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BackTable / MSK / Article
Genicular Nerve Ablation: Managing Knee Pain & Patient Expectations
Thomas O'Rourke • Nov 8, 2023 • 101 hits
Genicular nerve ablation is becoming an important procedure for any clinician working in pain management. Dr. John Smirniotopoulos has spearheaded the effort to make this procedure possible in his hospital, where he has also retrospectively studied the variables affecting its efficacy. Genicular nerve ablation can be highly effective for reducing knee pain and may be preferred by orthopedic surgeons over genicular artery embolization (GAE).
Patients who receive genicular nerve ablation maintain an intact blood supply to the knee, meaning whether they are thinking about knee surgery or recently had knee surgery, pain relief can still be achieved with an ablation. While significant and long-term pain relief is the intended goal of this procedure, management of patient expectations is also important. Ablation of the genicular nerve does not remove the anatomical cause of the pain, so physical therapy and patient education are crucial for long-term pain relief.
This article features excerpts from the BackTable MSK Podcast. We’ve provided the highlight reel in this article, and you can listen to the full podcast below.
The BackTable MSK Brief
• It was determined that the standout predictor of pain reduction success for genicular nerve ablation was patient age. Patients over 50 saw the greatest reductions in pain. This age-related efficacy may be due to more advanced grades of osteoarthritis in older patients or modified expectations in younger patients regarding activity levels post-treatment.
• A new algorithm is being developed for the implementation of genicular nerve ablation. Patients are first given a nerve block, which then gives the green light for nerve ablation if successful. If pain returns after 6 months, a second ablation can be done. If pain still persists, GAE may be considered.
• There are a variety of reasons why patients and physicians may opt for genicular nerve ablation. Whether healing from a recent knee replacement or contemplating surgery, genicular nerve ablation does not inhibit the healing process nor preclude patients from future procedures. It is also expected to be less damaging to tendons than long-term corticosteroid injections.
• Pre-procedure, patients are informed that the pain block may result in a 50% reduction, setting a benchmark for post-ablation pain relief expectations. It is important for patients to understand that ablation does not reverse physical damage such as cartilage deterioration, nor does it remove orthopedic hardware.
Table of Contents
(1) Getting Started With Genicular Nerve Ablation
(2) Advantages of Genicular Nerve Ablation in Unique Clinical Scenarios
(3) Predictors of Genicular Nerve Ablation Outcomes
(4) Navigating Patient Expectations & Genicular Nerve Ablation Outcomes
Getting Started With Genicular Nerve Ablation
The inception of genicular nerve ablation within Dr. Smirniotopoulos's practice emerged from a strategic expansion into musculoskeletal procedures and a collaboration with orthopedic colleagues, inspired by the desire to diversify clinical services. Drawing from the substantial foundation of pain literature and randomized control trials on radiofrequency ablation, his team built upon existing data, showing improved efficacy compared to other treatments like corticosteroid and hyaluronic acid injections. Dr. Smirniotopoulos also addressed potential reservations from orthopedic surgeons regarding GAE for patients who may need knee replacement surgery within a year. Wound healing after GAE may cause complications after surgery, making genicular nerve ablation an attractive alternative.
[Dr. Michael Barazza]
You said you've been doing this for about a year. How and why did you start doing this? Where did this come from?
[Dr. John Smirniotopoulos]
That's a great question. We wanted to start getting musculoskeletal procedures involved in our practice. We had an interest in genicular artery embolization, which we had already done some work on, in addition to a lot of vertebroplasty, kyphoplasty, and then malignant ablations, things like that. We do a lot of that at baseline, and then we had started incorporating more pain interventions, and we thought, we like the MSK field, what else can we bring to the table? I, again, went to a medical school where 20 people in my class went into ortho by Georgetown, and a lot of them, like myself, have moved back over the years.
When I came back, we started talking about what procedures IR can help them with, just because in IR, I feel that we learn a procedure, learn a disease pattern, maybe get bored, and then try to find something new to do. We started talking with our ortho colleagues, and I reached out to some of my friends and said, listen, what about controlling some of the joint issues that you guys are facing with your patients?
We presented ablation. We looked it up, read some papers in the pain literature, talked to the local rep for the specific company we use, which is Avanos COOLIEF, and started evolving the practice that way. It was out of interest in seeing what other specialty we can help with patients and maybe grow a clinical arm of our practice directed towards those ortho musculoskeletal patients.
[Dr. Michael Barazza]
Was there much information out there on it to research and learn as you started to take this on?
[Dr. John Smirniotopoulos]
That's a great question. A lot of the data in pain management in general, right, is going to come from the pain literature and then PM&R as well. That's where the bulk of it does come from. Certainly in the knees, it's probably the most studied compared to all the joints of the body. There's plenty of randomized control trials, again, from the pain literature, comparing specifically radiofrequency ablation to other conservative modalities of treatment, such as intraarticular corticosteroid injection, hyaluronic acid injection.
That data has existed now for several years, and it was something we could piggyback off of to learn about the disease process, the treatment paradigms, have those conversations with our ortho colleagues to say, this is what the data shows, this is what's out there, here's how we can help.
[Dr. Michael Barazza]
John, you mentioned that you guys are also doing genicular artery embolization there, and that's building steam as well, particularly in the academic world. I'm wondering if it was hard to carve this out as a second treatment when you guys are already doing something for knee pain there.
[Dr. John Smirniotopoulos]
The GAE is interesting. It's certainly recognized amongst our ortho colleagues as a modality to treat hemarthrosis, recurrent hemarthrosis, and that's primarily what we're doing those for. We have very good anecdotal results from that. It's clearly borne out in the literature. Treating primary osteoarthritis of the knee with GAE is in our literature, in IR literature. I've noticed that from the orthopedic side, it is taking a little bit of buy-in for the primary OA population. I think they have a very interesting rationale behind that. It's not just don't cut off the blood supply to the joint.
Their thought and their concern is if there is a chance the patient may have a knee replacement within 12 months, they are concerned about wound healing globally, and so when we presented the ablation as potential minimally invasive therapy, they jumped on that and they really enjoyed that as an alternative. Now, the question is where do you work GAE in into the treatment pattern? It's tricky. My algorithm for this, and the algorithm we're trying to really push forward at our institution in the appropriate patient, of course, is we'll start conservatively with the nerve block for the nerve ablation.
If that works, we'll do the ablation. If a patient has limited response, meaning under six months of treatment effect, which is the standard of what you would want to see after ablation, and at six months is also what insurance limits you in terms of a global period to perform a second ablation, but maybe if they have a short response, then we can consider GAE and going in an algorithm and in a very appropriate fashion that makes not only the patient happy because we have alternative treatments, it makes us happy because these patients will come back to you and they'll talk to you, and they'll say, my pain came back sooner than I thought it would. It makes our orthopedic surgeon colleagues also happy because we're trying to be as gentle as possible on the joint that they may eventually want to replace.
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Advantages of Genicular Nerve Ablation in Unique Clinical Scenarios
Genicular nerve ablation is a promising intervention in knee pain management, especially for patients who are not immediate candidates for knee replacement. This treatment offers a strategic reprieve from knee pain for those with medical constraints, such as recent coronary stents or transplant surgeries, and for those who wish to delay or avoid arthroplasty due to personal preferences, or the need to meet specific health parameters like BMI reduction. This procedure also serves as a valuable option for post-total knee arthroplasty (TKA) patients still experiencing pain despite well-fitted hardware and the absence of infection. Furthermore, it may also prove to be safer than intra-articular corticosteroids, which can be detrimental to tendons and wound healing when used long-term.
[Dr. Michael Barazza]
You mentioned there are lots of injections, there's arthroplasty, there are tons of procedures for knee pain. Why is there a role for a nerve ablation? Is there a gap in the existing therapies that we need to fill?
[Dr. John Smirniotopoulos]
The biggest reason we get referrals for genicular nerve ablation from our orthopedic surgery colleagues is a patient is not ready for a knee replacement. Either they don't want it yet or they just haven't been convinced enough that they need it, or they're not suitable medically. BMI plays a big role into that and they need to lose some weight. Or there's some other reasons such as, again, we have a liver transplant center, so they've had a recent transplant and they should not have an operation yet, and so they need something to kind of bridge the gap, but certainly, there's a patient population that doesn't want the surgery.
Or you have the post-operative patients, the post-TKA patients, where their joint hardware looks great. It's not loose, there's no infection, they've tapped them, it looks fantastic. There's no hemarthrosis, they just have pain. That's where that really plays a role is those scenarios. The nice thing about the nerve ablation is that it does not inhibit or prohibit any future therapy, whether it's an injection or a surgery. That really helps round out and comfort the patient and the orthopedic surgeon. That's where our role is. You mentioned, is there a gap with other injections?
Certainly, there's a lot of data in the orthopedic literature globally now for reduction of corticosteroids into a joint space. There's concern for tendon rupture there. There's concern for wound healing. Some of our orthopedic surgery colleagues are not wanting any corticosteroid, whether it's a hip or a knee, in the joint space within six months prior to an operation. If that's the case, we need something to bridge that gap for a patient for pain control. This is a good modality to do that.
[Dr. Michael Barazza]
John, you've been doing it for about a year now. Any major changes in how your practice, how it's evolved since then? Are they all coming from ortho?
[Dr. John Smirniotopoulos]
The majority are coming from ortho. It's an interesting paradigm how the orthopedic practice can filter into an IR practice. I feel that when we have clinic, we have clinic half day a week for us. When I was at Cornell, it was a full day a week. If you talk to your orthopedic surgery colleagues, they probably have clinic two to three times a week, and they may see 30 to 60 patients in that clinic. Maybe that orthopedic surgeon only does joints, and so, that person is seeing however many patients, 90 to over 100 a week just for a joint.
[Dr. Michael Barazza]
I just can't imagine.
[chuckling]
[Dr. John Smirniotopoulos]
When we started offering this procedure, I was the one that initially spearheaded it, which was great because I felt like I know the surgeons that are referring to me, there's four of them and they're my friends, so this is easy. Go ahead, just send me patients. Before you know it, your floodgates are opening and then they're sending a ton of patients. Our practice rapidly started recruiting patients for this intervention. I've talked to other colleagues throughout the country and it's the same story. When you start doing it, they'll keep sending you more and more from ortho. I had my partners then buy into it.
[Dr. Michael Barazza]
Of course. Now you're seeing you get all the patients. It does make a lot of sense, especially the way you lay it out for a lot of these patients, this is a bridge. They may ultimately get an arthroplasty at some point in their lives. And so, you're not directly competing with them. And you're really helping them with the challenging patient population. It's almost like pelvic congestion syndrome patients for OB. It's not like a UFE. You're helping them get to where they need to be with or without a knee replacement. It makes a lot of sense that they'd be happy to send them.
[Dr. John Smirniotopoulos]
One other thing about that is that we got eager with this when we started it. We had our orthopedic colleagues and I said, this is great. Why don't we go ahead and start giving talks to some of the primary care groups? So, we started doing that. Then we set up our website so people can self-refer on a form. Yes, majority are ortho, but we do get a lot of self-referrals and primary care that send it too. Once you start doing it and people start knowing you do it, you're going to start getting a lot of patients coming [crosstalk]
Predictors of Genicular Nerve Ablation Outcomes
Recent findings presented at the annual SIR meeting have shed light on the effectiveness of genicular nerve ablation, a topic predominantly discussed in pain literature but now enriched by Interventional Radiology (IR) insights. Dr. John Smirniotopoulos detailed a meticulous review of 47 genicular nerve ablation procedures, focusing on a study group's baseline and follow-up WOMAC and VAS pain scores. This research took a multivariate analytical approach, dissecting various patient factors, including demographics and medical history, to isolate predictors of successful pain reduction.
Notably, while all patients reported significant pain relief, those above the age of 50 emerged as the subgroup with the most pronounced improvement. This contrasts the belief held by many orthopedic colleagues that BMI would have been the greatest predictor for improvement. It is possible that the age factor might be due to more advanced osteoarthritis or modified patient expectations regarding post-procedural physical capabilities.
[Dr. Michael Barazza]
Your crew just presented some of your data on genicular nerve ablation at the recent SIR annual meeting, and it was selected as a newsworthy article and had a press release for it. Can you give us a little bit of details about the study and what you guys found?
[Dr. John Smirniotopoulos]
Yes. We started doing the specifically genicular nerve ablations and treating these patients a little over a year ago, and we wanted to analyze our early data to see how our results were. A lot of the data that is available is in the pain literature, which is good data, but we haven't really seen a lot come from the IR literature, so we thought, let's see how our patient population is doing. Specifically, we wanted to see if we have a way of predicting outcomes. Who is going to do better from this procedure? Does it help with selection?
What we did is we did a prospectively-collected, retrospectively-reviewed study of the patients that we had performed the procedure on. Specifically genicular nerve ablation. We looked back at their baseline WOMAC scores and their VAS pain scores, and then we called them for follow-up and try to get updated scores on them. We had help from a couple of our residents and very, very hardworking medical students to accomplish this. Was great. In total, by the time we submitted it to SIR, we had 36 patients that we had collected enough data on.
Of those 36 patients, 47 knees. What that means is several patients had both knees treated over the time period. That also means that they were able to give us a VAS score for each separate knee and a WOMAC for each separate knee because the treatments are done on different days. We'll get into that in a little bit. What we did is a multivariate analysis. We tried to, again, see what we can glean from our data to predict outcomes.
We looked at BMI, age, race, gender. We looked at prior surgical history. We also looked at inflammatory diseases such as rheumatoid or fibromyalgia. We essentially found that the biggest predictor of outcomes, and all patients had a significant reduction of their pain, but the biggest predictor of outcome was age greater than 50. Again, everyone, all comers had significant reduction of WOMAC and VAS, but that was our only real predictor of who was going to respond more than maybe another population.
[Dr. Michael Barazza]
Super interesting. I was wondering if there was going to be something like BMI, or whether or not the patient had an arthroplasty, but that was the big one, was age. I'll be interested to see if you guys have any ideas about why that is.
[Dr. John Smirniotopoulos]
That's a great point. That actually got brought up while we were giving the talk at SIR.
[Dr. Michael Barazza]
I bet.
[Dr. John Smirniotopoulos]
Someone asked the audience, why do you think that happens? We thought BMI actually would be the main predictor, and our orthopedic colleagues who refer us these patients, also thought BMI would be the biggest predictor, and it wasn't. We think that age greater than 50 likely pertains to a higher number of patients with maybe an increased grade of their OA compared to age.
If you look at some of the prior data that's out there, they look at their Kellgren-Lawrence scale, which is a degree of OA of 2 and 3. Certainly those above 50 are likely to have that. Also, to be honest with you, I think the population under 50 maybe has more sports-related injuries such as meniscal tears, things of that nature, but maybe there's also that expectation that's there. If you're younger than 50, you think maybe I'll get this treatment, I'll go run a half-marathon.
[Dr. Michael Barazza]
Right, I'll be back to normal.
[Dr. John Smirniotopoulos]
I tell everyone this is not a time machine. I think it's managing expectations that maybe has a bias in there as well.
Navigating Patient Expectations & Genicular Nerve Ablation Outcomes
Despite the many advantages of genicular nerve ablation, clinicians must educate their patients on reasonable expectations for the procedure. A transparent dialogue about realistic outcomes is essential, particularly stressing that while pain may be reduced by 50%, underlying anatomical issues remain unaltered. Improved pain does not indicate one can now go and run a marathon. The work is also not done following the procedure. Physical therapy is important to enhance patient activity levels and thus, recovery. Key to the post-procedural strategy is the six-week marker, a period identified for evaluating the peak benefits of the ablation, with patient follow-ups to assess pain relief and function. This approach not only ensures patients are informed and involved in their care trajectory but also enables a structured timeline for potential re-evaluation and further intervention if necessary.
[Dr. Michael Barazza]
Let's talk a little bit about follow-up. One of the most important things, I think, for pain intervention is setting reasonable expectations, and so I'm curious how you counsel these patients before genicular nerve ablation on what they should expect in terms of the degree and the duration of pain relief.
[Dr. John Smirniotopoulos]
I think the counseling and setting expectations might be the most important part of any pain procedure that we do. It's all about setting up expectations. I tell the patient, for the block, we're looking for a 50% or more reduction. They're likely to have something similar to that when we do the ablation if they're a candidate. Again, we're not a time machine. I'm not reversing their cartilage damage or their loss. Certainly, if they're post-TKA, I'm not taking away their hardware or whatever's irritated there. I think that's very important to really hammer in.
Again, I tell them, look, if I can reduce your pain by 50%, cut it in half, and start getting you to a level of activity that you want, that's going to be the biggest benefit to you. Again, that's where the physical therapy comes in. I really do hammer in the physical therapy. We don't have one particular physical therapist we send people to. However, within our institution, we have so many PT offices in the DC metro area. My referral form, it's a physical form that I actually give them where I can write down their ICD-10 code. It's a script, but I can also circle what I want the physical therapist to ideally focus on.
Range of motion, strength, stability, gait training. Then I will write a indefinite number of sessions with them, but they may ultimately need a referral. More importantly is that I'm the one giving them the script. I'm not asking whoever referred them to give the script. I think that helps the patient really, one, see you as the person taking care of their pain right now until they may or may not need surgery down the road, but also, once they have something in their hand, it might make them a little more compliant with it too. More importantly, though, I tell them whatever pain benefit they're going to have, they're going to see the maximum benefit at six weeks.
Not that it's going to go down, but it's going to take about six weeks or so to really calm down any inflammation and see how much of the nerve was destroyed, see where their functional status was. Beyond six weeks, I doubt that they would improve on their pain. Hopefully, they're not going to get worse with their pain, it won't come back, but that's the maximum benefit. I've seen that with several patients now because we try to follow up with them at six weeks after the ablation, just a phone call, not necessarily a clinic visit, see how they're doing.
That's what we're seeing, is six weeks that it really did start to improve after day two of the procedure, once that soreness from the needles going through the muscle has gone away, because they fixate on that. I tell them it's like a flu shot. You're going to go down the muscle, hit the nerve, and then that'll ease up in two days. Some of them will say even like two weeks after, they noticed a change from one week after, and so they start seeing that.
Our follow-up is a phone call at six weeks. Ideally, I have an e-visit or some type of follow-up at three months just to see where they are, and then again at six months, and at six months is when we start saying, are you doing okay? Do we need to repeat it at this time? If someone says, yes, pain's back. It worked great. It just came back a couple weeks ago. That's fine. They don't need to have the block again. If they have the block and the ablation, they can just schedule the ablation.
[Dr. Michael Barazza]
If pain comes back and it's after six months, you would repeat an ablation, whereas if it happens significantly sooner than six months, that's when you consider GAE or something else?
[Dr. John Smirniotopoulos]
Exactly. GAE has that nice role to play there, and it's a little easier conversation to have, especially some of these patients. Again, they're a little apprehensive about anything, and you start talking about their blood vessels. They might say, what else can we do that's not that first? I think if you trial things out and you set up that paradigm there, it makes the conversation easier to have.
Podcast Contributors
Dr. John Smirniotopoulos
Dr. John Smirniotopoulos is an assistant professor of clinical radiology in the IR department at MedStar Georgetown University and MedStar Washington Hospital Center in DC.
Dr. Michael Barraza
Dr. Michael Barraza is a practicing interventional radiologist (and all around great guy) with Radiology Associates in Baton Rouge, LA.
Cite This Podcast
BackTable, LLC (Producer). (2023, July 19). Ep. 22 – Genicular Nerve Ablation [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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