Long morning, a lot of lectures have all been very good, and I think this talk here is kind of appropriate, the second to last, I think our last talk is on outcomes. But, you know, normally, you know, we've done all the cool stuff, we've put in screws, we've come from the side, we've taken off the rib head, we've done a corpectomy, we've treated trauma. The last thing we usually think about is, is sort of the most important thing that we're trying to do with all these techniques, which is to achieve a bony fusion. And we sort of think about that at the end of the case, it's about six, seven hours in, you're tired, you're just like, yeah, let's just throw something in there and get out. But this is actually sort of the most important part of the case. And that's why, you know, if you actually do your own billing, you know that the putting in an extra seven levels of instrumentation gives you about one RVU, but, you know, in terms of fusion, it gives you about 70 add-on RVUs. And there's a reason for that, because the difficulty is in achieving the fusion. So these are my disclosures. So the learning objectives here are the, number one is to remember the importance of obtaining arthrodesis. That's the point of most of these cases, when you're doing complex spine. It's to understand some basics of bone growth physiology. So you don't do things to shoot yourself in the foot, you know, usually very basic things. Also to understand some of the properties of common bone graph extenders, because as soon as you get out and practice three, four years from now, people are going to start magically showing up in your office saying, oh, use this. The studies have shown that this will give you like a 10,000 times the rate of fusion. And you need to know what they're actually offering you and what the properties are. And then you need to know how to prepare your arthrodesis sites. You know, doing the decompression, taking out the tumor is important, but you need to also know what you're doing in terms of preparation for arthrodesis. And then also have a knowledge of some of the factors that can either adversely affect arthrodesis and also some things you can do to help you improve offline. So why care about arthrodesis? Instrumentation, you know, that's all exciting. Doing the big cases, you know, that's the Porsche, you know, we're all excited about that. That is really cool. But, you know, preparing for arthrodesis, it's like driving the minivan. You know, it's not exciting, you know. But, you know, but this is what's actually going to get the stuff done. I mean, you know, you can't go to the grocery store. You know, I've got three kids. I can't go to Costco in that. But I can go to Costco in this and I can take care of business. And this is what's going to get you there. And so you need to know about that, right? And so you also need to watch out because you guys are building Porsches in the operating room, beautiful constructs. And then, you know what, if you leave and you don't care about, you know, how you're putting in the bone or what you're putting in, something bad is going to happen, you know. Don't double park your Ferrari in Manhattan. It's just not a good idea. Pay for the valet, you know what I'm saying? All right, so here's some examples of what can go bad. You put in some nice, you know, interlaminar screws and then they halo because you didn't have a good, you know, fusion. You know, this is not my example, but I borrowed this from Praveen. He saw this recently in clinic. Somebody did a gigantic, you know, anterior operation. And then, you know, if you don't achieve fusion and you don't back it up maybe posteriorly, something bad is going to happen. And that's horrible for the patient to go through. And you could have, you know, done something to at least minimize the chance of that happening. And then you do a nice, big construct. You do a PSO and then guess what? You know, you have a rod fracture a year or two later because you didn't achieve arthrodesis. So doing the operation, getting off the table is important, but then long-term for the patient, you need to take care of this and get it fused. This is your view. I mean, I had this view. You know, it's late in the day, you're tired. Maybe your attending's like, you know, take care of this and he's left and he's dictating or he's rounding on patients. And you just want to throw some bone in and close, you know, just get some of these morsels, somewhere magically they appear, and you just throw them in. And then you close. And it's short-term gain, but again, long-term pain. And I'm hammering on this point. You know, it's repetitious, but that's, you know, how we learn. You're going to make a mistake and you're not going to want to do it again. I'm trying to save you from that first mistake. So pseudoarthrosis occurs in up to 40% of patients, especially in these longer constructs. The bigger you do a case, the more likely it is not to fuse. The more levels, the more likely it is you have a pseudoarthrosis. So you need to be aware of it and you need to know about this going forward. And you need to counsel your patients on it. Again, higher incidence in long level constructs. And it results in significant morbidity. Oftentimes it results in another operation. Sometimes it results in a much more difficult operation than the index or initial operation. And these reoperations do not give you happy customers. And exactly, you know, you don't want to have your clinic filled up with that. I don't know if you guys see clinic as residents. A lot of residents are insulated from clinic, but this is where you're going to spend your time. You're going to spend, you know, one on time with people that aren't happy with you if you don't get them treated as best as possible. So how to minimize, understand how bone forms, understand what you're putting in the patient. You know, why did you choose to demorsalize little kernels of allograft? Understand how to prepare the bone to give yourself a best chance of fusion. If you don't decorticate, you just throw a bone on top of it, it's not going to fuse. You know, place the graft in the appropriate place. Make sure you're putting it in your bed. You don't just kind of throw it in there. If you're doing an anterior arthrodesis, make sure you prepare the end place correctly. Make sure you place your graft in the best chance it has for fuse. You know, you don't want to impact your graft into one of the vertebral bodies and think you're done. It's not going to fuse. And then postoperatively, you know, manage your patients. Maybe avoid high dose NSAIDs. Consider bone stimulators as options for people that are maybe at higher risk. Bone formation, you know, this, I'm not going to go over a whole lecture on how bone forms, but it develops from replacement of preexisting connective tissue. And there really are several steps. The first is to lay down a osteoconductive matrix. Then you want to have the factors in there that are going to induce the cells that you need to form bone. Then you need those cells that are osteogenic. And finally, you also need a structural support, you know, especially if you're doing like an allograft, I mean, excuse me, if you're doing an anterior disc space and you want to fuse a disc space, you need something structural. You can't have something that's soft. So you need all these things in your bone graft. Unfortunately, none of them are 100% perfect. And this is a busy slide. You can see this in many different reviews on what type of bone grafts are available. But these are some of the basic ones that you have available. One of the most common ones we have are concellus autologous bone, either locally harvested or even better, iliac crest. And that's going to have a lot of what you need in terms of osteoconduction. Osteoinduction is going to have the factors you need. Osteogenic cells are also there. It's not going to cause an immunogenic reaction, which may impede your fusion, but it's not structural, especially if it's locally harvested or if you take some concellus iliac crest, it's not going to provide structural support. Cortical autologous will provide a lot of it as well and has some structural support. So like a tricortical graft, which we used to use for ACDFs, that will be a nice graft. Has some other problems which we'll talk about. You have other options such as allograft, which again, loses some of the positives of autologous, but it's there. It's a good extender. You may not have enough autologous for a big operation. Demineralized bone graft, DBM is often used under various trade names, and that has some positives and some negatives. There are some people doing bone marrow aspirate and then adding that into other types of extenders, and that has some positives, some negatives. And then you also have the non, basically the artificial ceramics and other types which are also being used. All of these have positives and negatives. None of them nail it all the way across the board, but the best are actually autologous. They have most of the things that you want in a bone graft. There's some limitations such as amount you may have. If it's a revision, perhaps the iliac crest has already been harvested. So there's some reasons to use extenders, and you have to think about the extenders that you're using and make sure that you use them appropriately. So iliac crest, I think, is a thing that we don't use as much anymore due to some patient complaints, pain, and the like, but it's one of the best things that we have out there. It's the patient's own. You don't have any issues with donation. You do have increased fusion rates as compared to locally harvested autograft, but there is some morbidity in terms of complications of harvesting. These can include post-operative pain. If you harvest it poorly, it can be nerve injury, and so you need to know where to go, and this is something that you may not do a lot, but you want to make sure you avoid, like this is posterior, you avoid the clunial nerves. You go into sort of the primary area where it is, and you avoid going too deep, and it's actually not a very difficult procedure, and it can give you a really good bone graft material, and you can also do it anteriorly as well, and again, you want to avoid nervous structures and approach it in the safe zone. There's also osteo, there's also factors, osteoinductive factors. This is one that you've probably heard of. I'm only speaking about the on-label use, which is anterior in a specifically threaded cage, but it's often used off-label, and there's some controversy around it. There's been shown to have some increased fusion rates in the literature, but not really improved outcomes, and there are risks of complications that you have to be aware of when considering this as an option for your intervention. So then, the next step, you know what you're putting in, now you have to prepare it, and the first thing, I'm gonna hammer on this again, is to know your patient ahead of time. You're not making this decision sort of after six hours of operating when you're not as sharp. You want to know your patient, how old are they, because age is important. You want to know the comorbidities that may affect their ability to fuse. Their smoking status is key. You do not want to be doing cases on smokers. I've done that, and they can really fall apart more quickly than you would expect, and you want to know their overall bone health, especially for people that are older, and you're considering doing large operations, and so get the DEXA scan, understand what their overall bone health is. And then when you're in there, you want to prepare your arthrodesis sites. You know, plan what you're gonna do. Are you doing only an anterior, you know, the T-lift? Are you doing a T-lift plus posterior lateral? And then when you plan on it, prepare the sites correctly. Prepare your transverse processes, expose them if you're doing it open, and make sure you really, truly decorticate them. Decorticate and get rid of the soft tissue or the facets to help you fuse as well. And when you're doing anterior, you want to prepare your end plates, and you want to make sure that, you know, the end plates are prepared properly, that you pick the correct graft that you're gonna use. If you just throw in peak, is that gonna fuse? Probably not. You may want to consider using, you know, another substrate as well to help you fuse. And then you want to pick, you know, structural allograft, peak, titanium, or if you, you know, if you go old school and harvest your own fibula or something like that, but that's probably not gonna be in your choice. And then posterior, make sure you decorticate properly. Make sure there's good bleeding, that there's a really nice bed for you to get your fusion to progress across. Which graft to use? Well, I can't really tell you that. Everybody is different in terms of their preferences. You want to make sure you have an effective graft. You want to avoid complications that you can easily avoid. And then you want to make sure what you're doing is cost effective, because coming down the road, you may not have a choice about what to use. There's a lot of insurance companies which really limit you in the choice of bone graft extended, because there isn't a lot of literature for a lot of that you use out there. Some of it's experimental, only in the rabbit model, and some of it is not really been shown to be more effective than just basic structural allograft. And then other factors to consider post-operatively, radiation, chemotherapy, avoiding infections, all these three can really adversely affect your arthrodesis. And you can consider bone stimulators in patients who are higher risk, multi-level, because it is FDA approved to use these as an aid to arthrodesis. And I tell patients that there is a slightly increased chance of you healing better. It's not that great, but it's better, because if you have a 15% chance, better chance of fusing, you either fuse it or you're not. It's like being, you're not a little pregnant, you're not a little fused, you either fuse it or you're not. And so I recommend using that. So in conclusion, understand your patient, prepare your fusion site properly, and choose your substrate wisely. And these three things will help you avoid some catastrophes down the road. Thank you.

arthrodesis

bony fusion

complex spine surgeries

pseudoarthrosis

bone grafts