A couple of other things, one point about that patella tendon shortening, where I've also found that very useful is in those patients who have had a previous patella tendon repair that has healed in a very elongated position. And if you don't want to take down that whole patella tendon repair, that's a way to get some patella tendon shortening. And so I've actually had to do that. I end up getting sent these things. So I end up doing that. I've done that more for those kind of patients with those stretched out patella tendon repairs that have that extensor lag to get the decrease in height without having to undo that whole reconstruction. So a couple things, these are my disclosures. This was a patient who was 22 years old, had a history of a right tib-fib fracture at age 13 pre-menstrual. She was cast in extension for eight weeks and then noted patella dislocation after coming out of the cast. She had less economic means and she was not able to see a physician for further treatment. She also had a diagnosis of trichorhinal phalangeal syndrome, which is autosomal dominant. This is cone-shaped epiphyses of her phalanges and hip dysplasia, so she had very short fingers. She had abnormal faces, but the knee component of this is not actually described. And one of the things is, if you start seeing these patients that have more syndromic issues, it becomes a lot more complex and they can have several things happening at the same time. And so this was an x-ray of her contralateral knee at age 14, and you can see substantial baja even in her contralateral knee. And then this is the bilateral x-ray in the age 15, and so this is her left knee and then her right knee, which was the symptomatic one. And you can see the patella is extremely laterally located. This was her x-ray by age 22, bilateral x-rays, and you can see this is with a little bit of flexion, but you can see the patella on the left side is relatively located and the right side is not. And this is going to be one of the probably more unusual lateral x-rays you'll ever see. So in extension she's clearly laterally located, the patella and the tubercle are clearly laterally located and she has habitual or obligate dislocation and flexion. And this is her overall anatomy. You can see her trochlea is quite abnormal as well. I thought her overall bullying alignment was reasonable and did not need a DFO. So in this case a couple of things were performed. You can see that I actually performed a proximalization of her tibial tubercle and also an MPFL. In this case we did a lateral retinacular lengthening, division of the lateral patella tibial ligament, tibial tubercle osteotomy. That was about 5 centimeters long. She's also extremely short. She's about 4 foot 10. Proximalized by about 10 millimeters and medialized by about 13 millimeters. I did a step cut lengthening of the extensor mechanism and I fixed it so that I would be able to get to 90 degrees in an MPFL reconstruction. So lateral lengthening, this was briefly discussed but the idea is with a lateral lengthening, I think many of you are familiar with this idea, but that you can cut the superficial lateral retinaculum and the deep retinaculum in a step cut fashion and lengthen it. And then you may also need to do, and again this is from some Jack Andrish's work, a release of the vastus lateralis. And so this is a modification. Dan Green also has a nice article about this. When I do this procedure I prefer to do the step cut on the lateral side of the extensor mechanism in order to get this contracted extensor mechanism out to length. I try to repair my vastus lateralis a little bit more proximally wherever it sits. But I'm trying to try to keep the medial structures and the distal medial attachment as much as possible because I think that's going to enhance my, again this is all about balancing vectors and forces at this point in time. So postoperatively we can see that we have a much better aligned joint. She's still in a little bit of Baja, but I was trying to run out of room on how much more I could proximalize her. So she had a stable patella postoperatively, range of motion 0 to 125 degrees, 5 out of 5 strength. You know, the area of the extensor mechanism repair was under a lot of stress I think. And she had some soroma in the sinus tract at 11 months. We did an IND and there was some disruption of the side-to-side sutures at the quadriceps repair and that was re-repaired. And subsequently her follow-up has been uneventful. So I think one of the important things with these kind of patients is to recognize an NPFL is not really going to pull that thing over. If your extensor mechanism is that, if you have a dislocation inflection, the vast majority of the time you have a contracture of your extensor mechanism. You're going to probably have to do something with that beyond just trying to loosen it on the lateral side and tighten it on the medial side. And so the tubercle transfer did provide a significant amount, but after I fixed the tubercle we were still getting dislocation because the extensor mechanism was so tight. And at that point we did the extensor mechanism lengthening. One of the challenges is trying to figure out what tension to set that at. In this case we were able, you know, I sort of looked at where I wanted it to be at about 90 degrees and then put the knee into more extension and fixed it in probably about 60 and then tested it to see if I could get to the 90 because I was worried about over-constraint. Sabrina? It's a great case. If you really felt like you couldn't get enough proximalization with the tubercle, have you done any patellar tendon lengthenings or is there a time where you might do just a soft tissue work instead of the osteotomy? You know, I worry about that because I think these patients have already, if you have a situation where you're going to try to, I think I'd rather have it, I'd rather try to get the lengthening of the extensor mechanism on the quadriceps side. But because I think the idea of trying to lengthen the patellar tendon makes me very nervous. I don't know if the other panelists have had experience with lengthening the patellar tendon in these kind of situations, but I think that could, you know, my concern with it, that could lead to some sort of significant failure. If you had a failure there, then you have a big problem. Is a Z lengthening of the patellar tendon an option? I think it's an option. Again, I think that's part of the concern is that you're going to have a lot less real estate compared to your quad tendon to get that lengthening. And I think that there's also a potential concern about what the healing is going to be like. So at least, you know, I've maybe done six or seven, but those were all in post-traumatic patients. Patients with patellar baja, that was traumatic, and they ended, all of them have had a very thick patellar tendon. But it is scary, and I always run their hamstring around to reinforce it. But in some cases, again, this one I think obviously looks great, but you don't have enough room to move that tubercle. I also worry a little bit about the next operation, because you'll probably have to take the tubercle off if she ever needs a total knee. Now she's young. But, you know, if this patient was, let's say, 30 with a post-traumatic baja, with a decent chance of arthroplasty in the future, I mean, it's not the end of the world to have to do an osteotomy at the same time as a total knee, but it's not a minor consideration. Yeah, I think post-traumatic baja is different than this type of situation. Yeah, yeah, completely. When you do that, you definitely worry about the healing, but it's not a Z lengthening like the quad. It's an A to P lengthening. So you can really split the tendon in half, leave half of it attached proximally and half attached distally, but different case. Yeah, the step cut would probably be similar to what was shown, except you complete the back half of the patella tendon. So you must have taken a very thin shingle of bone on the tubercle to avoid having a gap at the bottom after you proximalized it. I did. My goal, when I do my osteotomies, I do feather it, and so if you slide it, you can see that there is a depression, but it's been slid up, because I am worried about a potential stress riser at a vertical cut. I've seen with my distalizations, if I've done a step cut, that end vertical cut can take a really long time to heal. I've feathered it, and I've done distalizations, and still sometimes that distal part can take a long time to heal. If I am distalizing, that's one of those situations where I usually will use three screws, because some of the other work we've done in finite element analysis is that distalizing clearly increases the forces on that joint inflection, and so that shingle is under significantly higher load than if you just medialize it or anterize it. Just a quick question on the rehab side, given the forces for this case, how did you progress post-operatively to protect the quad, and maybe just a little bit of that early post-op rehab protocol, particularly in a young patient that may be not the most compliant? Yeah. I mean, I think, so first of all, I think there's no real textbook answer for this at this point. You know, so I typically will immobilize these patients in about, you know, an extension for about two weeks, and then try to gradually progress their range of motion, hinge knee brace, to about 90 degrees by six weeks. But, you know, again, I think with a lot of these cases and, you know, with our extensor mechanism repairs, I think, you know, there's always this difficult balance of, like, how long do you immobilize versus how long do you, when do you start immobilizing, because I think we've all seen patients who have been, you know, are our owner that have been sent to us that have had a quadriceps repair or a patella tendon repair, and, you know, we worry, we've gone away from immobilizing people in a cylinder cast for eight weeks, which we know causes contracture. But then we don't, you know, on the other side, we don't know how much to immobilize. And patients are variably compliant. So. Do you alter your weight-bearing precautionary post-op if you're going to do a height-changing TTO? So if you make it more proximal or distal, you change your weight versus if it was just like an AMZ and you have that intact corporeal hinge. I've had a few patients that, you know, kind of stomped on it right away and they got a fracture from their height change, but I've never seen one where I didn't change their height. Yeah. Well, I've been following sort of the guidelines that came out after the SCOE group, along with John Fulkerson, reported early, you know, actually stress fractures at the apex of your osteotomy site with an AMZ if you did early weight-bearing. And so that paper, which was published in AJSM, it was interesting because it was like the two groups combined with one paper, showed that they had a rate of stress fractures across the sort of that apex of the osteotomy. And they happened as kind of a stress fracture that propagated across and relatively later after early weight-bearing. So I've been pretty, I've been a little more cautious with weight-bearing in all of my tubercle osteotomies. And so I'm typically making them a touchdown or partial weight-bearing for the first six weeks. I think if you make a shallower shingle, that risk of a stress fracture is probably less, but I don't know how shallow is shallow enough. But then you risk fracturing the shingle. Right, which is another case that, are you presenting that? That was presented at the W thing yesterday, I think. But yeah, if you have too shallow a shingle, that can easily fracture. And I would say that I do a fair number of crystallizations, and so I do change my weight-bearing between an AMZ where I'm going to do a green stick, which I think is much more stable and is much more stable. It's a whole extra point of fixation, versus if I'm going to do a distalization and then I release that. And also, since I do a step cut, it's a definite stress riser. So yeah, I restrict them for two extra weeks. So my regular AMZs are four weeks of non-weight-bearing and then progress to full by six weeks. And these are non-weight-bearing for six and then progress, so I change it by two weeks. And also, if they're getting back to sport, they're somebody who I will do a limited CT right through that distal aspect before I look to get back, and that's usually around nine months. So they're usually physically ready to get back to sport in nine months, and I just always like to make sure that that distal aspect of that distalization is fully healed. And I think that is a big difference between a feather cut and a step cut, is that anterior cortex stress riser. Yeah, and I'll also palpate that distal. Clinically, I'll palpate that distal tip, and if they're sore there, that raises my suspicion about, you know, is this root truly united? So... Dave, what do you do for weight-bearing? I do 50% for six weeks, but it has to be two crutches. It's not one crutch, it's not 50%. And I wait until I see a radiographic immune before I let them come off the crutches. So if it's six weeks, it's not there, I've got to wait longer, bring them back for another x-ray. You've got to sit on top of these kids. Adolescents misbehave, right? Everybody in the room knows that. But yeah, the ones that misbehave because they feel pretty good, that's when you get a fracture. And do you differentiate if it's a distalization? I'll probably go eight weeks across the board for a step cut. It's going to take longer. But I do let them do... It's partial weight-bearing. I actively put bone down there at time zero. I'll even scoop some bone out, some autograft, put it down there, try to fill any little gap that helps. Yeah, the distalization part, that sometimes takes a long time to heal. So you used one, looks like a regular synthese screw and a headless screw, and then I think, Dave, you looked like that was a MyTech screw? Those are LimbaTech. They're really old screws. You don't even self-tap them, you just have to tap them. But they have a low-profile head, so I have to take a few of them out. They're pretty robust, four or five strong screws. Buddy's three. But this is a fetish angle, so we wouldn't apply here. Small patient. Yeah, and I think at this point, one of the things I've done is, I learned from Andy Kosgaria's, I used to use four or five standard, four or five synthese screws, and I was removing them about 50% of the time. The head is prominent, so I've shifted primarily to the three, five screws. And I typically will use at least two, and if I distalize or it's a big patient, because somehow I get these 280-pound patella instability patients. I don't know why anybody else in my neighborhood wants them, but I'll use bigger screws, more screws, and limit weight-bearing longer. Because the forces, your fixation strength is the same, but the forces are substantially different.

tib-fib fracture

patella dislocation

MPFL reconstruction

proximalization

lateral retinacular lengthening