually very low when we're doing anteriorly, but very high when we're doing posteriorly. In this case, what do I do? I don't avoid the case. I just go out of the muscle, find a little more anterior entry point, until I know that I'm in front of the femoral nerve. So let's see a little bit of the video in here. So when you look in here, you know I'm stimulated. This actually goes by colors. The numbers are somewhere in here. So I'm stimulated anterior, and now I have lower numbers anterior. And then if I go posterior, I have the other numbers. So what happened in there is probably in that case, I was probably right here, behind the femoral nerve. So that's why I'm having these lower numbers anterior, these higher numbers posteriorly. So if I put my retractor in here, it's going to be a horrible complication. So I'm going to pull all these nerves. The neuropraxia and the injury of the femoral nerve is going to be horrible. Not only mention that, but I'm going to hit the nerve anteriorly when all the instruments get through and through. So that's why it's so important to find that. And then I'm going to show you what happens when you, in this case, for example, this is a specimen, but I want to show you something very interesting. So this is the femoral nerve. I put a marker just in front of the femoral nerve where you really want to dock your retractor. And then, as I roll the video, so if I get in here with the EMG stimulation, and I don't have directionality or numbers, they're going to tell me, Dr. Uribe, you're very close to the nerve. So then I say, well, what should I do? I say, no, no, let's go more anterior where there is absolutely no muscles. So I'm going to go more anterior where there is any kind of muscles, when there is no nerves. So I get through here, very nice shot. If I do the EMG monitoring here, the numbers are going to be great. You know, 20s, who knows, because I'm far from the nerve. But see what happens. Because I'm too much anterior, somehow I have to end up, when I pull my retractor, getting the same position that I was before. So this piece of muscle, as you see here, instead of being my friend that protects me through the injury of the nerve, actually becoming a mass effect and actually is going to push more on the nerve. So this is probably the classic case that the EMG was perfect, the numbers were high, patient would come with a deficit. That's why it's so important when you're using this EMG monitoring, you're like hunting. You're trying to see where is that nerve. Because if I know where the nerve is, if I know where the enemy is, I'm sure that I can handle it. The problem is when you don't have any clear numbers. In that case, what do you do? You abort the case. Because you don't know where you're going. Everybody can put a cage going through lateral. The problem is at what price. What is the complication? So that's why it's so important to understand and know exactly how this is. The rest is just real carpentry. We go through the annulus, and that's what we do. We dilate, we stimulate, then we put the retractor exactly at this space. And you see here, you open the retractor very little. You just open the retractor enough to have access to this space. Why you don't open too much? Because if you open it more, what's going to happen? You're going to start injuring more psoas fibers. The psoas, don't forget, is the filet mignon. It's the most tender muscle that we have. That muscle is very susceptible to injury. So if you open this retractor a lot, great for the surgeon, but then what's going to happen the next day? The patient is going to tell you, I cannot even move my hip. The pain is so excruciating, I cannot do it. So how can you diminish that? By opening and working in a very small configuration. Then, also, if I open this too much, I'm going to start dealing with the segmentary arteries. Now I'm going to start dealing with vascular injuries for no reason. The real truth is that you're trying to put a 22mm cage by 8 or 10mm height, so you actually need only that opening. When you guys go into the lab, I want you guys to open with a very small configuration, because that will force you to do the procedure right. So once you get that in here, now you put a shim. This is important to put this shim on the posterior blade. Why is it important? Because it creates a true barrier, so the femoral nerve that you know is behind you, it will never come in front of the field. Because when you start doing the case, things can move. And even if you retract the nerve perfectly, if you don't have a barrier that keeps the nerve behind it, it will move a little bit anterior. You can hit it with a cove or something, then you have the deficit. So that's why it's so important. Once you put the retractor, you define where is your location, and then is where you need to flow. At this point is when you have 20 minutes to get out of there, because that's when you're retracting the nerve. So then you have to be efficient. And this is something that is very important for all of you. Because all of us, we were T-leaf surgeons when we moved into the lateral surgery. When we're doing the ischectomy, we tend to use the same instrument that we use in the T-leaf. Which ones are it? Brouches, angle cures, like a million things. Why do we use that in the T-leaf? Because in the T-leaf, we're working on the canvas triangle that is a 1.5 cm field. Believe it or not, even if this one is a small incision, the window to do the ischectomy on the lateral is bigger than the window that we have on the T-leaf. Because we're working to this window. So you can be more efficient. So you use less instruments. What do I use? I use the coves in and out, close to the end plates, pituitary, some box curette, a little bit of the end plate, and then I put the cage. So I don't use all these other things. So when you're in the lab, also try to be very efficient at this part. You see here, you go with the cove, and then you go with this box cutter. And it's very important that you have to release the contralateral side. Because if you don't release the contralateral side, then direct decompression cannot happen. And then you can have some subsidence. And also, you want to correct. So then you put a trial, then you put the cage. In this case, it's a lateral plate just for demonstration. But a lot of things can happen. And then before we finish, I want you to take a look at these images. This is a case doing somewhere else, but this case has a lot of problems. So what we're going to do, like on these magazines, you can identify five mistakes that you're seeing here. So any volunteers, or you want me to hit my own resident, I should be able to do this. Okay, perfect. You see, this is amazing how this is a great setup for a failure. Just look in here. The spinal processes are right here. It's a lot of rotation, yeah? So actually, if this surgeon, wherever he was trying to go, he's going to go more anterior or more posterior. Who knows? He's rotated this way. So one problem. Okay, second problem. Okay, the retractor. I don't know what the retractor is doing in here. It's not even under this space. You see why? Because this surgeon is not using a shim. So he thinks that the shim is a really bad thing because he thinks that the shim can hit the nerve. But the truth is, you find the nerve and you put your shim, actually the retractor is going to be stable. So what happens in here? The retractor moves up. Okay, so what is he doing in here? Who knows? He's like doing a massage to his segmentary arteries. That's crazy, yeah? What is this guy doing here? Just looking for problems. Take a look how much he messes around with the psoas. Instead of being here, limited opening the psoas, now he has an opening from here to here. He's ready to do maybe a corpectomy. Who knows, yeah? Okay, what else do you see here? What's wrong in here? Oh, exactly. This thing is like an open surgery. I don't see any MIS in here. This is like a... Well, he has cerebellars. Not only one, but two. And then you see the dilator. Way too much anterior. The images are horrific images. The end plates are not parallel. This is a horrible case. I don't know. I wanted to know how this patient wakes up. I wanted to know why there are too many problems with the lateral axis. And the answer is, the lateral axis is similar to an acoustic neurosurgeon for us. Why? If you do it perfect, the patient will do good. But if you just start going and pulling your finger like a dandy technique or whatever, this patient is going to wake up. Facial, any cranial nerve is going to be exposed. And not only that, you may even kill the patient. So this procedure is very sensitive to complications and requires a lot of finesse from the surgeon. If you're not able to spend your time and put all your efforts on this, you keep doing the other procedures that are more resistant to complications. Which one? Any posterior approach actually is a more resistant procedure to complications. So, just to finish, to recap, how can you avoid complications with this procedure? So, first, and this is the golden point, you have to know where this anatomy is. Spend your time. There are a lot of papers and chapters now with anatomy dedicated to the lateral axis of the anatomy. Take your time. When you're doing nothing, you're going on vacation, getting on the plane, read this. It's very important. And I know that, Praveen, are we starting asking on the boards questions about the lumbar plexus? Yes, we are. Okay, so hopefully they hit it because that way this is becoming more popular. How many of you are doing lateral in your programs right now? Watch. Three, four years ago it was one or two hands. So this is becoming more popular and it's a good tool. Obviously, it's not for everybody. It has its own unique indications. So, second, don't forget this. This is golden. The positioning of the patient. He has to be in perfect piano lateral. When you go to the stations in the lab, I want you to yell out all these scrub takes and the x-ray takes there if the patients are rotated. Don't do anything until you have a perfect image. Not only AP, but lateral. Because this is very important. This is also a minor aspect that actually can make a big difference. You see this patient, for example, how much jackknife we broke the table. This is great for the surgeon. You can have access for fiber easily. The accuracy is so low. The problem is we're putting too much tension on the psoas. And if the femoral nerve is in the middle, the femoral nerve is going to be like on this tension. So that nerve is not going to tolerate too much retraction. If you do it with the patient not too much break, the nerve is going to be this fluffy kind of loose. And then it tolerates better retraction. So how we do it nowadays? We only break the table what we need to get the access. In this case, this patient, we pretty much didn't break the table at all. And then don't forget this. Split the muscles, fibers of the abdominal wall so you can prevent this complication. You have to be very gentle with your finger in the rectoperitoneum. Understand the EMG monitoring. If you don't have a good EMG monitoring, my recommendation is do a mini-open approach. Open the whole thing. Dissect the entire rectoperitoneum. Find the psoas. Dissect it. Take a look where the femoral nerve is. Be careful because all these nerves look alike. They don't come with a sign that says I'm the femoral nerve. So you might better have something, yeah? And all of them are, some of those nerves are big. So you have to have somehow, sometimes surgeons that don't, they like to go directly. They get fooled with a big nerve structure and they think that it's a femoral nerve. And when you're working with the loops, everything is big. So you have to be careful of that. Then six, manipulate the retractor very gentle. See here, this is one of our cases. We work with a very minimal opening configuration. Because you prevent a lot of retraction injuries. Be a good carpenter. Prevent damage to the end plates. And then never oversize the implant. This is another bad tendency. Once you get to this stage, you want to put a train inside. Looks great right there, like a 12 or 14 high cages. But the problem is, is you put too much tension on the end plate, that then actually you're promoting subsidence. So you start with a patient that had this height, 4, 6 millimeters. Actually with an 8 millimeter cage, it's enough to do indirect decompression. You don't need to get too crazy about that. And then there's a lot of expanded indication. Next year, maybe when we get more sophisticated with the approach, we can go over that. But this procedure, you can go pretty much from T4 all the way to L5. And you can treat any amount of different pathology. You see here, these indications are possible with the lateral axis. And the formula, as you know, is a really good tool for this. And with Praveen and Mike and Park and most of the guys, most of us in here are involved on the ISSG that is also doing a big effort to try to prove the minimal invasive techniques on deformity. That is a combination. It's like the summit of the combination of all minimal invasive techniques. It really works, but has a good application. See, for example, thoracic calcified disc. This procedure required a massive mobilization of the posterior structures. If you go lateral, you can have a really good job and do a really good decompression. And if you're elegant, you can do the approach retro-plural with absolutely no need for chest tubes. So, in general, this is the message. Meticulous surgical technique, very good knowledge of the anatomy, and understanding of the EMG is critical to avoid the bad complications of this. And as I always show this, you know, sometimes as surgeons, this is what we do in the OR. Sometimes we get some clear rules to do it, but when you're in the OR, you have to be flexible. Sometimes you have to do things like this to get the job done. And, you know, you do this, but actually the thing goes and works. So be flexible, don't get too narrow in your mind, and always be flexible to other options. And third, we have an opening for the fellowship on 16-17, if you guys are interested. For some reason, we have an opening right now, and we're more than happy to come to a beautiful Tampa and spend a year with us. So thanks very much, and questions, and anything that you guys feel free to ask, because this is a good time for that.

lateral axis to the spine

minimally invasive axis to the spine

anatomy of the retroperitoneum

EMG monitoring

surgical technique

patient positioning

complications

implant sizing