Okay let's go ahead and get started. I know Dr. Yang is going to need just a minute to kind of get everybody set up. Welcome again to AAP Virtual Didactics today. We're excited for both of our lecturers today. We just had a great one on the Asia exam and we're excited today or now to hear from Dr. Aaron Yang who's going to tell us about one of the most common presenting problems of the spine clinic. So this should be interesting. We've gone through the goals. Again for housekeeping, we'll keep everybody video and audio muted. If you have any questions, my name is Sterling Herring. If you click on participants, my name should be up near the top somewhere. Double click me and send me a message and at appropriate times I will ask your questions. If you have any general questions related to content or the series in general, there's Candice's email on the screen or you can track us down on the Twitter feed or on the Twitter. And so without any further ado, we're excited to have Dr. Aaron Yang. Dr. Yang, welcome. Thanks Sterling. Before I get started, I'm going to share my screen and I want you guys to try to log on to this poll everywhere right here. And so just, you know, I'm just going to ask some questions. I think it would be good to keep it a little bit interactive. So I'll give you a second to go to this website, PollEV.com. Alright. So thanks again Sterling and everyone for setting this up. I'm going to be talking about different interventions for the sacroiliac joint complex. Let's see here. So I have no relevant disclosures. And so looks like based on our poll so far, we've got PGY3s, medical students. Oh, looks like it's almost like a little race. 3s and 4s mostly. So we got some 1s and 2s slowly joining on. Alright. So I just wanted to get a sense of who's joining us here today and who we're really talking to. So I appreciate everyone for filling this in. So we're going to, let's see, stop that here. So I'm going to basically, here's my outline. I'm going to go over the introduction here, just a little intro, go over briefly the anatomy and how it pertains to sacroiliac interventions, and then talk about intraarticular injections, sacroilateral branch blocks, and then radiofrequency ablation. So I was looking at the schedule, heads up, Dr. Prather is going to be talking about diagnosing posterior pelvic pain. I think she's an excellent lecturer, very well versed, probably do a better job than I can. So make sure you tune in on May 15th at 1pm. So I'm going to try to focus more on the interventions. I'll probably be talking a little bit about how you diagnose some of this stuff in order to pick the correct injection. But make sure you tune into this lecture on the 15th. So here's our second poll. This is sort of a pretest. So I want you guys to put in your answers here. We'll see what people think. What is the innervation of the sacroiliac joint? I have to admit, this is my first time using this poll everywhere, so this is pretty cool. So, so far the frontrunner is the S1, S2, and S3 nerves. You've got sort of a smattering here. Okay, so I'm going to close the poll here. We'll go through our lecture and make sure you hit on the key points to answer this question. So the second question, the following is the most reliable way to diagnose SI joint mediated pain. So far it seems like intra-articular joint injection is the front-runner. Okay, all right, that's followed by, they're all not that great, and then we have nobody picking imaging findings. Okay, all right, so we're gonna stop the poll there. So the winner there was intra-articular joint injections, and obviously we'll go over those questions here throughout the talk. So going on with the poll, using fluoroscopic guidance, accuracy of sacroiliac joint injections increases to 90%. What do you guys think, true or false? Okay. So majority so far think that the answer is true. Fluoroscopic guidance increases accuracy of SI joint injections to 90 percent. All right. We're going to keep going on. Last question before we get into the talk. I'm curious for those who've, oops, sorry about that. For those who are on the talk, how many of you guys are planning to do fluoroscopic guided spine procedures? All right. We're sitting around 72 percent plan to perform fluoroscopic guided procedures. Okay. That's interesting. So Sterling and some people that I work with, we gave a survey that some of you fourth years may have filled out. And this survey was targeting graduating residents. And so what we saw was that out of the 175 respondents, and they represent about 65 PM&R programs out there, that about 74 percent are matched into a fellowship program for 2020. And so again, 75 percent of graduating residents are doing some sort of fellowship. That's what we saw in our survey. And 80 percent of those are doing either an ACGME accredited pain or sports fellowship or a NASS spine fellowship. And so you could see that the majority of those who are doing fellowships are doing some sort of interventional spine procedures. I mean, we just did a very informal poll just now, and about 72 percent of you guys said that you're going to be doing some sort of fluoroscopic guided spine procedures. So look out for those results. We hope to publish them soon. But I wanted to throw this out there. You know, I think one of the very common questions that PGY3s and 4s, as they think about fellowships, come up with is, what type of fellowship is going to help me perform these procedures the best? And so, you know, I will tell you, when I entered fellowship training, we really didn't have a lot of information out there. We did not really have anything regarding NASS recognized spine fellowships, which are new. And so we are hoping that AAPMNR comes on. This is a little plug-in for a talk that we'll give. We're going to have a fellowship panel of different fellowship directors of each of these fellowships, and we're going to sort of talk about what's different, what type of fellowship would fit a trainee, and why. And so just throwing that out there. But I mean, these are the current landscape that we face right now of what types of fellowships exist for those who want to practice these procedures. So getting to the meat of the topic, there's really two main objectives that I want to go over is, first, distinguishing pain from the joint itself, from the posterior complex of the joint. And that includes the overlying ligaments and muscles. And then have some sort of general outline of best practices when choosing these different types of procedures that we have available. And then lastly, try to make a presentation with very limited interaction as digestible as possible. Again, it's great we have Zoom, but sometimes when I can't see people or look at different expressions on their faces, it makes, you know, bring up a question. It can be a little tough to digest. But again, hopefully this will be a topic that you guys will find interesting. So here's a typical clinical scenario. We have a middle-aged male that comes in, has persistent right buttock pain despite undergoing physical therapy. No radiating symptoms into the leg or associated numbness or tingling. Physical examination is positive for Patrick's test, Gainesland's test, and thigh thrust. And what is your next move? You're attending on spine. May have given you a lecture, given you a paper by Laslett in 2012 that talked about, hey, if you have a certain number of positive tests, increase your likelihood ratio of having a possible SI joint-mediated pain. We have three tests that are positive here. What do we do next? So in terms of what I'm lecturing about, here's a typical scenario that we may consider. You know, you start off with a intra-articular joint injection. You may use steroids with that. Most of us will use steroids for this injection. If it helps them and they have recurrence of their pain, at some point you may repeat that injection. If they don't have long-term relief of pain with the injection, sometimes you may see attendings go to what's called a radiofrequency ablation right after. Or they may do sacroilateral branch blocks. Sometimes if they don't have any relief with the intra-articular joint injection, they may consider the sacroilateral branch blocks. And so the point of bringing this up is that I want to sort of elucidate what is going on here. Why do we do certain things? And what's the evidence behind it? And what are we actually treating when we're doing these injections? So here's some assumptions I had during residency training. I thought if a SI joint injection did not work, then the pain must be coming from somewhere else. Pain can come from the SI joint itself. Sorry, pain can only come from the SI joint itself. History, exam, imaging are somewhat reliable in diagnosing SI joint-mediated pain. And lastly, it's easy to inject into the joint. And honestly, this was probably my favorite injection during residency, A, because it's one of the ones that the attending would let me do. And B, it seemed pretty easy to do. At the end of the day, my job is to show you that not all of these are true. Again, these were assumptions that I had during residency. Hopefully, you won't have all these assumptions as you're going through residency. So the first thing to think about is what is the innervation of the SI joint? So going back to our pre-test, the answer was all of the above. Anteriorly, here's the joint itself. This is the pelvis that overlies. You have contributions from your lumbosacral plexus. You have contributions from your gluteal and operator nerves, which are not shown here. Posteriorly, you have your L5 dorsal ramus that innervates the posterior portion of the joint, as well as the S1, S2, S3, and some contribution from S4. I think for most trainees, I think one of the popular answers was S1, S2, S3, and certainly that is part of the innervation of the joint, but we also have to realize that these nerves innervate the posterior aspect of the joint. You also have anterior innervation as well, and that's better seen in this picture right here, where you have the anterior aspect of the joint here, and then you have the posterior aspect, including the different ligaments that are innervated by the sacro-lateral branches, and then the L5 dorsal ramus. And then the L5 dorsal ramus. So this was a cadaveric study where they exposed cadavers and looked at the contributions of the nerves that went to the sacroiliac joints, and what they saw was that S1 and S2 contributed to all the specimens. S3 contributed about 88% of the time, and then L5 about 8 to 10% of the time, and then S4, again, even less. And so this is specifically talking about the posterior innervation of the joint. So what does this mean? Why do I even bring that up? Well, what this brings up is that you can have pain that comes from the joint itself, you can have pain that comes from the posterior ligaments and the posterior aspect of the joint, or you can have pain from both those sections. So intraarticular injections may only provide relief of pain arising from the joint itself, because you're putting the medicine all into the joint and not extraarticular. Pain can also come from the posterior aspect or the extraarticular structures, such as the ligaments and the posterior aspect of the joint. And then the third point is, we talked about radiofrequency ablation, and when we ablate nerves, we're ablating the sacroilateral branches. And so what is that treating? That's only treating the posterior aspect of the sacroiliac joint complex, because we talked about that the joint is also innervated anteriorly. So if you've had experience with an attending where you do an ablation and they get incomplete relief, that makes sense if the pain is also coming from the joint itself. What we already know is that it is difficult to diagnose SI joint pain. In fact, there's been inconsistent evidence that a combination of physical exam maneuvers can reliably diagnose SI joint pain. You know, I mentioned the Laslett article, which most of us may be familiar with. That was, again, published in 2012, where they concluded that if you had three out of five positive tests, then the ratio, the odds ratio of you having, the likelihood ratio of having SI joint media pain was almost as high as four. But since then, there's been other studies that have shown that that has not been the case. And so, again, I think one thing we can take away from this is that you probably can say if none of the tests are positive, if you do five tests and you're O for five, then it's probably unlikely that you have SI joint mediated pain. But, again, that's pretty much what we can take away from the inconsistent evidence that we've seen so far about physical exam. In terms of referral patterns, we have not been very specific in discriminating pain between the sacroiliac joint versus your lumbosacral spine or even your hip joint. And as we know, there's been some studies that have been published that show that intraarticular hip pain, which we always tend to think it always presents with groin pain, can actually present with posterior buttock pain. So not all butt pain is SI joint mediated. That's where I think you should really take away from this. Patient history items cannot be fully relied upon to be accurate in diagnosing SI joint pain. And there haven't been any studies that show the association between imaging abnormalities and a presence or absence of SI joint mediated pain with the reference standard being a diagnostic injection. However, that leads us to this. What about diagnostic injections? Unfortunately, most studies have shown that diagnostic injections can have a high false positive rate. Dr. Kennedy said that could be almost about 20 percent. But, again, here studies have shown they could be positive between 29 to 63 percent of the time. They can also have technical limitations, which we'll go over later. And basically, this assumes that all SI joint pain is intraarticular. However, we just talked about that pain can also arise from the posterior aspect of the joint. So here's some myths of SI joint injections. It's easy to get into the sacroiliac joint, which, again, I thought all through residency. The medicine stays in the joint itself after the injection, which many of us may just assume this. A steroid injection into the joint treats the pain coming from the sacroiliac joint area. And that was the last point. And so here's my next question. How much volume can a SI joint accommodate? So you drop the medicine to do an SI joint injection. What do you guys think? How much volume do you think it can accommodate? So we've got five to six mls. No one's saying greater than six so far. And a lot of this may be anecdotal by what you've seen different attendings draw up in terms of how much medication. Oh, we've got somebody who said over greater than six mls. Okay, so the answer is one to two mls. In fact, they've studied this extensively. And what they've seen is that about, it comes on average about 1.4 mls. But some have been able to demonstrate that it can fill up to about 2.6 mls. So again, when you think about how much medicine you can put into there, you have to ask yourself how much of the medicine is staying in the joint. If you're putting about six mls of fluid into that joint, I guarantee you that medicine is not all going into the joint. It is going extra articular most likely, which can confound what you're actually treating, right? Because that will get into the extra articular structures, which they can generate pain in and of itself. So moving on to the next question. How accurate are palpation guided SI joint injections? What do you guys think? Well, I've got some confident people. I never miss the joint. So it seems like majority of people are saying that less than 50 percent of the time. And so I would say most of you guys are right. Accuracy with palpation guidance is very horrible. I can say that with lots of studies that have demonstrated about 0 to 25 percent accurately into the joint itself based on either fluoroscopic confirmation or cadaver-based studies. And so yeah, hence the reason why imaging would be recommended for any intra-articular SI joint injection. So this one I did not put up whole, but you think about fluoroscopy, what do you think the miss rate is? Think about it in your head. The miss rate is about 4 to 20 percent, and that's a range. But if you think about it, we're not getting the medicine into the joint as much as we think we are. I think that's what I want you to take away from this. Even though using fluoroscopic guidance, we may not actually be in the intra-articular joint. And I will say a way to confirm if you're in the joint is to make sure you get a lateral view of your fluoroscopic image. There you can see that if the needle tip is in the joint itself as opposed to just getting an AP view. And then think about CT-guided SI joint injections. Do you think that is more accurate than a intra-articular injection using fluoroscopy? It's actually about 24 percent looking back at studies. So you guys may think that, hey, we're using CT guidance, we should definitely be in the joint, but there's also a miss rate with CT guidance as well. And then we talk about ultrasound-guided injections as it's becoming more of a popular modality. You can see the needle tip here, you can see the echogenic lines here going right into the joint itself. I think there's certainly advantages. Obviously, lack of radiation, you can do it at the bedside, you can visualize the different soft tissue structures around it. However, I think, in my personal opinion, the disadvantages outweigh the advantages in that you really cannot confirm very well if you're vascular or not. And if you look at most of the studies, successful intra-articular injection rates are very widely reported, 5 to 88 percent accuracy. I would say it's maybe closer to 40 percent accurate as opposed to as high as 88 percent. And the other disadvantage, it's very operator dependent. You may have someone who's very skilled in using ultrasound at the bedside for procedures and some who are not, some who are not familiar and looking at the different structures around the SI joint. And so just some food for thought on that. This table just basically summarizes some of the pros and cons of the different modalities. I probably would say CT would utilize way too much radiation exposure to use this regularly. Really, the bottom line is that there is a failure rate with fluoroscopic guided SI joint injections. We're not always into the joint as much as we think we are. And then there's technical limitations of intra-articular injections. You know, I mentioned about how much fluid the joint can hold. Well, we know that there can be a lot of leakage of the fluid itself, either from capsular defects or just not being into the joint itself. And then what happens is you're anesthetizing the posterior structures. We also know that you can have communication of the joint with the S1 foramen. So you might get epidural flow with an SI joint injection. And so that can also confound things. And then lastly, we've sort of talked about this significantly, about how difficult it can be to know if you're truly in the joint itself, and which can lead to false negatives or false positives. So I want to just briefly touch upon the evidence that we have out there in terms of SI joint injections. So there's been two randomized controlled trials that have been looked at for SI joint injections. This one right here, the top one by Magers, was a sham controlled study looking at efficacy. And what they saw was that those who had sham had no improvement at one month, as opposed to those who had steroids, had greater than 70% pain relief. The second one was more of a pragmatic study that looked at triamcylinal versus dextrose. And overall, they saw that dextrose had greater improvement in relief compared to steroids. However, the study had multiple limitations. They could have multiple repeated injections. So the outcomes were sort of harder to analyze, as opposed to the sham controlled trial by Magers in 96. And then lastly, you have three studies that looked at utilizing dual blocks as diagnostic criteria. So instead of saying, oh, you have SI joint median pain based on physical exam and and history and we're going to do this injection, they utilized diagnostic blocks first before they received steroids. And so there's been two retrospective and one prospective studies. And the outcomes have varied as well in terms of relief with the steroid. But there's still a lot of unknowns in terms of intraarticular injections. The first thing is joint access. And so there's two primary different ways that attendings get the fluoroscopic image before they actually inject. So the picture here on the left, under the label B, this is where you superimpose the joint lines. And so you tilt the fluoroscopic image contralateral oblique to look at the joint, and you see one joint line. The other way is basically a straight on AP view or PA view for fluoroscopic images, and you can see two joint lines. And as I always tell my trainees, the medial joint line here is going to be the joint line that you're going to be aiming for, not this joint line, because that is the anterior joint line. You're going to hit bone, but here this is where the capsule is. And so there's been no studies that compares those two different techniques or shows superiority of those two techniques. There's been some studies that looked at injecting at the mid portion of the joint as opposed to the inferior portion of the joint. The primary reason we inject the inferior portion of the joint is because there's more synovium. There's more capsule here. As you go higher up along the joint, it becomes more fibrous. And so there's not as much of a true synovium, hence the reason we're not really injecting all the way up here for SI joint mediated pain. And then the third thing is there's very small amount of literature to support contrast patterns in terms of efficacy of the injection. And so they looked at contrast patterns and seeing if the contrast, if it spreads significantly throughout the joint, does that lead to better outcomes? And there's really small amount of evidence to show that that makes a big difference. But just another food for thought. Second thing is instead of doing intra-articular, what about an extra-articular joint injection? And there's some mixed literature out there about doing an extra-articular injection where basically you're injecting the different ligamentous structures around the joint itself. And so some people will inject into the intra-articular joint and also inject some of the medicine along these dorsal ligaments as well and see if that will provide extra relief or not. And then lastly, some emerging literature on prolotherapy and PRP. Again, I would say the evidence or the body of evidence is very small. We don't have much out there and there's been pretty low quality evidence that PRP has been helpful for SI joint mediated pain. But some literature to come out here soon. So my last question before we decide to move on with the rest of the lecture. The answer here will determine whether or not I finish this or stop. All right, I think we have our answer. I think enough of us have been watching. Oh wait, someone has not been watching the last dance. All right, but this is good enough. I think I'm okay with going on with the rest of the lecture. A couple of folks from Cleveland, so there's probably some. Oh okay, that's true. There's probably a couple folks from LA, so that's a whole thing. Oh yeah, I get that. But majority here, 94 percent, I'll take that. Enough people have been watching the last thing. So in terms of using injections, how would injection help us determine where the pain might be generating from? We talked about intra-articular joint injections so far, but there's another area called sacral lateral branch blocks. We talked about two different areas that can generate pain. The intra-articular joint and then the posterior SI joint complex, which also includes ligaments. Dr. Kenney did a study where you're looking at fluoroscopic guided diagnostic and therapeutic injections. I'm going to be focusing mostly on the diagnostic part for injections. This is a busy slide. I want you to just have a couple takeaways from this, and we'll start from the bottom. Really what this is showing is that if you do a diagnostic block and you put steroids in there, the prevalence of SI joint mediated pain can be as high as 60 to 60 percent, and here you have sedation, 70 percent. So if we use a cutoff to diagnose somebody with SI joint mediated pain as having one injection, and we decide to use a cutoff as 50 percent and give them sedation, that means about 70 percent of them have SI joint mediated pain. Then if we decide to take away the steroid, you can see overall the prevalence goes down. Then let's begin up here where we basically add steroid, but we do controlled injections, meaning two separate injections, and then if you have the most stringent criteria right here, where you basically do two blocks with anesthetic only, you can see the percentage positive is low. So the whole takeaway is look at all these different studies and what they're using as their diagnostic criteria. That makes a big difference because the prevalence can really vary in terms of all. So the more stringent cutoff you use in terms of pain relief to diagnose someone with SI joint mediated pain, the less likely they're going to have positive injections. If you add steroids, that increases the chance that they're going to have greater relief, which makes sense, but you're losing the diagnostic capability of that injection. So if you want to be more specific to that, you should probably not use steroids. You should probably do more than one block, and we say dual blocks to see if they may fit the criteria of SI joint mediated pain at that point. So what do we get away from that slide? Really a lack of reference standard. We do have a false positive rate with injections, as you saw there. Probably would estimate that's around one percent. Even though studies with very rigorous criteria, there is some flaws. You have to think about how are we diagnosing patients with SI joint mediated pain. When we talked about physical exam in history not being very reliable, if we're doing injections, well it matters what your cutoff is. It matters what you're actually injecting. So then moving on to sacral lateral branch blocks. So instead of injecting into the joint, we are anesthetizing the sacral lateral branches that innervate the posterior aspect of the joint. And so this was a study that was done by Dreyfus. What they did was they took 20 healthy volunteers, and they basically injected their joint with contrast, and basically distended the capsule with contrast material. This is what you're seeing here, and they recorded if they had pain. Yes or no, did you have pain with capsular distension? And they would go to about two cc's of injectate. The other thing they did was they probed the posterior ligaments on these same volunteers, and they recorded if they had pain. So what they did was they recorded if they had pain with capsular distension and probing of the posterior ligaments. They brought them back a week later, and so before the injection, what they saw was that yes, everyone had pain with ligamentous probing. Yes, everyone had pain with capsular distension. They brought these same 15 people back a week later, and 10 of them got 4% lidocaine, and then 5 of them got normal saline. And what they saw was that for those who had anesthetic injection, they saw that about 40% of them did not have pain afterwards when they did a sacroilateral branch block along the ligaments, but 60% did still report after having these blocks, they still had pain. And then when they did the capsular distension, about 40% of them did not feel pain after capsular distension. For those with saline, they all felt pain along the ligaments with probing, which makes sense. I should step back and say this is what's called a single site, single depth sacroilateral branch blocks. That's in the title. The ability of single site, single depth sacroilateral branch blocks. What are they doing? Basically, they're going after where the foramen is, and they're going around the nine o'clock position of the foramen and injecting anesthetic at one spot along the lateral portion of the joint. So single site, single depth. So you have one, two, three, four spots here. And what they concluded after doing this was that these single site, single depth blocks do not reliably anesthetize the dorsal ligaments or the SI joint capsule. This test is not good to diagnose patients with pain with posterior SI joint complex pain. So after that study, they also at the same time did a study to look at the sacroilateral branches, a cadaver study, and they saw that there was very, there was significant amount of variation in the anatomy of the sacroilateral branches. And why is that important? Well, if you're doing a single site block, you may not capture those sacroilateral branches, because those branches could be out here laterally or inferiorly, and you may not be able to anesthetize those areas. So what Dreyfus did was basically the same study, but he did a different injection, what's called a multi-site, multi-depth sacroilateral branch block. And so before we get to this table, what they did was they would basically anesthetize multiple areas lateral to that foramen to compensate for the variation in the anatomy of the sacroilateral branches. And so what do they see with this study? Basically, this study showed that when they did the same thing again, they proved that they had pain, they brought them back, they did these blocks, they saw that this time 70 percent of these volunteers did not have pain along the ligaments with probing after they had these multi-site blocks. And this is different for single site blocks. They also saw that with capsular distension, really both of the groups did not have any significant difference in relief with capsular distension. So they concluded from this was that multi-site, multi-depth blocks anesthetize the dorsal ligaments but not the joint capsule. So really what I'm trying to take away from this is that single site, single depth blocks do not reliably anesthetize the dorsal ligaments or the joint capsule. Multi-site, multi-depth blocks more reliably anesthetize the joints, not 100 percent, but more reliably than single site, single depth blocks. So really what we have to think about when we do these blocks, what are we treating? Are we treating the joint capsule? Are we treating the dorsal ligaments? Are we treating the articular surface of the joint? We talked about these nerves innervate the posterior capsule and the posterior ligaments of the joint and not the full articular portion. So if you think about all the the intra-articular injections and the multi-site blocks, intra-articular blocks have been really, I think there's just a lot of unknowns whether or not we're truly diagnosing SI joint pain correctly just based on intra-articular blocks. We do know that, as I mentioned from the Kennedy study, that you should use anesthetic only and perform dual blocks if you really want to reduce the false positive rate. And then consider the goal of the blocks. Are you trying to purely do it for diagnosis and of what? And then are you thinking about prognosis? Are they going to benefit from a further intervention? So lastly, you know, now what? Now what do you do? If you have a patient who responds well to a sacroilateral branch block, what does this mean and how is it going to affect your treatment? And so last point we're going to talk about is radiofrequency lesioning of the sacroilateral branches. And so you guys may have seen this for lumbar facet joints, but we're going to be particularly talking about sacroilateral branches. And so what is radiofrequency ablation? For those who don't know, really the thousand foot overview is that you're creating electrical energy to cause a thermal lesion to coagulate nerves and you're anesthetizing as a result of that, a painful structure, whether that be the facet joint or the SI joint complex. You can see pictures here. This was a bovine model where they used different gauges of needles, and they're showing that at the needle tip, you can see different areas of lesion depending on different gauges of needles. These are probes for a lumbar radiofrequency ablation. So if you look at the literature, there was a systematic review in 2015 that showed moderate evidence for sacroilateral branch radiofrequency ablation. However, the relief was limited in extent. It was not, obviously, it was not effective in blocking all pain from the SI joint itself. So we sought out to look at the most recent literature and see what's been published. Now, we just talked about how do we diagnose someone for this type of pain? How do you know if it's for ablation? Which diagnostic procedure would you pursue? We talked about the limitations of intraarticular injections. We talked limitations about single-site, single-depth blocks. But what do you think most of these studies, and there's probably been about 30 to 40 studies on radiofrequency ablation, what do you think, which procedure do you think they most commonly did to diagnose someone to have pain that would be amenable to radiofrequency ablation? And so, surprisingly, or not surprisingly, it was intraarticular injections. Then we talked about what happens when you use different criteria for cutoff or relief, right? We saw in the Kennedy article that if you use a higher stringent criteria of 80% relief, the prevalence of SI joint pain goes down. But if you relax that criteria to, say, 50%, it goes up. So these are things to think about when you're looking at these papers regarding SI joint interventions. What are they doing to diagnose them? What are they using as a cutoff in terms of relief, because you can know that can affect the prevalence? And then are they doing just one block? Are they doing two blocks? So when we looked at the studies, I think there are two main takeaways from this. Majority of the studies, 27 out of the 32, used an intraarticular injection to determine whether or not they would undergo radiofrequency ablation. And more than half of these studies used anesthetic with steroids for those injections. There were no studies that we reviewed that demonstrated they used multi-site, multi-depth blocks. And so even though Dreyfus demonstrated in his study that these are much more accurate than single-site, single-depth blocks, none of the studies have used that as criteria. So what does that mean in terms of outcomes? Well, it means that your success rates are going to be extremely variable because we have a very poor selection criteria for those who are undergoing radiofrequency ablation. We talked about intraarticular injections are not necessarily treating posterior complex pain, but radiofrequency ablation is treating more posterior complex pain. So if you have poor selection criteria, hence the reason why you have such variable outcomes in terms of those who do well with ablation. Second point is that we talked about the variation in anatomy of those sacroilateral branches, right? We put the probe down and we're not even over the sacroilateral branch, well, what does that mean? That means we're probably not going to fully anesthetize that joint. And so the takeaway is that a positive SI joint injection does not equal successful outcomes with ablation. And so that's why we see such varying outcomes, probably 32 to 89% of patients. I mean, that's a huge range of people who may do well with an ablation. What this picture is essentially showing is a radiofrequency probe and creating what's called a bipolar lesion. You're trying to create a burn between these two probes. And what you're trying to do is, since there's such variation in anatomy, you're just trying to carpet bomb this whole area with the radiofrequency energy so you can account for the variation anatomy. So you're essentially creating a large strip lesion to basically ablate those nerves, no matter where it goes along out of the foramen to the joint. I'm not going to really go over this too much, but we have different types of technologies we use for radiofrequency ablation. Some of you may be aware that we have something called cool radiofrequency ablation. Basically this is creating a larger lesion than your typical conventional or monopolar lesion. I showed you in the picture before what's called a bipolar lesion. Basically you're creating a lesion between two separate probes. And then we have another type of probe, what's called a multilectrode probe, where they combine a monopolar and bipolar lesions. So basically, like I said, what you're trying to ensure by doing any of these ablations is to create a large enough lesion to account for a varying anatomy of those sacroilateral branches. There's been some evidence out there comparing cooled versus conventional radiofrequency ablation. The outcomes are varied. Some showed no difference, one favored the other versus the other. I think the evidence is really limited and varying for that. And then more recently, we've looked at different radiofrequency techniques and basically the bottom line for any of these is capture rate. We want to make sure we cover as much ground as possible. And what is the best way to capture as much of the SI joint as possible so we know we can capture all those nerves. So my key takeaways from the ablation part, the inability to ensure lesioning of all the sacroilateral branches, and then you combine that with poor selection criteria can explain why we have such varying success rates for ablation. Majority of the studies to date have used intraarticular injections as part of their diagnostic algorithm. And then we have mixed evidence comparing cooled versus conventional RFA. So we are reaching the end of my talk. Here's my take home points. History, physical exam, and imaging all have limitations in diagnosing SI joint pain. Not all pain is from the joint itself. There are extraarticular causes of buttock pain or SI joint mediated pain. What you do in terms of interventional treatments can vary depending on what area you're specifically treating. And then multi-site, multi-depth blocks are most reliable in diagnosing pain coming from the post-SI joint complex. Hence they should be used in studies for radiofrequency ablation, which none of them have done so far. I'm going to leave this up here. This is some recommended articles to read if you want to do a deeper dive. This is pretty much where I've gotten a lot of the different information that I presented you today. I've included a lot of these different articles. I think these are a great starting point. If you want to go even deeper, you can look at the references within those articles. But as you can see, a lot of these are reviews. And so it combines a lot of what's already out there. I've also included the landmark article by Dreyfus about the multi-site, multi-depth blocks, which is one of the articles you should definitely know about, especially if you're performing some of these procedures itself. So now, I've presented some of this information at AAPMNR, but some of the colleagues I worked with this on. All right, guys, thank you for your attention or lack of attention. I can't really tell, but I'll take some questions if anyone has any. You can also send me a message through Twitter if you have any other questions as well. Awesome. Awesome. Thank you very much. Somebody let me know, we were having some sound issues there for a second. I think I addressed them. If those continue, please let me know. So a couple of questions. One is talking about innervation of the joint. One of your quiz questions was, where does innervation of the SI joint come from? And like 30% is anterior, is that correct? You mean like how much of it is posterior contribution versus anterior contribution? Yes. Yes. That is a good question. I'm not quite sure if I know off the top of my head what percentage contributes to what. I would say if I had to guess, I think most of the contribution comes posteriorly. However, again, if you're talking about the joint itself, we know that the sacral lateral branches really only innervate really portion of the posterior aspect, maybe a third of the posterior aspect of the joint. So if you're talking about the joint itself, then I would say actually the anterior portion gets more innervation to the joint itself. But if you're talking about the whole complex, including the joint, I think that's a more difficult question for me to answer. Interesting. So if there's a portion of the joint and the joint complex that has anterior innervation, is there any approach to addressing any of that anterior innervation? I mean, does RF get some of that, but injection doesn't, or how does it work? Yeah. Unfortunately not. I mean, I think the best treatment we have currently is an intra-articular injection if you're talking about the joint itself. Someone asked me, well, can you ablate the innervation to the anterior portion of the joint? I don't think reliably. I haven't seen anything in the literature to say, okay, we're going to start ablating some of these other nerves to see if we can also get the anterior joint to target that area more. Okay. We have a question over here, have you had any experience with insurance reps denying your claims for SI joint interventions and any idea what literature they're using for their denials? Yeah. Actually, this is a very common question for a lot of attendings who practice this. Absolutely. You know, I know that Dr. Cheng mentioned three out of five findings. That is absolutely another big thing for, if you want to do an intra-articular injection, some insurance will say, sorry, doc, I only see two out of the five findings on this study, on your documentation, so we cannot approve this injection. And so, I mean, a lot of these studies, I could prove to them, hey, well, there's three other studies that show that those physical exam maneuvers are not very accurate. So it is very difficult as you're trying to battle insurance companies because they just want literally three tests written on there so they can approve an SI joint injection. For ablations, I think it's more difficult to challenge because, you know, I could say, well, let's look at the literature, but then we look at the literature and the rates are all over the place. Like I said, I think most insurance companies do not realize, hey, like I could sit here and I just gave you an hour lecture on this, but we're using the wrong diagnostic criteria to determine who gets an ablation, hence why you have all these varying studies. And the insurance companies take that as, well, it probably doesn't work. So we're not going to use, we're not going to approve this because it's totally, we consider this study as more of a investigational type treatment and not showing any good outcomes. And I think part of it is just the doing of the literature so far. I'll tell you, I've been yet successful to use that argument to get an ablation approved. Anecdotally, what I end up doing for these patients where I cannot get a SI ablation approved is to do an extra articular injection along with an intraarticular injection. So we talked about putting steroids and lidocaine into the joint, but you can also inject some of that medicine around the extra articular structures to see if they get relief. And I have one example. I had a patient who had radiographic findings of SI joint osteoarthritis sclerosis along the joint line, did very great with the injection, only lasted about one or two months. And so I said, okay, well, we could try a sacroilateral branch block. Some reason insurance approved that and they did, they had 100% relief with a sacroilateral branch block. We did it twice. And so I was pretty sure this patient would respond well to the ablation. The insurance did not approve it. And so we ended up doing an intraarticular injection. I also did an extraarticular injection and he's done fantastic. It's been about three months now. So I don't know, we're sort of limited on that. I wish there was an easier way to navigate that, but unfortunately not. Okay. I appreciate it. Another question. So CoolRF is looking promising. I know you mentioned kind of mixed reviews, but at least Steve Cohen's paper suggested that it might be helpful. But I understand it's far more expensive than traditional RF. Do you think that, A, do you think that is a barrier to further study and B, do you see that getting better anytime soon? Yeah. Yes. I think the cost to not only the payer, but also to the provider, because those are expensive equipment. Like I said, I think the bigger picture to take away, whether it's cooled or conventional is how much lesion are you getting? I mean, I think you can be just as successful with outcomes, whether you did a cooled RF, because like I said, the CoolRF, you're getting a larger lesion size, but you could do a bipolar lesion like I showed in that picture and get a significant amount of area covered. So I think it's more about coverage as opposed to the technology in my personal opinion. But I think there are certainly challenges of implementing cooled RF in a lot of different places because of the costs associated with it. I think the bottom line is just trying to get as much area as possible as opposed to just using one technology over the other. Okay. A couple of more questions. One, is there a specific scale you use to evaluate patients and decide who's going to be eligible for an interventional procedure or is it just kind of... That's a good question. I really don't. I'll be honest with you. I think everyone is very subjective on what they use as a cutoff in their head. Some people may use 50% cutoff. Some people may use a very stringent 80% cutoff. I personally, to be honest, I don't. I will say, for example, medial branch blocks, I think that's more published in SI joint, but for medial branch blocks, I'd want 80% SI joint. I don't have a stringent criteria for that. Okay. I think this is an interesting one. Given the biomechanics of the SI joint and kind of its connection with the rest of the pelvic ring, are you familiar with any studies that correlate SI joint pathology with pubic symphysis pathology in non-trauma cases? To be honest, no. You know what? I'm going to share these slides. I did review some articles. If you look up, I'm going to type this in this chat so everyone can see. I think it's Idiopathic Pelvic Girdle Pain Supplement, and it's in the PM&R Purple Journal, and there is a significant amount of literature. A lot of the studies I looked at here are in that, and Dr. Prather was actually one of the co-editors with Dr. Kennedy. But they did actually talk about manual therapies, and they talked about what's the evidence behind that with SI joint-mediated pain, because I think a lot of us think, hey, well, there must be some movement of the SI joint that's causing some of this pain, so let's send him to physical therapy and do manual therapy to maybe somehow affect the movement of the SI joint itself. But actually, there's a really good article within that supplement where they talk about how the SI joint actually does not move that much. There's really not much biomechanical change of the joint itself. It's pretty stable, and really, the manual therapies that come along with that is not really affecting the actual movement of the SI joint itself. So I probably would be a little bit skeptical, until someone shows me evidence otherwise, how SI joint-mediated pathology can affect the pubic symphysis pathology. Like I said, I'm personally not aware of that specific question of what is out there, but they did say that during pregnancy, that's when they actually see the most movement of the SI joint and pelvis itself. But other than that, how much is manual therapy really affecting the, what you say, mutation or biomechanics of the SI joint? The evidence has been shown to be very little. Okay. How often are you performing sacroilateral branch blocks alongside an intraarticular injection? Never, because I think that, I have to ask myself, am I trying to do this, like I said, is it diagnostically, am I trying to diagnose something by doing those two things? I think it would really confound what I'm trying to go after. I think as close to that as I come was the example that I gave where the patient was not approved for ablation, and so what I ended up doing was doing an intraarticular injection and an extraarticular injection. Not necessarily a specific sacroilateral branch block, but just putting some of that medicine along the extraarticular structures along those ligaments. Okay. All right, I don't think we have any further questions, but if any do come up, there is your Twitter handle, and I think I'm going to pull up your, I think we have your email here as well. Nope, just Twitter. All right. Okay. Do not email Dr. Yang. You can email me, it all depends on who's on there, but I'll put that in the chat here, so if anyone has any further questions, they can always email me, send me a message. Like I said, I think that's the name of the supplement, but it was published pretty recently, and so you can take a look at that. Awesome. Thank you very much. Thank you for joining us. We appreciate this lecture. It was really helpful. Thank you everybody who joined us today, and again, if you didn't catch all of this, or if you have a colleague that wanted to watch it and couldn't, that's the website psychiatry.org slash webinars, links to all of these recorded videos, and obviously the schedule for the rest of the week. Remember that we have an additional session this evening hosted by the AAP resident fellow council for wellness, and I think it's a group workout. So if you're interested, join us. If not, we have our next didactic lecture tomorrow. Thank you all, and we look forward to seeing you. Thanks, Dr. Yang. All right. Thanks everyone. Appreciate your time.

SI joint-mediated pain

diagnosis

treatment

limitations

pain differentiation

intraarticular injections

sacroilateral branch blocks

radiofrequency ablation

success rates

research