Thank you for having me and great turnout. I'm good of all of you to take time to come out and Learn what we think is an important topic going forward. So I have some disclosures. They're there. They should not be particularly relevant to alignment Talk so so Spinal deformity right? We're seeing it more and more The fact that all of you are here for this is is a testament to how important it's becoming and as neurosurgeons We're doing it more and more Scoliosis kyphosis and sagittal imbalance that you're hearing a lot about today And there's a lot of overlap on some of these talks I'm going to try and talk about a few things that we haven't been discussed as much and In sort of the global alignment perspective try and put it in a big picture But you will get some repetition but in certain things like the sacral pelvic parameter That's a good thing because it's a really important part of what we what we do and I know Justin I'll cover that in depth next so So the key in a when you have an adult deformity have to recognize the deformity try and figure out is this their problem? How what role does this play and then factor that into any of your treatment plans? And I always think about identifying that deformity. Is there a scoliosis kind of easy to pick up. Is there a list thesis that? Factors into how you're gonna correct it. Is it affecting a sagittal plane issue? Is it a lateral list thesis? Is there kyphosis where and is it normal is it abnormal the overall balance coronal balance obvious is important But sagittal balance is really what what we're talking about a lot and that's what the focus of my talk is gonna be a lot Today what's their SVA? What are their pelvic parameters? And then one thing that you miss a lot is is there a concavity stenosis? You have people coming in with a ridicular pain That get an MRI or a myelogram and it doesn't look so bad But they have radiculopathy and they stand and walk around It's because when they lay down the deformity corrects partially and when they stand up it it gravity You know sinks them in that frame and closes down and they get radicular pain So you need to think about that when you're trying to identify symptom drivers So I always talk about steps to correct a deformity and today we're just gonna be talking about the assessment of balance part of this So key concepts for me sagittal balance in spinal alignment is a single most important factor when we're talking about patients with deformity It has the greatest impact on function in the term the conus of economy is a John Dubois say Term that people use quite a bit because it really is an elegant way of thinking of how people function and stand up Coronal balance is important But being a little off in the coronal plane isn't that big a deal being off in the sagittal plane is a big deal And coronal balance is actually a little bit tricky to judge in surgery Sagittal is a little easier to tell whether you've got it or not. Coronals a little hard sometimes This is a video. It's from Chris Ames at UCSF who put these together So I have a few of these and this is showing that conus of economy Essentially see a patient standing up and if they stand in what we think is this Conus of economy if they're standing up with their head balanced over their shoulders balance over their pelvis balanced over their feet They can stand up and you can stand up all day. You're not using a lot of energy You're your motion is right you have economy You're not having to do any real work to stand up if a patient starts to lean forward and is out of balance here As soon as you lean forward and your gravity line gets in front of your feet You have to do something to keep from falling over and usually that's your lumbar extensor muscles start to work people get low back pain just from the fatigue of that and if you want to try it someday when you're in your hotel Room later by yourself try leaning forward for five minutes. It's miserable It really gets painful. So people get back pain and as it gets worse, you start to get do other compensatory measures So we talk about spinal balance again I'm not going to belabor this and maybe we'll catch this up on time a little bit C7 plumb line is sort of the where it all started It's mid-body c7 that post your superior aspect of the sacrum 36 inch x-ray is mandatory to measure that t1 tilt is an angular measurement It takes into factor a little bit more positional factors It's probably a a better measure if you think about it, but it's a little bit harder to use sometimes it but it's gaining steam I think but I'm not gonna cover too much of that today. And again a c7 plumb line That's in front of your sacrum is is a positive sagittal balance if it's behind that's negative Positive is the big problem negative usually isn't but we talked about cervical a little bit I'll show you a little bit in the global balance where that factors in and if you have global balance here We're talking about the sacral pelvic parameters getting that balanced and getting the spine Aligned is really the key Here's an old slide one of Steve honors old patients that has just some nice pictures with it a patient I was significantly maligned you see him trying to lean over you can see Why he'd be working his posterior extensor muscles trying to stand up and then post-operatively standing up quite nicely back to balance Not having to do any real work to stand up. That's why people can can do that without back pain without fatigue Being imbalanced is a fatiguing process. It is energy inefficient You are using energy and calories to stand up when you do that So getting back to balance to help people in a lot of ways So spinal balance we see people we see if you walk down the street you see lots of deformities if you're looking for them But not everybody is leaned way over people doing all kinds of crazy things To stand up because we're trying to be balanced people can't stand with that Lean forward posture using this their spinal extensor muscles for very long So you alter your other curves if you're bent forward at your lumbar spine you hyper extend your thoracic spine you reduce your thoracic hyposis It's the concept that you'll hear some people refer to as reciprocal change after an operation something That's hyper extending a thoracic spine and they have less thoracic hyposis than they're supposed to have or they should normally have because they're Compensating for a lumbar deformity and you fix their lumbar deformity then they get then they relax They get back their natural thoracic hyposis and then you look like you didn't get enough correction So that has to factor in so you can alter your other curves that are still flexible You can change your sacral inclination your pelvic tilt and that's the most common things people do you see people they sort of tuck their Butt in they lean back on their you know Hip flexors they sort of stretch those out and lean back on those and try and rest there that uses some of the leg Muscles start to bend your knees There's all kinds of things people do trying to compensate for this and looking at them Globally not just looking at their lumbar spine or the thoracic spine or even just their c7 to s1 You missed the the big picture of global alignment and the sacrum It's really easy to pick out an x-ray you right if you're looking for pelvic tilt you can measure everything else But just look at a sacrum if it's really horizontal versus really vertical you can tell a lot of compensation, right? If you like as soon as the x-ray goes up, you can tell whether somebody's it's a compensated posture or not It's pretty easy to to tell So here are two patients that are both Compensating and they're compensating for different things. So look at the global alignment of these two people This lady has a negative plumb line, but she's still extending her hips. She's still compensating She's driving her plumb line back for some reason. Why is she doing that if her c7 plumb lines negative this? Gemma has a thoracic kyphosis, but a lumbar flat back deformity. He's compensating. You can see his hips You can't really see him real well, but he's thrusting his pelvis forward To compensate for this trying to bring his plumb line back They're two very different deformities both doing the same thing and you sort of start to think why? why is that and This is a research project that Steve Andrew and I were sitting around and looking at that very slide showing things a decade ago probably Talking about that and trying to figure out what what is the difference here? And this is this began became a research project. We applied to Medtronic for a grant that's why they're on my slide of having to disclose this and so they funded this this project and Which doesn't have anything to do with implants. It's just looking at normal balance We said what's the difference here between these patients and and a lot of the alignment work was originally done by orthopedic surgeons, right? They look at a c7 plumb line and as a neurosurgeon That's sort of offensive that you're not thinking about the head and I always use the phrase I live up in my head I don't live in my c7. So when I'm trying to balance myself out I'm trying to balance my head over my my pelvis not my c7 over my pelvis and so we started thinking about that so we started thinking about things and C7 plumb line is good, but it doesn't really tell the whole thing So the true balance is trying to keep your head up over your sacrum pelvis and use that so you're in that conus of economy So what we did we took a hundred asymptomatic volunteers. So patients that did not have any prior back issues. No back pain. No surgeries No real issues in the 20 to 40 and then we took a hundred in the 60 to 80 year old age group We did a simple standing lateral radiograph and we looked at it got a few things We looked at their c7 plumb line We looked at their c2 plumb line and then we looked at their cranial center of mass and there was a nice study done back in the 80s Looking at trying to calculate how is it best to estimate the center mass of the head and they did Some some testing and they found if you drew a line from the nasion to the Indian the midpoint of that line really best Approximated where the center mass of the head really is That's not very hard to measure on an x-ray as long as you get the bottom half of the skull on there so we measured that on all of these patients and We came up with some normative values. So a cranial center of mass if you look at a 20 to 4 year old is 9 millimeters in front of the posterior superior aspect of the sacrum c2 was negative 2.7 In the 60 to 80 that's a little bit forward. So we're c7 11 millimeters or Can be in front 4 centimeters in the front here And we did some correlation coefficients and they really matched really well because they were sort of normal individuals and They didn't have a cervical issue. So things matched up and they should match up And so we came up with these values and we thought well, you know, that's important But it the people asked us well the correlation coefficient so high. Why don't you just use c7 in it, right? That's true. So we do use c7 a lot of the time because they match up really well We don't use c2 and we could it's a little better than c7 But when you look at that patient there and you look at the the ones that were compensating I'll show you the the differences here and why that really matters. So again, here's how we would measure it global balance You can see the adenosine in the online I hope up there pretty easy to draw you drop a point from the midpoint there and a point from c7 there That's what a normal looks like C7 is falling right over that posterior superior aspect of the sacrum in a fairly normal way Looking individual versus Here just in front of it. That's normal. That's what a normal individual should look like So we take this person here 68 year old female came in with low back pain radiculopathy and an MRI that isn't all that impressive She's got not a lot of stenosis her frame and looked pretty open again An MRI is a supine exam for the most part and you get a standing x-ray on her just a lumbar x-ray and look at the change in lower dose She is hyper lordotic in her lumbar spine compared to her her her MRI and if you get a standing x-ray Her c7 plumb lines way negative. She's got a scream in her dick when she's standing up If you measure her c7 plumb line, it's way negative. But if you measure cranial center mass, it's perfectly normal So she is compensating for her head not for c7 because she has a cervical kyphosis So cervical thoracic kyphosis is a cervical kyphosis So she's compensating but compensating for her cranial center mass not for her c7 and that drives her plumb line negative She hyper lordosis her lumbar spine and gets radiculopathy. She's closing on her for a minute, but that's just trying to stand up So this is a old Andre patient did a fairly crazy thing operating on somebody's neck for a lumbar radic and And it got better But if you look at after the operation, you can see that there's a little bit of a change in her c7 plumb line And And it got better. But if you look at after the operation, you correct that deformity those two parameters come back to normal She doesn't need to hyper lordosis her lumbar spine anymore and her symptoms go away Here's a patient of mine is a 62 year old female had a drop head syndrome Which is just a failure of the posterior musculature and inability to hold her head up The reason she got it is kind of crazy and I won't go into that but she's got this She's got a thoracic kyphosis too, but she's got a cervical kyphosis. That's iatrogenic actually after being in a collar for too long and if you Look at her. I corrected her cervical kyphosis now She had neck pain and low back pain that were equal to each other And if you look at her c7 plumb line again, she falls way negative if you look at a cranial center of mass It's perfect. It falls right over the posterior super aspect of the sacrum. So she's balancing her head not her c7 and Afterwards you look at those two parameters come right back to normal and her low back pain goes away So she's not hyper extending She's not overloading her facets and all of this comes from just looking at at patients You know, we sit in there and you don't understand something you sort of throw it up Everybody looks at it and you talk and that's how the study came about but it was a relatively easy research study I did it while I was finishing training and extended into when I finally got published recently, but It takes a while, but it's a project that I initiated in training wasn't very difficult We've got a little funding did it and it's something that you have a question you study it fairly simply You answer it and it and it works out fairly well So I'm not going to talk a lot about pelvic incidence, but the more you see pelvic tilt pelvic incidence sacral slope the better they are it is going to be a factor and the reason for that is You rotate around this femoral head so much There's so much variability and how you can change your posture from your from your femoral heads It's it's impressive and if you don't measure it you will be missing the biggest part of the picture and you're trying to pick this patient out from this patient and A lot of people see patients they see their x-rays They examine them sitting down or on the examination table You have to get patients to stand up That's step one and then get them to walk people can compensate and fake it when they stand for a few minutes if you walk They can't hold it anymore. They lean forward. You see all of these compensatory mechanisms come out and you see what their real deformity is Here's another video showing a patient that is Imbalanced as a lumbar flat back deformity Be coming out of that conus of economy and you can see how they retrovert on there and I'm Right gets them back into balance. That's what they do. They tuck that butt in they Have a really flat looking butt That costs energy they have to do something to do that, but that helps them compensate somebody that's even more imbalanced Tries to compensate so they start by retroverting their pelvis. They can't get all the way there then they bend their knees So you can see the low back and neck strain indicated there They can't go back any further on their pelvis because their femoral heads won't go back anymore in their acetabulum so they bend their knees now, they're now they're getting leg pain because their legs are fatiguing and The whole concept of patients that do well with the shopping cart. So we'd all learn shopping cart is Oh, that's a lumbar stenosis sign But that's also a sagittal imbalance sign somebody that can't stand up and stands up Gets a shopping cart or a walker Gets a shopping cart or a walker the reason that that works is The problem is their gravity lines in front of their feet and they're trying to balance out between the two points that are their Feet if you give them another point out in front whether it's a cane or a walker Now you balance between three or four points and you take some of that work away and that's why patients Do really well with that, but they're not real functional so if you can get them back to balanced and standing upright, you can get rid of a lot of those assisted devices or Alternatively if you get some disaster of a patient that is a medical train wreck and you don't think you get through an operation Getting them one of those little wheelie walkers will do a lot for their functionality and and keep them away for certain from surgery So when we talk about correction, I'm just gonna go through a patient on how I correct things It's very much like you just saw from from Praveen. I look at this patient This is a anesthesiologist old Harrington rod construct flat back deformity fairly classic thing You'll see quite a bit if I measure things. I measure a c7 plumb line. It's obviously way in front I measure pelvic incidence 58 degrees fairly normal. I measure pelvic tilt 35 degrees grossly abnormal We want it normal is about 12 to 15 We want it to be less than 20 and I measure where I want her spine to be and if I'm gonna cut a PSO I'm calculating that what do I need? What's that angle? That's what theta is there and that would be 35 degrees to correct her So I think I need 35 degrees to get her back from here to here Okay, and if I need to correct my pelvic tilt from 35 down to 20 That's 50 degrees of total correction and I double-check myself I say she's got zero degrees of lumbar lordosis right now if I give her 50 degrees of correction Am I gonna be within that 10 degrees or 9 degrees of her pelvic incidence, which is 58 which yes I am and if I can just execute that now I can get her back there I can't cut a 50 degree PSO in this in this patient So I do a an a lift at l5 s ones where she still moves I get 20 degrees from a simple a lift where She's really flatted out I put a hyper lordotic cage in there and I get her back pretty well balanced and then I do a PSO So here's after an a lift I do that One morning get her up three days later I bring her back into a PSO and we get her back to nicely aligned and you can see her post-operative CT that PSO showing There I don't have inner bodies at some of those levels, which is a risk for rod fracture But if you look at her fusion mass, that's you can see your staple still here So it's an immediate post-operative CT She is bone on bone through a very large portion of bone and and the chance of healing that is really good So I'm not gonna do a big literature review today But this is what I call the vicious cycle of failure sagittal imbalance There's plenty of literature that would lead you to think that that leads to poor outcomes It also leads to pseudo arthrosis and it also leads to increase adjacent segment failure That's a feedback mechanism on a sagittal imbalance If you have adjacent segment disease proximal junctional kyphosis, you get even more imbalanced that leads to poor outcomes so you want to keep your patients out of this cycle leading to poor outcomes and it starts with getting them sagittally aligned as We've evolved to a standing posture you can see that in this I show the slides of the evolution of thought but evolution of the pelvis has really changed significantly and The evolution of what we're doing in terms of evaluating is this EO system is coming out We're seeing more and more deformity centers are getting them. We're getting ours in the fall It looks at the true global alignment. It gets a full body X-ray from the head all the way to the feet and it does a Simultaneous apilateral with one-sixth the radiation of an x-ray. So it's a really cool new technology You can do 3d reconstructions from it. So we're excited to get one. It's like a this crazy phone booth They go in and get this x-ray done But but really that's where the future is and really seeing how these people are aligned You can see what their knees are doing. Are they bending in their knees? What's their pelvis doing? It's quite cool So just one case here's a It's just a good example of totally missing the forest for the trees 58-year-old female with multiple falls treated for cervical stenosis. They thought she had myelopathy. She kept falling on her face So she had cervical stenosis her poster ligaments look like they're buckling in a little bit Causing cord compression and a really well-known spine surgeon took her for a cervical laminoplasty Saw her in the office sitting there examiner. Yeah a little hyperflexic Laminoplasty did the surgery. I don't know how they even did the operation It must have been crazy getting her position, but they do this operation. She doesn't really get any better She's still falling on her face. They send her to see one of my partners He comes and grabs me and usually one of my partners come and says, oh I need you to come see this person It's usually not good news So I stand her up and that's what her her standing x-ray looks like and if you Photoshop her two x-rays together This is what she looks like Now who here thinks she was falling on her face because she had cervical myelopathy Anybody right I've of course not so she had a huge problem and this is her best effort at standing I stood her up there her head would droop One of her biggest complaints is she was a smoker and she kept burning her stomach with her cigarettes when she'd try and take them out of her mouth Right people really really like smoking. So So I I did this to her over a few surgeries, which also is not normal But she doesn't burn herself with her cigarettes Which I actually made her quit and she stayed off. But so that's not normal either and that's a huge huge operation But it's back to a normal upright alignment So she can stand up and walk and do all sorts of things that she couldn't do before. So So inclusion sag the balance is key c7 plumb line isn't enough though. You got to look at the pelvis You got to look at the head as neurosurgeons. We definitely should be looking at the head and thinking through that Know your pelvic parameters though and think big-picture on all these patients if you have a Grade one spondy the question earlier. Should you get a full-length film? Absolutely, stand them up walk them get a full-length x-ray know what you're doing if you're Right, you can get lucky and do a decent job And even if you're not doing a big deformity correction knowing what the balance is Knowing what you have to do to try and set them up for future success is really important. So, thank you

spinal alignment

deformity correction

sagittal imbalance

back pain

radiculopathy

surgical interventions