So I will be talking about one specific cartilage repair procedure, I'm a little conflicted, I work both with Viracel, the maker of Macy, but also with JRF, the maker of osteochronal allografts, and I'm about 50-50, so this is just part of my practice that we're talking about. So how does cartilage fit into this? Well, biomechanics, you've heard a lot about in the first part of the symposium how important biomechanics are. If the biomechanics are off and you have a patella dislocation, your chance of actually having cartilage damage is pretty much 90%, and it doesn't mean that all of that needs to be fixed, but this is one way to fix it. So what is Macy, ACI, autologous chondrocyte implantation, in one form or the other, it's been around for almost 30 years now, since the first publication with Britberg and Peterson, and over the times it has evolved from something that is very painful to the surgeon and patient, meaning you have to procure and then suture in place a periosteal patch, and luckily now it's a little bit easier with the development of collagen patches, and in its latest iteration, Macy, where the cells are actually grown on the collagen patch, and instead of having to suture something and inject cells underneath, now we get this patch that you can glue, or if you want to even suture in place, and this is also amenable to arthroscopic delivery. So what are the pros to this, well you can address any size, shape and location, why is that important, well the patellofemoral anatomy is much more complex than the tibiofemoral, the femoral condyle is essentially round on round, it's much easier to get a plug that fits, you can rotate it until it fits, but in the patello, the trocha, you don't really have that chance. So it's nice if you have an implant that you can mold, there are other implants on the market where you can do that as well. It's also nice that it's a surface treatment where you don't have to compromise bone, so an osteochondral allograft, if it fails, it makes potentially a condyle, so just a surface defect into an osteochondral, so a deeper defect, this wouldn't do that. It's nice that there's lots and lots of data going back 20 to 30 years, and because of that, it's covered by the majority of insurance plans these days. But not all is well in the Macy land, there's some cons, most of them resolve, but some remain. So a, hypertrophy, that was a huge issue with the first generations, but that's essentially resolved now with collagen membranes, it wasn't really an ACI implant problem, it was a periosteal problem. The one thing that's not resolved, it's a two-stage procedure, and at least in this form will always stay a two-stage procedure. So it increases cost, increases morbidity, it also means it takes a lot longer between seeing the patient and having the final procedure, because you have to put that scope in between. It does give you a little bit more diagnostic certainty, you know the joint, you've been there, so in my own practice, that's not much of a negative, but certainly can be used to criticize. It does have an extended rehab, so if you compare this with osteocondyl allograft, for example, in the trochleum, if I see my patients back at two weeks, they can do an open-chain knee extension without much problem. If you do any kind of cell-based therapy, whether it's microfracture, particulated juvenile allograft, or MACE, it takes a lot longer before they can do that, because you have a soft implant that doesn't protect the bone, and that hurts a lot longer. You do need good bone, so it's nice that you don't have to mess with the bone if it's good, but if it's not good, then you put a new surface on a potentially crappy foundation, and that's not helpful. So you have to keep the bone in mind with all of these surface procedures. Doesn't mean that you can't do them, but you might have to do something to the bone, something like a sandwich ACI where you bone graft, and then you put your surface treatment on top. Where do I use it? Well, as mentioned, it's for full-thickness defects, obviously, it's greater than two square centimeters, that's mainly an insurance, not a medical exclusion, it's so expensive that insurance companies don't let you do that for small defects, and they're probably right for that. You can use it anywhere in the knee, specifically in the PFJ, as mentioned, it lends itself to the complex anatomy. Ideally, the defect should be focal, meaning shouldered by healthy cartilage, and again, that's true for all of these cell-based therapies. Bipolar in medical policies, that's an exclusion, but in medical practice, the vast majority of defects that we have looked at in studies are actually bipolar, so trochlea and patella, and the outcomes, surprisingly, are actually not that much worse than that of a unipolar defect, and I think I've beaten the subclonal bone to death. So which defects can be ignored? Initially, if you look at someone who had dislocated their patella, they have a 90% chance of having cartilage defect, doesn't mean that you need to do this or any of the other cartilage repair techniques for 90% of patella dislocators. If you have a small defect in patients with instability but no pain, you can ignore that. If they're really young, maybe monitored, but by and large, tell them, if you have a small defect, if you get pain or swelling, let me know. If you have inframedial defects, so most inframedial patella facet, it's not a very loading part of the patella, you can generally ignore those unless it crosses the median ridge. Those are the ones that are more significant defects, and you saw a few MRI scans previously. And then if you have an older patient, has an infralateral defect from chronic lateral maltracking, those are well treated with just a TTO alone. So talk a little bit about ACI data. Most of this dates back many years. Jack Farr had one study back in 2008 where he looked at his patella ACIs, together mostly with TTOs, had less than 10% failure rate. This is a study that we had done multi-center between ourselves, Tom Minus, Gilogli, Cole, Farr, and 8% failure rate, 92% of these patients would have the procedure again, which is a lot to say. And this is the study that showed there's not a significant difference between unipolar and bipolar defects, which was surprising. This is an actual MACE study from Australia, also no significant differences between patellofemoral and tibiofemoral. So the old adage that, hey, in the patella, this stuff doesn't work, the new data shows that's not the case anymore. And then this was impressive just because it was in a very high demand population. It was an army population and 78% original occupational specialties, which I think is a true testament to how vigorous this is. And then last but not least is my old partner, Tom Minus. He looked back at bipolar defects and showed survival rates in 90% at five and 10 years in a primary ACI with a TTO. But as soon as you add a microfracture to the mix, all of a sudden survival goes down. So microfracture, while having its role, I don't think that role is in the patella. So be a little careful. Just last comment, if you have a patella dislocation, oftentimes they are somewhat uncontained inframedially. You can either suture into the synovium, as you can see down here, or you can make it contain, just take a small oats plug and put it in the area of uncontainment. So overall, the PFJ is very sensitive to concurrent pathology, of which there's a lot. As you've heard, you need good bone, it's an extended rehab, slow return to sports, and it's expensive. But on the other hand, it's probably the most carefully vetted procedure there are at this point, thousands of patients in various studies. It's versatile. It has excellent long-term outcome. And now there are no significant difference, patella versus tibiofemoral. So consider this for your treatment of patella defects. Thanks very much.

autologous chondrocyte implantation

patellofemoral joint

cartilage repair procedure

collagen patches

Macy technique