Hernia Episode 3-MillertimeBTK.mp3

Hello and welcome to Behind the Knife. This is the hernia team at the Cleveland Clinic. I'm Ryan Ellis here with Michael Rosen, Benjamin Miller, and Sarah Maskell. Today we're excited to talk about a recent publication in the field of abdominal wall reconstruction entitled Quantitative Tension on the Abdominal Wall and Posterior Component Separation with Transversus Abdominus Release, which was published in JAMA Surgery in October of 2023.

A prospective cohort study of abdominal wall tensiometry in 100 patients undergoing posterior component separation with a transversus abdominis release, which we're going to refer to as a TAR going forward. The primary study outcome was a percentage change in tension on the anterior and posterior fascia associated with each step of the posterior component separation with TAR.

Because most of the audience probably doesn't know what a tensiometer is, can one of you please explain what it is and how it's used for the listeners? Tensiometry is just sort of a fancy way to describe measuring the tension on something in this case, the abdominal wall. And the tensiometer

is based on a scale used to weigh things.

And so it basically looks like it has a, as a hook on one end to Catch a coker clamp or leaky clamp and that's attached to a spring and the spring is housed in a stainless steel body And then the spring is hooked up to a handle So the way it works is pretty simple actually just like you would weigh anything On a hook you hook the hook that a coker clamp is attached to the fascia at the hernias widest point And then you hook the tensiometer to the clamp and then pull on the handle.

And as the, as you pull the edge of the fascia toward the patient's midline, the spring is extended in that tension is registered on the body of the scale. What inspired you guys to study this concept of abdominal wall tension? What's, what was the. Behind starting this project is Rosen's idea.

Sure. So, so listen, I think this stuff you know, anything you do in surgery,

what I tell all young people is you should be curious about why you're doing what you're doing and never just accept. That we're doing it because that's why I was trained how to do it and that's what I was taught and always dig deeper and try to understand why we're doing what we're doing.

And so the concept here was, you know, after doing, you know, well over a thousand of these operations, you see things and you think you understand why the releases that we're doing are having the effect that we think in the abdominal wall. But it's important to measure these things, and it's important to quantify them, and it's really important to do that so that people understand why we're making each move in the operating room, so that they can balance what they're trying to achieve with those releases versus the potential harm or complications associated with those releases, so that you can have a thoughtful approach to abdominal wall reconstruction.

And just to add

on to that, this isn't something new. This was done a generation ago by some European surgeons. using a spring based tensiometer just like we did. And Will Hope's group in North Carolina has also done some of this work as well. I think the one thing that we did that made it much easier for our group was that we designed it or had the prototype department here at the Cleveland Clinic design a tensiometer that could be sterilized.

And so it was easy to use in multiple cases and have a bigger case series than what had done, what had been done before. Okay, and just to talk a little bit about kind of abdominal core and tension and how all this relates. Obviously, there's a new interest in kind of renaming or rebranding our field into abdominal core health.

And when you think about abdominal core health, it is essentially looking at the abdominal space or cavity and all of its borders by the diaphragm, the pelvic floor, The anterior abdominal wall muscles and the spine and kind of trying to think

about. the effect of each of these muscles on your core function.

And more importantly, as reconstructive surgeons, both the benefits of bringing things back to normal, but the potential downsides of disrupting some of the key core muscles. And as a perfect example, if you talk to most physical therapist, the transverse is abdominous muscle really is one of the most important core muscles that there are.

And so I think kind of understanding that from their perspective, there is a potential in cutting this muscle to cause core instability, spine. Instability and all the consequences that go on. We've looked at this in our lab in other series and have not been able to find that in the medium term follow up, but it just weighs into when you think about things as a cylinder, any kind of cause and effect of what's happening on the posterior cylinder to the anterior

cylinder should all be weighed in and also understanding in the realm of tension that this cylinder is not a tension free cylinder, right?

This cylinder functions under physiologic tension. And actually Ben Miller and some of his other work has looked at that as well to establish that the native abdominal wall, there is baseline tension kind of like a tendon in the hand. And when you lose that tension or completely make it tension free, it's no longer functioning.

So as mentioned earlier, this cohort study was conducted at the Cleveland clinic. Patients were included if they were adults with midline hernias, that is the European hernia society classification of M1 through M5 who were planned for a posterior component separation with tar exclusion criteria included prior component separation, presence of a stoma or lateral hernias.

All patients underwent an open tar, which we'll discuss, and had tension and pounds measured for the anterior and posterior fascial elements at each step of the operation. Can you talk to us through the steps

of the posterior component separation of tar at which you measure the anterior and posterior fascial elements?

So we measure the posterior and anterior fascia at each step of the tar and we divide it into three steps. The first step is the retrorectus dissection. So that included an incision on the posterior rectus sheath and then a complete dissection to the lateral. edge of that to the neurovascular bundles in the lateral space of retrorective space.

So that was the first step, retrorective dissection. The second step was dividing the posterior lamella of the internal oblique aponeurosis. And then the third step was the tar itself where the transverse abdominis muscle is divided, but it also It doesn't include just dividing the, if you, just for a brief review of abdominal anatomy.

So in the upper third of the abdomen, that muscle, the transverse abdominus muscle, you can see the muscle belly, which is medial to the linea semilunaris. And then as you transition into the mid abdomen, it becomes more aponeurotic, and then it disappears. In the posterior sheath anyway, below the arcuate line.

And so the you divide the pustule of the middle of the internal oblique, and then you divide the transverse

thalamus muscle. But that also includes a dissection laterally, a preperitoneal dissection laterally. You can take all the way down to the retroperitoneum to the medial border of the psoas. So the tar is not just dividing the muscle, it's a very wide lateral dissection in the preperitoneal or pretransverse cell space.

If I could add just a couple things to that, so I think for any person who's contemplating doing this operation, kind of the reason that those are the steps, it's really important to understand and to interpret this data correctly is the goals and objectives of a TAR, or any retromuscular surgery is the reality, which is that you must create a posterior uric.

Dissection plane to provide a posterior sheath that can close without excessive tension. And then you also ideally want to bring the anterior fascia together to cover up your mesh and limit the amount of bridging. And so, Thinking about which muscle inserts into

which plane can help you interpret the anatomic reasons for our findings and why this data should not be surprising but is often not considered by the surgeons to understand why they're doing what steps.

And so if you kind of take what Ben said to, you know, the posterior rectus sheath inserts in the anterior structures at the linear output. The posterior lamella, the internal oblique also inserts in an anterior structure, but also interdigitates with the transversus abdominis. And then the transversus abdominis is strictly a posterior structure with no connection to the anterior.

And kind of putting together all that anatomy is why we broke up those steps and why it fits into kind of just logically why we would do what we're doing in the operating room. The primary study outcome was a change in tension on the fascia of the abdominal wall during posterior component separation with TAR.

Just to quickly go through the results, a hundred patients were

included and measured, so we had two hundred measurements. In the analysis most patients had a recurrent hernia, about 55%, median width and length of the hernia were 13 and 23 centimeters respectively, and mean baseline tension was 6.

78 on each side. And for reference, as mentioned earlier, the physiologic tension is about one pound on each side. And then, just breaking it down by steps without going through all of the numbers exactly, there was release in the anterior sheath tension that was mostly affected by the posterior rectus sheath incision and dissection.

To a lesser extent, there was some reduction in tension with division of that posterior lamella of the internal abdominal oblique. And the posterior sheath, in contrast, had very little reduction in tension by the posterior rectus sheath incision and dissection. for your attention. But it was more affected by lamella and by the tar itself.

Yeah, to kind of put it simply, that was a

great review, Sarah, but just to kind of put it simply, when you do the an incision on the posterior rectus sheath or a retrorectus dissection gives you anterior fascial advancement or reduces tension on the anterior fascia. So say that one more time. So retro rectus dissection gives you mostly anterior fascial advancement, not posterior fascial advancement.

You get posterior fascial advancement by dividing the posterior medial internal oblique and through the tar. So, but you get almost zero anterior fascial advancement with the tar. You get posterior, but not anterior advancement with the tar. And I think for a lot of people, This can be very complicated to understand.

And the first time I think when people hear this, particularly people who are less experienced with this operation, the first response would be, well, then why should I do a TAR? This data is suggesting that I should stop doing TARS. And I would tell you that that's a misinterpretation of this data. This data is telling you exactly why you should be doing a TARS.

And so, if you

extrapolate this to understand that if you're doing a posterior rectus sheath dissection and the hernia is small enough or the rectus muscles are wide enough, that the posterior sheath is closing without excessive tension and you can put a wide enough piece of mesh to fix the hernia based on your judgment, you can stop.

You do not need to do a tar. Cause you're done. But what this will tell you, what is most important for anybody who does this operation is if the posterior sheath is not coming together, it's under too much tension, which happens often in retromuscular surgery. That's when you should be doing the tar and that's what the tar will allow you to achieve.

And even more importantly is If the posterior sheath is not coming together, you likely did not do the tar, even if you think you did. And you probably are in the intermuscular plane and stop for a minute and make sure that you've actually divided the transversus abdominis muscle to get in that preperitoneal

plane.

And that, that's why understanding each step allows you to troubleshoot in the operating room. Maybe we're going to talk about that with more questions coming up, but just how to interpret this data into real world practice is actually why, and this data, as Ben had said, has been done in smaller studies without the ability to kind of do subgroup analysis and was even done in cadavers.

But again, unfortunately, in a cadaver, they don't really have a hernia. It's not particularly realistic to what's happening in patients with hernias. So I think that's why this data in a hundred patients, 200 measurements, one on each side allows us to really see the story and understand that information.

Were any of you guys surprised by the results of this paper, this study? I wasn't surprised at all. I mean, I think seeing this every day I think that's just reinforced my understanding. And I think that Again, as I mentioned before I think my hope is that people can interpret this and be able to

troubleshoot in the OR with real data.

Because what I am often surprised by every day is the amount of redo TARS that I do with linea semilunaris defects, the amount of posterior sheath breakdowns that I see because of excessive tension on the posterior sheath. And so what I hope And I think any surgeon who does a large volume of retromuscular surgery, this is what we see every day that those who are on their learning curve can use this to understand and really troubleshoot that.

You know, the tar is critically important for posterior sheath. And that's, that's really what this message is. And the anterior sheath, it all comes really from the retrorectus and a little bit from the posterior mella. But that's not why we should be doing tars. Particularly for smaller hernias. To piggyback off of that, I, something that I always found interesting when Dr.

Ramirez first described the interior component separation back in

1990. After the, at one of the final steps of the interior component separation, he performs a retrorectus release or that incision. Now, is that something that you think carried over from Reeves and Stopa or is that something that you as a you know, a hernia surgeon, you've noticed is like, once that incision is made, I have some release.

So Ryan, I'm glad you brought that up. So let me tell you right now, everybody listening to behind the knife, I want you to take a moment and I want you to go back and read Oscar Ramirez paper, because it's actually even more of the story than you think. Because when Oscar Ramirez originally described the anterior component separation, he numbered it in his pictures.

And step one of an anterior component separation is raise the skin flap. Because that frees the skin off the anterior fascia. But step two, and little known and often misquoted, was cutting the skin. The posterior rectus sheath, because he probably recognized just as you pointed out, that's where a lot of the anterior fascia advancement came.

And step three, and only if

necessary, was cutting the external abdominal oblique muscle. But I would tell you that I hope, we don't do a lot of anterior releases, but I hope that somebody listening to this who does, takes our tensiometer and studies what is the contribution to the external abdominal oblique release.

Because somebody who's done several hundred of those earlier in my career. I actually think that what that does do is make the external oblique retract laterally and make it seem like you're getting a lot of advancement, but I think most of that advancement actually comes from the posterior rectus sheath, but that needs to be studied and repeated in the same way that we did this in patients with hernias to figure that out.

Since we're talking about other operations that might be, might have some implications based on this data, what do you think this says about ETAP? or when that's useful. I would just say the most surprising results to me are how little posterior sheath advancement, posterior fascial advancement the

retrorectus dissection gives you.

And I think people who do this operation know that, you know, really, if you just do a, you know, you can only do a retro rectus repair and e tip for a small, pretty small hernias. I mean, even, even with no hernia, sometimes getting that posterior sheath back together without tension is impossible. And so I think That to me the most surprising results are that, that you get anterior advancement with a retrorectus dissection, but really no posterior advancement.

And so I just think that this confirms sort of what I find in the operating room is that it's hard, which is a retrorectus repair, it's hard to even fix small hernias. And I think that with the ETEP it's, it can be easier if you use the hernia sac, but if you know, with a retrorectus dissection, Repair if it's open and you take out the hernia sac it can be really hard to get the posterior sheath together So I think this just adds more evidence to the fact that if you're gonna be in the retromuscular space If you decide on that type of hernia repair and you have tension on the posterior sheath when you go to close it You have to be prepared to extend your dissection

laterally and it's important to know what each of these releases does And so I don't think that we need to stop doing this retro rectus to be aware of the limitations of each one of those releases.

I, I'll just add a little bit to that. I think as far as it goes with ETEP, I think that the message should be a word of caution to people depending on where you are in your retromuscular learning curve. Because I think the worst situation that you can be in is closing the posterior rectus sheath under tension, putting an uncoated mesh, and that breaks down for a small hernia.

So I think that this is why for small hernias, a thoughtful consideration to whether or not the retromuscular space is worth the risk. And then I think often, one of the reasons that people are doing robotic TARS for small defects in the, in this situation, is not because they're over utilizing TARS.

It's because they're in the situation where they're in the retromuscular space, for a

relatively small hernia, and the posterior sheath won't close. So they're doing what's right. It's safe to get the posterior sheath closed. But I would just challenge, if you back up on that algorithm, just ask yourself the question, should I have ever been in the retromuscular space for a small hernia to begin with?

Because often you are committing yourself to these large dissections for relatively small hernias. Now that you guys have written the paper is there still an indication, do you still use a tensiometer? Does it ever help guide your interoperative decision making or do you put it away and it's going to be there for the next research project?

I'm glad you brought it up, Ryan. I think that there's still room, there's so much to learn about who, about, you know, how we can, we don't use this tensiometer to guide therapy. That's not what it's there for yet, but I think that there's a lot we can learn about. Thanks. abdominal wall tension and trying to predict, one of the things that, that we can't predict well is who is going to have a complete fascia closure.

Like Rosen mentioned, the two goals of the operation, the one is to

get a big retromuscular pocket made for wide mesh overlap, and the other, if possible, is to close the anterior fascia over the mesh, but In some cases, and it's rare, it's like 5 to 10 percent of patients, we can't get the anterior fascia closed over the mesh.

And so, using a tensiometer to be able to identify those patients is useful. And what I mean by that is, if we could somehow link preoperative imaging, whether it's CT scan or ultrasound or something, to be able to recognize who may benefit from a preoperative adjunct, like Botox, say, I think that could be really useful to help, maybe you know, decrease the rate of people who are have a bridge.

In this case, we call it a bridge repair where we can't get the anterior fascia closed. I mean, listen, I think measuring tension is in its infancy. I think this is kind of the first step, but I can just imagine having this hooked onto a robotic arm. And understanding when you get back to physiologic tension, when you should stop I think doing this in open to understand kind of the tension on the posterior sheet

versus the tension on the anterior.

I think there's unlimited value to tension. And, you know, when you think about. the concept of physiologic tension. And now that we understand what that actually is, it gives us an endpoint of where we need to get to with abdominal wall reconstruction. And it also gives us kind of the ability to say, okay, I've done enough.

And as we learn more about component separation, retromuscular surgery, and we start to see, a little bit more high volume complications and downsides to it. This idea of a graduated approach really has a place in hernia surgery particularly for smaller defects. So, so I think that this is just the beginning.

I don't know if it needs for us on every case now but I think that as hopefully as this becomes more popular, as people use it more in the literature, as other groups replicate some of the stuff that we've done this stuff can potentially be used to guide therapy, or at least let a surgeon know when they've done enough.

Thank you to Dr.

Miller and Dr. Rosen for sitting down and talking with us today about this paper. And from all of us at Cleveland Clinic on the Behind the Knife Hernia Team, dominate the day.