Alright, thank you guys, we're marching down the spine and now we've come to thoracic and we're going to talk about thoracic pedicle screws. These are my disclosures, most of them which are about to expire. Learning objectives, today we're going to talk about some indications for instrumentation, this is not the primary point of the talk, we have a lot of other talks about that. We're going to talk about some basic anatomy for safe placement and we're really going to be talking about free hand placement. We're going to talk about the technique of placing the screws, what you should do, we're going to go step by step, talk about some of the things you can do to avoid complications. So basic indications for thoracic fixation include fractures, dislocation, tumors as we had a discussion on recently, electron, patients with kyphosis, kyphotic deformities as well as scoliosis, especially now with adult degenerative deformities. All these patients require fixation and the goal of surgery is not to put screws in to have a nice x-ray and to have a good looking film post-operatively, it's really to establish a solid fusion and these are tools that we use to help us over time, help the patients achieve proper arthrodesis and we'll have a talk tomorrow about some things you can do to improve that as well. So one thing you want to do is pick the optimal patient for your thoracic fusion. Very rarely you can find a perfect patient but this should be obviously a non-smoker if possible or somebody encouraged to quit, patients not on long-term steroids and patients without osteoporosis so checking that is an important thing to do in the elective setting. And then you're going to want to use optimal technique in addition to placing your screws appropriately, you're going to want to focus on preparing your bone graft bed, you're going to want to make sure that you remove the soft tissue, you prepare the bone and then you decorticate properly and then consider iliac crest autograft and patients that you're concerned may not heal with standard autograft that's locally harvested or with halograft. So what are some of your fixation options in the thoracic spine? Well there's options such as some laminar wire which is generally not used as much these days. There are some newer tapes coming out that hook around the pedicles, those can be useful in certain situations. And then hooks, I still make use of hooks every once in a while, certainly in some patients you may not have good anatomy for screws, previous fusion mass or I use it at the top of the construct if I'm afraid of proximal junctional kyphosis I may put a hook up at the top, sometimes transverse process hook, otherwise you can also do sub-laminar hooks. But they have some downsides as well, they do take some space up in the canal and they're not as good as screws at being able to help you with your, addressing your deformity. So pedicle screws are pretty much the standard option for fixation. Often times you can fixate fewer levels if you have a good screw purchase, you can apply a lot of corrective forces for your deformity correction. If you put them in properly there's no spinal canal invasion, if you put them in improperly obviously then that doesn't come into play. There's also the issue though of cost, that's really not as much I think an important thing now because there's really nothing that's as good as screws. So use them as you see fit and put them in the proper places, but you know the one thing you need to be concerned about is mal-positioning. And this is a talk designed to help you learn how to position them free hand with some useful aids such as fluoro and really understand the pedicles and what you have to do going forward. Step one really I think is to prepare yourself for this operation. Nobody goes into a complex cranial case without looking at where the tumor is and where it's invading and you should really treat every spine case that you're about to do in a similar fashion from something as small as a microdisc, but definitely for something like a thoracic fusion. Thoracic fusion is key and that means not just operating off an MRI. If you really want to understand the bone anatomy you should probably get a CT scan. If it's important enough to do a thoracic fusion where you may get a CT scan afterwards, get one ahead of time. And then each level on the CT scan evaluate. Look at the size of the pedicles in both the sagittal plane, axial plane. You can look at the rotation and you should note that down and you can kind of create a virtual model in your head of what the spine is going to look like on the CT scan. Then when you get in there you can translate that into what you're seeing and that will help you with your placement of your screws. But write it down. I think making a plan for your fusion is always a good idea. Measure each level. Write it on a piece of paper. This is sort of a graphic showing you know you put both sides. You put the size of the pedicle. Screw which you think will fit. You put the depth which you think you should put it at. You can also put the rotation maybe. You know in a T10 there's a curve change you should note or the rotation changes back to neutral. And you can write that all down and hang it somewhere that you can look at it during the surgery and then that will help you avoid some mistakes going forward. So once you get in there the first thing you need to do is meticulously expose your operative bed. And that includes proper hemostasis. You don't want to be struggling through trying to figure out where the starting point for your screw is with skin bleeder constantly pouring in there or something that you can stop. And then expose the bony anatomy. Make sure the lamina is exposed. Make sure you have the facet exposed. And I would even take away the soft tissue in the facet as long as it's at a level you're going to fuse. Expose the transverse process all the way out to the tip so you can see everything going in to one another. The lamina where it goes into the facet where it goes into the transverse process. Because in general that's going to indicate to you where your starting point is for your screw placement. This is kind of a busy slide and this is something that you know would probably behoove you to look at offline. To look at the various starting points for each screw and to have an understanding of where in the thoracic spine the starting points are and how they change as you go from T1 down to T12. In general if you have the starting point, if you have an idea of where the transverse process is, you have an idea where the lamina is and you have an idea where the facet is, you're going to have a general area of where you can start your pedicle screw. And then you know one easy way to understand what angle you should be going at is to take a right angle and put that there and basically you're going to be going perpendicular to your lamina. And so all those things can give you a basic idea for where you're starting. If you're at a place where you can easily visualize on fluoroscopy in the mid to lower thoracic spine, you should definitely check your starting point with lateral fluoroscopy. I find that very useful and avoids mistakes. But you're going to have to understand where to start in the medial lateral so you can place that properly because it's hard to have both AP and lateral at the same time. So there are several techniques. You can do a freehand technique when you're comfortable with that. When you're starting out and you're concerned, a lot of you know the more traditional way is to do a little laminal foraminotomy so you can feel the side of the pedicle. And then there's also a question of image guidance, navigation. All those are very useful. But I think when you have an understanding of the freehand technique, one, it may be faster. Two, it will also give you an idea of when your image guidance may be off and your navigation is off because when it comes down to it, you have to put the screw in properly. If you don't know how to put it in without help, then you probably don't know when this is not helping you anymore. So the first thing you do is you find your starting point for whatever level you're at. You confirm the level, obviously, prior to starting. And then if it's in the mid thoracic spine, upper thoracic spine, you make a burr, usually a mastic, over the area where you want to start. I just make it an initial starting point. Oftentimes you will see a pedicle blush. This is actually a lot easier in the lower thoracic spine, T10, 11, 12, where you can often take a Lexcel and bite off the transverse process and see a bigger blush. And that's going to be your entrance point to the pedicle. Sometimes you may not see that blush in small pedicles or pedicles that are not amenable to that. And then you're going to do your technique for placing the thoracic pedicle screws. Again here, showing some standard starting points. The first thing you're going to do is you're going to put your probe in. I recommend you use a curved probe, and I recommend you use the curved probe away from the canal. The idea here is that you will be able to cannulate the pedicle with less chance of breaching immediately and entering into the spinal canal. And then you're going to want to go down, basically, to clear the canal depth. And then you're going to want to take it out and change it to medial trajectory. And roughly how deep do you think you need to be before you've cleared the canal depth? Does anybody have an idea? 20 to 25. Yeah, I'd say, you know, 20 to 25. I think 20 is barely, 25 you've definitely mostly cleared it. And so that's a good thing to know. You can also check in on lateral fluoroscopic guidance, but you want to at least get down to 20 before you take the x-ray, otherwise you're wasting x-rays. And this is kind of an example of what it should look like going in. When you have it faced out, you should cannulate that pedicle, enter into the body, take it out, turn it around, you should go down that pathway and be able to medialize it to a greater extent. So again, it should always advance smoothly. And any time you have something that's going to be too hard, if you're pushing a lot, you may be off. Check a fluoroscopic picture to see if you're going in a funny angle, if you're going too superior or inferior, perhaps you're going too medial, perhaps you're trying to break out laterally. There's something often wrong if it's very hard to push. And so you should check it again and not just muscle through. And if you see anything give, it's oftentimes a bad sign as well. It should be a constant sort of resistance as you go through. I recommend two hands. You don't need to be a cowboy and have one hand on the drill and one hand on your probe. Two hands to prevent plunging, because if you plunge lateral far enough, you can get into some things that we don't want to deal with. And then basically you want to palpate all five walls when you're done with your probe cannulating the pedicle. Oftentimes you just put it in, feel the bottom, we're happy. But we need to feel the bottom, but we also need to feel all four sides, both the medial and lateral walls as well as the cranial and caudal walls. And that way you'll know that you're not too lateral, you're not too medial, and you're in the body. And then there's some different trajectories you can take, and in the lab you should practice probably both trajectories. The traditional anatomic trajectory basically follows the pedicle, and that would come from a cranial to caudal trajectory. And then you have the more straight-in trajectory, which may have slightly better pull-out strength, but it probably requires you to take more fluorode so you understand which way you're going. Whereas this one here, you can follow the more anatomical landmarks for freehand approach and have more likelihood of having successful placement. So once you've cannulated the pedicle, the next thing is to tap. I recommend tapping through the pedicle. You undersize it by about a millimeter for what you want. And typically you're going to be putting in 5-5 and 6-5 screws in the mid-thoracic to lower thoracic, and obviously smaller in the upper thoracic. So you want to tap with a 4-5 or 5-5 tap, depending on what you're going to put in. Again, I recommend palpating again to make sure something hasn't changed. And then I recommend placing the screw at that point. Some useful adjuncts that you can employ when you're putting in the screw is lateral thoracoscopy. I use it quite a bit. That's what I was trained with. Some people don't use it until the end, but I use it quite a bit. I also use neurophysiological monitoring when I do thoracic instrumentation. And again, that's up to your choice. I generally use MEPs and SSCPs, and I check it after every screw sort of as a time machine. So if something changed, then I take out that screw. But usually that doesn't happen too much, but it's a good way to check yourself. Some people do stimulate thoracic screws. Again, that's not really been proven to be that useful. So we'll have a talk about lumbar pelvic screws, and that may be more of a useful adjunct for those. And then if you have it, use an intraoperative CT or an ISOC or something that can give you a good picture of where that screw is besides just an AP and lateral fluoro. When I trained, we'd use lateral AP fluoro. If it looked good there, you were done. But oftentimes, you're going to have a misplaced screw, you know, sometimes 5 to 10% of the time. And so an intraoperative CT or ISOC can really help you. You're out of the room, you can get a nice picture, and then you can come in and readjust the screw, which may not be appropriate, and they'll save you from coming back in the future. Some people use navigation. I think that's also another good idea. Again, it has its pluses or minuses. But I think before you get into that and, you know, so you don't become a surgeon that's relying on navigation, you should really have an understanding of the thoracic spine, its anatomy, and what you're doing with the pedicle screw so that you can get by without navigation. And just use navigation to make you either more accurate, or for certain cases where the landmarks may not be clear, like a previous fusion, something that had a hair in the rod that you're trying to transition into something with a pedicle screw so that you can get through the case. So in conclusion, careful preparation is key. Going to this case prepared. It's not something where, you know, you just kind of do it on the fly. You need to have a knowledge of the anatomy, and that's patient-specific anatomy. Not every patient is going to have perfect anatomy because they're coming to you for a reason, especially with severe degenerative change. It's not going to look like it does on the cadaver that's not having degenerative problems or on your sawbones model. So you need to look at each patient. You need to plan appropriately, plan for rotation, plan for a size of pedicle, and then you need to develop a way to use aids to help you with either confirming your placement or making your placement better. Thank you.

thoracic pedicle screws

spinal fixation

indications for thoracic fixation

solid fusion

pedicle screw placement