So welcome, everybody, to the Multi-Institutional Sports Medicine Fellows Conference. Please keep your microphones muted, or computer muted, so that everybody can hear our professor give his lecture today. This is being recorded and will be transferred to the AOSSM playbook on their website. It'll be in the learning management system and will be available next week. So all of this week's lectures will be available next week or starting next week. If you have questions, please submit it on the chat function. And then I will ask Mark to answer the questions. And as far as the faculty, also let me know. And I'm happy to unmute you to contribute conversation, discussion, commentary, questions as well. So it's my honor and pleasure to introduce Mark Miller, who needs no introduction. He's the S. Ward Cassell Professor of Orthopedic Surgery at the University of Virginia. He's a team physician at James Madison University, formerly the Air Force. All the Miller books and the Miller review course. He is trying on his preparing for Christmas to see what his Santa Claus beard will look like. And has, I think, given the ultimate name, the name that will stick for this lecture series, the Misfit Lecture Series. So without further ado, I give to you Dr. Mark Miller. So he's going to talk about the revision ATL. So Mark, thank you for doing this. Really appreciate it. Well, thank you, Mark, for putting this together. This is a great thing that you've done. And I would encourage this Misfit group to continue well into the post-COVID era. And so a little cartoons to lighten the mood here a little bit. This is a COVID era. It's a really difficult challenge for all of us. And hopefully, we can learn through this process. So here are my disclosures. The most relevant is Arthrex, because I'll show you in a minute that I developed some of this technique with the help of Arthrex. So ACL graft failure really isn't the end of the world unless you're the patient. And as we all know, patients really are challenged and upset and really affects their lifestyle when they have a failed ACL. So we're going to start with an introduction and talk about some of the common causes of ACL failures, focus really on osteolysis or tunnel widening, and discuss how to address that, either with one or two stage approach. We'll look at some CT studies we've done, some biopsy studies we've done, some future studies we're planning, and then we'll show some bonus cases as time allows. So the best way to avoid an ACL revision is to do it right the first time. So I think we're all in agreement that you really should do independent femoral tunnel drilling. Now, that means that you should not go trans-tibial. The reason is that multiple papers have shown that going trans-tibial is not as effective as consistently getting an anatomic location for your femoral tunnel. You can do that a variety of different ways. You can use an accessory medial portal, you can use a flexible drill, or you can go outside in. But the important thing is not how you do it, it's where you put it. So in the tibial tunnel, we like to put it in the center of the footprint, and maybe air slightly anterior medially, as Clancy at once showed us. So I'm an advocate of using fluoroscopy in the surgery center. So you can use these many fluoro techniques, and you can put your pins in, as indicated here, up to the aperture on the femoral side, back it up, and then go ahead and take a shot. And so get a perfect lateral. And when you do, I suggest that your femoral pin should be 3 quarters away across Blumenstadt's line and below Blumenstadt's line. And the tibial tunnel should be about 35% across the tibia. This line's been described by Staubli. He recommends put it in more posterior, but our study suggests that you should put a little more anterior than that. So we started this fluoroscopy with a study that we've done, a series of studies at UVA. And I did this primarily to look at a tibial tunnel. And the added benefit we found was that about 10% of the time, I adjusted the femoral tunnel because I thought it was fine, but I got fooled. And so even senior surgeons can get fooled with landmarks. And therefore, I would advocate for this, especially for you guys just starting your practices. So the MARS study has shown that there's quite a few different problems that resulted in requiring revision ACL surgery. And this is a Venn diagram originally proposed by researchers at the University of Pittsburgh, in fact, during the time of my fellowship, which is almost 30 years ago. And so this combination of technical errors, biologic failure, or repeat trauma can be shown in varying different proportions. So the MARS study group is studying revision ACL, multi-center ACL revision study group, demonstrated that there's a combination of different failures that cause the problem. And this is a figure from Review 8. I hope that some of you have that book, and it's our newest adventure. And this is what I call a composite figure. I love composite figures because you can show multiple problems on one figure. And Steve Thompson, myself, and Brian Warner, my current partner, came up with this drawing that shows a variety of different problems that can result in ACL failure and that need to be addressed during ACL revision. These include widened tunnels, deficient anterolateral complexes, meniscal tears, anterior femoral tunnel placement, excessive posterior tibial slope, and a variety of other problems. And so you can see that this composite diagram demonstrates many of these problems. But we're going to focus today on tunnel diameter osteolysis, widening of the tibial tunnel. Again, though, there's lots of problems, and the technical errors occur most commonly on the femoral side. Hopefully, you've never seen something as absolutely horrible as this. But you can see on the lateral radiograph of exceedingly anterior femoral tunnel. You can sometimes see endo buttons in above the suprapatellar area where there's a vertical tunnel. And these vertical tunnels cause rotational problems. So hardware failure can be common, too, especially early on in the failure paradigm, because interference screws need to interfere. That is, they cannot diverge outside that tunnel and not fix the graft. So you've got to be careful where you put those screws. And then especially in revisions, you've got to recognize that cortical buttons need to engage the cortex. And if you have a deficient cortex, which is very common in the revision setting, then perhaps you need a bigger button or a different technique. Also, missed concurrent injuries can be a problem. Here we see a meniscal ramp lesion that was subsequently repaired. Here we see a root tear that was repaired. And the meniscus, especially the medium meniscus, has a secondary stabilizer to the ACL. And that's why it's critical that we address this meniscus pathology. Sometimes you need to augment your ACL reconstruction. We're currently doing a modified lamere. We take a strip of the iliotibial tract and tubularize it, place it under the LCL, and fix it up just proximal and posterior to the LCL insertion. This is one of two popular augmentation devices. We're currently studying when to do it. And I think probably if you have gross instability and perhaps in the revision setting, you should consider this. You also need to pay attention to the tibial slope because basically the tibia will act like a slide. And it slides down and puts excessive graft. The femur slides down and puts excessive tension on the graft. And the tibia goes forward as a result of that slide. And therefore, sometimes if you have excessive slope, more than 12 degrees, you should do a closing wedge osteotomy. We'll show a case of that towards the end. But one of the biggest technical challenges is tunnel widening. And so although tunnel widening may not in and of itself be a problem or cause of failure, it's certainly something you have to address during your revision. The cause of osteolysis or tunnel widening is still widely unknown. People have hypothesized that it's a windshield wiper effect or bungee cord motion. And Dr. Dedeck and I showed early on that when we used cortical fixation, there was more of this osteolysis in those patients. Perhaps that made it clear that there was a windshield wiper or bungee cord effect. But perhaps the biggest problem with osteolysis is they occur with allograft reconstruction. Others, especially from Ohio State, have suggested that this may be actually an indolent infection. And they use polymerase chain reaction in order to diagnose these. They weren't able to diagnose very many of them with plano cultures, nor have I. But there may be something to this. And perhaps this is a biofilm that's very subtle and can't be picked up on ordinary cultures. The astrology that comes from these revisions shows fibrous tissue, giant cell reaction, and surgical debris. Kind of an amorphous picture. Imaging should be complete with flexion PA radiographs, so-called Rosenberg view, hyperextension lateral to look at the roof impingement, sunrise, long-leg cassettes to look at alignment. I'm a big advocate for stress radiographs. You can consider a stress radiograph to look for collateral ligament injuries and PCL injuries. And also MRI. But the most helpful imaging modality, in my mind, for revision ACL reconstruction, especially if you're concerned about osteolysis, is the CAT scan. Because this allows us to see and measure and quantify and plan for osteolysis. So there's lots of options to fill these big cavernous defects. You can use Iliac crest autograft. You can use autogenous grafts. You can use femoral head. You can use allograft bone dials. You can use demineralized bone matrix, calcium phosphate, interference screws, or dilation technique, where you dilate adjacent to your tunnel to try to create a new tunnel adjacent to it. But regardless of your choice of fill options, you first have to drill and remove all the debris and then fill the defect. And if your tunnel is more than 14 millimeters after you're done removing all the debris, or you're going to have overlap with your new tunnel, then you need to stage it. So we've been advocates of allograft bone dials. And I'll show you some of our results with that. And in fact, we're currently doing a retrospective study comparing our results with allograft bone dials with Kevin Bonner. He has a series of patients that are using calcium phosphate. And we hope to get that data soon if we can get people in post-COVID to evaluate it. So there is one biomechanical study that compares several of these techniques, including not filling it, putting a bone plug in it, a bone dial, putting an interference screw, I know that's a popular technique, dilation of a new tunnel adjacent to the previous tunnel, and then comparing that with primary ACL reconstruction. And the bone plug was the only technique that had results comparable to the primary ACL reconstruction. So let's talk about bone dials. Bone dials are harvested allografts from the proximal femur. They have no cells. They can be fashioned in 10 to 18 millimeter diameter dowels. And they've been modified to be fully cannulated and bullet tipped. So the way that you insert them is you do serial drilling. I like to go by two millimeter increments. I usually start with eight or 10, and then I go to 12, 14, 16, often up to 18, especially in the tibia. And you keep drilling until you do, you put your scope up the tunnel, and I call this tunneloscopy, and you see no more fibrous tissue. So here you can see in these series of images, there's lots of fibrous tissue until we're done drilling, and there's nothing but bone. And then it's time to fill it. And we fill it line to line with a bone dial of equal size and ideally equal length. And you can do this by centering a guide pin and using a cannulated tamp. Our first tamp, one of our nurses modified through a friend of his in the maintenance shop, and Arthrex eventually got hold of this, and we're interested in manufacturing these, and they're available commercially now. No matter what tamp you use, however, it's important, and this falls against the principles of orthopedics, especially in our world, but you gotta gently tap them. And so I know that's hard when you got a mallet in your hand, but if you hit this too hard, it'll crack, and then that's a problem. So again, we try to do single stage whenever we can, and this basically, if you have tunnels that are less than 14 and they're not gonna interfere with your new tunnels, then you can usually get by with that. You debride the remnant graft, center the guide pin, serially drill, and then put the bone dowel in there. And you can drill a new tunnel next to the old, where the dowel is, as long as you don't violate more than 50% of the dowel. So the dowel will stay in place with a press fit technique. If you drill to the side of it. Here's an example. Debride the old graft, center the guide pin, serially drill, and then place the dowel. Here's the dowel going in, and here's the dowel in place. Notice it's not cracked. And then you can do a little bit of a notch plastic, smooth it out, figure out where you want your new tunnel. There's where we wanted our new tunnel. And then we're able to drill the new tunnel. Note the dowel has only been a little bit violated of the previous dowel, and our tunnel's adjacent to that previous dowel. Note also that the dowel stays in place where we drill adjacent to it, and we haven't violated more than 50% of it. And then you place your graft, and look at this, the interference screw secures not only your graft, but also the dowel. Here's an example where we had a pediatric ACL done previously, and the tunnel was placed too anteriorly. And so we placed a dowel into that location and put our new pin behind it. So we reported our results with the single-stage study in 12 patients, and it's in the Yellow Journal, and they did pretty well. Note that their IQDC is nothing to write home about, but that's what happens with revisions. We all know we don't get as good of a revision as you do a primary, but that's still pretty good for revision. Now, sometimes, unfortunately, it's a two-stage approach, and you need to be a good used car salesman if you have to do this, because patients do not like this option. So you have to convince them that they'd rather have a third operation rather than a failed second operation. So here's an example, two-stage revision with allograft bone dowels. Here is the defect approaching skeletal maturity. CT scan, again, is the imaging modality of choice. Center the guide pin extensively to breed, and then place your graft in. Again, gentle tapping. Here's our dowel in place. Here is our dowel, and we're very happy with this particular dowel. Now, there's alternatives for the femoral side. If you had a previous trans-tibial ACL reconstruction and the tibial tunnel osteolysis is more than the femoral side, then you can first start on your tibial side and serially drill it, and then access the femoral tunnel through the tibial tunnel. Now, when I first started doing this, I said, this is a great idea, and I got carried away, and I filled the tibial tunnel, and I go, uh-oh, that was not my plan. That was not my plan. So, resist the urge to fill that tibial tunnel until you first address the femoral tunnel. Address the femoral tunnel, drill and fill, and then go back and fill the tibial tunnel later. You can also go retrograde on drilling and filling on the femoral side. So, if you're worried about going next to the medial femoral condyle, especially with the large graft in the femur, then back your pin out and make a small incision on the lateral side and serially drill and fill from outside in or retrograde. Here we are filling this in retrograde. You can see the dowel coming down with the arthroscopic fluid turned off. Then address the tibial side, serially drill, tunneloscopy, nothing but bone, fill. You can sometimes use two dowels. Now, the newer dowels are longer, so often we haven't had to use this as much now that we have the longer dowels, but that's a good option. It's kind of expensive, but it's a good option. Here we are placing the dowels in, you can see. I hold it with a coker and insert the dowel through that tibial tunnel we've already prepared. Now, it's a little prominent, so we need to address that. You can address that by just simply burring down that prominence. And there you are, you've filled both tunnels. So now you just need to put it in the oven and wait for it to cook, which is about four months I've found. Here we are at four months, and we're checking our dowels with a repeat CT scan. In this case, rather than using two dowels, I use the dowel and some DBM chips. The DBM chips, not really happy with, and so I've abandoned that and try to use longer dowels or two dowels. So that may be a bad choice. Also, smokers take longer to fill in, shouldn't be surprising. And the final thing is if you happen to crack that dowel when you're putting it in, it's not a good thing because it won't heal in and it'll not heal. Here's a second stage revision. You can see where the previous dowel was with our new tunnel. Here you can see the tibial tunnel. You have no idea where that dowel was and it doesn't matter. Here's our new graft in place. And so we actually found a study that used Iliac crest graft and they were able to study what their union ratio and occupying ratio which is pretty complicated not worth going into except suffice it to say it's a measurement of how well they're integrated. So their study with Iliac crest bone graft that they studied at both 12 and 24 weeks had incorporation 75 to almost 90 percent. Our dowels at four months had incorporation of 75 to almost 90 percent. So the dowels incorporate equally well as Iliac crest bone graft especially in the femur. The tibia is a little harder. The tibia has often has larger osteolysis and also the effect of gravity adversely affects the tibia. So we're doing some CT studies both two-dimensional and three-dimensional. Here the 2D study showing this dowel that's fit very nicely in the tibial side I'd say probably 90 percent occupying ratio. Here you can see a 3D CT study where it's really cool because you can actually see where the cannulated portion of that dowel is. And on the reverse image you can see where the dowel is and how you filled your defect. Defect and fill. We hope to report this soon because we have pretty good results. Well how about the histology? Well we decided to take a few of these patients and ask them if they mind if we take a biopsies of their dowels and we found that at time zero as we suspected there's no cells in there. That's good because cells can cause a host immune response as they had been shown to do with osteochondral allografts and so you have to wash all the cells out of there. Fortunately you don't have to wash these cells out because there's no cells in there. It's just a scaffold. And then we biopsied at four months and so when we look at this at four months of varying high-powered fields we see that there's good integration, new cement lines between the host bone and the dowel. But the dowel doesn't have any cells at four months so we biopsied these So we biopsied these at a year and we started looking at the integration which is just as good or better but there's cells now. So creeping substitution has allowed the host cells to repopulate the scaffold. That doesn't happen with calcium phosphate. The few biopsies that have been done with calcium phosphate often shows immature bone formation and residual calcium and residual calcium phosphate in the biopsy. So that brings us to our current focus is to compare these two techniques. I alluded to the fact we're going to do a clinical study. We also plan to do a biomechanical study and I know that Jason was with you Mark and he's now at Colorado I think and so he's going to be involved in this. And then we'll also do some other studies with matched pairs once we get approval from the IRB. So let's look at some cases. Here is a 20 year old 19 year old female undergrad. She had a primary ACL in 2015 and they used a technique with this peak fixation. If any of you have any experience and I know Dr. Dedeck does, with this type of fixation I can tell you that it's no pleasure to take these out and to address these. And so she had an injury and her MRI showed she had an intact ACL graft which is not unusual because the MRI only shows collagen. It doesn't show whether the collagen is functioning. And so we fought with insurance companies and most of the time win to get a CT scan in addition to that. This time we didn't win so we had to go in with more than one option, plan A, plan B, plan C because I wasn't sure whether or not we could do this in one stage. Here's a model of the aperfix. This used to be metal, now it's peak. Nevertheless it's still a problem because these arms expand and it makes it difficult to pull them out. The design is you can take a screwdriver supposedly and unscrew the screw and the arms will collapse and you can easily pull it out. That's not the case. So here is that little screw you can, we ordered that screwdriver ahead of time, thought we're pretty smart, so we could use that to pull that out of there. Here's the MRI. And then here's the ACL again. That's why the MRI showed it was intact is because there's collagen there. But you can see how lax it is. It's not going to work. Patient had instability. So we start by debriding the graft and taking some of this peak out of the knee including the tibial tunnel which had a peak sheath in it. Here's we got our special screwdriver. We're able to take that screw out but lo and behold it did not collapse and it's still stuck in the tunnel. So you need to pull that out of the tunnel which is not easy. And then serially drill. And this tunnel we felt was in pretty good location so we're able to preserve this tunnel and reuse the femoral tunnel. The tibial tunnel was too posterior. You can see that here. Very posterior tibial tunnel. So we're able to serially drill the posterior tibial tunnel and place a bone graft into the tibial tunnel and create our new tunnel anterior to that tunnel that's now filled with a bone dowel. Here you see where we did that. The bone dowel is filled and we have a new tunnel that avoids the previous tunnel and diverges from that tunnel. Here's our final construct and the patient did well. So next case we have a 21 year old female, several months history of knee pain. She had an ACL repair done and this is becoming popular, maybe too popular. And so the initial results of this has been pretty good. And so this patient had that and she did well for like three or four years. But then she had a new injury. Here's her MRI from the original injury. You can see that this ACL abulsion was off the femur. So an ideal candidate for ACL repair, at least according to the advocates of that technique. And so we followed their prescription and put sutures in it and put a suture bridge in there and did our reconstruction, repair that is. You can see here four years later she fell and she injured herself again and the ACL was torn with a pseudo-lock. And here at the time of arthroscopy, you can see that suture bridge not doing much good. So we debrided it, did a very easy revision with a patella tendon autograft and that worked out fine. So the advocates of this will tell you that the best option is with type 1, Sherman type 1, which is a vault stop the femur as this patient was. And their early reports are encouraging, but again, so was Fagan's. So be careful about doing repairs until we get some more data. Final case, 40-year-old male, twisting injury by boxing. He had a patella tendon reconstruction in 2008. He did fine until recently. A grossly unstable knee. You can see he had rotational instability because his femoral tunnel was past high noon. Also it suggests that maybe the bone plug never was integrated properly. Here we see an MRI and CAT scan is very helpful. Shows the osteolysis, in this case 15 millimeters in a tunnel that's probably too posterior. Femoral tunnels, as you would suspect, is very vertical and not really a player. So we measured the slope on this tibia and it was 15.5 degrees. This paper from Australia says that any slope more than 12 degrees is a risk for a high failure with ACL. And therefore, we decided that while we're going to go ahead and do a bone dial to fill this defect, we would also do a correcting osteotomy. So we've planned a two-stage ACL revision with a closing wedge osteotomy and bone grafting of the tunnels at the same time. Here the ACL is lax. Meniscectomies were shown, no new tears. The prior tunnel is too vertical, so we didn't have to worry about the femoral tunnel or remove the hardware. The tibial tunnel, again, I think and then when you're doing a revision ACL, it's helpful to have fluoroscopy, in this case real fluoroscopy, because you want to put that guide pin right in the center of your tunnel so you can serially drill it. So you serially drill, do tunneloscopy, and then we can fill it. The cultures were negative. And then we planned our osteotomy. We did this particular one below the patella tendon. And so you simply basically subperiosteally dissect all the structures off of the proximal tibia below the level of the patella tendon. You got to be really careful around there. Cut the osteotomy and then close it by placing the leg in hyperextension. Here's the radiographs before and after. I show you this primarily because I wanted to show you that the alignment hasn't changed. And here the lateral radiographs before and after changing the slope. And the fellows from New Mexico, including one of our former fellows, Dustin Richter, came up with this idea of fixing this with a suture staple, which is basically swivel locks with fiber tapes loaded into them. This allows us to fix this without having metal hardware all over the point when we do a revision. We protected the weight bearing. We allowed his motion. And here is radiographs at early follow-up and we're planning a revision at four months after we get a repeat CT scan. So we've talked about common causes of ACL failure, focused on osteolysis, including our plug technique with both one and two stages, showed some preliminary CT studies, our dull biopsies and future studies we're planning, and showed some bonus cases. And so now we're available for questions and that's all I have. What do you got, Mark? Sorry. Can you hear me now? Yeah. Sorry. So I'm waiting for people to ask questions. So please send me a thing if you want to ask questions. But somebody I unmuted has a kid around. They can't ask it. So did you say what is the size ranges of your prefixed dowels and do you have any concern if you've got a defect that may be, you know, 14 millimeters in one plane but 18 in the other that you have to dilate it up to 18 or 19? And how much beyond what you see on the CT scan? Sorry, it's a complex question. But let's say you see on a CT scan that it's 18. Do you feel like you need to go to 19 so that you got good bone all the way around? So those are three separate questions. Yeah. So number one, the dowels come in sizes from 10 to 18 millimeters in diameter and up to 30 millimeters in length. Sometimes even you can get them close to 35. So this technique involves serially drilling and then relying upon what you see at the time of arthroscopy looking up the tunnel to ensure that you've got all the fibrous tissue out of there. So yes, if you have a tunnel, then you're often kind of ballooned in certain aspects of it. So I drill until I have all the fibrous tissue cleared out. And so yeah, you're taking some, a little bit of normal bone in some areas, but that's okay because it's probably got some fibrous tissue in it anyway. And so you want to go line to line. And so I go up to 18 and put an 18 dowel in there if I need to. If it's bigger than 18, then you need to fashion your own dowel and the back table out of a femoral head allograft because they only go up to 18. Okay. And so, and you, so you have no concerns about taking it, taking something that may be 14 by 17.5 and making an 18 all the way around to get good. Okay. So here's some questions. Sorry. As I'm trying to unmute some of the other faculty, but so Mike Pullen, Dr. Miller, thank you for a great talk. Can you talk about your approach to the patient who has had one stage one grafting, but the graft didn't incorporate either dowel that only partially integrated or the use of the DBM or chips, which did not integrate. And actually to that, I'll also add, have you seen some of your dowels not incorporate? Okay. So that's a great question. And so if somebody else failed a revision, then you don't have to inherit the bad karma from that happening. You've just got to convince the patient that you can improve upon their results. And so you should never compromise your results by having an additional stage. If you don't think you can do it and you feel sorry for the patient, haven't gone through those previous surgeries, but you got to do what's right. And you don't want to set the person up for another failure. And so in that case, you just simply say you do the right thing and you say, okay, this failed. This is probably not the best material to fill a tunnel for you. And I recommend we do this. And if that requires two stage, then that's what we're going to need to do. And so I think you always do the right thing. What was the second half of that question again, please? So the second half of that question was as far as your approach, when the patient, the graft either didn't incorporate either the dowel or part that only partially integrated or the use of DBM bone chips, which did not integrate. Yeah. So that's, I think we addressed that. And so DBM, I think is the bad choice for this. And so, and I showed that case where I had the experience with it. So you just address it at that time and do the right thing. Now, as far as patients not integrating, again, I told you smokers, that's a problem. They don't integrate very well. And so I've seen them not integrate. I've also seen a case where I cracked the dowel, putting it in the femur and I said, oh, that's probably all right. There's a lot of good bone in there. That's not a good idea either. If you crack the dowel, you got to put a new one in. All right. And so other than smokers, I mean, what, how often do you see them not integrate? And do you get a CT scan actually before you take them back to do the second stage of the operation? And have you ever had a delay because the CT may have not suggested good incorporation? Absolutely. Yes, I get a CT scan every time that I, before I go back to the second stage. And yes, I have seen delayed incorporation in smokers primarily, but there's other people that have delayed incorporation. And in that case, I wait and I'll re-CT them later. Great. J.U., Dr. Miller, thank you for a great talk. Can you comment on the association with tunnel osteolysis and biocomposite screws? Would you recommend peak or bio screws with primary soft tissue ACL reconstruction? Yeah, so that's a good question also. So I don't think it's all worked out. There are certain screws that have been in our armamentarium over the years that are associated with more osteolysis. And so I don't think it's completely worked out which screws have the best profile for that. I still use metal screws for my cases for patella tendons. And the reason is because they work and they don't have to be tapped. And I'm not embarrassed about where they are, so I don't care if they show up on x-rays. So I still use titanium screws. So I don't have a problem with people using other screws. It's just that, you know, we've got to figure out which screws have the worst profile for causing this problem. Yeah, I agree. I think seeing the soft tissue with the bio screws are the ones you see the most osteolysis in, especially with allograft soft tissue. Yeah, allografts are the worst. Hey, Mark, can I answer that? This is a great talk, Mark. I appreciate seeing that. I learned some stuff. So on that question, so I do mostly BTBs. I use metal screws. But in my hamstring patients, for years, I used peak screws. And probably once or twice a year, I would have a peak screw that backed out. And it would be late. It would be four years after the fact. Patients would come in with their peak screws backing out. And so because of that, I switched over to using Smith and Nephew BioSure screws. Or sorry, I do it. Sorry, MyTech Intrafix, their bioabsorbable Intrafix screw, which I think does pretty well. It's the Milagro screw, which I think, of all the screws, has the least amount of osteolysis. And I don't have to worry about screws backing out anymore. Well, we're not going to get into proprietarial questions. I appreciate that, Latul. But you know, each person should have their own figure. And ideally, there's some research to be done here to figure out the best screws. What's fascinating to me is that I used to use the sheath, the expandable sheath with the screw on the femur. And the sheath was made out of PDS. Okay, so PDS has an absorption profile of months. And yet, years later, like four years later, you go back and there's still PDS in the femoral side. It's wild. I agree, it takes forever. A little bit here, Mark. You know, I also do BTBs with metal screws. And, you know, I don't think any of us have had problems with tunnel widening there. I do have a growing experience with quad autographed soft tissue only using modern suspensory techniques. I do get x-rays at a year and two years. And I am worried about asymptomatic tunnel widening in those patients. I've tried to modify by getting very tight on my aperture fit, so being more aware of that. And, you know, I guess, Mark, a question to you. Do you get imaging over time? Do you counsel patients about asymptomatic widening? Do you worry about it? Or is it just something for the surgeon to think about in the back of our mind as we evolve our techniques? No, I'm very worried about it. And the popularity of the suspensory fixation with all inside techniques a very worrisome problem. We may see a whole new generation of this problem. So yeah, I'm worried about it. Do I get routinely get x-rays? No, because I don't see these people, they're gone. So, you know, it would be good to do that if your practice allows that, that's great. Good thinking, and that's a great plan. But you gotta remember just because they have osteolysis doesn't mean they're gonna have a failure. But if they do have a failure, it's a whole nother problem. There's a question from James. Do you test your dowel to make sure it is well fixed? And if so, how do you do this? Yeah, so as you insert it, you'll get a feel for the integrity of it. And, you know, if it's not well fixed, it's gonna fall right out. And so, you know, you can probe it and, you know, palpate it. Those dowels, they fit in there really well with just line to line placement that they're not coming out of there. I've never had a problem with them coming out. Yeah, it's the same thing if you use, you know, allograft and you pack it in there. I mean, it tends not to become loose bodies and floating around. But I'm gonna, before we get into the, there's another question here from Andrew Morris. Dr. Miller, are you addressing tibial posterior slope in every revision case when the slope is greater than 12 millimeters? And I'd like your opinion, and we'll get the other faculty to comment on what they're doing with, what is their threshold? And then I'll have another question that follows that one up. So we'll start with that. Yeah, 12 millimeters is my threshold because of that paper. And because also Ned Amendola, I've talked to him a lot about this. You know, Ned's an outstanding osteotomy expert and he's taught us a lot about this. And he's even doing this prophylactically. So that's how strong he feels about this slope. Does anybody else, anybody else here doing the anterior closing wedge osteotomy for increased posterior slope in revision situations? I can chime in here again. I have done anterior closing wedge in repeat revision. I think of the tibial slope, I measure it every time in revision by standing tibial X-ray and also on advanced imaging studies. I use it as a modifiable risk factor, sort of similar to how I may use trochlear dysplasia in patellar instability. In that, if I have a tibial slope and I have other reasons, they might have problems like meniscus deficiency or hyperlaxity, I might work around it in that first revision, correcting the other factors or other alignment. But in repeat revision, I'm quick to add it. Or if I have a biplanar deformity, a varus end slope, always a great one to get a double bang for your buck. So I don't do it. As a minimum in those patients with excessive slope, you should probably augment those patients. You got to do something else besides just the standard revision. Always using autograft for me for those revisions and adding extra articular tenodesis. So being mindful to do a little bit more, I think is the key point, if you're not going to. So let me ask the other faculty and Dave Didik, if you want, I'm happy to unmute you as well. I think I did unmute you, but I think you're muted back. But you've got a athletic individual that just tore their ACL. They're active. They're about 21 or so. And you notice that they're preoperatively from the primary ACL is 15 degrees posterior slope. Are you doing an osteotomy with those people for their first ACL? Anybody? Mark, the tool? No. Seth, no. Mark? No. I think I would do that. You would do it? Yep. The problem with osteotomies is getting, especially people that are on land-based sports, impact sports, running and jumping, getting them back to doing those sports after a proximal tibial osteotomy, I think is tough. So Dave, are you doing any of those? I just unmuted you. Thank you. No, certainly not with the primary yet. But I think osteotomy in general is a very powerful tool, but I just think we're all still learning here. So let me ask Mark, if you seem to be the most aggressive of them, I mean, I've done it in revision situation, but let's say you've got somebody who's 12, 13 degrees of posterior slope, and you're doing this osteotomy, obviously, to help with the healing, proximal to the tibial tubercle. Are you also moving the tibial tubercle down or maybe one of the tools, the teller tendon shortening procedures that he talked about last week? Or do you think the patient's able to compensate with that, but might be now affecting their extensor mechanism strength? Sure. Let me clarify something, first of all. I wouldn't do it with 12 degrees in the primary. You said 15. That's different, okay? So- No, no, I'm saying let's say it's a revision that's 12 degrees. That's fine. Okay, all right, all right. So, in that case- So, I missed the question. Now, I got tied up with the first part of it. If you're gonna do a closing wedge, anterior closing wedge osteotomy for somebody who's 12 degrees, right? And so you're taking out a fair amount of anterior tibia. You're essentially, that's almost like a relative lengthening of the patellar tendon, right? And you're affecting their quad mechanism strength. Are you doing something to compensate for the extensor mechanism? Basically, relative lengthening of the tendon relative to the bone-tendon-bone fixation? Yeah, I apologize. I forgot that half of the question. So, yeah, we carefully measure the CD ratio preoperatively, okay? And if it's normal, if it's one, then I'm not gonna mess with the tibial tubercle. If, however, there's some baseline alta or baja at the time I'm doing it, then I'm gonna exacerbate that even more. Then I'll combine either a proximalization or a distalization of that tubercle and at the same time that I'm doing this. And so I credit my partner, Dave Dedeck, for helping me figure this out. And he's been really a good leader in this whole area. And so, yes, I will combine that when it's indicated. But if I have a perfectly good CD ratio, I'm probably not gonna worry about it. Seth? Yeah, I've done these with and without taking the tubercle off. And for me, it's just technically easier taking the tubercle off and I'm facile with that. So if I have any question or problem, I take it off. Do you have a threshold when you do that? I'm concerned about recurve bottom also. And I don't do any posterior capsular or anything, but I know the French have braced them in a little bit of flexion just for a couple of months early on. I wonder if you have any experience with that problem, just getting too much recurve bottom from your closing weight. It's amazing how that just seems to correct itself over time. I'm totally amazed. Cause you first do it, you go, holy crap, what'd I do? You know, guys got like crazy recurve bottom. That's what I find myself. I don't know why. Agree. All right. TLC asks, what is your preferred graft choice when the ipsilateral BTB has been used for the primary ACL? So what's your graft of choice for revision situation? Yeah, so it depends upon the patient and patient factors. There's a whole bunch of things, okay? An older patient, I have no problem using hamstring like older, like over 30 or something. For a younger person, I would encourage them to consider either a contralateral bone patella tendon bone or an ipsilateral quadriceps tendon with bone. And anybody else want to comment on what they use for their graft of choice when somebody's had a ipsilateral BTB for their primary? Yeah, I'm doing contralateral BTB and those patients rehab amazingly well. They walk out the hospital on the graft, on the knee that you took the graft on with minimal pain. And the BTB knee on the revision, they have very little pain to get their motion back. And it's impressive. Seth? Yeah, I do ipsilateral quad, probably a dozen or so of those and I've been very happy with that. And I think Dr. Zeroginez has done, I think he said 70 or 75 as well. So I think it's a good option. Steve? I'll use contralateral BTB with bone. I'll use contralateral BTB really only in an elite athlete or I'll use ipsilateral hamstring. Dave? An ipsilateral hamstring or soft tissue quad. I'm a little afraid of patella fracture with the bone plug on the quad there. I tell you, so I mean, I have a little bit different approach. I mean, if somebody has a failed autograft BTB and I've used contralateral when people insisted on having an autograft type of graft, but one of the tricks I've done is, especially if it's a 16 millimeters tunnel or less, is use a BTB allograft. And then you end up making that as your, instead of a dowel, you just have a large allograft, a 16 millimeter allograft if you need. And that fills your holes, you get your interference fixation. And you can make sure that the soft tissue is more towards the poster in on the femoral side. And if you need, you know, you twist it and you have more in the anterior end on the tibial side. But I always, you know, if they fail an allo, I do an auto. If they fail an auto, I do an allo type of thing. But- Well, you know, Mark, there's a much higher failure rate with the MARS study group with allografts. I saw that. I saw that. That's not been my experience, but I know that's the MARS was clearly showed that. I totally know. But, you know, when I've looked at my data from it, I've not seen that kind of failure rate. So- Collegiate athletes? Huh? Collegiate athletes? Collegiate athletes and just general population, both. So, but I don't have the huge numbers, but I also know that I've made sure that their tibial slope's okay, their meniscal root's okay. You know, they don't have a ramp lesion. You know, the alignment's fine, those types of things. So, you know, just making sure that the tunnel's in the right spot and that those other issues are corrected for. Adam asks, wonderful talk. Could you please comment on how you came to select a 50% convergence of old new tunnels to be an appropriate cutoff? Yeah, that was just trial and error. So, you know, we did some, we tried to push the envelope and it fell out. And so I think probably maybe even 40% is a better number. But yeah, you certainly don't want to go beyond 50. They'll fall out. Okay, Sean Sitton, thanks for your talk, Dr. Miller. What are your thoughts about just using ipsilateral or contralateral BTB autograft for single stage revisions with isolated tunnel widening of either the tibial or femoral tunnel and just take a bigger bone plug when you harvest the graft to fill the defect? Well, that's a great idea, but you can't take an 18 millimeter bone plug. I mean, I sometimes am very aggressive and get 12 millimeter bone plugs, but that's really pushing the envelope. So your central third is not going to be 18 millimeters. Yeah, no, exactly. You start to take more than half of the tibial insertion, then you run, you know, you can take it deep, but you also got to be careful when you're taking that distal bone plug that the lateral slope of the tibia, if you come straight down as opposed to angling in, you're going to be undermining that lateral third of your patellar tendon insertion and you can end up with an avulsion fracture or something from that as well. So you're limited based on what you have from normal anatomy from my experience on that. Are there any other questions? It's not I'll throw out another one since we've got a panel. What's your single best trick or tip that you have about revision ACL reconstruction? Start with Dave. Have plans B, C, and D. They always take longer, always take longer than you think. All right, Steve. A couple of things that probably one thing I learned from Mark is don't be afraid to drill through old hardware. You know, a little metalosis in the tunnels is actually not damaging to the graft. So being prepared for that is generally good. And I think Dave's comment is having different tricks for what your fixation is going to be. And I always back up my fixation on the tibia no matter what in a revision setting. Pat. I'd say aggressive treatment of your secondary stabilizers. That means looking for and fixing ramp lesions. If you have meniscus deficiency, then two-stage meniscus transplantations and a liberal use of lateral extraventricular tendensis in these settings with tough cases. Latul. So I like the idea of using bone dowels. It's not something that I've ever incorporated in my practice. Instead, I just use cancellous, freeze-dried cancellous chips, you know, just off the shelf. And I use, and the trick when using those, I use the reusable mosaplasty cannulas to feed the bone graft into my femoral tunnel. So like Mark mentioned, once I get done debreeding the tibial tunnel, I have a lot more play in that tunnel to get into the femoral tunnel. And I'll use that to feed the cancellous bone chips into the femoral tunnel. And I think they do well. I never see T people unless I have serious concerns. And I come back somewhere between four and six months, and it's usually pretty solid. Will Workman. You there? Will? Yeah, hold on. I'm on this iPad. I can't get it to work. I can hear you. Oh, you can hear me, okay. Sorry, I missed a question. I got distracted. Single best tip for revision ACL. You know, I was thinking about this earlier, and Dr. Miller mentioned the Lemaire procedure, if I'm pronouncing it right. You know, we talk about asymptomatic tummal widening, and sometimes I think that can be a red herring when we go to revision. I think doing a very careful physical exam, I've had a couple of patients who really had not much of a Lachman, had a bit of a pivot shift test, and tunnels are wide, whatever, the graft doesn't look good. And I really felt like their graft was probably in pretty good shape. And going in and looking at arthroscopically, things look pretty good. And just adding a little Lemaire procedure to it, instead of doing a big revision, ended up working out pretty well. So I guess that's kind of a different take on the Lachman thing. So I guess that's kind of a different take on one-stage revision, but I thought that might be worth adding. No, that's a good tip. Tim Wang, you have one? Yeah, I've got a response, and actually a question for Dr. Miller. I think, like somebody else said, having a kitchen sink available. So having equipment to do both intramedial, retrograde drilling, and always consenting the patient for possible two-stage bone gafting, you know, if something interrupt doesn't look right. Question for Dr. Miller. Thanks for a great talk. I know we talked a lot about single or dual-stage bone grafting, but, you know, obviously I've had, I'm sure we all have had situations where the tunnel's not necessarily dilated too much, but the location's kind of Mickey-mousing. So it's not perfect, but it's not too far off. And in those situations, your thoughts on managing those, because I've messed around with, you know, your single-stage technique, stacking screws, upsiding screws. I don't know if you had a preferred technique and, you know, yourself on the panel. So it's out of place, but not so much that you can't completely avoid it. You're going to overlap. Yeah, it's going to jeopardize your press fit fixation. Well, I think you have to decide how bad it is, okay? You have to decide whether or not you're willing to accept it. And if you're willing to accept it, then use it. If you're not willing to accept it, you may have to stage it unless you can put the dowel in and be far enough away where you're not going to violate the dowel. This is where fluoroscopy can be very helpful also. So you got to make a decision whether it's good enough or not. Yeah, I guess, assuming that it's not good enough, and let's say you're at that like 40% overlap, are you bone grafting it every time or? Yeah, because otherwise you're going to have an oval tunnel. You don't, you want to avoid an oval tunnel because the graft will migrate into the oval tunnel. Yeah, yeah. So I guess in terms of upsizing your screw, or stacking screws, or other techniques that have been reported out there, but you're- Yeah, that's where I use the dowel. Gotcha. All right, here's a question from Santiago Hash. Thanks for this great talk. How do you secure your bone graft chips inside your femoral tunnel against gravity? And since Mark is not using chips anymore, but did you ever have any problems with the chips when you've kind of packed them in migrating, or is that a non-issue? It's a non-issue. I pack them in and they stay where they're supposed to be. I get x-rays, they stay right where they're supposed to be. That's been my experience as well. Mark, have you ever had any dislodge to cause a problem? Well, I used to use a technique where I used what I called a manhole cover. So I'd take a big round piece and jam it up there, and then put a sandwich in all the chips, and then put another manhole cover on the other side. So I had like a sandwich with two cortical pieces of bread. Yeah, I end up using just like a cannula. I take a big eight millimeter cannula, and we'll put my graft through that to pack it up into the femoral tunnel, and then use a bone tamp and just push it in there. And I find that they don't tend to migrate on me. Well, this is the draft day version of our Misfit Talk. So Mark has now given a new official name to this lecture series. So I appreciate that, Mark. I appreciate everybody's contribution. The NFL draft is in one hour. We all have to get our beer ready and our Zoom draft teams together. But Mark, really appreciate it. Appreciate everybody's participation and contribution to this. I think outstanding, again, as always, Mark. I followed you at Pitt. I always continue to learn from you. So this is totally awesome. I really appreciate it. And I appreciate the time and effort for the talk. Thank you for inviting me. Thank you for what you're doing for us. And thank you for contributing to the AOSSM library. Thanks, everybody. Have a good one. Remember, the draft is the Cleveland Brown Super Bowl. Remember that. Good job, Mark. It's all downhill from there. Is that it? Was that what you were saying, Phil? Yeah. See you on Monday. Have a good weekend, everybody. Thanks. Thank you, bye. Thanks, Mark. Thank you.

revision ACL reconstruction

anterior cruciate ligament

ACL surgery

tunnel widening

graft choices

bone dowels

defect filling

ACL failures

tunnel placement