Chris Tucker: Welcome to the Arthroscopy Journal podcast. I'm Dr. Chris Tucker from the Walter Reed National Military Medical Center and the podcast founding editor. Today, we are discussing revision ACL reconstruction. I'm joined by a friend and a colleague of mine, a thought leader in the field of sports medicine, an active educator and leader in AANA, and a true clinician scientist, Dr. Jorge Chahla, from Midwest Orthopedics at Rush University in Chicago.
Dr. Chahla was the senior author on the recent article titled Consistent Indications and Good Outcomes Despite High Variability in Techniques for Two Stage Revision Anterior Cruciate Ligament Reconstruction: A Systematic Review, which is published in the September 2023 issue of the Arthroscopy Journal. His co-authors include Varun Gopinatth, Felipe Casanova, Derrick Knapik, Enzo Mameri, Garrett Jackson, Zeeshan Khan, Johnathon McCormick, Adam Yanke, and Brian Cole. Jorge, congrats on your work. Welcome to the podcast.
Dr. Jorge Chahl...: Thank you very much, Chris. It's a pleasure to be here with you this morning, and excited to talk about this project, which I think it's important for our patients. And I think it's important for us to understand that sometimes taking one step more may lead to better outcomes. So, excited about this, Chris. Thank you for having me.
Chris Tucker: I think for knee surgeons, the revision ACL is one of those cases that really gets us excited. It's a test of so many aspects of our skillset with so many variables that we need to take into consideration, patient factors, injury characteristics, patient's timeline, their goals, anatomic variables, their prior surgical history, et cetera. It's truly never the same case twice no matter how many we've done.
I'm excited to tackle this fairly broad topic in a relatively brief podcast with you, of course dialing down on your specific focus of the two-stage revision ACL. So, let's get right to it. Can you tell us a little bit about your own knee surgery practice and what motivated you to look into this specific aspect of the revision ACL reconstruction?
Dr. Jorge Chahl...: Yeah, Chris. That's one of the main reasons why I decided to tackle this, because I have a fair amount of patients that come to us for revision surgery. And as you said before, it's multifactorial. And there's things like age or other things that you can't change, gender and so forth. But there are things that you can change. And we learn more and more about the topics and features of the knee that we can potentially change such as the slope, such as potentially malposition tunnels, meniscus deficiency, alignment and so forth that we can actually change.
So, I think we're getting to be more and more experts I would say in this topic because when you think about the revision rates as ACL reconstructions are increasing and our numbers, although technically potentially better, our numbers are still, in my mind, unacceptable. If you think of a cardiac surgeon failing 20% of the cases in people that are under the age of 20 in their lifetime, it's unacceptable to them. But we still have a surgery that is very good for a lot of people, but also that may have unacceptable failure rates.
And to that extent, I think we need to become proficient in understanding what are the things that we can fix to begin with so that we don't have a failure. But also, when we have a failure, just look at every single component so that we can try to prevent another failure from the second surgery.
Chris Tucker: The unfortunate reality of our profession is that failure is unavoidable. As you said, primary ACL reconstruction failure rates vary based on a lot of factors. But most systematic reviews recently have reported incidence between 2% and 4%. With technical surgical errors contributing to many failures, one realizes that at the time of the index procedure an ounce of prevention really is worth a pound of cure. I wanted to run through the common causes for surgical failure and hear your thoughts on how to best avoid those pitfalls when performing the initial ACL surgery.
Of those errors, your study mentioned tunnel malposition, missed meniscal injury, inadequate fixation, and poor postoperative rehab. I'd also add to that list missed concomitant collateral injury and unrecognized malalignment, whether it's in the coronal plane or sagittal plane. Could you touch on each of those for us and share your thoughts on how you address them the first time around?
Dr. Jorge Chahl...: Absolutely. So, I think those are all things that we recognized at the beginning and there's things that most people would be willing to tackle in an initial surgery and some people potentially tackle other things in a revision setting. In the first surgery, I think it's important to recognize from a meniscus perspective, two things. One, the most common ones is the LMORT or the oblique meniscus tear of the lateral meniscus, which is extremely common. Almost up to 20% of ACL injuries as well as ramp lesions, just that meniscus capsular damage both on the top meniscus capsular and the meniscus tibial ligament as well of the medial meniscus. Those should be inspected and for sure ruled out at the time of surgery.
As you said before, collateral damage can also increase the strain of the ACL and the PCL. So, understanding if there's an LCL injury, an MCL injury. Even if it gaps in extension, you know that that's going to be a surgical endeavor on the medial side as well.
Alignment is something that we look very carefully. Mostly we know how the slope can affect our outcomes on ACL as well as coronal plane misalignment mostly varies. And those are things that although we sometimes see it now because we're looking for them, we're not willing to correct in an initial surgery. I would say most people would not do an osteotomy for an acute ACL tear.
That being said, if you see a chronic case where there's varied stress for example, and you have a concomitant ACL, then that primary surgery maybe indicated to have an osteotomy as a primary procedure. But in the acute setting in a young patient, it's hard to justify doing an osteotomy.
When you do your first surgery, I think it's critical as we've seen in multiple reviews and multiple papers talking about failure that you position your talents well. And this is a game of being able to see. So, whenever you don't see the back wall, whenever you can't understand the anatomy very well, you should take your time, continue to clean until you have a pretty good understanding. Because changing sometimes some of these features at the time of surgery such as putting your tunnel to anterior to vertical will aid into having potentially a nearly failure rate.
So, it's important to correct these things and understand that each of these things that we do at the time of surgery can affect the outcome of a patient, which could be life-changing. If you have a patient that goes through the OR in a span of three to five years, then that patient may stop playing sports and so forth. So, it's a big deal to try to get things right for the first time.
Chris Tucker: Absolutely. In your paper, the stated purpose was to systematically review the current literature regarding indications, techniques, and outcomes after two stage revision ACL reconstruction. I wanted to cover all three of those eras separately, the indications, the techniques, and the outcomes and discuss your key findings. So, could you start us off by telling what you found out regarding the indications that surgeons are using for two stage revision ACLs?
Dr. Jorge Chahl...: So, this paper, the indications were fairly broad I would say. Because some people will potentially fill the tunnels when they were 10 millimeters up to 14 millimeters. And that makes sense, Chris, because I think it's a combination of a multitude of things. One is the location of the tunnels. I tell my residents and fellows when the tunnel is completely off, that's a great thing because you can ignore it completely. When the tunnel is perfect, then that's great because you can use the same tunnel.
The main issue comes when you have an almost perfect tunnel when it overlaps 30, 40 or 50% with your new tunnel because you can actually get a much bigger tunnel that will aid into very poor fixation. In the femoral side, we have other techniques that we can try to do to get away from that. But on the tibial side, mainly if you have a tunnel that is too posterior, there's not too many ways that you can deal with that.
So, in my mind, I would do a two-stage revision in two settings from a tunnel position. One is when the tunnel is slightly misplaced or it's overlapping with a new tunnel that I want to create and/or when the tunnel is in the perfect position and it's over 13 or 14 millimeters of widening, so it's too wide in the setting of a revision that I will not be able to reliably get good fixation.
That being said, there's some techniques in which some people can put a bone down, for example, and ream through the dowel. The promise is that without bony ingrowth of that dowel, it's a little bit more risky, although it can be done. That's as far of indications.
The second question was techniques. I think any techniques that you do for this can work and have been shown to have consistent outcomes. You can use bone chips. You can use DBM. I think as long as you follow the principles, you should be okay. I like to use bone dowels because they allow me to ream down in the same direction that it was reamed before and then get some press fit.
And it's important to me because when you get a CT scan at four or five months, sometimes the CT scan may not be as convincing to show bone healing, but when you go back and you see the bone ingrowth, it can be quite successful and it looks quite nice. So, that's why I like the bone dowels. One pearl if you do use dowels in the tibia is you want to bone pack the cannulation in the middle because some of that synovial fluid can come through that and cause like a cyst at the bottom of the tunnel. So, I would encourage you to fill up that little cannulation in the middle of the dowel.
And finally, the outcomes, although outcomes of revision surgery are never as good as the primary setting, you can actually get really good outcomes in the 85 to 90s for most of the PROs as well as avoidance of new surgery in most cases, if you correct all the factors that you came with. So, I think although not a perfect situation, you can actually achieve extremely good satisfactory outcomes.
Chris Tucker: I think it's a wonderful summary of all three topics you discussed. I had a few followup questions specifically about the techniques. Your article implies there's a wide variety, which I think there is, and you discussed a wonderful pearl on how to use the bone dowels, which in my practice I have similar practice of doing that.
Along the lines of diverging from just what kinds of bone graft people are using, what are the timelines that you were seeing between stages one and two? I know people have different thoughts on how long they need to wait before reevaluating with imaging and/or proceeding to stage two. What did your group find regarding the general practice of that timeline and staging?
Dr. Jorge Chahl...: That's a good question, Chris. I think it varies significantly. As I said before, sometimes those CT scans are not as reliable and sometimes the bone healing is not as robust as you would see on a fracture, for example. And that gets you very concerned to say, "Yeah, I think we're fairly safe to get this done." But I would submit to you even if you have partial healing of those bone dowels or the bone that you have in there, when you get back in there and you ring your tunnels, it looks like native anatomy.
So, I think we're just looking for a couple of things, which is one, that it doesn't degrade, so it's not completely reabsorbed. The second thing is that you want to see some partial healing, at least to the extent of the borders of the tunnel. And once you have that, I think it's feasible or reasonable to go back and redo the surgery. I would say that in most cases, most people waited about four to six months to come back for the revision setting and do just normal tunnels where they belong.
Chris Tucker: Another quick followup question. Did your group or find anything out regarding ACL graft selection for stage two? And if not, what's your own thoughts and practice on the discussion about graph selection for stage two?
Dr. Jorge Chahl...: In this study, it was all over the place, Chris, and I think it had to do with the primary ACL because if they used hamstrings. Most people I think would've used BTB. If they used BTB in the primary setting, they used their quad hamstrings. But in my practice, I tend to use BTB as much as I can. We know that the failure rates of BTB are potentially a little bit less.
When you look at the Danish or the Norwegian registry data, there's some newer data that says that it may be comparable, but for the most part, I don't think the graphs are an issue. I think it's a fixation method. And we have bone to bone fixation with a screw. So, I think that that is undefeated in regards to outcomes. So, in the second time around, you don't want to be leaving anything outside your control. And I think using this bone to the bone with screw fixation is potentially still the best option, at least in my hands.
Chris Tucker: One more question about the nuances of performing potential slope correcting osteotomy, whether it's for varus or for posterior tibial slope or even a biplane or to correct both. What did you find regarding whether surgeons were doing that at the time of stage one with their bone grafting or were they waiting to perform it at stage two with the revision graft placement, or was it variable?
Dr. Jorge Chahl...: I think for the most part, Chris, most people would do it in the first time. And the reason being is that you can wait for that bone to heal and then you can actually take those staples or plates, whatever you use to make your tunnel. You have to remember that most of the times the staples or the plate will be in the way of the ACL tunnel. So, it can make it much more technically challenging to do your ACL at the time of doing the same osteotomy.
So, I think most people do it the first time, and these are really fun surgeries. The closing wedge osteotomy can go a long way. As we know and we've learned from the vets, tibial leveling osteotomy can actually be all they need. And I've had cases, Chris, where I've done an anterior closing wedge osteotomy in a 17, 18-degree slope patient and they'll come back in four months and say, "Doc, I don't think I need it. I feel pretty good." And they're doing squats and feeling pretty good. Osteotomies can be very, very powerful.
I think we just need to understand sometimes that a biplanar osteotomy can't always correct to the same extent on both sides. If you do a medial opening wedge biplanar, we've shown with Robert LaPrade in another paper that was published in arthroscopy that it's really hard to modify the flow. You can keep it the same way that it was and potentially decrease a little bit even by putting a staple on the front, they can't modify it too much.
So, if primary issue is in the sagittal plane, that's where you should correct. So, you should do an anterior closing wedge osteotomy. That could be differential on the medial and lateral side, but again, you can correct a lot of the coronal plane if you do an anterior closing wedge and vice versa. If you have a lot of sagittal deformity, you can't do much from a coronal plane osteotomy.
Chris Tucker: That's insightful. Now, Jorge, when meniscal pathologies being addressed, are folks doing that during stage one or two and is that dependent more on what's being done, whether it's a meniscus repair or a meniscus allograft transplant? What's been your experience with that?
Dr. Jorge Chahl...: I think as you said before, it depends on which type of procedure. I think most people will not buy an unstable knee. So, I think most people would potentially wait for the second stage to do a transplant if needed. But if you have a meniscus repair, I see it as if you had two chances. The first chance, let's say you have a root tear, you put the root back, you put the patient on an ACL dynamic brace, and then you come back and then you have a second chance. If it tore again, you have a second chance to repair it.
But if it healed, then it's one thing less out of your plate on the second surgery and then you know that that ACL graft would be more protected than if it would be ACL deficient in way. So, I think it depends on which type of tear, but I would submit to you that in my practice, I'll try to do every meniscus repair that I can on the index procedure, and then if I come back, I will check on it. If it's torn again, then I have a second chance to repair it again. And if it's healed, then it's great.
Chris Tucker: Yeah. That's a great perspective. Now, as you said earlier, we all know that compared to primary ACL reconstructions, the revision surgery tends to have less predictable outcomes. As you showed in your study, patients often have lower patient reported scores, more residual laxity and some higher complication rates. What did you find out about the prognostic factors involved with these outcomes? And is there any modifiable factors that we can control to potentially improve on those either preoperatively or intraoperatively with our techniques?
Dr. Jorge Chahl...: I think there's multiple, Chris. There's the ones that we can't modify such as age, gender and so forth. There is some that we can modify. They're in two big realms. One is the psychological issue, fearful re-injury, understanding that some people may not want to even go back to sports after a second surgery because from a financial perspective or a mental perspective where they say, "You just can't go through this anymore. Stop playing sports." And sometimes it's not because they can't, it's just because they don't want to.
The third factor, which is the one that we are all excited about are the factors that we can modify surgical. And I think it's a matter of just looking at the knee as an organ. One of my mentors, Bert Mandelbaum used to talk about this all the time. And I think you have to look at the cartilage disease. You have to look at the align. And you have to look at the meniscus situation. More so, there's other things they have shown to reduce retear risk. For example, an anterolateral complex reconstruction such as an ALL or a LAT is something that I do in all my revision. So, I think there's a lot of things that we can try to do to avoid failure.
But a different thing is how to improve our outcomes, meaning how do we get those patients to feel just as good as a primary ACLs. And I think this depends on other things. A lot of the times when you look at a revision setting, these are patients that have, as we showed in our study, more meniscus tears, more cartilage damage, almost impossible for those people to feel just as normal as a primary 15-year-old ACL they just tore.
But for others in which there was a mechanical issue or something that was not done properly in the first procedure, I've had patients that say, "My knee never felt 'connected' before. It still felt a little bit lax." Or if you have, I don't know, for example, a graft that was fixed in 20 or 30 degrees of flexion and they could never get their extension back, as soon as you fix the graft in extension and they are able to get their extension back and potentially do some capsule releases to get that back, they actually can feel even better than before. So, I think it depends on the case.
The problem sometimes with the systematic reviews is you're pulling data from multiple studies that may not have all the confounding factors that we know exist accounted for, and I think that can yield some data that may be not as perfect as we would hope.
But again, based on personal experience, I would say that it depends on the case. If you have things that cannot be corrected so easily, such as chondromalacia, and things of that nature, those patients may be more not as happy or more inclined not to achieve a perfect outcome. But if they do have some things that can be corrected, they can have an outcome that is very similar to a primary setting.
Chris Tucker: And I mean, I think even with the limited data in the studies that you use, I mean you and your co-authors should be commended on the number of questions you were able to address and answer in your systematic review.
Now, you've nicely touched on several of the more contemporary topics I wanted to discuss. We've already discussed the correction of the posterior tibial slope, and then also you mentioned the lateral extra articular augmentation, which I think a lot more of us are considering using in multiple settings, including the revision ACL.
The last topic I wanted to ask you about along those same lines is biological augmentation. Do you think there's any data to support use of any various biologic augmentation techniques or substances or devices out there to help us with the revision ACL?
Dr. Jorge Chahl...: I don't think we have enough data, Chris, to routinely or systematically use biologics, at least from an ACL perspective. There's other meniscus papers. There is one paper that we've published with my partner Brian Forsythe, where there's a trial on bone marrow aspirate concentrate injected in the ACL on allograft, which seem to improve some of these outcomes.
But I guess in a revision setting, I would try never to use an allograft. You want to make sure they use the graft that would be the strongest and potentially have the least potential for failure. And I would say that in a revision setting, that would be a BTB for me. And sometimes I would even go to the other knee if I don't have a good option of the same knee, I would not hesitate to go to the other knee. And we've done this several times and it's actually a very reliable procedure. People recover very well from just that graft harvest.
But from a biological perspective, although it's been described and it's out there in the literature, I don't think we have enough evidence to routinely use it. I don't think it can hurt patients. So, if patients are aware and there's no financial restraint, I don't think it's a bad thing to do, but certainly not something that we can do from an evidence-based medicine perspective.
Chris Tucker: As we both know, the ACL remains the most studied topic in all of orthopedic sports medicine, and one would think we've left no stone unturned, yet it seems like the more we learn, the more we seem to realize how much we don't know. What do you think is currently the most exciting area of investigation in the ACL, or what do you see as the most important unanswered question still yet in this area of research?
Dr. Jorge Chahl...: That's a great question, Chris, but I think we have short-term goals that we have as ACL surgeons that we need to address. I think we have a contemporary genius who's one of my friends, Alan Getgood, who is leading two very important studies, one that is completed stability one, and the second one, stability two, that it's underway, that I think will help solve some of the contemporary questions that we have right now in regards to lateral tenodesis in different ACL settings.
I think that's the one thing that will change the way that we practice potentially based on the results of those studies. But then we have more long-term studies that I think we need to do, and that goes to, for example, ACL repairs and more biological ways of healing, potentially the native tissue, which I think it's on its infancy right now, but I think it has some potential to be one possible solution for us moving forward.
I just don't think that the data is there as of now, but it's certainly exciting to think that we can harness the body's own ability to heal and potentially have a native tissue that it's regenerated into the wall, because it has clearly some potentials, but I just don't think based on where we are right now, it's ready for primetime yet. That being said, I think that in the future as we go through this, that we might find ways to make this a more optimal solution for our patients.
Chris Tucker: We've covered a lot of ground on the revision ACL and Jorge, you've provided us a very nice summary of the most currently available data on the two-stage revision ACL. Did you have any other closing remarks you wanted to share with us before we close out?
Dr. Jorge Chahl...: No. I wanted to thank you, Chris. I think these podcasts are phenomenal. I listen to them every time when I go to work, and I just enjoy learning from this type of format. Sometimes reading a paper can be somewhat boring if you're going through, but talking to the author and understanding what their purpose was and what they actually got from the paper is sometimes way more insightful than just reading the paper. So, thank you for that. I encourage everyone to listen to this podcast because at least I have a lot of fun, and I learned a lot when I hear them.
Chris Tucker: I appreciate your feedback, Jorge. We certainly try and deliver some educational and hopefully entertaining conversations, and it's mostly dependent upon the volunteerism of great knowledgeable authors like yourself, taking the time to share your thoughts with us. So, you have contributed substantially to our experience. So, thank you for taking the time to do that with us.
Dr. Jorge Chahl...: Thank you, Chris, and I wish everyone a great day.
Chris Tucker: Great. Thanks Jorge. Dr. Chahla's article titled Consistent Indications and Good Outcomes Despite High Variability in Techniques for Two Stage Revision Anterior Cruciate Ligament Reconstruction: A Systematic Review is available in the September 2023 issue of the Arthroscopy Journal, which is available online at www.arthroscopyjournal.org.
This concludes this edition of the Arthroscopy Journal podcast. The views expressed in this podcast do not necessarily represent the views of the Arthroscopy Association or the Arthroscopy Journal. Thank you for listening. Please join us again next time.
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