the theme here. This is obviously a patellofemoral patient, 35 years old, BMI is 21, pretty classic retropatellar pain. Something that people brought up that's important that this patient definitely complained of is a sensation of it getting stuck with ambulation and transitioning from flexion to extension. I think patellofemoral patients with cartilage defects really sense that abnormality versus patients that have femoral condyle defects. I don't think complain of mechanical-type symptoms as much or the pseudo-instability. I think it is important to tease out who's actually unstable and who's not. That's why I like MRIs. If somebody says I had an event and dislocated, I'll get an MRI right away, not just to rule out a cartilage defect, but to make sure they had the bone bruise if I ever had a question about their clinical situation. You can see these x-rays compared to some of the ones we're looking at before. I think we're saying some of the same things over and over, but maybe the repetition is helpful. But again on that lateral view, you can see that there's an osteophyte proximal. This is very flat. There's a little osteophyte distal. Obviously you can see one here. Anybody want to add anything else to the x-ray interpretation? Probably not. So then we take a look at the MRI. For her, her TTG was relatively normal. So it was less than 15. I think it was actually 12. Then you can see here that she had a pretty significant patellar defect. On the lateral or on the sagittal here, I think it's important to get used to looking at trochlear defects on the sagittal plane. So this patient has normal cartilage here. Then this is all gone, all the way down to here. So I think that these are pretty hard to evaluate on axial cuts. So I rely on sagittal quite a bit. Then you can see there's some bone marrow signal here in the distal patella. And then the patellar cartilage here is pretty significantly worn. So that's, she actually did have a staging scope for the sake of time. I'll kind of keep moving through here if I can find the right button. It just keeps playing the scans all the time. So this was the diagnostic arthroscopy. I do put patients through this. Very rarely will I do a single stage cartilage procedure. That defect is primarily central with some medial component. And then she had this larger patellar lesion. So I think with the information that you have right now, let's say she had the staging arthroscopy. She didn't feel better after the debridement. She still had the same mechanical symptoms of the catching and locking that she didn't like. She's 35. She's very fit and active. She's a skier and just generally healthy otherwise. Let's say we're going to do a cartilage procedure or some surgical procedure beyond the scope for them. Does that, anything I'm telling you so far at the lesion location size, what would you guys be thinking? On the patella? It's a little more central. It's like along the ridge. She probably didn't went down to bone. It did. I can show that again. How old is the patient? She's 35. What does she want to do? She's a pretty avid skier. She hikes, she runs, stuff like that. So she's pretty active. BMI is 21. So Adam, if I look at that scope here, this is a 35 year old who basically looks like she has diffused changes in the entire patellofemoral joint, certainly the majority of her trochlea all the way up. She has a borderline patella alta, but she doesn't have the pattern that you see in a patella alta typically where you would have more proximal wear on the trochlea. So this is somebody where I'm worried that there is a little bit more than just mechanical behind that. This is somebody who is probably an anterior knee abuser in conjunction with, like Jack Farr likes to say, just bad cartilage matter. These are the ones that are problematic because how do you go about fixing almost the entire trochlea here? Patella I'm less worried about, but that trochlea component worries me. Yeah, I completely agree. Just to be clear, I don't think these are traumatic defects, but she has pseudo-mechanical symptoms now. So if you would raise your hand if you would do a MACE and plus minus TTO. Raise your hand if you would do an osteochondral allograft. And then raise your hand if you do a patellofemoral arthroplasty. I don't think it's unreasonable. It's not a crazy thought. You're saying biologically how healthy is this knee? The other compartments were actually pristine, so she didn't even have to start. Some people you see this, then you see a one centimeter defect in the lateral femoral condyle, one centimeter defect in the medial femoral condyle. You're just diagnosing early tricompartmental arthritis in that patient. But this one really seemed like she could have had something traumatic a long time ago, but now has turned into this from abusing it. So I think that when they do have symptoms like that, I really do like osteochondral allografts. I do think that they help give you an instantly smooth surface. You get rid of that catching symptom, and you can address almost the entirety of the trochlea if you have to. So here we're putting a line down the center of where the groove is. Then we put the amber guide on to see where it sits medial to lateral. We try to get the same percentage of where the groove sits within the graft on the donor and the recipient. And then we're prepping it here. This always ends up being a pretty deep graft that's very asymmetric. Dilating it's very helpful. And then you can see we covered most of the defect. There's a little bit proximal medial actually there that we couldn't get to. I thought it would take too much healthy cartilage to do that. When you take the donor here, it's important too to really stay perpendicular to your lesion. You actually have to remove some of the cartilage and the bone on the side to even be able to get some of these guides to sit down. Otherwise, they'll sit high, and they'll be prominent. I think, Cassandra, did you do a trochlear positioning study? Am I thinking of that right? So there's certainly some guides and ways to improve the positioning here. But what I was showing there is the tilt and the sagittal plane is the most variable part. And when you measure the recipient site, and then you make your marks on this plug, if that line matches up, then you know that you're going to pretty much be flush throughout. And you really want to be flush, proximal, and distal. And then you can trim the fins on the side if you have to if the sulcus angle doesn't match the donor and the recipient. And I do like putting the suture in the back now so I can press fit this by hand only, no impaction. Sometimes you can use the impactor part without the mallet from the arthroplasty set because it matches the trochlear groove. And then once we're happy with that and the contour, we can remove the suture. And in this setting, I just drilled that proximal medial component. And so there's no panacea. There's a little bit of continued damage vertically there too. That's why the Macy might not work well. It's going to be too broad of an area, I think, in this case. That's why I think it's a good choice. Yeah, and hard to hit it all. So I've done some that's like a Coke can, the OA graft, and you're covering the entire trochlea side to side. So you've got to do something with the osteochondral allograft, right? Yeah, and I didn't want to remove, she had enough healthy cartilage laterally that I was willing to just drill that part versus trying to cover it with the entirety of the graft. But these people really do see elimination of that sensation of the maltracking or that catching almost immediately as soon as they get their motion back, which I don't have any limitations on motion for these patients. So as soon as they can get it, I let them. And this is the patella or osteochondral allograft. So I think what I just want to show here is that you just want to find the, I always call it like the dental matching, where these are three different cases. You'll see different imprints. If you can get the same imprint on your donor and your recipient, then you're likely to have a good match and you can make that work regardless of what part of the patella you're taking it from. And so everybody's patella, the donor and the recipient, are going to be different. But if you can get that pattern to be similar, then you're probably going to be happy with what you end up with in the end. And the rest of the process is really similar. I would say that depending on the system and the amount of mismatch that you have, dilating is extremely important. The patella, it's a very firm bone. You'll be very tempted to hit this in place with a mallet. But if you do chamfer your graft just a little bit and do the dilation, you can usually do a press fit. And then you can actually get it close and then flip the patella back in its native position and just push it down onto the trochlea with basically your body weight. And that's a great place as well. And so for the sake of time, I'll show this. Yeah, they have some of them. I try to look at how dysplastic they are. So she was on the dysplastic side, so like on her MRI, her medial facet started to become fairly non-articulating. And so in that setting... Yeah, we did that. There's also an oblong patella option for osteochondrial allograft prep. I haven't done that. I've done it in the femur. But I haven't felt comfortable doing it in the patella. I've done it in the lab only. And this is the RF set? This set is, yeah. That part is important because it has a millimeter of mismatch. So it's very, very tight. Yeah, that's just why I bring it up. The nice thing about this set is that it doesn't stop. Especially if you are working with fellas in your own room, I think this set is nice. What I don't like is that it's really tight. You definitely have to chamfer it and dilate it. And you obviously mentioned that, but it's a little more interesting almost to do in a case. These are the MTF set. I like that set. That's a good ACT set. And MTF is nice because they are larger. So for a big surgery like this, you have to be happy with that. I don't do the pre-cut that you were doing. With that set, you can hold it all together. It's tough to recreate the contour. You did a great job. Yeah, that's I think the most important point. It's really hard. Yeah, trochlear more than patella, I think. Patella, you can actually have more futz factor, but the trochlear, you're kind of one and done once you prep it. And that sagittal plane movement I think is the one that's the hardest for me. And if I can get close for the proximal distal transition, then the rest of it looked good because the anatomy matched. That's not me. That's the fact that the sulcus angle was similar. So that's not always like that. I'm not going to show the bad ones, but you can only take credit for so much. And some of it is getting some matching that's reasonable. So in closing, this one I did do a straight 90 degree anteriorization. So you can use this with a guide or not. The key here, which I guess we haven't said specifically, even if I'm doing like a 60 plus, I make a counter cut. So I do whatever the vertical cut is. And then I'm not going to carry that all the way through the posterior tibia. So in this setting, it's a straight anterior to posterior cut. And then making a chamfered proximal posterior to distal anterior cut. And so you can see that there. These don't need to connect inside because it's just cancellous bones. The osteotomy will connect it. And then just as was mentioned, I make kind of a doorstop out of a tricortical compressed allograft. And then it's usually a centimeter that I'll put in there. And I just do that routinely because I don't know. We don't have the preoperative measurements. And then these screws go at 45 degree angle so that I can compress the graft as well as the overlap that exists on the side. I don't know if any other comments about technique for these. That's an allograft. Okay. Yeah, the centimeter, there's some biomechanics that looked at less and more. And like you said, some of the historic stuff, when it gets more, they used to do 12 to 15 millimeters. That's when you'd have skin breakdown issues. It's really prominent. They definitely clinically can see it and notice it. So I'm not using any science to the 10 other than some of the biomechanics data shows that offloading more than 10 doesn't seem to add much more. But going less starts to drop off, so it might plateau. And this is closing of that lateral lengthening that Christian was mentioning, which I just do for all TTOs. I haven't done any. I wouldn't know where to begin with that.

patellofemoral pain

cartilage defects

MRI scans

osteochondral allograft

patellofemoral arthroplasty