Many providers have grown weary of offering the same old treatments – physical therapy, steroid injections – to their patients with knee OA, an increasingly prevalent condition that accounts for more than 80% of OA-related chronic pain and disability in the U.S. Fortunately, a new option has emerged: geniculate artery embolization (GAE), described in this talk by interventional radiologist Alexander Lam, MD. Hear and see how GAE works, view the data supporting its safety and efficacy, and find out which patients are the best candidates.
Hi, my name is Alex Lamb. I'm one of the interventional radiologists here at UCSF. Uh, today we'll discuss genicular artery embolization, a novel intervention for knee pain, uh, from osteoarthritis. Uh, I have no relevant disclosures. Uh, the goals, uh, for today's lecture is to discuss the epidemiology of knee pain from osteoarthritis, review the pathogenesis and rationale underlying GAE for knee pain. Uh, briefly present the procedural steps, uh, discussed the literature supporting GAE and provide some guidance on patient selection and adverse events after embolization. Uh, here is my outline, and first we'll get into uh a bit of background before we get started. Um, so osteoarthritis is the leading cause of chronic pain and disability in the US. DOA accounts for more than 80% of the total disease burden and affects 19% of American adults, 45 and older. Province of The Province of NOA has doubled since the 20th century and is expected to increase as the population continues to age. Uh, multiple options are presently available to manage pain, including physical therapy, NSAIDs, and joint injections. Physical therapy has been proven to be quite effective. However, it can be logistically challenging to schedule and physically taxing, uh, for patients in, in some instances. Joint injections, uh, provide excellent relief. It may last a few months, uh, and potentially can accelerate joint replacement, uh, in a few studies. GAE is a novel procedure that complements the current treatment options. Next, I'll go into the pathogenesis and, and rationale. Uh, and this, this slide is a little busy. This, this picture from Lanson in 2019, uh, is quite good, but again, it is a little, little busy. I'll do my best to kind of parse it out into, uh, more digestible pieces. Um, so it all starts with some cartilage disruption from wear and tear that incites chondrocyte hypertrophy. Uh, that does then lead to the generation of pro-inflammatory mediators, and I've done my best to circle a few here on the image. Um, chondrocyte function is then deregulated and synoviocytes are activated. That then leads to tissue hypertrophy, increased vascularity. I've circled, uh, V for vascular endothelial growth factor in this slide, and that leads to the increase in vascular vascularity, uh, within the, within the joints, and that'll play a role, uh, with respect to GAE. Um, so this is more of a macroscopic view of the pathology that was published in rheumatology back in 2005. Uh, this image from, this image outlines the relationship between inflammation, angiogenesis, and innervation. OK. Um, all starting with mechanical forces that lead to degenerative changes that then causes inflammation within the joints. Inflammation, angiogenesis, and innervation are all tightly, uh, integrated processes. Uh, angiogenesis is typically accompanied by fine unmyelinated nerves, particularly in the articular cartilage and the synovium. And, and neoinnervation may also further facilitate inflammation with the release of vasoactive peptides. Uh, so what we have here is beginning with inflammation that can stimulate angiogenesis. Angiogenesis then in turn facilitates inflammation, OK? Angiogenesis also causes increase in nerve formation and that leads to, uh, further vessel formation through the release of the vasoactive neuropeptides as we discussed. Uh, pain in joints arises from the perarticular soft tissues such as the synovium, the fat, the periosteum, and the joint capsule, and is exacerbated by these abnormal neal vessels in the vascularity. GAE GAE occludes these abnormal vessels, um, surrounding and supplying the inflamed tissue. This limits the periarticular inflammation and decreases the neo neuro innervation. Resulting in decreased pain. Um, so briefly we'll go over the procedural steps. Um, so it's an outpatient procedure with same-day discharge, uh, and, and moderate sedation is typically provided by our nurses. Uh, and moderate sedation is sedation provided through an IV, uh, to help keep patients relaxed during the procedure. Just generally speaking, the steps um involved include obtaining access into the arterial system, performing an angiogram, which is essentially a picture that's obtained with our X-ray after we inject contrast directly into the artery. Uh, we can identify the pathologic blush, so to speak, which corresponds to the abnormal vessels. Uh, we treat that territory with these particles, uh, called embolic agents. Uh, and then we close the access site that we've created in the artery, uh, typically with the plug, uh. The time it takes is approximately 2 hours for the procedure, uh, with about 2 hours of recovery, uh, in our IR holding room. So here's a, here's an example um of a procedure that was recently performed. Um, this is our initial angiogram. So, uh, this is done through a catheter or a small tube that is uh within the femoral artery, uh. We inject dye and the contrast gives us a bird's eye view of the knees' vascularity. OK. We also identify possible targets, uh, for treatment. I'll run this in one more time. And And there's a still image on the right, and if I can direct your attention to the inner or the medial aspect of the knee, you can see these fine uh vessels that are surrounding the, the, uh, Knee joints. We'll get better pictures in a little bit. Uh, so we obtained more selective imaging and how we do this is by, uh, advancing an even smaller catheter into the genicular artery that is supplying that abnormal flush that we've identified earlier. Um, and so we focus on, we focus on this area of flesh by performing another angiogram, and you can see it highlights the area that we're going to treat. We advanced the small tube, the catheter, deeper into the artery, um, and this is where we'll plan to treat, OK. Here is our angiogram, uh, and what we can see is, you can see that fine network of vessels that is wrapping around, uh, the inner aspect of the knee joints. From here, this is where we're going to treat. So we Then proceed to inject small plastic beads, again 100 to 300 microns in size, so quite small, uh under live X-ray or fluoroscopy to prune the abnormal arteries. Uh, after we treat, uh, by injecting the small beads, we repeat the angiogram, um, and what we're looking for are, are two things. One, we want to make sure that we don't have, um, those abnormal vessels that blush that we discussed. But also wanna make sure that we have, uh, persistent flow into the knee joints. So we wanna make sure that we still have, uh, flow. And so what we see here, um, there's still image on the right, we still see the chunks, so to speak, um, but the leaves have been, have been pruned, OK. After this is done, we proceed to close the hole in the artery that we've created again with a small plug that dissolves completely on its own. Uh, here are just the before and after images, uh, before embolization, you see that fine lace-like, uh, blush, and after embolization we just see the, just see the branches. So we'll go over some outcomes and risks. Uh, safety and efficacy has been shown in multiple studies. Akuna was the first to publish his experience on geneive artery embolization, and he found an 86% rate of clinical success at 6 months and 72 patients. The clinical success was determined to be a 50% or more, uh, decrease in pain. APA was the first to publish these results, uh, and results in the US specifically, uh, and this is a significant decrease in the visual analog score from 76 to 30 in 20 patients, uh, and Little was the first to publish his results, um, looking at patients in the UK, and, and, uh, this group found a significant improvement in the visual analog score from 60 to 36 in 38 patients. Um, more recently, in, in 2022, um, there was a, uh, a, a multi-center trial comparing GAE to sham procedure, and the authors found that there was a significant, uh, significant improvements in pain and disability in the patients who were treated with, uh, embolization compared to those who received the sham procedure. And a meta-analysis of 10 studies, which included 351 knees, found a significant decrease in pain scores at 136, and 1212 months. Uh, some studies, results have shown that, um, the pain improvement have persisted up to 2 years, uh, it's quite remarkable. Uh, in my experience, in general, about 60-80% of patients derived significant pain relief from the procedure. Uh, the risks are overall quite minimal, OK. Uh, no major adverse events were found in multiple studies. Uh, there were a few minor adverse events which include axis at hematomas or just blood bruises, uh, around the area that we access, uh, knee discomfort, uh, following the procedure that can last a few days. Uh, and skin discoloration, which is actually relatively common, OK? In earlier studies, it's seen in up to 65% of patients, uh, and it's typically transient. With newer techniques, newer embolics, uh, that number has been reduced to about 20%, um, but it's still present, uh, and not, not uncommon. Um, And in, in Okuno, uh, in this study published in 2017 found there has been no evidence of bone necrosis, cartilage loss, li ligaments rupture, or muscle atrophy in 2129 patients who received an MRI at follow-up, uh. And there is limited data that suggests that post-embolization, uh, knee replacements are safe. Um, newer studies suggests that there is improvement in chronic pain, um, in patients who, uh, have received, uh, prior knee replacements, uh, treated with GAE, um, which is again, a pretty promising indication for this procedure. Um, so in terms of patient selection, who are the ideal, uh, genetic artery embolization candidates? Um, so patients with mild to moderate OA on a knee or greater graph are, are, are the ideal, uh, patients. Um, GAE can be performed in patients with more severe knee OA. Uh, however, the pain relief is less durable. Uh, and some studies have found that you get relief up to 6 months, but then after 6 months, that pain relief, uh, pretty much becomes insignificant. Uh, patients at high surgical risk are good GAE candidates, uh, because GAE is performed with moderate sedation, OK, and sometimes even, uh, local anesthesia, uh, if necessary, you know, OK, as compared to, uh, a larger surgery where anesthesia is, is required. Uh, patients would like to avoid or delay surgery, um, this is also a good option, um, because GAE has been found to, uh, result in durable pain relief for up to 2 years, uh, which is a significant amount of time. Uh. And for patients who have exhausted more traditional options such as physical therapy, joint injections, and weight loss, NSAIDs, etc. this is a good option, really because it's, it's, uh, treats knee pain in a different fashion, in a new fashion that's separate from, uh, these separate, um, uh, modalities, uh, and can potentially complement the, these other interventions. Um So we'll go over to a quick summary as well as logistics. Um, GAE is a novel procedure for managing knee pain from osteoarthritis with a growing body of evidence, uh, showing safety and efficacy. Uh, procedure is performed as an outpatient, uh, and well-tolerated. It's a great alternative for patients who have tried, uh, more traditional non-surgical interventions, uh, and for those who would like to avoid surgery, for one reason or another. Uh, in terms of logistics, all patients who referred to, to, to UCSFIR for genetic artery embolization are seen in clinic, uh, before and after the procedure. Uh, in clinic, um, in clinic, patients are given the opportunity to discuss the procedure further, the risks, benefits, and alternatives. Following the visits, if the patient would like to proceed, uh, the IRS staff will manage the additional workup that may be needed, if any, as work, as well as work on the insurance, uh, coverage, uh, part. At UCSF there are multiple specialists, including orthopedic surgery and pain management, to name a few who are available to discuss the alternatives uh to GIE, if that's not the road that they want to pursue. Um, just, just briefly, so here's some contact information. If there's any interest, feel free to call this number to uh UCSF Interventional radiology. Um, I have a website here, uh, for more information, and of course, there is my name. Um, and for those referrers who would like to place a referral, you can place an amla referral to IR. Once my staff receives the referral, they'll take care of the rest. Uh, here are the references that I'm happy to share. Uh, otherwise, thank you so much for your attention.
