Adam Yankee, thanks for having me, thanks Miho and everyone else on the panel. My topic is the lateral soft tissues, which I think is the one that the most junior person gets, but also I kind of think it's interesting and the more people have made me talk about it, I've learned about it. So hopefully I can help with some of what I've learned as well. Anatomically, I think we just need to understand what structures are contributing here. It's been described by multiple authors in the past and there's really, it seems to be two layers, a superficial oblique and a deep layer laterally and it can also be described as a thickening of the lateral retinaculum and as you dissect it out more, you really can appreciate that it is its own separate ligament and we'll show some pictures to help demonstrate that. And it's more than just the LPFL, there's the lateral patellofemoral ligament and there's also a lateral patellofemoral complex similar to what we see on the medial side of the knee. And again, this has been described by multiple authors. We ended up doing a dissection study that was similar to some of what has been done in the past and we saw really conserved across about five studies that the LPFL has a broad insertion on the femur. It's distal and anterior to the lateral epicondyle and has an insertion almost on the entirety of the patella with some distal insertion into the soft tissue. There's also the presence of a LPTL and LPML or LPML in all of the specimens that we dissected in our study and this entirety is the lateral patellofemoral complex. I really am focusing on the LPFL because I don't think we know when to utilize the other ligaments or certainly reconstruct them, so most of it has been focused on this lateral soft tissue. The origin, just as mentioned, really is very broad, very vertical, and again distal and anterior. So you could imagine just by looking at this, if your patella sits here and this is your length and then you bring your patella down, that length shortens very quickly. And so the LPFL really functions more significantly in full extension, even more so than the MPFL. So this shows the osseous insertion laterally, which you can do osseous-based reconstructions. It's a little bit more difficult because that real estate is very small and it may ultimately not be necessary. There is a native insertion one centimeter distal into the patellar tendon and you can utilize that with a soft tissue reconstruction. We did look at the length changes as discussed and this is the LPFL and we can see going from 0 to 90 degrees of flexion. But it really does seem to decrease throughout flexion with the largest changes happening earlier. Actually with the LPML and the LPTL, those have higher degrees of changes in further flexion, which is kind of what we see on the medial side where they act more in flexion. This is an arthroscopic video showing the lateral retinaculum. You can see that was the distal pole of the patella. You can really see how it's this broad band-like ligament that comes down to that insertion again in the same spot on the femur. And then this is what it looks like during an open dissection. Some patients have it really well defined and you can really palpate it with your finger and I'll show a video where you can really see how robust it is and it's really very reproducible. And when you cut proximal and distal to it, you actually just get into fatty tissue because there is no other tissue deep there. So this is not a new concept but it's one that really helped me understand it where when you're trying to balance the patella, which we've heard the word balance a lot today, it really is like a horse's reins. And so if a horse was pulling too far to the right and you correct it by letting go of the right rein and pulling on the left and then the horse starts pulling too far to the left, you're just going to the left. So you need to have control of both reins and you can adjust your tension on them but you don't want to let go of one of them unless you have a very specific situation. So this is just some animation that I think helped me kind of understand this. So when you have the patella and you try to translate it medially, ultimately there's some tilt that happens and it tries to lift up on the LPFL and it does resist that when both are intact. When you try to translate laterally, the MPFL is the one that's going to take up the primary restraint initially and then once that ruptures, you can get far enough over that the lateral side starts to pick up the restraint. So it is a secondary restraint to lateral translation and should not be released in patellar instability routinely unless there's other good reasons. So this is what an arthroscopic lateral release would look like and don't be fooled by the effect of an arthroscopic lateral release compared to a large open lateral release. I think that as we get more comfortable with arthroscopic techniques, it used to only be the patients that had the big incisions that had really loose lateral retinaculum. Now it really can be anybody that comes in that had a release. So when you try to do, I think it can be difficult to try to isolate the role of the lateral structures alone when you look at translation because the medial side is contributing to that. So when you try to do, if you try to evert the patella laterally, that is a better way I think to isolate the LPFL and look at its integrity. So most patients it's 10 to 15 degrees, they have minimal eversion. And then if you rupture that, obviously you can get significantly more eversion. And this is a patient, that MRI is a little annoying looping back and forth, but there's a big gap laterally there. And so that's a patient that had an arthroscopic lateral release. You can see how there's about two to three centimeters of a void there and that can allow for full medial translation that's essentially purely iatrogenic. There's potentially a few described cases where it's happened without release, but that's very uncommon. And then again, the easy way to try to see, so we're trying to tilt or evert the medial side. Then when you do the lateral side, we can see that patient has really no restraint there. So that's about 90 degrees of eversion. And this patient had symptomatic medial patella instability. And you can see how far over they come laterally even as well. And some of that's due to her hyperlaxity as well as the lateral release. And so when we see patients and we check lateral translation, we have a separate video here. Sorry, I'm going to go back for a second. So this, I have another video that will show, but if you watch the animation, when you try to do lateral translation in somebody that has a lateral release, their patella glides up. It doesn't just come over, so you'll feel like they have more translation, but it may not actually be more lateral translation. It's just that you have more degrees of freedom and it allows the lateral facet to come anterior. And I do have a separate video that will go through that. So lateral release has been used as a treatment for patellar instability, also maltracking or compression or lateral patellar thermal overload. And the release, as we mentioned, increases translation in both directions. And this is a lab study that we showed that it has increased lateral displacement with an isolated lateral release in particular in full extension, kind of just going along with the rest of the story. Atrogenic instability has rates up to 57% depending on the study after lateral release. And it's more likely to happen if a patient has a vasoslateralis release, which also just has to do with the extensiveness of the release, or if they weren't tight to begin with, which is why we really have to select the correct patients. Lateral lengthening has the ability to decrease forces and compared to release it has less translation and less quad atrophy. So I think lateral lengthening has been something that I've really utilized quite a bit. I think lateral release is rarely but sometimes indicated. Lateral lengthening is great if you do have somebody that's excessively tight or you're making a large correction, in particular the tibial tubercle. And then LPFL reconstructions I think can be useful in patients that have symptomatic instability medially. So the outcomes of lateral release have been shown to have improved resolution of pain and it does decrease the forces in the lateral patellofemoral joint. And the failure rate, or I'm sorry, it's a fairly conserved outcome. So if you have the outcome early, the failure rates down the road are pretty low with regards to pain relief. Looking at lateral release versus lateral release plus soft tissue realignment, meaning stabilization for patellar instability medially, the lateral release group was more likely to have recurrent instability and again it's because it's a secondary constraint. So we really want to have a good reason to add it if we're doing an MPFL reconstruction. Similarly looking at lateral lengthening versus release in this setting, looking at hypercompression showed that patients had less atrophy, less issues with the lateral lengthening than with the release. I think you get the idea here. So I'm going to go through just two cases to try to demonstrate the use of a lengthening as well as the use of a LPFL reconstruction to hopefully illustrate these points. So this is a 26-year-old female. She has chronic lateral patellar maltracking. She really has pain. She has no significant history of dislocation. She has basically uncomfortable tracking and pain in her knees. She had a prior ACI biopsy for a possible transplantation outside institution and really on her EUA, her patellar just tracked laterally throughout all range of motion. On her imaging, she had four degrees of valgus. She had a questionable small spur and maybe a crossing sign there with a double contour approximately. She did not have increased patellar height. And this is her merchant view and you can really just see how she is fixed laterally. So she could not be centralized passively. When we look at her tracking here, we can see that it stays fairly lateral. Sorry. Let's get past this. Her TTTG is 26, so fairly abnormal, and TTPCL is 27. So just as Jack was mentioning, you know, the thought is that that means that there's a deformity coming from the tibia. And then we can see that convex trochlea. She did not have a jumping J sign or really a J sign at all. She just stayed out lateral. No significant femoral anteversion. And then this is what her patella and trochlea looked like from the outside surgeon. And you can see there is some conjural wear, but a lot of this is not in areas that are particularly engaging, but she did have enough pain. And this was actually a very large bump in the middle of the notch that you can see on the bottom right that we did talk about doing a resurfacing for her to try to really get rid of that prominence in the center. So you could have potentially just excised that, but it was very central, and my concern was that we would be removing an area of articulating cartilage. So for her, she had a convex trochlea, chronic lateral maltracking, a bipolar defect, and a severely lateralized tibial tubercle. So we did a tibial tubercle osteotomy, lateral lengthening, and NPFL with possible conjural cartilage transplants. So here we can look at her examination. I can tilt her medially and evert her, but I cannot do it laterally. She comes out pretty easily laterally and just really stays lateral throughout most of her tracking, and she was able to be partially dislocated while asleep at least. This is looking at her examination from the side and also looking at her ability to be dislocated laterally or translated laterally throughout flexion. So even as you bent her knees, she had no osseous restraint as she had no groove that she engaged in as she flexed further and further down, and it took almost 90 degrees of flexion to stop her patella from wanting to dislocate. And so this, I'll go through this briefly. So she had a lateral lengthening approach due to her chronic lateral maltracking, and when we really push the patella laterally, you can see it visually there being pointed out, and it should be a very robust structure. And then, hopefully this will let me fast forward. So as we come through and do the dissection again, you want to revisualize it, and you can really feel it as you cut through it, and you want to try to separate out the superficial oblique and the deep transverse layer. And as you do that, you will start to see the fibers connecting from the patella to the femur as it comes down. And so I usually use a 15 blade knife with a tourniquet, and then as this comes down, we can really start to see where the ligament really is, and then proximal to that, there's kind of nothing, it just is synovium, and then here you can see the ligament. And then as you take that further down, you just cut transversely so that you can do a step cutter, a Z lengthening, and there you can see that even the capsule is still a little tight in that area, and you can get some release as you let go of the capsule as well. And that's sutured end-to-end at the conclusion of the case. So you can see how she really had an abnormal medial trochlea throughout flexion just because she's never lived over there, and then had a fairly significant chondral defect on the patella. And so in this setting, we did do a patellar osteochondral allograft plug, and then the tibial tubercle osteotomy with the closure of the lateral soft tissue. After all that's been completed, so the order of operations is important, and then this was her pre- and post-operative tracking. So I think in this setting, you could potentially do a lateral release, but if you have enough soft tissue there, why not just try to rebalance it, unless there's not enough to connect it anymore. If it's such a severe deformity, then you might just leave it open. This is one more case. So this is a 17-year-old female who had knee pain, and she had subluxation events where she described medial subluxation events. She had an arthroscopic lateral release done two years before, it was the MRI that I showed prior. And then we had performed physical therapy, and something that's very helpful is I use a brace that's a patellar stabilizing brace where you can flip the mechanism. And so I have them wear it, pushing them laterally, pushing them medially. And usually they feel very good when they're being pushed laterally, and that's been a really useful way to indicate these patients. If they also have prior lateral instability, then it's not as useful. This patient didn't have instability complaints prior to their lateral release. On exam, 3B medial translation with apprehension, which 2B is a little bit more common. So for me, B is a soft endpoint versus A is a firm endpoint. 1A lateral translation without apprehension. She was able to be everted 20 degrees laterally and no J sign. No significant patella alta. Only mild trochlear dysplasia, and again, she didn't have baseline instability. And here we can see the prior lateral release on MRI. TTTG is essentially normal, as well as TTPCL. So in this setting, her main issue was the prior lateral release and medial translation. And so we planned for an LPFL reconstruction with a hamstring allograft. This is her examination under anesthesia, which we'll talk about the translation components. So that's the lateral eversion medially. We cannot tilt her up at all. And you can see as you do the lateral translation, it really slides up and out. And even though she had no complaints of lateral instability, as soon as you hold the patella down and stop that component, it doesn't translate laterally significantly different. It's significantly less, even though you're putting in a lateral structure. So they're really pulling from front to back. They're not just pulling directly side to side. So here we did a soft tissue-based reconstruction. That case on the bottom is an older case, but you get the general idea. And this is looped through two incisions, just lateral or superficial to the lateral epicondyle, and then associated incisions as close as you can get to the distal pulled patella and the proximal pulled patella for an all soft tissue reconstruction. And then after it's complete, this is the examination under anesthesia. As you can see, the patella doesn't tilt up anymore. And then you really just want to set the length so that it has a similar amount of eversion compared to the contralateral side. So LPFL reconstructions can be done osseous or soft tissue-based. And we did a biomechanics study trying to look at the difference between the two and see if one was more superior than the other, since really the native insertion is primarily osseous-based. And we saw that when you released the lateral side or the LPFL, we saw significant increases in needle translation throughout all degrees of flexion. And then when we did the osseous and soft tissue-based reconstructions, we didn't see any difference between the two, actually. So both seem to function fairly well, but none of them function as the same as intact. And I think this is part of an issue where this one is, I think, more, at least for me, subjective in the way that you set length compared to an MPFL reconstruction, which I think we have dialed in fairly well at this point. So there's probably still some room for improvement. I still perform soft tissue-based reconstructions. There's really only that I'm aware of two outcomes studies that have been reported. Both had significant improvements with no recurrent instability. This was an osseous-based reconstruction. This is a soft tissue-based reconstruction using an IT band and turning a flap up. So it has been helpful, and unfortunately, it's still a small series and somewhat anecdotal. And so the lateral side really does play a significant role, again, in primary lateral instability without any significant other associated factors. So it's hard to recommend a lateral release. Lengthenings can be useful, and reconstructions are rare but helpful in patients with medial instability. Thank you very much.

lateral soft tissues

patellar instability

LPFL

ligaments

lateral release