So our next topic, Mark Schaffrey will give a talk on adult deformity surgery in the osteoporotic spine. I appreciate the opportunity to present this information. Still no financial disclosures. By now you realize probably I'm not Chris Schaffrey, but most of you can't tell the difference between us anyway. So here I am. You get me. So we all know the population is aging. By 2030, 20% of the population is going to be over 65, including me. That's 70 million potential patients. And we've got to get this figured out before I get there. There's a huge prevalence of adult spinal deformity in patients who are elderly or even aging. Up to 70% have some type of asymptomatic or symptomatic spinal deformity. And what is more daunting is that half of those patients, about half, are going to have a reduced bone mineral density at the lumbar spine or the femoral neck. Women are obviously more prevalent than men, and even more frightening that this number may grow to as much as 90% in women over the age of 75. So a lot of people see patients like this in their clinic, 84-year-old, in generally good health at 84. If they're 84, they're probably going to make it to 90. A couple years ago they were walking a couple of miles. Now they can't make it to the mailbox. They have back and leg pain when upright. She lives independently, but her kids are saying, you know, that's coming to an end. ODI is 61. Get a CT. There's compression deformities. There's loss of lordosis. There's significant spondylosis, central stenosis, a lot to do. And so, you know, do a five-hour surgery, about 1,300 cc's of blood loss, all but open. A 10-day hospital stay, complicated by delirium in the early postoperative period, ileus, urinary retention. They go to rehab for 28 days. At the end, they heal well. They have good-looking X-rays, but they're not living independently. Despite this, good reduction in ODI. And you have to ask yourself, and, you know, it's a societal question, was this surgery worth it? And we have to provide an answer, because the lay press is portraying surgeons who operate on the elderly as bloodthirsty profiteers, and this is what's out there. So if we look at the literature, this paper by Justin Smith, and you say, you know, do we have literature about operating on the elderly with adult scoliosis? And the answer is, we do. And, you know, some of the literature is quite good. And what we've seen is that there's actually improvement in ODI and leg pain, leg pain NRS, that's significantly greater than their younger cohorts. And it's really quite amazing that as the disability grows, the potential for improvement in both ODI and in leg pain NRS scores are substantially better than in their younger cohorts, but at what cost? And this is the information you need. If you look at major complications, they're doubled in the 65 to 85 age group as opposed to 45 to 64 or under 45, where they're quadrupled. And so what's included in those major complications? Well, it's PJK, it's instrumentation failure, it's adjacent level compression fractures, it's things that make revision surgery even more complicated. So we have to learn to deal with bone quality issues up front. And bone mineral density is probably falsely elevated in the lumbar spine. In our practice, we only use femoral neck scores when trying to calculate bone mineral density. T-scores, Z-scores, not as accurate. So we look for a BMD. If it's less than 0.6 grams per centimeter squared, it's very concerning for implant failure. And people may have been in the same position as we are. We get this shipped in on Friday night, patients in and outside ED. Poorly planned surgery in an elderly patient, and this is the type of catastrophic failure you can have if you don't plan correctly. So bone mineral density is the single strongest predictor of pull-out strength, and it's linearly related to insertional torque, fatigue failure, and pull-out strength for pedicle screws. The tactile sense of purchase predicts construct strength, and so insertional torque less than four inch pounds is likely to fail early. So bone mineral density normalization improves stability much more than bicortical purchase of screws. So it's really important. How do we address that? Well, thankfully, we have some analogs of parathyroid hormone now, one of which is teriparatide. And if you look at the literature, you know, if you look at prospective, randomized, double-blind literature on this for patients, women who are postmenopausal and presented with fracture, prior vertebral fractures, and you compare them to placebo with supplementation of normal calcium and vitamin D replacement and look at endpoints for vertebral and nonvertebral fractures, bone mineral density, you get really great information where, over a period of 18 months, you can have, on average, 12% increase in bone mineral density. But if you look at it now and you look at some of the literature, you can see substantial increases in bone mineral density even as early as six months. So here's the linear relationship between resistance to pull-out and bone mineral density. And so is there real-world experience, you know, in pedicle screws that show a difference in insertional torque? There is. And in this study, some patients were treated with teriparatide. Other patients were treated with bisphosphate. Other patients were not. And if you look at, in this study, there was a substantially improved increase, improvement in insertional torque for pedicle screws. So over 200 pedicle screws placed from T7 to L5. And there is significant evidence that teriparatide can improve the insertional torque. And if you look at patients who have been randomized between teriparatide and bisphosphonate, again, what you can see is an extra little bump that's potential, where you can actually increase the fusion rates between those two groups, one of which can build bone, essentially, and the other which is probably more likely preventing bone loss. And the difference in the bone union rate was 82% in the teriparatide group, 68% in the bisphosphonate. So a significant bump there. Well, what can we do with the screws themselves? Is there an effect of length and diameter? And the answer is yes. If you have anteriorly placed screws, you improve the fixation and decrease the loosening. And you need to get the screws past the halfway point in the vertebral body. So these are studies specifically done in the osteoporotic spine. And so anterior purchase of the cortex is probably kind of dangerous anywhere but S1. So I think you really have to, though, think about getting screws at least to the 80% point in the vertebral body. How about larger diameter screws? Well, they work initially. So you put in a larger diameter screw in the osteoporotic spine, and there is definitely superior pull-out strength immediately. However, over time, you know, if you don't achieve fusion, those just are creating bigger holes when they start to move around. So when you look at post-fatigue, loading on those screws regardless of diameter, they will eventually have similar rates of failure. So initially you get a bump. Down the road, you have to achieve fusion. So it's a race. So another technique we can use when we need to, either when we don't get improvement with parathyroid hormone or we simply have to force into doing procedures on an osteoporotic spine is pedicle screw augmentation. So we can use polymethylmethacrylate augmentation. It's been proven to improve pull-out forces and have significant improvement up to 350%. But at what price? We know when we, with the polymerization process, there's heat that's generated. There can be reflux through either compression fractures or back into the pedicles if not done appropriately. And there's even some sense that in some animal models there might be an osteosarcoma risk. So I think we have to be very, very careful about that. So if we use conventional screws, what technique do we do? Well, we drill and tap and we fill the body with some polymethylmethacrylate. We look at it on fluoro and then we place the screw. And, you know, some risk for reflux as we do that back into the pedicle. You know, the newer technology is obviously to use fenestrated screws, but you have to watch location of the fenestration. You want to make sure you place your screws anteriorly enough that the polymethylmethacrylate is actually going into the body, either halfway or anteriorly into the body. So another potential technical nuance that you can do, particularly at the proximal part of your constructs, if you have poor pedicles or, you know, there are concerns about using pedicle screws, is you can use hook constructs. The great thing about hooks in the osteoporotic spine is that low bone mineral density does not affect the pull-out resistance for hooks. However, you have to be careful. You can't decompress or decorticate at the lamina before you place your hooks. And another little technical nuance is that if you use two superior claw constructs at the upper levels of your construct, they're actually stronger than screw and hook construct at the top. So I think that's something that you can consider. But if you've ever seen a failure, you know, with two level claw constructs, it's really devastating. And so, you know, it has to be done, you know, very judiciously. And I think a lot of people would say that, you know, the bang's probably not worth the buck. You know, try to get a pedicle screw in there. What about our alignment goals? Are they different? Well, this is a nice study. It utilized a linear regression analysis from the ISSG database. And alignment thresholds were identified in the elderly. And they are definitely different than a middle-aged cohort. So in a middle-aged cohort, you may look at a T1 pelvic angle less than 15, and you'd like to get your SVA less than 2 centimeters. In the elderly, you're looking at a T1 pelvic angle of less than 24 as a target, and an SVA of less than 5.5. So, you know, I think sometimes we look at the x-rays and we say, you know, 5 centimeters doesn't seem appropriately corrected. But when you look at the data, it actually supports that, you know, getting adequate but not perfect x-rays may be the right ticket in elderly patients. So what about PJK? It's a problem everywhere. You've heard it in virtually every talk. You know, it's probably, you know, the incidence is probably between 20 and 40 percent in adult scoliosis surgery. And what's the primary risk that's been identified? It's increasing age. With increasing age is osteoporosis. So what can we do to try to mitigate that? Well, there's a nice study where 41 patients were studied with spinal deformity who received two-level prophylactic vertebroplasty at the UIV and the UIV plus one levels. And these patients, only 8 percent developed PJK and only two developed PJF. And this is substantially lower than reported incidents in the literature. So it develops and holds some promise there. But I think the kind of sexier new technique that you're hearing in all the lectures is using this pet tether technique where you're incorporating these polyethylene bands at uninstrumented levels and tethering it to the rods. And I think this is potentially a very powerful technique. And Shea Bess and other authors reported on this technique where you looked at the UIV plus two fixation and anchoring it between the UIV and UIV minus one rod. And this was the best construct for dissipating range of motion at the adjacent level above your construct. So there's a number of manufacturers who are making these devices now. They're easy to use. But actually one of our residents is publishing with this group and presenting this data at EuroSpine that the benefit really diminishes with this tether device with excessive preload that places that proximal segment into extension. So how do you get that? Well, you over tension the device and you go from a tensioned segment that's in inflection to one that's in extension. And you will, in theory, lose a substantial amount of benefit from your tether. So here's just some of the different loop and weave techniques for these adjacent tethers. So for optimal osteoporotic fixation, what do we need to do? Well, we know we need to use as many fixation points as possible to get the job done. We didn't talk a lot of anterior column loading, but obviously in these cases there's a lot of sagittal imbalance that needs to be corrected. So you're using some type of cage anteriorly and that helps share the load. For screws and fixation optimization, we use large diameter screws that are long at least 80 percent of the vertebral body. We either don't tap or we substantially under tap in the osteoporotic spine. We preserve dorsal cortex, especially when we're using any kind of hook or claw construct. And we use polymethylmethacrylate judiciously if we're either forced to operate on kind of a disaster coming in acutely prior to the correction or mitigation of the osteoporosis, or in cases where we simply don't get a good response to teriparatide. The last two points are restoration of the sagittal alignment is great, but don't overdo it. Overcorrection is going to lead to more complications down the road. And finally, vertebroplasty or tethers at adjacent levels can help to avoid PJK, we think. But if you use one of those adjacent level tethers, please avoid over-tensioning the device and putting the patient into extension. And I think I'll stop there. Thank you very much. I think we have a couple minutes for questions if anybody has some for Dr. Shaffery. Hi, I'm Greg. Whoa. Okay, yeah, I'm Greg Ricker from Jones-Bargus. I actually didn't have a question. I just had a comment about the tether. I've used a tether on the same level as my top screws to help prevent screw pullout on people that I'm worried about, and I've been happy with it. Same spinous process? No, I put the tether on the lamina. I put the tether around the lamina as if it was a claw, and so it's very thin, and then I put my top screws in. Yeah, don't have, interesting idea, don't have obviously any information about that, probably going a little off-label on that, but I think it's, you know, it could potentially act like, you know, so you're using it like a screw and hook construct you're trying to, yeah. Interesting idea. Okay, thank you.

adult deformity surgery

osteoporotic spine

spinal deformities

bone quality issues

parathyroid hormone analogs