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Ask Me Anything: LFCN Issues · AHF Podcast

• 0:01
  Joseph M. Schwab: A quick note before we dive in.
• 0:02
  Joseph M. Schwab: This podcast is for education and professional conversations among surgeons as well as other healthcare providers.
• 0:09
  Joseph M. Schwab: We're talking education and general practice patterns, not specific medical advice for any one patient, so always use your own clinical judgment and follow your practice policies and local standards of care.
• 0:21
  Joseph M. Schwab: The Anterior hip foundation, myself and our guests aren't responsible for any decisions made based on this discussion.
• 0:28
  Joseph M. Schwab: Now let's get to the show.
• 0:52
  Joseph M. Schwab: Welcome to the AHF podcast.
• 0:54
  Joseph M. Schwab: I'm your host, Joe Schwab.
• 0:56
  Joseph M. Schwab: Today's episode is an ask me Anything focused on a problem that every surgeon using the anterior approach for total hip arthroplasty has seen, but not everyone has a clear algorithm for lateral femoral cutaneous nerve issues.
• 1:11
  Joseph M. Schwab: Here's the exact question that came in from Tim Keating.
• 1:15
  Joseph M. Schwab: What is your treatment algorithm for patients with LFCN, dysesthesia, neuroma, and other lasting bothersome effects?
• 1:24
  Joseph M. Schwab: The rates of numbness are high and long-term negative effects are low, but that still leaves some patients left for further treatment.
• 1:32
  Joseph M. Schwab: In this episode, the plan is to do three things.
• 1:36
  Joseph M. Schwab: First, quickly frame what LFCN problems look like after anterior total hip, and why most patients don't need anything more than reassurance.
• 1:45
  Joseph M. Schwab: Second, walk you through a stepwise treatment algorithm.
• 1:49
  Joseph M. Schwab: What I actually do in clinic from early observations to medications, injections, and rarely surgery, and third.
• 1:57
  Joseph M. Schwab: Bring that algorithm to life with a couple of patient vignettes so you can see how this works in real practice.
• 2:05
  Joseph M. Schwab: So let's start with the big picture.
• 2:08
  Joseph M. Schwab: So what are we talking about with the direct anterior approach?
• 2:13
  Joseph M. Schwab: Lateral femoral cutaneous nerve disturbance is common.
• 2:16
  Joseph M. Schwab: Many series show that a large proportion of patients, depending on how you ask the question, report some kind of altered sensation on the anterolateral thigh and certainly around the incision.
• 2:27
  Joseph M. Schwab: Early after surgery.
• 2:29
  Joseph M. Schwab: For most of 'em, it's a patch of numbness.
• 2:32
  Joseph M. Schwab: They might say, doctor, my thigh feels weird when I touch it, or It's a little numb, but it's not painful.
• 2:39
  Joseph M. Schwab: Well, that group actually does very well over time.
• 2:42
  Joseph M. Schwab: The hip works, the function is good, and the sensory change fades into the background.
• 2:49
  Joseph M. Schwab: They notice it less over time or it goes away completely, but there's a smaller group.
• 2:54
  Joseph M. Schwab: This is the group behind the question who have persistent dysesthesia or burning or allodynia, the classic, oh, every time my jeans touch my thigh, it drives me crazy.
• 3:07
  Joseph M. Schwab: Or some have neuroma type pain, very focal electric, sometimes provoked by pressure along the incision or near the anterior superior iliac spine.
• 3:19
  Joseph M. Schwab: And while those patients are few.
• 3:21
  Joseph M. Schwab: They suffer and they're exactly why an algorithm for this type of problem can be helpful.
• 3:27
  Joseph M. Schwab: So when we talk about a treatment algorithm, we're not talking about fixing harmless numbness, we're talking about a structured pathway for patients whose LFCN symptoms remain bothersome.
• 3:39
  Joseph M. Schwab: Well beyond the standard recovery period.
• 3:43
  Joseph M. Schwab: So let's start with step one, which is often the hardest for both the patient and the surgeon.
• 3:49
  Joseph M. Schwab: It's really do less, but do it deliberately.
• 3:52
  Joseph M. Schwab: So in the first few months after surgery, most LFCN injuries are neuropraxia.
• 3:59
  Joseph M. Schwab: The literature and my clinical experience both tell us that a large share of these improve over six to 12 months with pain and burning, settling down, and sometimes only a small area of numbness left over if even that.
• 4:16
  Joseph M. Schwab: And here's how I handle that in the earliest phase, and first of all, before you're even talking after surgery about symptoms a patient has, it's really important to talk to them before surgery about what they're likely to expect.
• 4:31
  Joseph M. Schwab: And that's why I think it's important to tell every patient there's a good chance you're gonna have some numbness to the outside part of your thigh or the outside part of your incision.
• 4:40
  Joseph M. Schwab: Which will be temporary in some folks.
• 4:43
  Joseph M. Schwab: It only last for a few days to a few weeks, but in some folks it can last up to six months or 12 months, and as long as they know and are expecting it, it generally doesn't bother them as much when it happens afterwards.
• 4:56
  Joseph M. Schwab: So if you haven't incorporated that into your preoperative education for your patients, now is a good opportunity to do that.
• 5:04
  Joseph M. Schwab: Well, when they start to show up with symptoms afterwards and they're asking questions, if the patient's complaint is only a numb patch, no burning, no hypersensitivity, I don't treat the numbness.
• 5:18
  Joseph M. Schwab: I remind them of what we talked about before surgery.
• 5:21
  Joseph M. Schwab: I explain why it is what it is, and I try and normalize that situation for them.
• 5:26
  Joseph M. Schwab: I'll tell 'em it's a small sensory nerve.
• 5:29
  Joseph M. Schwab: It doesn't control any muscles.
• 5:31
  Joseph M. Schwab: It doesn't control any motor function, and so your hip is safe and the implant is safe, and over time, most patients will stop noticing this.
• 5:40
  Joseph M. Schwab: I also decide which patients I want to tell what to watch.
• 5:46
  Joseph M. Schwab: For most patients, I don't need to say this, but in some cases I'll say if you start developing increasing pain that's burning, or if your clothes become intolerable to touch around your incision or along your lateral thigh, or if it interferes with your sleep or your daily function, then of course I want them to let me know.
• 6:06
  Joseph M. Schwab: But I tend to give these patients at least six months, and quite honestly, close to a year before, I would consider them having persistent LFCN dysfunction.
• 6:17
  Joseph M. Schwab: And during that time, I might suggest some loose fitting clothing and avoidance of pressure near the ASIS, no tight fitting belts.
• 6:26
  Joseph M. Schwab: Um, but I'm not aggressively intervening.
• 6:28
  Joseph M. Schwab: So let me give you an example.
• 6:31
  Joseph M. Schwab: A 65-year-old woman comes back at six weeks after an uncomplicated anterior total hip, and her hip scores look great.
• 6:39
  Joseph M. Schwab: She says, the only thing is this numb strip here, and she points to about a thumb wide band on the lateral thigh.
• 6:47
  Joseph M. Schwab: It doesn't hurt, it doesn't burn.
• 6:50
  Joseph M. Schwab: It's just a bit odd.
• 6:52
  Joseph M. Schwab: And in that scenario, my entire algorithm, for lack of a better term, is to educate, reassure, and document, and I explain this is extremely common with the approach.
• 7:03
  Joseph M. Schwab: It rarely interferes with function, and I don't recommend treatment because the potential downside of chasing that numbness outweighs really any benefit.
• 7:14
  Joseph M. Schwab: And the patient almost never needs anything more than that.
• 7:18
  Joseph M. Schwab: But let's talk about more persistent neuropathic symptoms.
• 7:23
  Joseph M. Schwab: So step two, now, let's move to the group.
• 7:27
  Joseph M. Schwab: The question really cares about patients who, after several months have persistent, bothersome neuropathic symptoms.
• 7:36
  Joseph M. Schwab: This is where the second step.
• 7:38
  Joseph M. Schwab: Comes in and medical management and a basic workup can be really helpful here.
• 7:44
  Joseph M. Schwab: First, I think it's important to make sure the hip itself is okay.
• 7:49
  Joseph M. Schwab: If someone has thigh pain, you wanna rule out infection, loosening other mechanical issues.
• 7:54
  Joseph M. Schwab: If imaging looks good, labs are fine, and the pain fits A classic LFCN distribution.
• 8:02
  Joseph M. Schwab: Anterolateral thigh, no motor deficit.
• 8:04
  Joseph M. Schwab: Then the LFCN becomes the prime suspect.
• 8:08
  Joseph M. Schwab: And at this stage, my tools look like standard neuropathic pain management, maybe a low dose neuropathic agent, whether it's gabapentin, um, a tricyclic antidepressant or an SNRI.
• 8:22
  Joseph M. Schwab: Following general Neuropathic pain guidelines, there aren't randomized trials specifically in post total hip LFCN injuries, at least none that I'm aware of.
• 8:33
  Joseph M. Schwab: So this part is extrapolated from the classic meralgia paresthetica literature, as well as other sensory neuropathies.
• 8:43
  Joseph M. Schwab: If you're aware of some literature on this, please drop a comment below.
• 8:48
  Joseph M. Schwab: Also topical theory therapy can be helpful for focal hypersensitivity.
• 8:53
  Joseph M. Schwab: A lidocaine patch over a very sensitive area or a cautious trial of topical capsaicin is something I'll occasionally try.
• 9:02
  Joseph M. Schwab: And on the rehabilitation side, I might involve a therapist for desensitization strategies, especially if it's a patient that could benefit from a little more handholding.
• 9:14
  Joseph M. Schwab: So gradual exposure, trying different types of fabrics and textures, light brushing techniques can all help reduce allodynia.
• 9:24
  Joseph M. Schwab: And again, I try to be honest with patients.
• 9:27
  Joseph M. Schwab: This is about symptom control and giving the nerve more time.
• 9:31
  Joseph M. Schwab: We're not repairing the nerve so much as quieting it down while healing continues.
• 9:37
  Joseph M. Schwab: So let's talk about a patient vignette that's similar to this.
• 9:42
  Joseph M. Schwab: 58-year-old male, nine months post anterior.
• 9:47
  Joseph M. Schwab: Total hip radiographs look perfect, no groin pain.
• 9:51
  Joseph M. Schwab: Gait is excellent, but he says every time I put on my jeans, my thigh is just on fire.
• 9:57
  Joseph M. Schwab: The pain is in the classic LFCN zone, tapping near the ASIS, and along the incision really aggravates it.
• 10:05
  Joseph M. Schwab: And in that scenario I explain that this seems to be consistent with an LFCN neuropathic pain state.
• 10:13
  Joseph M. Schwab: I might offer a low dose neuropathic medication.
• 10:18
  Joseph M. Schwab: I might add a lidocaine patch if there's a really sensitive region, or I might give them a handout or instructions.
• 10:25
  Joseph M. Schwab: Or even a referral to therapy to get some desensitization treatment, and I'll schedule him for a follow up in a few weeks to a few months to see how much improvement we get with these measures.
• 10:38
  Joseph M. Schwab: Now suppose that same patient comes back and he's still miserable.
• 10:45
  Joseph M. Schwab: He's tried medications, he's tried topical agents.
• 10:48
  Joseph M. Schwab: He's done desensitization both at home and with a therapist, and he gets some relief, but it's not long lasting and it's not enough.
• 10:57
  Joseph M. Schwab: This is where step three really becomes important in my algorithm, and that would be a targeted LFCN block.
• 11:07
  Joseph M. Schwab: And I like this step because it does two things at once.
• 11:10
  Joseph M. Schwab: One, it's diagnostic.
• 11:12
  Joseph M. Schwab: If a well placed block gives substantial temporary relief that strongly confirms that the LFCN is the pain generator, and two, it's therapeutic.
• 11:24
  Joseph M. Schwab: Some patients get prolonged benefit from the injection and a subset may do very well with one or more blocks and never need surgery.
• 11:32
  Joseph M. Schwab: In fact, one report.
• 11:34
  Joseph M. Schwab: Indicated that a single injection handled about 70% of patients, an additional 20% benefited from a second injection, and a third injection was beneficial for another few percentage points.
• 11:47
  Joseph M. Schwab: But not all patients got better with a series of injections.
• 11:52
  Joseph M. Schwab: So in practical terms, I might refer for an ultrasound guided LFCN block, specifically near the anterior superior iliac spine, along the usual course of the nerve using a local anesthetic.
• 12:06
  Joseph M. Schwab: And most often I'll do it with a corticosteroid, but you could do it with or without a corticosteroid for just a diagnostic effect.
• 12:15
  Joseph M. Schwab: Now recent work focused on persistent LFCN lesions after anterior hip procedures shows that ultrasound guided injections can provide meaningful symptom relief and are the main interventional step for many patients who need more than medication.
• 12:32
  Joseph M. Schwab: So if the patient comes back and says, for the first time in a year, I could wear tighter pants without pain, even if it only lasted for.
• 12:40
  Joseph M. Schwab: Hours, days, or weeks.
• 12:43
  Joseph M. Schwab: That's incredibly useful information 'cause it tells me.
• 12:46
  Joseph M. Schwab: Yes, this is an LFCN derived problem, and yes, further nerve directed interventions may have a rational basis.
• 12:57
  Joseph M. Schwab: So back to our patient.
• 12:59
  Joseph M. Schwab: He gets the ultrasound guided block.
• 13:01
  Joseph M. Schwab: He reports that his pain vanished the day of the injection and stayed markedly improved.
• 13:07
  Joseph M. Schwab: For a couple of weeks before slowly returning, we repeat the block once more.
• 13:12
  Joseph M. Schwab: Again.
• 13:13
  Joseph M. Schwab: He gets multi-week relief.
• 13:15
  Joseph M. Schwab: Now, that second injection, if I didn't include a steroid in the first one, I would definitely include it in the second one unless there's any contraindications.
• 13:24
  Joseph M. Schwab: So if he gets multi-week relief with that response, I know two things.
• 13:30
  Joseph M. Schwab: He's a responder.
• 13:31
  Joseph M. Schwab: Two blocks and the LFCN is clearly the pain generator now that opens the door if needed to talking about surgical options.
• 13:40
  Joseph M. Schwab: Step four is reserved for a small minority of patients, and these are patients who have had at least nine to 12 months of symptoms, have tried medications, and ideally at least one or two image guided blocks and have clear localized LFCN pattern pain.
• 14:03
  Joseph M. Schwab: That significantly impairs quality of life.
• 14:05
  Joseph M. Schwab: And in this group, I have a frank conversation about surgery directed at the nerve.
• 14:10
  Joseph M. Schwab: The options based on both total hip related series and broader meralgia paresthetica literature include external neurolysis, so freeing the nerve from scar tissue or entrapment, sometimes relocating it to a slightly more protected area.
• 14:28
  Joseph M. Schwab: Small series suggesting that neurolysis in carefully selected patients can improve symptoms or neurectomy or neuroma exploration and excision, which is resecting a painful neuroma and burying the proximal stump in muscle or deeper tissue.
• 14:47
  Joseph M. Schwab: And this approach, again, supported by case series and some meralgia data tends to reliably relieve pain.
• 14:55
  Joseph M. Schwab: But at the cost of permanent numbness in that territory, and I emphasize this is a quality of life operation.
• 15:04
  Joseph M. Schwab: The hip is fine.
• 15:05
  Joseph M. Schwab: We're not saving the implant.
• 15:07
  Joseph M. Schwab: We're trying to trade intolerable, neuropathic pain for an area of numbness that the patient can live with.
• 15:15
  Joseph M. Schwab: And that trade off has to be crystal clear going in.
• 15:20
  Joseph M. Schwab: So imagine 62-year-old woman, 18 months after an anterior approach, total hip replacement, who's got constant burning over the anterolateral thigh, a very focal trigger point at the lateral edge of her incision, and a history of excellent but temporary relief with an ultrasound guided LFCN block.
• 15:43
  Joseph M. Schwab: Imaging is fine.
• 15:45
  Joseph M. Schwab: Labs are normal.
• 15:47
  Joseph M. Schwab: We discuss options and she elects to proceed with surgery for symptom control.
• 15:52
  Joseph M. Schwab: Operatively, a neuroma of the LFCN is identified in the scar.
• 15:57
  Joseph M. Schwab: The neuroma is resected, and the proximal stump is buried in the muscle postoperatively.
• 16:04
  Joseph M. Schwab: She has a numb patch, uh, over the lateral thigh, but the burning is gone, and if follow-ups, she says, I'll take the numbness any day over what I had before.
• 16:13
  Joseph M. Schwab: That's the exact trade off.
• 16:16
  Joseph M. Schwab: This step of the algorithm is designed for.
• 16:19
  Joseph M. Schwab: Well, before we wrap up, there's one more step that isn't about escalating treatment.
• 16:25
  Joseph M. Schwab: It's about knowing when to stop.
• 16:28
  Joseph M. Schwab: And even with a good algorithm, a number of patients end up with chronic pain that is really out of proportion to any single nerve lesion they may have central sensitization, multiple pain generators, or significant psychosocial factors, and for those patients.
• 16:46
  Joseph M. Schwab: The best thing we can do is not keep doing bigger procedures.
• 16:53
  Joseph M. Schwab: Instead, those are cases where I would shift the focus to multidisciplinary pain management, a combination of pharmacologic strategies, psychology and functional rehab, and setting realistic goals, maybe talking about a reduction in pain intensity and impact rather than getting rid of their pain.
• 17:14
  Joseph M. Schwab: Having that boundary in your algorithm protects patients from endless interventions and protects you from chasing a cure that might not be surgically achievable.
• 17:26
  Joseph M. Schwab: So to bring this back to the original question, what's your treatment algorithm for patients with LFCN, dysesthesia, neuroma, and other lasting bothersome effects?
• 17:39
  Joseph M. Schwab: Here's how it looks in one breath.
• 17:41
  Joseph M. Schwab: Step one, early after surgery, numbness alone gets education and reassurance.
• 17:48
  Joseph M. Schwab: I don't chase asymptomatic or mildly asymptomatic numb patches.
• 17:52
  Joseph M. Schwab: Step two, persistent, bothersome, neuropathic pain.
• 17:56
  Joseph M. Schwab: You wanna rule out problems with the prosthesis.
• 18:00
  Joseph M. Schwab: You want to start standard neuropathic pain meds and topical agents if you're comfortable doing so.
• 18:07
  Joseph M. Schwab: And add some desensitization strategies and just give it more time.
• 18:12
  Joseph M. Schwab: Step three, ongoing.
• 18:15
  Joseph M. Schwab: Clearly LFCN mediated pain despite conservative care.
• 18:20
  Joseph M. Schwab: This is where I would order an ultrasound guided LFCN block, and I'd use the response to both confirm diagnosis and in many cases to guide treatment.
• 18:31
  Joseph M. Schwab: Step four, severe refractory block responsive pain.
• 18:37
  Joseph M. Schwab: These are people I might discuss surgical options, neurolysis or neurectomy, and neuroma excision with a clear explanation that the goal is pain relief.
• 18:48
  Joseph M. Schwab: At the cost of permanent numbness and step five, if symptoms remain disproportionate or diffuse, involve a multidisciplinary pain team and avoid endless procedural escalation.
• 19:03
  Joseph M. Schwab: So yes, the incidence of numbness after anterior total hip arthroplasty.
• 19:09
  Joseph M. Schwab: Which varies anywhere in the literature from 20% on up to 80%.
• 19:13
  Joseph M. Schwab: It's high and serious.
• 19:15
  Joseph M. Schwab: Long-term problems are fortunately rare, but for that small minority of patients left with meaningful LFCN mediated pain, a structured stepwise algorithm makes these decisions more rational and more reproducible.
• 19:31
  Joseph M. Schwab: Thanks for listening to this AMA episode of the AHF Podcast.
• 19:37
  Joseph M. Schwab: As always, please take a moment to like and subscribe so we can keep the lights on.
• 19:42
  Joseph M. Schwab: And keep sharing great content just like this.
• 19:46
  Joseph M. Schwab: Please also drop any topic ideas or feedback in the comments below.
• 19:50
  Joseph M. Schwab: And since this is a unique style of podcast, I really want to ask you, what do you do for LFCN issues?
• 19:58
  Joseph M. Schwab: Was there a treatment I missed or something that you would do differently?
• 20:02
  Joseph M. Schwab: Let us know in the comments and keep the conversation open.
• 20:06
  Joseph M. Schwab: I'm also gonna put links to some of the sources that I used for this episode in the description below.
• 20:11
  Joseph M. Schwab: So feel free to download those and check 'em out.
• 20:14
  Joseph M. Schwab: And if there's sources you think I missed, share 'em with me.
• 20:17
  Joseph M. Schwab: You can find the AHF podcast on Apple Podcasts, Spotify, or in any of your favorite podcast apps, as well as in video form on YouTube slash at anterior hip foundation.
• 20:31
  Joseph M. Schwab: All one word, episodes of the AHF podcast come out on Fridays.
• 20:37
  Joseph M. Schwab: I'm your host, Joe Schwab, asking you to keep those hips happy, healthy, and free of lateral femoral cutaneous nerve damage.