All right, I think some people are still coming in, but it's 3.02, so we're gonna get started. So welcome to our session on new concepts for radiofrequency ablation. We're spanning anything from the SI joint to the vertebral body to the knee. So it's really a talk on the technologies, not necessarily a body part. I'm very lucky that all I have to do is introduce our four amazing speakers, and thank you to the four of you for agreeing to do this. I think we should have plenty of time afterwards for Q&A. So if you have questions, just park them in the back of your head, and we'll open up for questions when the four talks are over. So the first speaker is Dr. Matt Smuke from Stanford, and he will be talking on basal vertebral nerve ablation. Were you waiting for a bigger introduction? No. He has a long list of accolades. I didn't know if you were gonna introduce everybody first, or just me, and then that's all right. Good deal. Thank you, Byron. I'm happy to be here. Welcome everybody to the session, and I'm going to talk about basal vertebral nerve ablation. My disclosure is that Stanford received funds for our participation in the standard care RCT comparison to basal vertebral nerve ablation sponsored by Relievent. And so I received a small amount of salary support during that time for my work performed on the study. I put this picture up here because for years in the spine community, we've been saying the same thing over and over again, and that is that, well, the reasons why the effect size of our treatments is so small is because back pain's a heterogeneous problem, and we have this heterogeneous population, and we provide a nonspecific treatment, and some people get better and some people don't, but the effect sizes overall are small. And what we really need in the spine world is to find specific phenotypes of back pain and deliver specific therapies that target that specific phenotype in order to improve the outcomes. I've been saying that for years at meetings like this. I've said it. I've heard multiple other speakers say it, and the story of basal vertebral nerve ablation is a success story of that, an example of that. And these are the two people that figured it out, and I'm not going to go into all the basic science work that they put in to defining vertebrogenic pain, but it's a huge amount. And the evolution from that to a therapy that targets it was also their work, and so both Mike Hedgeness and Jeff Lotz, Mike Hedgeness, orthopedic spine surgeon in Baylor, Jeff Lotz is a PhD researcher at UCSF, they deserve the credit for making this therapy available to us today. So I just wanted to say that. All right, so I'm going to focus really on the clinical part of this, not on the basic science. What is the clinical population here? It's pretty straightforward for everybody in the room. There are two criteria for patients to be considered candidates for basal vertebral nerve ablation. Criteria number one is they have to have the clinical phenotype of anterior column pain. So these are the patients you see in your clinic that you think of as, that we used to call discogenic type back pain, okay? Now you're going to have to think more broadly in that patient population because anterior column pain can include the disc and it can include the vertebral implants in addition to some other things. So that clinical phenotype matched with a radiographic biomarker, which is MODIC type one or type two changes from L3 to S1, is the indication to consider basal vertebral nerve ablation to treat that person's low back pain. So for us physiatrists, this is a pretty simple patient population to identify and then hopefully talk to them about the treatment options. Now a lot of work has been done by one of my co-presenters here, Dr. McCormick primarily, on trying to better define that patient population. Like what if the amount of MODIC changes is big versus small? Are they a better candidate for the procedure? What if they're older versus younger? Are they a better candidate for the procedure? What if this and that and the other, and it turns out none of it really matters, all right? The volume of MODIC changes doesn't predict outcome, whether it's small or large. It's a binary issue at this point as far as we know. If they have it, they're a candidate, if they don't have it, they're not. And all the other clinical features really make no difference. There's a few things that I could point out here which are basically meaningless, where there's a statistical difference in outcomes, but the amount of effect of those few variables on the actual outcomes is so small that you're not going to ever make a decision about whether or not to treat one of those patients based on whether they have some gapping of their facet joints, which turns out to be a predictor, a slight predictor of a statistically significant but very small predictor of negative outcomes. So you're not going to withhold the therapy because of that. But what does emerge from this work that Zach has done is a little more information about the clinical phenotype. These are people with midline low back pain predominantly, okay? So you can see the heat map there of the responders and the non-responders, and while they look fairly similar, you have to understand that in the clinical trials, everybody was being recruited into those studies based on this syndrome of anterior column pain. So we're already pre-selecting people that we think have a disc or an in-plate sore, so they are people that we think of with more predominant midline pain because we knew that already from prior studies that that's a feature of anterior column pain. But even within that patient population, the responders have a more dominant presence of midline pain, so it confirms that, you know, what we thought we knew, we know. All right, so let's talk a little bit about the patient population and the volume of the patient population. How many patients like this do you see? Another co-pres—well, our moderator, Dr. Schneider, did this work, and what he basically did is he looked at the Vanderbilt database and the PM&R physicians that were seeing spine patients and said, if we look at all the patients that come into the clinic and we apply the criteria of the randomized trials on BV and ablation to all of these patients, how many of them turn out to be candidates for this therapy? And through all that work, he showed us about 3% of patients that walk in your door are candidates for this procedure, so that's a meaningful population when you think about all low back pain. And a population of patients that we now have a targeted therapy, which we're going to talk about. So in order to understand the outcomes, let's look at the meta-analysis. The meta-analysis pools data from all of the clinical studies that have been done on this. Here are the ODI outcomes from the meta-analysis, and on this forest plot at the top, you have the six-month outcomes, and on the bottom, you have the 12-month outcomes in ODI. And what you look for in a forest plot is separation from the center line, because if the whiskers are not crossing the center line, that means you have a significant effect. And so you can see in each individual study, at both of these time points, there's a significant effect for baso-vertebral nerve ablation. And then you compile all that information into a diamond and say, if we put it all together, we group all this data, does it remain statistically significant? And if the diamond crosses the midline, it means it's not a significant effect. If it's separate from the midline, then it is. And so here you can see consistent and robust improvements in ODI at six months and 12 months in patients that are treated with this therapy. What about pain? This is the pain outcomes, again, same format, six months and 12 months. You can see there's one study where the pain outcomes appear a little less statistically significant, but less pronounced, so a lower effect size. There's two studies where the pain effects seem to be even better than they are in the remainder of the studies, so a little less consistency here than you saw with the ODI. So what gives? What's up with these studies that had the better outcome? Well, maybe it's because studies are industry-funded, right? Because we often criticize the data when it's an industry-funded study because that inserts a potential for bias, so you have to be aware when there's industry funding of research of that potential for bias. And it turns out that, yes, a lot of these studies were industry-funded. That's how a new technology gets launched. What about these two studies that had the best pain outcomes? They were the only two non-industry-funded studies in the published BV intubation literature. Both of these out of Europe, both of these using different tools that were available to those teams because they didn't have access to the tools that were used in the studies, and both of them reporting better outcomes than you saw in the industry-funded studies. So if anything, that further validates the outcomes that were reported in the industry studies. Now let's pause for a minute here because we kind of can get caught in some closed-minded thinking, all right? We're used to thinking about treating low back pain with a needle or some sort of percutaneous type of procedure where before we do that treatment, we do some sort of needle-based test to tell us whether or not the person's a good candidate for it. And one of the criticisms that I hear frequently from people about this therapy is that, well, you know, we're ablating a nerve and we haven't even blocked the nerve to determine if the person's a good candidate for the procedure. And that's flawed thinking. We do have procedures that we can perform, which you'll hear about, where we do nerve blocks in order to predict who's going to be a good candidate. But we don't do that for this procedure. Why don't we? Well, there's lots of reasons. But the best reason I can tell you is that because you already get a 75% success rate, which I just showed you the data, by identifying the patients based on a clinical phenotype and an imaging biomarker, right? So where else do we do treatment like that? Radiculopathy. These patients have a clinical phenotype and they have an imaging biomarker. And we treat them. And in the best-selected patients, how successful are epidural injections? About 75%, right? So we already do that for a similar outcome in a group of patients who have the same situation, a clinical phenotype and an imaging biomarker. So that's the reason I put this slide up here, just to say, you know, get checked. Let's not get trapped into thinking that we need to have some other tool to diagnose these patients because we're already achieving outcomes like we get from our best procedures in a patient population that has a similar situation. In fact, it makes me start to think a little bit, kind of bigger picture. If you look at the...this is discectomy, not injection data, by the way. But even the discectomy data for lumbar radiculopathy shows around a 75-ish percent improvement on average, success rate on average, up to 90% in the most controlled circumstances. But I think that with all of the issues in musculoskeletal care, there's not a lot of musculoskeletal conditions where high success occurs above the 75% threshold, maybe 75-80%. But you'll see that over and over again in the musculoskeletal literature. So the fact that we're already there with this therapy tells me that, you know, that's pretty good. And should we stop trying to make it better? No, absolutely. Let's keep doing good research and figuring things out more. But that's not a reason for us to criticize what already exists and is already working. All right. What about safety? Well, in the first randomized controlled trial, which compared BV inhibition to sham, which then demonstrated the efficacy of the procedure, which is what a sham-controlled trial does, there was one patient who had a vertebral compression fracture following their BV inhibition. And it was one of the control patients who crossed over, had BV in, and then had a fracture. When you calculate out the rate, that shows...it comes out to about a 0.4% rate of vertebral compression fracture in patients that were selected using the inclusion and exclusion criteria of the randomized trials, which excluded patients with osteoporosis. You also had about a 2.7% rate of device-related complications. And most of these complications were things related to misadventures with a trocar. Very similarly, in the second randomized trial, comparing to standard care, you had a 10% complication rate. Most of those were temporary radicular symptoms, and almost all of those were related to pedicle breach. So good technique in this procedure matters in terms of its safety. Now there's a publication that looks at real-world data in patients treated with this procedure and shows that the rate of vertebral compression fracture is actually higher in this population. And this group...this is compiled data from two centers. They were treating patients outside of the inclusion criteria from the trials, including the things I listed in red here. They treated patients who had prior surgeries, and they saw vertebral compression fractures adjacent to those surgeries, which you could expect. And they saw vertebral compression fractures at a high rate in people with osteoporosis. In fact, of their eight vertebral compression fractures, all of them had osteoporosis, with an average T-score of minus 3. So 0.4% under the trial. Much higher rate of vertebral compression fractures if you're going to treat people who have osteoporosis. What about long-term data? This looks good. The result from this, RF ablation appears to be durable and permanent. It's not like a medial branch RF, and it has to do with the architecture of the nerve. The basal vertebral nerve has very little collagenous architecture and myelin, and so once the axonal damage occurs, there's not really a pathway for reinnervation, unlike the medial branch, which is a robust peripheral nerve with a lot of architecture that remains intact even after you create the axonopathy, and there's a pathway for reinnervation. So the nerve anatomy explains why this is a durable procedure. Now I'm focused in, look at this top left two-year outcomes graph from the second RCT. I'm going to focus on that for a second just to tell a little story, and that is that in spine care, when we want to compare some novel or new treatment, or some treatment that hasn't been studied already, to another outcome, what do we do? We do standard care as the comparator, because we don't have a gold standard treatment for low back pain, and in study after study after study after study, when you look at the standard care arm of those RCTs, they tend to demonstrate about a four to five point improvement in ODI in the standard care arm, no matter what the treatment group is. The standard care arm has about a four to five point improvement in ODI, and what did you see in the BV in ablation study comparison to sham? That top gray line is all five point improvement in ODI in the sham, so another gut check. Does this outcome look like I would expect based on what I know about the spine research? And the answer is yes. The difference, however, is that the BV in ablation improvement was greater than 20 points on ODI, and when you look at sham comparison to a lot of things that we do, nonspecific things we do for low back pain, like the things listed in green, we know that there's a short term benefit that's about another four or five points greater than the standard care. Even spinal fusion surgery is barely better than that, but at least we know that long term that provides some benefit. So this just gives you an idea of, you know, this is not research, this is not a study, this is perspective, right? This gives you some perspective on the effect size of what we're seeing here. In fact, the effect size of BV in ablation is about four times the effect size of segmental fusion surgery. We also know that the therapy's very good in terms of improvements in healthcare utilization. Patients that receive this therapy stop getting the treatments for back pain that they were getting prior to it, including opioids, injections, and other things. And then hot off the presses, we know that it's cost effective too. In fact, if you look at this graph, this shows the cost effectiveness of the procedure in a single graph. On the left side, you have the cost per QALY, the traditional, the current willingness to pay threshold's about $125,000 to $150,000 per QALY, and you can see at six months you're already at that threshold. By nine months, you're below it, and you go way below it the further out you go on this procedure, so highly cost effective. So my point here is that this is an effective treatment. It's useful in a very specific patient population that you all see, and improvements are durable. But I want to point out one thing, a point of caution, and that is after I finished the trial and started doing this on regular patients, the rep one day said, hey, Dr. Samouk, we have this seven-minute lesion protocol, you want to try it because you've placed the electrode perfectly at L5 on this patient, so now we can do the seven-minute protocol. Everything I presented to you is based on the 15-minute protocols, and I wasn't thinking that day because I said to myself, okay, yeah, great, let's do the seven minutes. I should have said no because I knew what the data was and what it was based on. So we did a seven-minute lesion at L5 and a 15-minute lesion at S1, and look at the S1 lesion. It looks like the lesions published in the studies on this procedure, but look at the L5 lesion. It's small, and it only goes cephalad from the base of vertebral foramen. Doesn't even include the base of vertebral foramen, so did I misplace that electrode? No, I didn't. It was perfectly placed. That's why we decided to do the seven-minute lesion, right? They said it's perfect, let's do the seven-minute lesion. This patient really didn't get better until we got insurance authorization to go back in and redo the lesion from the contralateral side, and then the patient improved dramatically. So I tell you this story just because I care about your outcomes out there. I have an N of one from the seven minute lesion and I have a 0% success rate with it. So, thank you. Thank you. Thank you very much for that, as always, Dr. Smoot. So next up we're going to be talking, we have Dr. Zach McCormick coming up. He's ready to go. We're going to talk about genicular nerve radiofrequency ablation, another topic where you'll see his name on all of the papers. So thanks for giving the talk. Thanks Byron, and thanks to the Academy for having us. I think, obviously, wonderful talk by Matt. I will talk about genicular nerve radiofrequency ablation, and as Byron alluded to, we're talking about somewhat common technologies, to an extent, but very different conditions. And, you know, as I get into talking about the procedure, I'm really going to keep us pretty focused on what I would consider some top technical pearls that I think everyone should consider if you're doing the procedure or you're considering adopting it. Out of curiosity, how many folks are currently doing genicular nerve RFA? So maybe half, half the room or so. And then same question, but how many folks were doing it, let's say, two or three years ago and are no longer doing it now? Maybe a few. I'll just share that, you know, I've talked to colleagues around the country who had tried it and were using it, were not particularly happy with their outcomes and dropped the procedure. I think there are other, yeah, right, and we talked about this. I'll give you my thoughts on, you know, on some of that and ways that you can maybe improve your own patient outcomes. Or again, if you are someone who perhaps you had been an early adopter, you had been using old protocols and were not happy with how your patients were doing, there are some changes that you can put into place that will make a difference, and I'll show you the data for that. So these are my disclosures. I do have research grants related to radiofrequency ablation technologies and some consultancies with companies that do manufacture radiofrequency technologies. So you know, the story of genicular nerve RFA is old, emerged out of, really out of, you know, after the early anatomical studies, out of work from a plastic surgeon who got interested in being able to treat chronic knee pain by a nerectomy. So doing open nerectomies, and this was a plastic surgeon at Johns Hopkins, and he defined his own protocols, published his results, and that was going on in the mid-90s. And then he kind of stopped publishing and there wasn't much about it until about 2011 when Choi and colleagues published the first randomized control trial, and this is a sham control trial, that used a three nerve protocol, and I think that's what probably everybody in the room is very familiar with, the original three nerves, or let's say three target locations that were proposed by Choi, and that was really carried forward. There was a whole cascade of studies, and I mean, there are easily over a dozen, there's probably more than 15 randomized control trials at this point of addressing genicular radiofrequency ablation. But a lot of the early studies, they used those same three nerves based on assumptions from the Choi and colleagues, and some of the anatomical work that they did. When we look at the earlier data, and this is from a systematic review that's now, the search is about three years old, and I'll show you some newer stuff, but a lot of these outcomes look pretty good, and in a lot of the early prospective work, we were seeing responder rates between 55 and 75%. Dr. Smook made a great point about there's probably a ceiling in musculoskeletal medicine, I think you said 75, 80% is probably the top end of what we can expect in a responder rate for an intervention for musculoskeletal pain of whatever type. I will also emphasize that in the knee, this is different. So back pain, as was well articulated, very heterogeneous complaint, meaning many different ideologies that potentially could be contributing or driving the back pain symptoms. Patients that are getting genicular nerve RFA, there's not really much of a secret about what's going on. These folks have knee arthritis, or maybe they have a TKA, and that's a little bit trickier, but the vast majority of these patients in our practices and in the studies, they have native knees, and they have OA, and they have pain, and there's not a whole lot of diagnostic dilemma. But what's different about this compared to basal vertebral nerve ablation, compared to the set joint ablation like Dr. Cranor's going to talk about, is there is not a single nerve. There is a much more complex network of nerves that innervates the knee, and we are probably never going to have a way of fully denervating the knee joint. It's just not going to work for a number of reasons. But so anyway, the point is that this responder rate, 55% to 75% in the early studies, is pretty good. There's nothing to sniff at. But as we go forward, there are additional studies that are coming out where the outcomes are not so good. I'll draw your attention to this one right here. This is a study that was not industry-funded and came out of Europe. They looked at a cooled technology that creates a very large lesion, and outcomes had looked really good in their early studies, Davis and Chen, and a number of studies that people are probably familiar with, the earlier large RCTs of genicular nerve ablation with cooled technology. And they found a 33% responder rate. So what's going on? It's a whole lot lower than what was seen in some of the earlier work. Another study here from Thailand that was not technically sham control, I guess you can argue over whether it was a true sham or not, but one group got RFA, genicular nerve RFA. The other got a sham RFA, but steroid injection. So there is an active component to the control group. And there were a few more studies trickling in like this where we're starting to question was there some false signal in the early work. And I alluded to this, but probably as we dig into what's going on in these studies, yes, some of them, perhaps there's some bias or potential for bias with industry funding and some of the early work that followed Choi. But if you start to hone in on what's going on, the studies that appear to fail or the outcomes don't look as good, they either use small gauge electrodes or they don't reposition those electrodes. So there aren't multiple lesions, they stick with three nerves. And conventional technologies that are inherently going to produce smaller lesions. So this is more recent anatomical work that now isn't that, it's not that new anymore actually, but it's the newest thing along with some companion work that was done out of Europe. This is from John Tran and the group in Toronto. But they really carefully, meticulously dissected these and mapped out where various genicular nerves run. And this may be, many of you may have already seen this, but just a level set. Each of these colored lines is showing you where they found that particular genicular nerve in a unique cadaver. So this isn't like multiple branches of genicular nerves, it's that in this particular cadaver the nerve ran here, and in this cadaver it ran here, and so on. So in other words, from one individual to the next, that nerve may be living in a very different location, which is not the case for the basal vertebral nerve. It's not the case for the most part for medial branch nerves, minus maybe the cervical spine from some new studies. So the important thing here is after this work came out is, I think it made a lot of us start thinking about the fact that we are missing these nerves, and that is probably the explanation for why we're seeing variability in some of these studies, particularly those that don't use a more comprehensive lesion protocol. So that's, in theory, this is the solution, right? So we either use larger gauge electrodes, or we place more lesions. We move them and burn again, and move them and burn again, or reposition, et cetera. Or we do both, perhaps even better. And just qualitatively, that makes sense. Just eyeballing things, an original lesion per the CHOI protocol and the original protocol, maybe it would cover an area like this. But if you start placing a lesion back here, and here, and here, and you create what might be considered like a strip lesion across the transition to the femoral condyle, you're going to have a better chance of capturing these nerves. So at this point, a lot of people have thought through, how can we optimize a lesioning protocol? This was a protocol that we put forth a number of years ago with a cool technology, trying to get to more of these nerves, multiple lesions, large gauge technology. This is a piece that was put together by a colleague in Nova Scotia, who was using a three-tined electrode technology, and more or less gets at the same thing. We're going to use a larger gauge lesion, and we're going to create many more placements than the original three-nerve protocol. This is showing how you might achieve the same using a dual-tined electrode that has a very long lesion. So this particular technology, two tines there, but the lesion actually probably extends to about where that radio density begins from. So it's a very long lesion, and it's going to be broader, of course, than a conventional electrode. This can also be done with bipolar technology. So whether you're using conventional electrodes, large gauge bipolar, or perhaps even multi-tined with bipolar, the principle is that you're trying to expand the territory of lesioning. So at this point, there are no prospective, controlled, or comparative pragmatic trials that look specifically at what happens if we expand lesion size or number compared to a control or relative control, pragmatic control group where we're using a classic protocol. But from our own experience, I can give you the next best thing, which is essentially kind of a case control. So this is data. This is old now, but this was a study where we looked at practice audit data from Northwestern. These patients were treated probably a decade ago now, or almost. And you can see, this was an internally cooled technology, so it does create a large gauge lesion. But we use the classic three landmarks in this lesioning protocol. And this was real-world data, again, so all comers, folks who may have been obese on opioids, various comorbidities, not tightly selected clinical trial patients. But we saw, this is the responder rate we saw. And this was the initial work that got me really interested in this arc of, is this just a flawed procedure, or is there something wrong with how we're doing it or how we're thinking through doing it? So fast forward to much more recently, we did another study, same design, cross-sectional cohort data, real-world patients. Same thing, just folks that we treated in our practice, and then we contacted them by telephone, gave them a standardized questionnaire to collect outcome data. And we see a 48% responder rate. And the only thing that we changed is the number of lesions we were placing. Same technology, internally cooled, large gauge lesioning technology, but the responder rate is now 13% higher. 48% is still not ideal. We certainly have room for improvement. But in a real-world cohort, and comparing that to our relative control of the old study, that's a leap. That's certainly a leap. So again, the big take-home here is that implementing some form of large gauge lesioning, whether it's conventional with bipolar or large gauge, or it's multi-tined, or it's internally cooled, using large gauge lesion technology and increasing the number of lesions to cover this territory is what I believe will make a huge difference for your patients and outcomes of our patients. This is a study that is now just closed, which is exciting. It's been enrolling for probably close to four years. Multi-center, 28 sites across the country. It's called the SCOPE trial. And in this study, it's actually really complicated. There's two different phases and three treatment arms in each of those two phases. But in phase two, the interventional portion of the study, patients are randomized to genicular nerve RFA with a very comprehensive protocol. And there's some flexibility given to the treating investigator physician as to which nerves they select. But the goal is actually to target up to 10 nerves that have been described as per TransWork. The next group is sham genicular nerve RFA, but a steroid chaser, essentially. So sort of a pseudo-sham control. And the third group is inter-articular hyaluronic acid plus steroid. We don't have the data yet, but it's exciting because it's now closed and we're following out these patients. And I want to say there are close to 1,200 patients in the interventional arm. So what that's going to do is give us some really meaningful numbers to take a look at, start looking at predictive analyses, et cetera. So more to come. More to come on that. I will end with just alluding to a multi-society practice guideline that is in the process of development. AAPMNR, as a society, is involved, is at the table for this, among, I think, 10 total societies. These are the questions that are being addressed. And in the time allocated, we don't have time to talk about everything, but these are all, I think, very relevant questions that are partially answered. And this guideline is going, there's a formal new systematic review being produced to inform this guideline. So very broad scope, but I will hone you in on the new lit search. This is kind of hot off the press. It's not published yet, but this is a new data poll. And just to get back to this question of how many lesions and size of lesions, these things do matter. We're not answering 7 versus 8 versus 10, but when we do comparisons between large and small lesion technologies, and we pool the data across everything published in the literature so far, I circled the pragmatic trials, mainly because these are prospective, so the quality is a little bit higher than the observational. But you can obviously see the full pooled cohorts here. You look at large gauge, 60% responder rate at six months, compared to 40, I can't see it from where I'm at, but thank you, 46%. So that's a pretty big leap. And then you see similar trend where there's a little bit of degradation of the responder rate, but as expected from six months to a year with the peripheral nerve ablation procedure. And then similar with lesion number. So we don't have enough data out there at this point to look at 4 versus 5 versus 7 or 8 or 10 lesion protocols, but we can say classic versus greater than classic. There is a very real difference. So again, pooled data, classic three lesions at one year, 41% responder rate. Again I can't read it, but 60, thanks, yeah, 68 at a year when you're using more expanded lesioning protocols. So I'll end there. These are just summary points. But I hope maybe this, if you're not already doing this, that it maybe changes your practice in a way that is a benefit to your patients. So thank you so much for your attention, and I will turn it over to Dr. Kreiner. Good afternoon. Full room. Before we get started, how many do lumbar facet ablations? Okay, about half the room. Excellent. How many are totally happy with them when they do them? All the time. Okay, yeah. So it's a procedure that isn't perfect, and part of that I think is patient selection. Part of it, it's a complex problem because a lot of these patients have degeneration at multiple spots. But we'll go through some maybe new ideas on nerve innervation and how we can target the medial branch nerves in the lumbar spine a little bit better. I don't have any direct financial conflicts with anything that we're going to be talking about today. Okay. So what we're going to be talking about is the, you know, for my talk here is the anatomic course of these medial branches and having an understanding of how we can block and treat these nerves adequately. There's geometric considerations in understanding how these lesions are and how they apply individually to the patients that we treat. I don't think I'm teaching anybody anything new here, but understanding the anatomy is important. So the L5-S1 facet joint is innervated by the L4 medial branch and by the L5 dorsal ramus, and the L4-5 facet joint is innervated by the L3 and L4 medial branches. So when you're documenting, document appropriately. I think it's interesting when I have discussions with people trying to get off, they think I'm trying to do the wrong level or whatever else, like that level's fused. I'm like, no, no, you don't understand, right? So sometimes we may have to explain or just, you know, when you're writing your notes, say I'm going to ablate the nerves going to a particular joint if people are confused. But as we look at the innervation of these joints, and this is the original paper by Bogduck looking at the medial branch nerves, as the medial branch nerve comes off the dorsal ramus, it runs basically in the gap between the superior articular process and the transverse process and goes underneath the mammal accessory ligament. So let's see here. We'll show some more pictures as we kind of move along here. But that's the key area where we can consistently find that nerve. And as we look at it radiographically, we can see that nerve kind of courses down, going into, branching into the top of the facet joint from the level it's coming out, and the bottom of the facet joint of the level above. And as we look at this in an AP view, we see similarly this branch comes in a caudal approach. And so if we're trying to create a parallel lesion to this nerve, which is the goal, right? We want to create as long of a lesion in this nerve as we can when we're doing it. We want to be parallel to that nerve. And if we look at how these nerves are aligned here, and this relative to the end plates, we can see, again, once again, these nerves are caudal. So we want our approach from these needles as we do a radiofrequency ablation to be caudal to the end plate, which, you know, usually when we're taught how to do procedures, we align the end plates to start, right? Well, in this particular case, we probably are going to be tilting caudal as we align the area where this nerve is. And I'm going to focus here a little bit now on just the radiofrequency part, because, one, we need to understand a couple things about radiofrequency ablation. As Zach was talking about, the size of the lesion matters, right? And the lesion is parallel to an electrode in typical RF. And as I mentioned a second ago, we want to be parallel to these nerves. We have other technologies, multi-tine electrodes, bipolar. I'll touch on those in a little bit. But if we have a parallel approach to these nerves, it's best. Perpendicular is typically not going to work. That's demonstrated here. So if we're using a perpendicular approach with these needles, we're not going to get a good ablation. And similarly, this is the type of approach we'd like to see. So I'm going to talk a little bit about some new studies. These have all come out in the last year, and I'm going to go over three of them. This is the first one by Tran. All the ones I'm going to talk about are by Tran. But in this particular study, he did very meticulous dissection of 17 different cadavers at multiple levels in the lumbar spine, trying to track the medial branch nerves, the intermediate branch nerves, and the lateral branch nerves as they came out. And then he did 3D mapping of these nerves and overlaid them on the spine so we could see very directly where these nerves are running. And in this particular study, what he was trying to determine is, how far anterior do we want to go when we do this ablation to determine, is it safe to avoid getting the intermediate and the lateral branch nerves and just the medial branch nerve? And, you know, the discussion here, if you go to that, is that the further you go anterior relative to the space on the transverse process when you're looking at the superior articular process, the more likely you are to bring the intermediate and the lateral branch nerves involved. And obviously that's not our goal. One of the things I routinely do when I do my RFAs, though, is I do motor stimulation of those nerves, one, to make sure I don't have stimulation in the limb, but also if it looks like we're stimulating the intermediate or lateral branch nerves and we're getting longitimus contraction, iliocostalis contraction, we might pull the needle back to make sure we don't get that. So at least we do have some safe ways to look at that. But then he looked at, you know, these nerves and said, how do we, you know, can we identify these nerves also from a medial lateral standpoint as we go deeper in? And so in the picture on the left here, he's showing, what they're showing is a medial branch nerve that comes off early in the foramen and runs right in the groove between that SAP and the transverse process all the way along the course of that groove. And then in the pictures to the right, the anatomic picture and then the one next to it, that is actually a medial branch that's coming off lateral. And so there's a gap. So that nerve isn't in the groove right there. It doesn't come in the groove until it kind of arches over and comes down and then runs again under the mammal accessory ligament. So in this particular case, if we're targeting the groove and we're more proximal into the frame or into the groove, we might be missing the nerve or not particularly parallel with it when we're doing that. So staying a little bit more posterior, as you can see, these heat maps show on the, you know, on this superior articular process here, if we stay a little bit more posterior, we're likely to have a greater amount of nerve present in that groove. Okay. So the further we go ventral up here, the more likely we are to not necessarily be missing that nerve. And then the last study that he did is they did, you know, a similar study anatomically dissecting these nerves. And then he looked at the angulation of these nerves relative to the end plate. And then they compared that to the RF angle needle approach used by the experienced doctors in the practice as they're doing the ablation. And what we can see is in that table on the left, or excuse me, on your right down here. And so if we look here, we can see kind of the angles that where the anatomic specimens were at the various levels. And then we can see where when they look at radiographically, what is this angle at? And experienced practitioners typically were not going shallow enough as they were coming in. They weren't quite parallel. So anatomically, when you're looking at your patients and you're trying to figure out how shallow do I need to go, keep angulating that CR probably a little bit more caudal. We can see the angulation here probably increases a little bit as we go lower. But we're looking at about 50 degrees relative to that end plate from a caudal approach. So it's quite a bit of inferior angulation as we do this. So if we're really trying to maximize our lesion size, this is an approach that we would want to take to do that. Now, I will say, you know, we all have, you know, this is a cadaver and it's 18 patients, right? Patients are different. Everybody's anatomy is different. Some facets are more coronally oriented. Some are more sagittal. Some are really hypertrophic. Everybody is a little bit different. And so you're going to maximize the views on your CR. But I think the point you can take home from this is there's a couple points we can probably take home. One is you're going to tend to go more caudal with your approach on these than you normally would, would be more successful. And you may not have to go as ventral with your needle as you might have been doing already to optimally catch this nerve as it's running in the groove. This is a little discussion. You know, Zach talked a little bit about bipolar lesions and everything else. You know, this just gives a graph to show if we're trying to optimize lesion size, there's a bunch of ways we can do it. And, you know, the other thing that we can do in the lumbar spine is there's some studies looking at other types of, you know, ablation using multi-tine electrodes, et cetera. And so this is another thing that we can do to try to target these. You know, I'm in private practice. So for me, paying for multi-tine electrodes, they're expensive and cooled RF is expensive. So for me in private practice, I'm like, you know, just give me the, you know, regular RF needle and I'm going to try to orient it as best I can to get the best lesion size I can. The data on these, though, you know, using the out-of-plane approach is also pretty good. It's equal to the literature for typical RF in the lumbar spine. And so the key points, parallel technique is necessary if you're going to be effective if you're using conventional technology. The medial branch course is variable. It depends on the level being treated and the individual and the degenerative changes present. But optimize your fluoroscopic views. And, again, you probably want to go a little more caudal than you think you need to. And here's the references. Thank you very much. Thank you. Hi, I'm going to talk about sacral lateral branch radiofrequency neurotomy. I have no financial disclosures. I will actually review a little bit about the SI joint complex, just more so for our early learners. Some of this will be familiar to a lot of you guys, and then we'll go over some of our current research that's being done. So the SI joint itself is a small weight-bearing joint between the sacrum and ilium, demarcated by that green space there. The joint itself is quite limited. It is, again, a very small joint. In terms of volume, it holds somewhere between 0.6 and 2.7 milliliters. Beyond the joint itself, on the right, you'll see that there are some ligaments that overlie that joint itself, including the interosseous ligaments and the posterior sacroiliac ligaments. Altogether, this does form the sacroiliac complex, which has some different innervation in the anterior and posterior portion, which becomes a little more relevant as we go on with this. So in terms of pain for our early learners, this contributes to about 30% of all patients with lower back pain. Pathology there can be attributed to hypomobility versus hypermobility. Hypomobility will be a little more related to degenerative osteoarthritic changes. Hypermobility itself can be related more so to hormonal changes related to pregnancy, inflammatory arthritis, hypermobile individuals like Ehlers-Danlos patients, Marfan's patients, and trauma. So within innervation, there's the anterior SI joint itself, which previously, I think, has been thought to really have been receiving contributions from the lumbosacral, trunk, femoral, and obturator nerves. But this study by Cox et al did look at some cadaveric studies, did show that the vast majority of this actually comes from the L5 ventral ramus. And then a few of them will have L4 ventral ramus contributions, and then a combination of the two. But the vast majority is L5. Posteriorly is what we're really dealing with for the most part. So this study by Roberts et al, also a cadaveric study, looked at the innervation of the posterior joint, and essentially, innervations from the posterior sacral network, which is really highlighted in that purple bit there. What they did find was that 100% of these cadavers did have contributions from the S1 and S2 lateral branches, 88% had contributions from the S3 lateral branches, and then from the L5 dorsal ramus, there was maybe 8% of these cadavers had contributions, and then 4% from the S4. So the vast majority of these lateral branches were found to cross over the lateral sacral crest by the transverse sacral tubercles on the periosteum and not within the ligaments themselves. I don't think I'm using this very – there we go. So do we actually have a reliable way of diagnosing pain from this area? So traditionally, we all think of this as like pain below the beltline, buttock pain, and that comes really from Fortin's study, where he injected the SI joint, and 10 healthy patients really were found to have hypoesthesia within this region that was 10 centimeters below the PSIS and 3 centimeters lateral to that aspect. But this study on the left here now by Van Der Werf in 2006 really shows that they did dual blocks of the SI joint and found that responders and non-responders had this pain referral pattern, which is really not located in the butt, really. So we don't really have a good way of looking at SI from just like a referral pattern, being localized to the buttock. And then, so what do we do then? We really rely on our physical exam. And so most of us classically understand that like Laszlo's cluster is what we were taught to use, right? We are looking at sensitivity and specificity of 94% and 78% respectively for if you have three positive maneuvers in the absence of centralization of pain with McKenzie maneuvers. But then my esteemed colleague here, Schneider et al., looked at some individuals, 35 individuals where they basically did also an intra-articular joint injection, but also performed SI maneuvers prior and post injection and really found that there was no really combination of physical exam maneuvers that would predict response to an intra-articular injection. So now what about imaging, right? Because that's the next step. That's what we kind of try to rely upon. But within imaging, we really can't use that to diagnose SI joint pain either because other than spondyloarthropathies, in which case you'll see erosions, sclerosis, or trauma where there's some sort of fracture or joint diastasis. So not really promising in terms of figuring out how to really diagnose this other than some sort of clinical gestalt, really. So now moving on to this whole lateral branch radiofrequency neurotomy, right, in the past that's what we have used as a treatment option for SI joint complex pain. But as of March of last year, Medicare no longer covers this procedure. So they cited a lack of established practice standards, patient selection criteria, and long-term outcome data as reasons to not cover this. So that has downstream effects. And so in the literature that we have for sacral lateral branch radiofrequency neurotomy, there are variable studies that use either the intra-articular joint injection as a patient selection versus a lateral branch block. The problem with this is that the diagnostic SI joint injection may not capture individuals that are actually having pain from the ligamentous portion, right, because it's in the joint itself. And so as you can see here that like in prior studies that there are dual intra-articular SI joint injections show that really they're positive in about 10 to 33 percent of patients that have clinical SI joint pain. On the flip side, when you're dealing with lateral branch blocks, you're not covering any of the individuals that actually have pain from stemming from within the joint itself. And so that's problematic in other ways. We do have one validated study from Dreyfus in 2009 that did show that multi-site, multi-depth lateral branch blocks will cover about 70 percent of individuals with posterior ligamentous pain. He also did take a look at single-depth, single-site injections, but found that that was not quite as effective in covering all of the lateral branches. All right, so how do we optimize our targeting for sacral lateral branch RFN? In 2018, there was a cadaveric study by Stout et al. that used radio-opaque wiring to kind of refine the targeting that Dreyfus used in 2009. And so based off of the targets that Dreyfus had indicated in 2009, really only 60 percent of all of the entire SI joint was actually denervated. And then, really, what that came from was like a pretty high miss rate, I think, from the S3. You see that it's 35 percent versus the S2, where there's only 0.99 percent. And then S1 is pretty high at 9.4. And so using these radio-opaque wires, they were able to identify new targets, which you see kind of in that middle section there, that by altering this, you end up with coverage for 95 percent of the entire SI joint. And so that's that there. Okay. Practice standards are a little trickier. There's a significant amount of variation in techniques when it comes to lateral branch radiofrequency neurotomy. So Shannon et al. essentially took the same cadavers that were used in the Stout study and evaluated coverage of radiofrequency ablation with 17 different versions of monopolar and bipolar techniques that were described in literature. And these were only the ones where they were able to recreate the procedure based off of whatever people had studied. So there's a ton of different ways to do this. But generally speaking, they fall into that monopolar and bipolar section there. And so as a result, really what they found was that bipolar needle placement is better able to capture all lateral branches, which is kind of like a throwback to what Zach was saying, you know, larger lesions are going to be better able to capture things. And so really at the end of the day, sorry, in terms of this chart here, on the left side we have the yellow, the red, the green, the blue, that's going to be all of our bipolar lesions there. And then on the left side, it's more so like how many percentage of the lateral branches that could be covered. And on the right side, that chart shows how much of how many total SI joints would be denervated by this procedure. So overall, bipolar seems to be a little more effective. But I think what this study really highlights is that there's a really important need to really create this like continuous strip of overlapping lesions to really capture all of the lateral branches. Okay. So what do we know so far? So the most recent systematic study was published in 2023. This was restricted only to randomized control trials and observational studies that were published before 2022. This looked at really 33 studies. It really encompassed CAT scan guided procedures, fluoroscopy, ultrasound. And the primary outcomes of this study was really to look at whether or not people had pain improvement with greater than 50% of their pain scores on VAS or NRS. And so no meta-analysis was able to be performed just because of the heterogeneity because I showed you before there are so many ways to do this. But all of these studies did target the S1 to S3 lateral branches as well as the L5 dorsal ramus. So listed here I do have four of the four randomized control studies that are pragmatic as well as the ones that are explanatory. And so these are kind of our best sort of data for this procedure. The only overall what was found was that the lateral branch RFA is successful with the exception of this Van Tilburg study there. And then when we account for all the observational studies in general they found that there was moderate evidence for pain and disability reduction at 1, 3, 6, and 12 months. The recommendation though is to use dual comparative multi-depth which is our Dreyfus validated form of branch blocks there. This chart itself encompasses basically most of the studies that they had looked at and in general there's a lot of red there, there's a lot of green, but in general there's more green than red. And particularly looking at that six month sort of mark and anything sooner than that. For the studies that did have data, continuous data throughout 12 months, even though there's a lot of red there, they did find that the patients who did have relief had at least 40 to 60 percent relief. And so now it brings us to what's new. Not much really because it's no longer covered, but Amato et al. also in 2023, they basically performed the largest retrospective cohort study to date with 128 patients from one practice between 2016 and 2021. And they did look at different block paradigms, different cannula types as factors to predict the success rate of lateral branch radiofrequency neurotomy. Block paradigms that they looked at were dual lateral branches or single lateral branches with one intraticular injection. These are the three techniques that they did look at. So there's a quadrupolar, a trident bipolar, and a 16 gauge longitudinal technique. So their primary outcome was to see if there was a greater than two point reduction in the NRS or greater than 50 percent NRS reduction or greater than 17 point reduction in pain disability quality of life at three months. So what they found was overall, again, that this RFN despite, no matter what the technique was fairly successful. So more specifically for the NRS decrement of two points, there's 66.9 percent of patients had that reduction and then 53.9 for a 50 percent reduction and 50 percent of patients had a greater than 17 point reduction. They also did determine that there's no statistical significant difference in success rates of treatment when comparing a single lateral branch block versus a dual lateral branch block except for that they did see that there was a lower success rate for the RFN if you did use a single lateral branch block with a less robust criteria. The other thing they found was that quadrupolar lesion also had a four times greater likelihood of success compared to lesions that were created by the 16 gauge longitudinal approach. So what they kind of think there was happening there was that the quadrupolar lesion has a shorter distance between the two, between the intracannulas. And so then you can cover the topography a little better for the sacrum. And then the other newest thing would be from Cohen et al. That was published earlier this year. And so this was a randomized multi-centered pragmatic RCT with 210 patients. So these are kind of our biggest studies so far. They looked at cooled RF versus standard pharmacological care injections and integrative therapy. So a pragmatic study here. Their primary outcome was an NRS reduction at three months and their criteria was a single lateral branch block and a SI diagnostic injection, intraarticular injection. So they looked at a peripheral technique for cooled RF and in general they found that there was a mean reduction of pain from 6.3 to 3.8 at three months, which they found to be statistically significant. So our two latest studies really have looked at really a three month sort of time range after intervention. And then our last thing that is the latest and greatest would be people are still coming up with different techniques for how to do this. And so this is basically an alternative to people who have access to multi-electrode probes, multi-tine electrodes, or cooled RF. So it's just a general single, creating a general strip lesion essentially with one probe. But this has yet to be kind of evaluated in terms of research. So it's just a technique. So our main takeaways here now, that is that intraarticular SI joint injections and sacral lateral branch RFA really treat different issues. So an intraarticular SI injection will treat the joint pain emanating from the joint itself and the RFN is really looking to treat posterior ligament pain. There's a lot of heterogeneity in the studies and the techniques used to perform lateral branch rate of frequency ablation, but overall it seems to work reasonably well. So about 50% of patients will have about 50% relief at three months. Not the best thing, but it's something, right? It's something that it's a treatment option that you can provide these patients who don't really have other options. And then at the end of the day, we still need more rigorous research to obtain insurance coverage. So whether or not that means using dual multi-site, multi-depth blocks as a criteria. But also if we look back to that Shannon et al study, really they're finding that all these branches are only laying on the periosteum. So should we look back and maybe validate a multi-site single depth block as something that can be done and maybe revisit some of these studies that have been done and see, look through, look through that lens and see what, what our evidence is there and that's it. Awesome. So I think we have about 10 minutes for questions. I'd invite the panel to come sit up here. If you do have any questions, please use the microphone so it can be recorded and a reminder to please just state your name and if you have any relevant disclosures. Mike's yours. Kush Goyal, Cleveland Clinic. No relevant financial disclosures. Excellent talk. I know we have some of our preeminent interventionalists here. Thank you for a great talk. So a lot of you guys presented great data. I know Dr. McCormick presented like 15 studies for the knee that had shown effectiveness and Dr. Chen mentioned several also for the SI joint. But I know me and a lot of other people in the room have had trouble getting things approved. Could you comment on why you think that is for knee RFA and SI RFA? I'm going to be a little bit, just working, a little critical. The SI and the knee papers just showed that we get a 50% reduction pain in about half the patients that we treat. I think everybody wants better, right? This is an area where we need more good research to figure out how to do these things better if you ask. This is my opinion. Okay. But I think we all desire to have better outcomes than 50% of our patients are going to do 50%. 50% of our patients are going to have a 50% relief to their pain. So whether that's a diagnostic ability to figure out, you know, Zach didn't talk about, you know, do you block your nerves in advance? Do you know what, why is that, why do they not respond as well, right? I mean, I know you want better, right? Like you spend a lot of time doing an RFA on somebody and if only half of your patients are going to come back and say, I didn't get any better, that's a struggle, right? I mean, that's a loss of our own time, right? So I don't know. I mean, I'll let somebody else talk about it, but I think payers want better too. So that's why. There's another answer too, obviously, and that there's a little bit of a zero sum game with Medicare and as there's a lot of new, yeah, very much a zero sum game. So as new technologies come out, so basal vertebral nerve ablation is now being covered, right? And that didn't exist in a commercial sense, what, six years ago? And something, you know, that has to be paid for. So in a Medicare beneficiary, I mean, what isn't going to be paid now or where are the costs going to be, the fees going to be dropped to make room for this new technology? So the, you know, the other side of this is simply, you know, the Macs got together and said, you know, what do we need to take a look at? What's being highly utilized? What maybe doesn't have as good a data as other stuff? And that, you know, SI procedures became a target. SI lateral branch, excuse me, sacral lateral branch blocks and RF became a target. I think we all know that it's coming next with genicular nerve, RFA. The difference is that there are a lot more randomized control trials and Scott's right. You know, I would love an 80% responder rate, maybe we'll figure out a way to do it or 75%. The flaw though, I think there, and again, in the knee is that we're never going to get to all the innervation and we probably, we shouldn't be trying to for safety reasons and vasculature, et cetera. So we're always going to have a bit of a lower ceiling, I think, with genicular RFA. But I think we all share the disappointment with the state of coverage for SI procedures. Hi there, Robin Mata, University of Miami, no financial disclosures. Leading into those questions that have been brought up about anatomic variation and low responder rates and emerging technologies, what are your thoughts in terms of high frequency ultrasound that leverages being able to target that precise nerve so that you know for that specific patient that you're ablating and maybe future directions, RCT with a sham and arm for HIFU and then also RFA to show superior outcomes in the long term? Where do you think that's going? Of those three new studies that I just talked about, the medial branch anatomy, one of them actually specifically mentions and defines targets for high intensity ultrasound ablation of the nerves. And I think that's a technology that is, you know, emerging and I think there's a high likelihood that we're going to see some penetration of that into the market. I think it'll be quite interesting to figure out how that's going to work within the CPT code and payers and how that looks like. Most ultrasound codes are not necessarily in the same sets as the typical procedures that we use. And so it may come about and look different. I'm not entirely sure like where that's going to go and how it's going to go from a coding standpoint, but it's interesting. Yeah, so. I'll just add that I think it's really interesting. I mean, clearly if we have a way of reaching the same outcome of destroying the nerve without entering the skin, that's a wonderful thing for patients. You know, I wasn't involved in any of these early studies with HIFU, but I do wonder about tolerance, like how well the patient tolerates the actual ablation because you're not anesthetizing anything. So I don't know. I've never done it myself. You know, we'll have to see. That's one thing. I think the second question that comes to mind for me is safety. What if the patient moves in the middle of the sort of the cycle of HIFU? And the target that's been focused on, and you know, there are, there's not just one technology out there, but the one that's been published on so far essentially it's affixed to the AI, right, image intensifier. And then you're basically using fluoroscopic imaging in real time to direct where the HIFU is going to be focused. What happens if the patient shifts and all of a sudden that point of focus is now on the neural frame end? I don't know. And I'm sure that the folks that are developing these technologies are coming up with safety measures, you know, risk mitigation strategies that are somehow built into the algorithm how this works. And maybe if it leaves the bone interface it shuts off. I don't know. But those are things that come to mind for me that they may be barriers in how well this works, you know, tolerability and safety. But I think it's a really cool idea. I'm curious to see, you know, I know there's more data forthcoming. It seems like there are quite a few nerves that need to be burned at the same time, but I was thinking about the way the studies were done. It seems to be that you're lumping everybody together and you're trying to determine how everybody responds to a single treatment with, depending on the, regardless of the status of the knee. I have pretty good success rate with the hyaluronic injections, and I know the study, the company, this says when, at least the Sinvus company, when they came out, they said it was 58% with severe, I think it was 78% with moderate, 92% with mild. And that's been probably at least as good or better in my experience. And then when I was, when I'm evaluating patients' knees, I'm looking at the severity of the disease, and so we're measuring how much degenerative changes are there. So when you're getting your 48% result, is it, were all these severe, or were all these mild, or were they moderate, how much did they weigh, how old were they, it'd be nice to have that on your study. And then in your study, you mentioned also that you had combined, one study combined the hyaluronase and the steroid together, and fortunately, my experience, or at least what the literature says when you start doing it, it says that if you do that, you're probably inactivating the ingredient, the hyaluronase. So I don't usually put the steroid with the hyaluronase. So what is your comment on that? So Zach, if you could give a quick answer, because we're out of time, and there's a few questions online, at least one I want to get to before we wrap up. So great comments. That data's there. So I didn't, there's not time to share it all, but most of these studies stratify by Kellgren-Lawrence score, and what's interesting about a lot of the genicular nerve RFA studies is that it is effective still, efficacy or effectiveness is maintained in the KL4 group, severe OA, which actually, in a lot of the viscous supplementation studies, they did not include KL4 patients, they only included less severe OA. And I would just say from experience, I mean, a lot of my own patients that I treat, I'm trying steroid and HA, and if that's no longer working for them, then I might offer them genicular nerve RFA. But at the same time, they probably might not work at the same point. If you're doing, if they're combining those therapies, they probably would inactivate the hyaluronase. The only quick comment I'll make is that there actually is data showing that there's a synergistic effect when you add steroid and, remember, hyaluronic acid and hyaluronidase are not the same thing. So I think this is an important point for Dr. Smoot to maybe answer. We have two questions. I'm going to wrap them into one about BVN ablation. So there was one question about if, when, or when there's an indication potentially for the seven-minute protocol for BVN ablation, and then there was a follow-up question on how you went about getting authorization to repeat it when there was, let's expand it to say when there's technical failure. So there is no indication for the seven-minute lesion in the literature. That's your guess as much as mine when that's indicated. There's no data at all published anywhere in the literature on seven-minute lesions. My N of one is my anecdotal information on that. You can tell me whatever your anecdotal information is, but I'm going on my N of one, and I'm never doing a seven-minute lesion until there's proof that it's beneficial. We know 15-minute lesions get a 75% success rate. I'm not going to mess with that. So you can tell I feel strongly about that, right? We got lucky getting this guy approved for a secondary procedure by explaining to the insurance company, look, you know, the lesion failed. We have an MRI. It shows the lesion failed, and we want to go back in and redo the treatment, and it was approved. I'm not going to take the chance to have to make that argument again, but I can conceive of issues where there are technical failures. You fail to get in during a procedure, and you want to try it again sometime. I guess, you know, there's opportunities, but you're going to have to do the explanation about why there was a technical failure and what you want to do about it. Perfect. One last question, if we're quick. Actually, I have a question to the ablation of the ramus medialis nervus dorsalis in the lumbar spine, meaning this is not a pure sensory nerve, this is a mixed nerve. So the question is, how do you select the patients? Because if you innervate motor branches, you innervate the nerve, and the deep stabilizers of the spine are important, right, because they provide major stability. So are there any criteria in order to select the patients who might benefit best from these procedures? They are convincing. So the sensory nerve and the sensory information is blocked, but the motor output is, in some patients, also blocked. So if you look at the MRIs, if there is a lot of fatty imbibition, right, so you can probably estimate that they are already denervated, so it probably doesn't really make a major side effect in the longer term. But in those who do not see it, would you actually find them eligible for this intervention? So Dr. Smukes published something on this. I'll let him answer quickly what they found. So we looked at MRIs, pre and post medial branch RF, and did quantitative measurements of the multifidus muscle and fatty infiltration of the muscle. We also looked at progression of degeneration of the facet joints at and adjacent to the RF lesions, and compared them in the same patients to segments that weren't treated. And what we found was that there was a trend towards reduction in multifidus size at the level of the lesions, to the tune of about 10% of multifidus size reduction. But that was not statistically significant. However, this is a convenience study, it has a P-value of .07. I think it probably is meaningful, if you want my gut feeling about it. But we didn't see any meaningful changes in degeneration as a result. So I was surprised. I expected to see more multifidus denervation from this procedure than what we found in this study, and it gave me more confidence that it's probably not much of an issue in terms of destabilizing the segment. But if I do have somebody with an unstable spondylolisthesis, where there's instability on Flex-X films, I'm very reluctant to do the procedure, and will only do it with full consent that, hey, if I do this, you may develop a radiculopathy, and you may be visiting my friend, spine surgeon down the hall, very soon. I would agree, you need to be very careful with somebody who has facet diastasis on imaging. So if there's gaping facets, probably should order Flex-X views before you even talk about RFing that patient, and you need to be very careful if you're going to do it bilaterally. And the higher you go, so L3, L2, the more multifidus that you're going to get with your medial branch. So, you know, the lower levels at L4 and L5 don't have quite as much multifidus innervation. So probably not as significant there, and so I think you just need to balance your risks and benefits of that. It would be interesting to see effects 10, 15 years after this intervention. It would be. All right. Thank you very much. Thank you to the speakers.

radiofrequency ablation

RFA techniques

vertebrogenic back pain

genicular nerve RFA

knee pain

lumbar facet ablations

sacroiliac joint pain

SIJ pain

nerve denervation

pain relief

insurance coverage