Latest / AHF Podcast / 2025 Great Debates: The Hip-Spine relationship does not matter for Anterior Approach

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2025 Great Debates: The Hip-Spine relationship does not matter for Anterior Approach · AHF Podcast

• 0:00
  Joseph M. Schwab: Hi, this is Joe Schwab and if you recognize my voice, it's probably because you've heard another episode of the AHF podcast, which means you're listening again, and I can't tell you how much I appreciate that.
• 0:15
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• 0:28
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• 0:37
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• 0:41
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• 0:47
  Joseph M. Schwab: Now let's get on with the show.
• 1:04
  Joseph M. Schwab: Welcome to the AHF podcast.
• 1:07
  Joseph M. Schwab: I'm your host, Joe Schwab.
• 1:10
  Joseph M. Schwab: One of the reasons we host these great debates is pretty simple.
• 1:14
  Joseph M. Schwab: Orthopedics moves forward when thoughtful surgeons disagree respectfully.
• 1:20
  Joseph M. Schwab: So much of what we do in the operating room comes down to judgment, often more judgment than maybe we'd like to admit, and when the evidence isn't definitive.
• 1:30
  Joseph M. Schwab: When two smart people can look at the same set of data and reach different conclusions, that's exactly the moment when debate becomes valuable.
• 1:40
  Joseph M. Schwab: Today's topic is one that every anterior hip surgeon has wrestled with in one way or another.
• 1:47
  Joseph M. Schwab: Does the hip spine relationship really matter for the anterior approach?
• 1:52
  Joseph M. Schwab: Taking the pro position, we have Dr.
• 1:54
  Joseph M. Schwab: Nathaniel Nelms taking the con position.
• 1:57
  Joseph M. Schwab: Dr.
• 1:57
  Joseph M. Schwab: Edwin Su.
• 1:59
  Joseph M. Schwab: What you're about to hear isn't just a clash of viewpoints.
• 2:02
  Joseph M. Schwab: It's a glimpse into how experienced surgeons think, how they weigh risk, and how they decide what matters in the pursuit of safer, more reliable outcomes.
• 2:14
  Joseph M. Schwab: Let's get into it.
• 2:16
  Joseph M. Schwab: The next debate topic is:"The hip spine relationship does not matter for anterior approach".
• 2:25
  Joseph M. Schwab: Taking the pro position, Dr.
• 2:27
  Joseph M. Schwab: Nathaniel Nelms, taking the con position, Dr.
• 2:30
  Joseph M. Schwab: Edwin Su.
• 2:31
  Joseph M. Schwab: Four minutes to you.
• 2:32
  Joseph M. Schwab: Dr.
• 2:32
  Joseph M. Schwab: Nelms.
• 2:33
  Nathaniel Nelms: Thank you very much.
• 2:35
  Nathaniel Nelms: I posit to you that this is the most important debate that you guys are going to face.
• 2:40
  Nathaniel Nelms: In your practice at all?
• 2:41
  Nathaniel Nelms: I think that in everything we hear, we need to do more, more, more.
• 2:46
  Nathaniel Nelms: You need technology, you need the robot, but have you guys all been made to feel guilty if you're not getting five extra hip and then spine x-rays and then all this extra technology?
• 2:56
  Nathaniel Nelms: But I ask, where is the evidence?
• 2:58
  Nathaniel Nelms: There is not one study that's published when it comes to anterior total hip that demonstrates any advantage to using the hip spine relationship period.
• 3:09
  Nathaniel Nelms: End of debate right there.
• 3:11
  Nathaniel Nelms: So you do not need to have functional spine x-rays, a full body EOS CT, save that for the posterior robotic total hip patients.
• 3:20
  Nathaniel Nelms: First, let's come back to what's the problem.
• 3:21
  Nathaniel Nelms: All that the hip spine relationship was ever designed to deal with was dislocation.
• 3:26
  Nathaniel Nelms: And the problem came because surgeons that were doing their patients in a lateral position.
• 3:31
  Nathaniel Nelms: And, um, we're having dislocations despite using navigation in robotics.
• 3:35
  Nathaniel Nelms: Why was that?
• 3:36
  Nathaniel Nelms: It was because they were putting the cup in a position relative to the pelvis, but not thinking about the functional position, which we can get just by laying the patient's supine and doing an anterior hip.
• 3:45
  Nathaniel Nelms: The pelvic tilt is already accounted for when you use fluoroscopy and put the cup in an appropriate position.
• 3:51
  Nathaniel Nelms: You're already taking into account those differences in pelvic position.
• 3:56
  Nathaniel Nelms: So when it comes to evidence, is there, uh, any evidence?
• 3:58
  Nathaniel Nelms: The hip spine relationship is important.
• 4:00
  Nathaniel Nelms: Absolutely it works in the posterior approach.
• 4:02
  Nathaniel Nelms: For the anterior hip, there is zero.
• 4:04
  Nathaniel Nelms: Vigdorchik one of the founders of this principle.
• 4:06
  Nathaniel Nelms: He applied this to a large group of patients.
• 4:09
  Nathaniel Nelms: He found he was able to bring his dislocation rate down to 0.8%.
• 4:12
  Nathaniel Nelms: That's still higher than most series with the anterior approach.
• 4:14
  Nathaniel Nelms: And to do that, he had to use eight dual mobility.
• 4:17
  Nathaniel Nelms: In 8% of his cases.
• 4:18
  Nathaniel Nelms: Do we use dual mobility?
• 4:19
  Nathaniel Nelms: 8% of our cases.
• 4:21
  Nathaniel Nelms: We don't need to.
• 4:21
  Nathaniel Nelms: It's an unneeded expense.
• 4:23
  Nathaniel Nelms: There was a study in JOA in 2024, looked at 180 anterior versus 180 posterior approaches all two Bs.
• 4:29
  Nathaniel Nelms: The worst hip spine classification, there was 0.6% dislocation in the anter approach.
• 4:34
  Nathaniel Nelms: That's about the same as in the studies that aren't using it, and 2.7% in the posterior approach still not as good.
• 4:39
  Nathaniel Nelms: So why does approach matter?
• 4:40
  Nathaniel Nelms: It's because we're able to lay the patient's supine, but also we're able to disrupt the tissues less.
• 4:45
  Nathaniel Nelms: You can keep your obturator externus intact.
• 4:47
  Nathaniel Nelms: You can keep your posterior capsule intact, maybe repair your anterior capsule.
• 4:50
  Nathaniel Nelms: Your stated goal could be wrong in making these corrections.
• 4:53
  Nathaniel Nelms: You could actually make the problem worse.
• 4:54
  Nathaniel Nelms: You could, IM measurement errors.
• 4:55
  Nathaniel Nelms: It doesn't always take into account hip flexion contracture.
• 4:58
  Nathaniel Nelms: Think about that.
• 4:59
  Nathaniel Nelms: And femoral anteversion is often not even considered in the whole thing of, am I gonna adjust my composition?
• 5:04
  Nathaniel Nelms: When you look at what's recommended in hip spine classification, if you put your cups at 40 degrees and 25 degrees of anteversion, you're gonna hit all of them, your one a's your two as.
• 5:13
  Nathaniel Nelms: Two, two B's.
• 5:15
  Nathaniel Nelms: Two, two a's all of those are included.
• 5:17
  Nathaniel Nelms: So the difference you're gonna make is maybe five degrees in composition is always changing.
• 5:20
  Nathaniel Nelms: Just the anteversion, you're really not making any difference at all.
• 5:23
  Nathaniel Nelms: So what does matter?
• 5:24
  Nathaniel Nelms: Do an anterior approach.
• 5:25
  Nathaniel Nelms: Minimize soft tissue releases, recreate your leg length and offset.
• 5:29
  Nathaniel Nelms: Stop worrying about this little tiny change of cup position that you can't actually make.
• 5:33
  Nathaniel Nelms: Even with the robot, you might be hitting the wrong target.
• 5:36
  Nathaniel Nelms: I yield my time.
• 5:37
  Edwin Su: Nathan, Nathan.
• 5:37
  Edwin Su: Nathan.
• 5:38
  Edwin Su: Uh, boy.
• 5:39
  Edwin Su: Am I gonna school you?
• 5:40
  Edwin Su: Uh, this is my first, uh, invitation here and, uh, I feel like I just got invited to a special club.
• 5:47
  Edwin Su: So thank you to the organizers.
• 5:49
  Edwin Su: Uh, so I, I, I, um, I'm gonna start this debate with a survey.
• 5:53
  Edwin Su: So, how many of you are using fluoroscopy for your DA total hip replacements?
• 5:58
  Edwin Su: Show of hands, please.
• 6:00
  Edwin Su: 93 people.
• 6:01
  Edwin Su: Okay.
• 6:02
  Edwin Su: How many of you are positioning your cup based on the standing pelvic position?
• 6:07
  Edwin Su: Show of hands.
• 6:10
  Edwin Su: Okay.
• 6:10
  Edwin Su: Not as many as I thought actually.
• 6:13
  Edwin Su: Uh, so, um, well, I would argue that if you are trying to position your cup at the time of surgery to the standing pelvic position, then you are already taking into account the hip and spine position.
• 6:27
  Edwin Su: And the mechanics and how it affects your, uh, cup stability, your hip stability.
• 6:32
  Edwin Su: So you said that there were no holds barred for this debate.
• 6:35
  Edwin Su: I tried to look up all dirt on Nathan.
• 6:38
  Edwin Su: Uh, he runs a pretty clean ship.
• 6:40
  Edwin Su: I didn't see any, uh, evidence on social media, so fortunately didn't have anything.
• 6:45
  Edwin Su: Uh, but that may be because he's been living under a rock and he hasn't seen in the last five years about a hundred pa papers written about the hip and spine relationship.
• 6:56
  Edwin Su: I wish I could believe your magical thinking, that DA approach could make our dislocations disappear.
• 7:02
  Edwin Su: But we can't overcome the laws of physics.
• 7:04
  Edwin Su: We are making an incision.
• 7:06
  Edwin Su: We are gonna disrupt the soft tissues more in the anterior than the posterior granted.
• 7:10
  Edwin Su: And I think you'll all do a beautiful job, and that's why we're here talking about the DA approach.
• 7:15
  Edwin Su: But our dislocation rate will not be zero.
• 7:18
  Edwin Su: The the ball that we insert is smaller.
• 7:20
  Edwin Su: We have the soft tissue compromise and the hip spine mechanics will influence where the pelvis is in space.
• 7:26
  Edwin Su: And we have to take that into account when we position our cup.
• 7:30
  Edwin Su: The two situations where that's important are in the stiff spine and in pelvic tilting this will occur because the pelvis is a bridge between the hip joint and the spine.
• 7:40
  Edwin Su: So Nathan, the hip bone is connected to the pelvis bone, which is connected to the spine bone, and that is why we need to take this into account.
• 7:49
  Edwin Su: Okay?
• 7:49
  Edwin Su: He's given some eloquent, uh, arguments that you don't need to take that to into account because our soft tissue envelope is good.
• 7:57
  Edwin Su: Um, but I would submit to you even in those papers that show there, there is a reduced risk of dislocation with the DA approach.
• 8:03
  Edwin Su: It is not zero.
• 8:05
  Edwin Su: And you all are surgeons here who are interested in education, learning from others, and doing the best for our patients except for Ben Domb, who just came here for the social events.
• 8:15
  Edwin Su: But, uh, I would submit to you if you are interested in that.
• 8:19
  Edwin Su: Then you must take into account the hip and spine relationship.
• 8:23
  Edwin Su: So from a practical standpoint, you don't need to get 14 studies, you just need to realize that the spine does influence the pelvis.
• 8:31
  Edwin Su: And basically the two situations that I'm concerned about that keep me up at night are the stuck standing position where the pelvis does not roll back in the sitting position and then you're at risk for posterior dislocation.
• 8:43
  Edwin Su: And I will give you that.
• 8:44
  Edwin Su: The DA approach, I think mitigates.
• 8:46
  Edwin Su: That to a large degree.
• 8:47
  Edwin Su: So most of the time you don't really have to worry about that stuck standing position.
• 8:52
  Edwin Su: It's the stuck sitting position that you really have to worry about when you look at that standing pelvis, and it looks like an ob, an outlet view, they are basically posteriorly tilted and they're gonna be at risk for anterior instability, and those are the ones that you have to be careful about.
• 9:07
  Edwin Su: Minimize your cup position and even minimize your anteversion on the cup and consider dual mobility.
• 9:13
  Edwin Su: So, um, in conclusion, Nathan, I think if you wanna do the best for your patient, you need to realize that the hip spine mechanics are a risk factor for dislocation.
• 9:23
  Edwin Su: You recognize risk factors for other conditions and you don't ignore them.
• 9:26
  Edwin Su: Why ignore the hip and spine relationship?
• 9:29
  Joseph M. Schwab: One minute rebuttal.
• 9:31
  Nathaniel Nelms: Wow.
• 9:32
  Nathaniel Nelms: Um, I don't believe any of that.
• 9:34
  Nathaniel Nelms: Let's start with that.
• 9:36
  Nathaniel Nelms: Um, I think maybe what we should all do is do hip resurfacings.
• 9:39
  Nathaniel Nelms: Like you, I'm sure you use all the hip spine classification for every one of your hip resurfacing patients you take care of.
• 9:45
  Nathaniel Nelms: I just question, you know, I just go back to my points of, um.
• 9:49
  Nathaniel Nelms: You know, can we keep it simple?
• 9:52
  Nathaniel Nelms: Your goal is maybe to get it to 0% dislocation.
• 9:55
  Nathaniel Nelms: Is that reasonable?
• 9:56
  Nathaniel Nelms: Is that possible?
• 9:57
  Nathaniel Nelms: There are some patients who have soft tissue abnormalities, they're hyper lax.
• 10:02
  Nathaniel Nelms: Some of the recommendations from the, uh, hip spine classification are go dual mobility.
• 10:07
  Nathaniel Nelms: Well, if, if you have to go dual mobility, can you really get an optimal composition that's gonna get you to 0% dislocation?
• 10:13
  Nathaniel Nelms: So maybe we could get closer to 0% if we just put, dual mobility in all of our patients.
• 10:17
  Nathaniel Nelms: But we're not gonna get there.
• 10:18
  Nathaniel Nelms: Even doing that.
• 10:19
  Nathaniel Nelms: There are weird things that happen.
• 10:20
  Nathaniel Nelms: We all absolutely want to do our best, right?
• 10:23
  Nathaniel Nelms: Do it.
• 10:24
  Nathaniel Nelms: But this isn't gonna get us there.
• 10:26
  Edwin Su: I think it'll, I think it'll get us closer, Nathan.
• 10:28
  Edwin Su: So if we recognize that in that, in that, uh, situation where the spine effects the pelvis, we can modify certain things, just little tweaks and try to get it as close to zero as possible.
• 10:39
  Edwin Su: I think we're on the same page, but I think you should take into account the hip spine mechanics.
• 10:44
  Joseph M. Schwab: All right.
• 10:45
  Joseph M. Schwab: Thank you.
• 10:45
  Joseph M. Schwab: Thank you, debaters.
• 10:46
  Joseph M. Schwab: Please go to your app.
• 10:49
  Joseph M. Schwab: Vote for who won.
• 10:51
  Joseph M. Schwab: At the end of the day, whether you lean towards Nathan's call for simplicity or Edwin's emphasis on biomechanics, there's one point they both agree on.
• 11:01
  Joseph M. Schwab: Our goal is the same.
• 11:03
  Joseph M. Schwab: We're all trying to give patients the most stable, durable, and predictable hip replacement possible.
• 11:09
  Joseph M. Schwab: Some of us approach that by reducing variables.
• 11:12
  Joseph M. Schwab: Others approach it by trying to measure and account for them.
• 11:16
  Joseph M. Schwab: And the truth is both philosophies have merit depending on the patient in front of you.
• 11:21
  Joseph M. Schwab: Hip spine mechanics won't matter for everyone and they won't matter in every case, but they do matter when they matter.
• 11:29
  Joseph M. Schwab: And part of being a thoughtful surgeon might be knowing when that moment is.
• 11:34
  Joseph M. Schwab: If today's debate helped you sharpen your thinking or reconsider your assumptions.
• 11:39
  Joseph M. Schwab: Then it accomplished exactly what these conversations are meant to do.
• 11:43
  Joseph M. Schwab: Thank you for joining me for this episode of the AHF Podcast.
• 11:47
  Joseph M. Schwab: As always, please take a moment to like and subscribe so we can keep the lights on and keep sharing great content just like this.
• 11:55
  Joseph M. Schwab: Please also drop any topic ideas or feedback in the comments below.
• 12:00
  Joseph M. Schwab: You can find the AHF podcast on Apple Podcasts, Spotify, or in any of your favorite podcast apps.
• 12:08
  Joseph M. Schwab: As well as in video form on YouTube slash at Anterior Hip Foundation, all one word.
• 12:16
  Joseph M. Schwab: Episodes of the AHF Podcast come out on Fridays.
• 12:20
  Joseph M. Schwab: I'm your host, Joe Schwab, asking you to keep those hips and spines happy and healthy.