Thank you. My disclosures are listed in the program. So we're going to go over an overview of LET, try to focus this on the patient group that we're concerned about. We'll talk about the biomechanical considerations and femoral fixation options. So we're all here because we're trying to get better outcomes for our patients and the ones that this matters the most in are at the highest risk of failure, and that's the young patient. And BRIT reported just a couple of years ago, 32% of female soccer athletes less than 18 that return to sports sustained a graft tear or conflatory ACL tear. That's a pretty high rate. 28% in Webster's study of males under 18 sustained a graft tear returning to pivoting sports. So that's a big concern. There's a picture here, a photograph showing the lateral knee radiograph, 15 degree posterior slope. That's one of the things we're considering. And so LET has made a large resurgence lately when trying to treat these adolescent patients that are at elevated risk of failure. You can see a low energy pivoting mechanism on the left video and on the right video. This is an unfortunate young individual who had an ACL at 12, another at 14, and then I ended up seeing her and doing a re-revision two-stage procedure. So that's a pretty big deal when you're 16 and you've had four surgeries on your knee. So we're trying to find ways to reduce this failure rate. So over 30 years ago, Lars Engbretsen reported on LET and he used a larger graft, a 20-millimeter graft past superficial of the FCL, and this is a biomechanical study at the University of Minnesota. And what they found is that there's a protective effect on the ACL graft force and a reduction in the ACL graft force when you had an LET of about 40%. Notably, it did reduce the interim rotation compared to intact and there are some concerns for over-constraint and we've heard about that already today. Eric Sletty reported on a systematic review looking at biomechanical results of an LET and found that the LET reduced load in the ACL, but again, the concern about over-constraint was discussed. Based on a very large expansion of the literature from about 2013 over the last 10 years approximately, there was a need to get some consensus or at least try to get some consensus on this issue. And so Al Gatgood and Charlie Brown got a group of international researchers together who had done some of the recent work on this topic and at that time, there was encouraging results in case series but we didn't have any randomized trials. We suggested at the time though that a consideration for appropriate indications may include revision in ACL patients, those with a high-grade pivot shift, generalized ligamentous laxity and young patients returning to pivoting activities. A couple of years later, Dr. Gatgood's multicenter trial came out when they compared hamstring only to hamstring plus LET. They looked at the high-risk group under 25 years old and grade 2 pivot shift and returning to pivoting sports with ligamentous laxity. And they defined failure as any asymmetric rotatory laxity and they also defined graft rupture as a failure. And it was approximately 60% relative risk reduction with hamstring only having a failure clinically of 40% but when you add hamstring plus LET, it brought it down to 25%. Well, this is a staple technique. You can see the image on the right here, right knee with the staple. You should note the position of the staple relative to the FCL. You can't see it very well but the LET is brought underneath the FCL and the staple is placed a fair amount proximal to that. So that's the staple technique. We'll be talking about the non-staple technique. So in order to think about this, I think you have to think about what's required from a fixation strength. So we can use some studies but we don't have great studies on this. We have to look to other parts of orthopedics to help us understand this. So we can look at subpectoral tenodesis as a model and collateral ligament repair strength. We do have some data though on the LET load and Kaplan failure strength. So we'll look to that. This study was published just recently this year and it reported that there's 112 newtons that goes through the LET graft in combined internal tibial torque and anterior tibial force. So that combined loading stimulating a pivot shift. So 112 newtons is the number that you'll see reported for that. You can look at John Godin's paper from about five years ago where he loaded the Kaplan fibers to failure and the proximal failed at 71 newtons, distal at 170 newtons. So we're seeing somewhere in that around 100 newtons is an important load for this structure. Subpectoral biceps tenodesis, there's some conflicting results but this is a reasonable area to look at when we're considering similar fixation for an LET. And the cortical button and double loaded suture anchor performed pretty similarly in a study in 2020 and the interference screwed in performed quite as well. But in opposite form, the interference group performed better in another study in 2011 compared to the anchor. And we're seeing again around that 100 newton, 100 to 130 newton load is potentially important. You can have different suture patterns, a crack out suture pattern has left gap formation and a pretty high ultimate strength in this study in 2014. So we have to take all that information together when we're thinking about our fixation methods. There's multiple fixation methods. We can perform onlay fixation or a tunnel. You can use an anchor of multiple different materials, single or double loaded. You can use an interference screw, the tenodesis technique or a pull through or the staple that was published in Al Geckut's study. So my preference is to use a double loaded suture anchor. When I do this procedure, I'll palpate the bony and soft tissue anatomy and this is from John Godin's 2017 paper nicely showing that soft tissue anatomy. So I'll find first the lateral pecondyle, girdies, tubercle, fibular head and then I'll palpate the FCL, biceps and ITB borders in order to localize my incision. Here we're looking at a left knee. The incision is approximately five centimeters in length, centered over the lateral pecondyle and just a little bit distal. Harvest the central strip, the IT band. If it seems like it's a little bit thinner, I'll maybe take a slightly wider graft. Anywhere from 10 to 15 has been reported. I find that an eight centimeter graft length is okay for an anchor or a staple. You might need a longer graft though if you're performing an interference screw due to the need to pull the graft into the tunnel. After you've identified and harvested the graft and you've identified the FCL, you can put some sort of a passing device. I typically just use a small curved hemostat and I deliver the graft underneath the FCL. Then I use my anchor. It's a double loaded anchor and I drill and insert the anchor approximately one to two centimeters approximately on the pecondyle. I don't try to go right next to the FCL as it's described. In some studies, I'll go a little bit more approximately. It's very important, I think, to avoid the FCL origin and not cause an iatrogenic injury to the FCL when you're trying to help someone's stability. You also want to avoid ACL tunnel convergence. So the fixation options that are used most commonly include a staple and although some people think that the staple is prominent, if you put it in the right position, I don't think it's an issue. Approximately 10 of 291 patients in Dr. Gedko's stability trial underwent removal due to hardware irritation. But if you put it proximal, you're not going to have that issue, in my opinion. Interference screw can certainly be used, but this is a larger tunnel, perhaps a six millimeter tunnel. You have concern for collision with the ACL tunnel and it requires a longer graft in order to get that interference fit. And an anchor has, some have had concerns about the security of the fixation, but the biceps tenodesis literature supports this technique. It's the same technique I use for sub-pectoral biceps tenodesis and I think it's adequate based on the studies I was quoting for fixation of the LAT. This is a pretty rudimentary animation, but what I'll do is I confirm the graft length, I confirm the anchor location, put minimal tension on the graft, we typically quote 20 newtons, and then I confirm the starting point for the suture. I drill and I insert the anchor, there's one suture, and like I said it's double loaded, I run the first limb of the first suture through it in a crack-out or running-locking fashion, and then I pass the second pair with a horizontal mattress fashion. Then you pull on the first suture and it delivers the graft down to the bone, and you can tie that first suture, the red one, and then you tie the second suture, the blue one. So it's just a running-locking followed by a mattress, and it's a pretty straightforward technique. It's very minimally prominent, just the little knot stack, and in my opinion, at least in my hands, it's been a reproducible technique for me. So in summary, I think you should consider LAT for high-risk ACL patients. We're learning more and more about who those patients are and what our indications should be. You need to recognize the biomechanical loads on the LAT, and then recognize there's several options for fixation. Some have drawbacks, but I think all are suitable for this procedure as long as you understand the technique and where to put the anchor or the implant. Thank you.

Lateral Extra-articular Tenodesis

ACL graft tear

ACL failure

fixation options

double loaded suture anchor