Thanks to the committee for allowing me to present and be part of this program. It's really an honor and it's great to be back in person. I do want to cover some pearls before we get into it, so it's a little bit of potpourri of anatomy and biomechanics before we get into the actual video and the technique itself. So let's just start with the femoral side of the anatomy because clearly it's very crucial. What we really want to make sure is we understand the relationship of the adductor tubercle, the medial epicondyle, the saddle point that's in between, and that the MPFL typically sits just posterior to this location. So similarly, when we're at this step in the surgery, we want to be able to palpate the adductor tubercle. It's usually the lighthouse of the medial side of the knee and I think is easier to palpate, but sometimes it is variable. And then you move directly distal to that location and that's really where we want to try to put our guide pin. I usually find that after the guide pin's in place, it's easier to then palpate directly posterior to it and make sure that you still feel that prominence of the adductor tubercle. And we'll talk about checking this on x-ray as well as with length changes as well just to triple check to make sure that we don't get this wrong as it clearly has been shown to be crucial for patient outcomes and success. Here when we look at a radiographic study, looking at a point cloud of the adductor tubercle on a perfect lateral radiograph followed by the MPFL point cloud, again, it is directly distal and this is where Shottel's point really originated from. When we take these boundaries, we really want to make sure that it is a perfect lateral in the operating room and I'll show the use of a leg positioner to do this. The idea of Shottel's point is that this location in this line or the distance between the anterior trochlea and the point itself, as this rotates down, that line doesn't change length and that it's relatively longer because the distance between the osseous points have now become closer. So we should usually see lengthening inflection and this is what we check in the operating room. This is not as well visualized in the other surgical technique video so I want to show it here. And this is the use of a hemostat just posterior to a pin through Shottel's point and as we flex, we can see that it gaps there about 8 to 10 millimeters and as we fully extend, the hemostat becomes tight up against the posterior aspect of that pin and to me, that's the ultimate check to make sure that I've gotten things correct. The medial patellofemoral complex involves the MPFL and the MQTFL. This has been described by Fulkerson and Tanaka and others and this can be beneficial to reconstruct soft tissue because there are concerns about patellofracture rates after MPFL reconstructions. This is obviously a devastating complication. Aaron Critch did a study looking at this and found that if you use cortical fixation instead of sockets, that risk does go down significantly. But this is still nonetheless due to the fact that it does exist, the MQTFL, the concerns for osseous constraint that can be too strong as well as the complications from fracture. This has been popularized and utilized now more than it has in the past. I just want to talk about the anatomy here. So the MPFL has its most distal insertion at the midpoint of the patella. The most proximal aspect of the MPFL in the osseous insertion is the superior medial corner and then the MQTFL extends about a centimeter proximal to this into the quadriceps tendon and deep to the VMO. And so these two components are important but the question is what's the difference in the length changes and what are the relative biomechanical contributions? And so when we look at these changes going from zero to 90 degrees of flexion for these four points, the midpoint of the patella only has about 2.5 millimeters of length change from zero to 90 degrees. So it's almost purely isometric or has a favorable anisometry with gradual lengthening. If you look at the most proximal component of the MQTFL, this has about 12 millimeters of lengthening. So there's a significantly greater amount of anisometry and we should make sure that we remember that when we're doing our reconstruction. So if a patient has ALTA or if we're doing a proximal based reconstruction, we would likely see significantly greater length changes and it may not be isometric in the operating room. Most of these changes do happen within the first 40 degrees of knee flexion which is really where the MPFL is the most functional and so that's why I think it is important to try to get something close to isometric. This is also why I think it's useful to have your two free ends of your graft going into the femur or doing your two free ends on the patella but as the final step so that you can set length individually. You're not tensioning these so you can set length separately even though you cannot tension them separately. This is just a video showing the difference in how robust and stout the MPFL is compared to the tissue of the MQTFL and we did look at this biomechanically and found that there was a significantly greater contribution of the MPFL to resisting lateral restraint and so this is looking at lateral release and looking at lateral translation compared to intact. So we did have increased lateral translation after lateral release. Section of the proximal MPFC did not significantly increase lateral translation. Isolated MPFL sectioning had significantly increased translation and the combined sectioning was ultimately the most significant. So they do all play a role. There's just a differential role and I just was setting this up for what you're going to see in the technique. So the proximal and distal extent have different length changes so again I like to set isometry separately with the free limbs being fixed second. The longest distance between all points in the MPFC for all reconstruction types is in full extension so I still do perform the fixation in full extension and the MPFL is the primary restraint and so I do an osseous based reconstruction and cortical patellar fracture rates are very low so I do use small patellar anchors. And with that we'll move on to our case here and the patellar anchor placement, we really want to make sure that we just don't aim too anterior. You want to have your finger on the far side of the patella. Unfortunately there's no guides for this but it would be useful and we want to make sure that we're not aiming towards the articular surface. Similarly as we move up to a superior medial anchor, make sure that we're aiming distal and lateral so that we stay perpendicular to the cortex. This is a relatively straightforward patient that we're going to see the video of, 15 year old male, multiple dislocations. The anatomic risk factors I'll talk about in a second. Here's some of the information that Latul mentioned with increased lateral translation with apprehension and a mild Baden score. She has CDI of 1.08 and some medial hypoplasia with some underlying dysplasia as well and a double contour. Mild varus, no significant femoral anaversion and her TTT, GNT, TPCL I would say are borderline and something I was able, I was willing to accept in this setting. And so we separate these out into concerning and not concerning factors and elected for an isolated hamstring allograft reconstruction. Here's the technique itself now, so we make our incision superior medially, I usually mark out the midpoint of the patella as well as the superior medial corner. Usually this gives adequate visualization, I do not use fluoroscopy to place these anchors, I think with palpation you can really find that midpoint. I find using a tourniquet is particularly helpful to make sure that you stay in the correct planes and once you dissect down through layers one and two, we can usually find the capsule fairly easily and we try to stay extra articular. If you do get into the joint, I don't think it's a significant issue, but I do close it. Sometimes a 15 blade knife is useful to separate off the capsule, especially if there's been an osseous avulsion here and that can make this dissection a little bit more difficult and so you wanna make sure you know that that's there before you get in from the MRI so you're not surprised if it's more difficult than normal for exposure. Then use a bovie electrocautery to ablate off the periosteum on the superior medial aspect, we're gonna place a trough, this area is then rongered to create that recipient trough for an onlay technique for the loop end of the graft. I've moved to hard bodied knotless peak suture anchors and I like these primarily because they have a very short handle, I think that with a lot of the anchors that go into the patella, they're not made for the patella. These are actually foot and ankle anchors and I think it makes it easier because there's just less to manage and move around. Again these are knotless and I have switched over from that from knotted, I think that both can work very well, it just so happens these short handled ones are also knotless. After the first one is placed in the midbody of the patella, you can usually use that as a partial retractor and then place the superior medial anchor here and making sure that we have good relationship. This is the use of a leg holder that is useful for positioning in multiple planes and so we correct first in the axial plane, so we correct rotation first to get the posterior condyles to line up. We then move in the coronal plane in varus and valgus to try to improve the overall alignment until we really do get that perfect lateral radiograph. I then use a hemostat to localize Schottel's point, really just to make a somewhat smaller incision more accurately, especially when patients have a significant amount of femoral anaversion. It can really fool you and this can really end up very far posterior and then we connect these two superficial to the capsule. Once that hemostat comes out, you can really palpate the adductor tubercle at that point and then we use that palpation to try to figure out where we think the pin should go and then re-verify it on Schottel's point. These are then brought through and as was mentioned, we use the hemostat posterior to the pin to check length changes and we should see that they're clearly loosened throughout flexion. I would say a very small percentage of the ones that I perform are isometric, I almost always feel some loosening. This is a semi-T being prepared with a whip stitch on one end. I then pass this superficial to the capsule and around the pin and bring it back up. Even though that's the opposite of how it will ultimately be implanted, we try to get about 25 millimeters over the patella so that we can figure out the length of the graft. We then remove that and prepare the rest of the graft on the back table. This is a smaller point but the graft preparation, I've moved much further away from doing line to line. This is, for instance, a six millimeters here, very snug, difficult to get through. Here it just fits through a seven and so in this setting, I would actually ream an eight. I really like to have the free ends move very easily into the femur so I don't get any artificial constraint due to the friction of the reconstruction itself. Here you can see the passing of the knotless sutures, so this just goes through in a simple fashion. You could probably even just put it around the graft. Once both of these are in, we can then use it to advance the graft down to the patella in that onlay fashion. Use of sockets in this area has been described. I do have concerns about fracture. I think with sockets done correctly, the fracture rate's still relatively low but with modern technology and new suture anchors, I do think it's helped advance this portion of the procedure. So here you can see the loading of the knotless suture anchors and really bringing that part down. The next step of, once this is down, placing this in the femur, I do this in full extension with proximalization of the patella and so again, that should be the longest length. You have no constraint to the trochlea in full extension so you should be careful because you can over-reduce it and cause the patella to tilt medially and that really is worse than if you had it fixed in flexion. So we really want to make sure we have a generous reaming here and that they easily dunk into place without any issue and then we use a peak interference screw to fixate this in the femur and check on arthroscopy to make sure that we have an extra articular graft as planned. Afterwards, patients can have immediate weight bearing with a brace locked in extension until they have enough quadriceps control to really walk without a lag. After six weeks, that's discontinued and we try to increase activity until four months which at that point, hopefully, we can start releasing them to full activity but it does take a little bit longer for them to really get there and to return to sport. We've looked at this as well as others and it's pretty clear that femoral tunnel placement is the most important thing to get right with regards to failure. It's been shown time and time again and so we've got to make sure that we do get the technique correct to have better outcomes and again, return to sport by about six months is what really should hopefully be expected. Thank you very much for your time and attention.

anatomy

biomechanics

surgical technique

patient outcomes

hamstring allograft reconstruction