 I wanted to give a talk today on cartilage injuries, in particular focal cartilage lesions and not diffuse osteoarthritis. So as everybody knows, as we get older or even sometimes at a younger age, cartilage starts to wear out and osteoarthritis has a rather formulaic treatment that eventually typically results in joint replacements. However, this is a specifically different entity. And we're talking about when just one area of cartilage gets injured or damaged, particularly when the rest of the joint looks good and doesn't have any osteoarthritis. So these can be, these lesions can be found in younger patients, sometimes even teenagers. And these cartilage lesions can progress and they can be very challenging problem to treat in young patients. So what I wanted to talk to today is with regards to how to identify these lesions, how do we treat them? What are some of the treatment options we have today and what are some possible treatment options in the future? We'll certainly leave some time for questions in the end. So I have no disclosures and they had sent out the objectives of this lecture which I just reviewed. So just to refresh your particular cartilage is a protective surface that you found in nearly every joint in the body. It has many different functions but the primary function is to decrease load across the joints to protect the underlying bone and also decrease friction so that your joints can move nice and easily or so the bones can move nice and easily against each other. So it has to be very strong in many regards because a lot of the stresses are in all different in all different types of forces. You'll have compressive forces but also you have shear forces. So it has to be able to withstand different vectors of force. What's important to note is that there's actually no nerve fibers in cartilage. So the pain you actually get from having a cartilage defect is not in the actual cartilage. It's in the bone underneath that sees increased load. It can also be in the synovium around the cartilage and other structures within the knee but not the actual cartilage. Also important to note that there's absolutely no blood supply to the cartilage. So it has very limited healing capacity. It does get nutrients from the surrounding joint fluid but the fact that it doesn't heal is one of the biggest challenges that we have because once it's injured, it's more or less injured and it's just gonna be worse and not ever heal. So this is a slide. I just discussed some of the composition of the cartilage. These are probably things that you're all hoping to forget about after medical school. But just to highlight that it's type two collagen that cartilage is made up of. So type one collagen is what you'll see in bones and many other structures. But type two collagen is more resistant to compressive force, which is obviously important for cartilage. And as you can see, the majority of cartilage is actually water and with a small percentage of proteoglycans. So here's just a quick histology slide. Just to give an idea of that, this is a very complex structure. This has what we call zonal architecture. Specifics of it aren't that important. But as you can see, the closer to the surface, the collagen fibers and the chondrocytes are parallel to the surface. And that helps resist shear forces. And then there's a transitional zone and then the deep zone is also called a radio layer. And you could see that the collagen fibers are actually perpendicular. And so that's more of the compressive forces. And then there's what's called the calcified cartilage layer, which is think of it like the transition to bone and then underneath is what we call subchondral debone. So the native cartilage that we're born with is actually a very complex structure. If you look at the histology and trying to recreate this is actually one of the biggest challenges of any type of treatment approach. So here's just a close-up of some of the histology. So this is an arthroscopic view of the knee. So I do a lot of knee arthroscopies as a sports surgeon. And if you look at on the left, this would be the view of a young person without any problem. So this is the medial compartments and on the top of the screen, you'll see the medial femoral condyle. On the bottom, you'll see the medial tibial plateau and you'll see the meniscus in between. So this white shiny surface is what perfectly healthy cartilage should look like. And so then if you look to the right, this is actually a 21-year-old patient and that's their troglia and this is what can happen. So as you could see, it's not a nice smooth surface. It's starting to peel off. That's my metal probe showing that there is a flap there at the edge. Not quite down to bone, so you can't see bone yet, but I'm willing this appears to be at least 50% of a defect. So that's what unhealthy cartilage can look like. So as I discussed in the opening, there's a distinct difference between osteoarthritis and a very focal cartilage lesion. So they're very distinctively different entities, although there might be some overlap. Certainly having a cartilage injury can affect the cartilage that it's articulating with and actually cause some focal post-traumatic arthritis. Also osteoarthritis, think of as a global kind of disease of the knee. You'll start to get changes in the joint fluid. You'll get synovitis. You'll start to get this gradual breakdown of the cartilage elsewhere. So if you look at the image on the left, that's an arthroscopic image of osteoarthritis. So obviously if you try to fix just one area that osteoarthritis, it's very, very unlikely that they're actually gonna get better. I like to use the analogy that you have a forest fire and you're just putting out a couple of trees in the middle of it. So obviously that's not really gonna stop anything. Neither is some of the more advanced complex procedures we'll talk about later on in the talk. This is an example of a focal cartilage lesion. So as you can see, you can actually see the bone there. This is actually a college football player after an injury. And but you could see the surrounding cartilage is that nice, healthy, thick white cartilage. So think of it, I tell patients it's kind of like having a pothole in an otherwise well-paved street. So this is where we can help make a difference potentially by trying to fill in that pothole and try to recreate the best we can some of the normal function of cartilage. So these cartilage lesions can be full thickness or partial thickness. That image I showed a couple of slides ago was a partial thickness cartilage defect, which means it's not down to bone. But in this case, as you could see, you're staring at subchondral bone. So that's what's considered a full thickness defect. So again, these are the differences and we're gonna be focusing on the cartilage lesions today. So first of all, these cartilage lesions are very common. We see them all the time and we see them in all ages. You can get cartilage osteocondrol injuries for kids. They're called OECD lesions. You can see them in high school kids. We see them a lot in college athletes and then in the 20s and 30s. And I know I keep talking about quote unquote younger patients. In general for the health of the age of the knee, we consider 40 and younger young. However, certainly everybody's knee age is at a different age, at a different rate. There are some 50 year olds that are still running marathons and you stick the scope in there and their knee looks like a 20 year old. So when we talk about treating these cartilage lesions, what's most important is the physiologic age of the knee. Do they have any arthritis? Is there a good healthy cartilage thickness there? So if they're an older patient but they have a knee that is relatively healthy and have an isolated lesion, we would treat those on the same pathway. So you can get them after a traumatic event. You dislocate your patella. You fall on the knee, you get hit there. So there could be any number of potential traumatic injuries that will just knock off a piece of cartilage. So that would be the case you'd have two problems. Not only would you be missing cartilage in that area, but now you have a big piece of cartilage floating around in your knee that needs to be addressed. But oftentimes there's not a specific injury like that. It's just a more gradual pain and swelling that the patient gets. And we get an image and there's no loose body. It's just one specific area gradually wore out for one reason or another. So there are some predisposing factors. A ligament instability certainly can put some more stress on certain parts of the knee, in particular the cartilage. If you're missing meniscus from a certain area, that's gonna cause more load, increased force, because it doesn't have the protection of the meniscus. And so that can wear out the cartilage quicker. If you have any malalignment, if you have a varice or valgus knee or the lay terms would be knock-kneed or bow-legged, that will certainly put increased stress on certain parts of the knee. So if there's any cartilage that's having increased stress for any of these reasons, you can get cartilage lesion. The most important thing is that the symptoms are really variable. Often as we talked about earlier in the talk, the cartilage in itself doesn't have any nerve fibers. So just because you're missing a little cartilage, oftentimes we'll just find those on MRIs or arthroscopies and they've been completely asymptomatic for patients. And I've seen smaller cartilage lesions that have been very debilitating. And I've seen larger ones that really aren't bothering people at all. So, and it seems to really not correlate with size. Some of them can progress. I mean, I guess in reality, all of them will eventually progress if you live long enough. But some of them progress really quickly and others seemingly reach a steady state and patients can go decades without having any worsening of symptoms. It's really hard to predict that. However, if you have any of those predisposing factors like ligament instability, malalignment, or meniscal deficiency, predictably the patients will get worse sooner because of that overload in that area. So as for the history, like I mentioned, it's extremely variable. Sometimes they'll have a history of an injury. But most importantly, cartilage lesions tend to cause swelling and effusion. So for me, when I see a patient, a young patient with swelling, first of all, and someone without arthritis, that's never normal, a true effusion of the knee. But I always think more cartilage because meniscus, if you have a chronic meniscus tear, that's typically unlikely to cause the type of swelling that you see with cartilage. You tend to see it more with activity and especially higher impact activities. So if they have more pain and swelling when they're running, or jumping, or weightlifting, or playing sports, but it improves with rest, particularly if swelling is involved, that's the typical story that you'll get with a cartilage defect. And when I say cartilage lesions or cartilage defects, they are more or less the same thing. So those are both terms that we'll commonly use. So we'll also use the term osteocondrial defect if it not only involves the cartilage, but also if there's a cyst or some injury to the bone underneath. So that's sometimes what you'll see as well. What's also important to notice, sometimes you'll have catching. A patient won't feel like something's clicking or catching. And that's if at the edge of the cartilage lesion, if there's a flap, like a flap tear of the cartilage, that can, as you bend and extend the knee, that flap can get caught, almost like having a hangnail that gets caught. And that can also cause some mechanical symptoms like that. And oftentimes just cleaning up the flap and making sure that there's no unstable cartilage edges is all that needs to be done. And we'll talk about that later. And the physical examination can really be variable. And I mean, if you might, I would definitely look to see if there's an effusion. They might have tenderness over that specific area and that can be very, very helpful. So as I mentioned, it's very common to get, to see have incidental findings of just finding a cartilage defect that doesn't seem to correlate with where they're having pain. And what I mean is if somebody is saying that they have a lot of pain under the kneecap, but you get an MRI and their cartilage lesion is in the back of the knee, like on the femoral condyle, and they're not having any tenderness there. And then it probably means that that's not what's really causing their pain. So it's really, the history and physical examination is very important for us to really determine whether it's this cartilage lesion causing pain or if it's something else like patellofemoral syndrome or meniscus tear. So it has to really make sense and also be in the same location. But oftentimes they will have tenderness right over where they're having that cartilage defect or in that general area. So we always start with nonoperative treatments. So just because it's a young patient with a cartilage injury, it doesn't necessarily mean that we need to do anything. Now, if they had knocked off a piece of cartilage that's floating around like a loose body, sure, that would be something we'd wanna get after. But just the fact that they're missed, that they have a cartilage lesion does not necessarily mean that they're gonna need surgery. All of the treatments I'm gonna talk about to fill in that cartilage, none of them have actually proven to prevent the progression of arthritis. Now, there's some thought that if you successfully do this, that it will. That's very hard to study and really hasn't been convincingly shown in the literature. So the indications for surgery is really pain, pain relief. So if we can relieve their pain and symptoms with nonoperative treatments, we could potentially save them from having to have a surgery and also a long rehab involved. So the inflammation and the swelling that are caused by these lesions typically cause the most pain and symptoms. So anti-inflammatories and really getting that swelling down is one of the best things you can do. So we'll usually start with some ibuprofen or an aproxen or whatever your favorite NSAID is. Tell them to elevate ice. And then all of the other things that we can do to decrease load on the knee, such as weight loss, really strengthening the muscles around the lower extremity, including the hip and the core. Having good strength can help take pressure off the knee. It can help the biomechanics. So that certainly is helpful and physical therapy can be helpful for that as well. Sometimes we use a brace as well. So if all of their pain is in the either side of their knee, potentially we can do a medial unloading brace to take some pressure specifically off that defect. So these are all things that are worth trying. Typically I would give at least a six or eight week course of it before trying any type of surgery. Injections are helpful as well. Now my personal philosophy for patients that don't have arthritis and it's just a defect, I really try to avoid corticosteroids. Now there is some research out there that suggests that corticosteroids, particularly repeated injections, can cause accelerated arthritis and cartilage wear. I think the jury is still out on that. And if the patient is really suffering from osteoarthritis, particularly advanced osteoarthritis and we're just trying to control pain, I think the cat's out of the bag a little bit at that point. So those are cases where I would do steroid. But if it's an 18 year old that's having some knee pain and swelling as a result of a cartilage defect, corticosteroid really is not my go-to because I think it could cause some damage and is unlikely to really fix the problem. However, the two injections that I will do in this situation are hyaluronic acid injections and PRP. So hyaluronic acid injections, otherwise known as gel or lubricant injections and some of the brand names will be synvisc, hyalgine, just to name a few. And I'm not supporting any of those brand names, but sometimes people will call it synvisc. But the hyaluronic acid injections, I have personally found to be very helpful for young patients with cartilage injuries. So oftentimes we'll help an athlete get through the season. And I would say anecdotally in that situation, it has been helpful. At least to give them a few months of pain relief and allow them to rehab. Platelet-rich plasma, I mean, that's a whole another talk on itself and itself. Some of you may have heard about that. It's considered a biological type of injection where we, in the office, we will do a peripheral blood draw typically just 15 or 20 CCs. There's a special centrifuge that we put the blood in and it separates out the different layers and we will take just the plasma and the platelets. And there's a lot, there are many and there are thousands of growth factors there. And to be honest, nobody's sure exactly how it works, but it tends to restart a healing process and if you inject into soft tissues, but it can have a lot, it can really help with inflammation in the knee. I am not saying that, to be clear, I'm not saying that we regrowth cartilage or anything like that and no one has ever proven that, but it can help with the pain and the swelling. And I have found that to be helpful as well in this population, although the downside to that treatment is it is out of pocket expense. So I found that both of those type of injections can be helpful in helping an athlete, particularly I've done it more often in college athletes to help them get through a season, especially if they're planning on a surgery at the end of the season. So the big question is what if none of that works? What if they're still having problems from this defect? What if the rest of their knee looks great on MRI, but they have a one centimeter area where the cartilage is damaged and they're 22 years old and they can't even run or work out. So that's when we start, once they've failed the nonoperative treatments, that's when we start talking to them about some of the surgeries that we can do. So really the indications are if you have a symptomatic defect. Again, like we talked about earlier, just really everything should make sense. So the defect should be where they're having pain. Like if it's, like I said before, if all their pain is at the patella but their defect is in the posterior knee, then that's not a great indication. If they have cartilage flaps and you can definitely see those on MRI or loose bodies, those tend to be particularly, cause the particular make them particularly symptomatic. So in those cases, I'll be a little bit more aggressive recommending surgery. Although I said the size doesn't necessarily correlate with symptoms. It does have some type of a factor on what we do surgically speaking. Cause some of the options will be more ideal for smaller lesions and some that you won't be able to do for the larger lesions. And then there are a lot of, there's a large gray area, let me put it that way for relative contraindications. Some of those would be malalignment, instability, not having enough meniscus in that area. With the thought that, let's say you have a pretty big cartilage defect of the medial femoral condyle and it's caused because you're missing all your meniscus there and you have an ACL tear. Well, going in there and just taking care of that cartilage defect is very, very unlikely to be successful cause it's still gonna have too much force because you don't have meniscus. So oftentimes in those cases though, we can do an ACL reconstruction, we can do a meniscus transplants and take care of the car as at the same time. So it's oftentimes you can address some of the other factors but you can't just look at the cartilage by itself. You need to look at the whole knee. A contraindication would also be osteoarthritis. Now, of course there is a gray area there if it's a younger patient with maybe some are early arthritis but like one or two areas that are really big. You know, we still may address that. Another would be bipolar lesions and that is where let's say femoral condyle and the patelle and the tibial plateau where they articulate if both sides are down to bone. Those tend and they're rubbing up against each other. Those tend to be less successful with all of these treatments. And then having a high BMI obviously puts more stress on that any kind of repair that you do that's more likely to fail. And also these because a cartilage restoration is a term we use for trying to regrow or transfer or heal cartilage. They require really to protecting it for a while. And if it's someone that is just not gonna be compliant or is unwilling to be non weight bearing afterwards then it's really not even worth doing because it's just not gonna be successful. And I put it quite smoking obviously can affect the healing of any part of the body and including the knee. On age is a relative contraindication. Historically, you know, decades ago some of these advanced cartilage surgeries were only done for patients under the age of 40 but since then some research has come out for having basically equal results for younger patients and carefully selected patients over the age of 40. So for most of us, age isn't really a contraindication. It's just more physiologically of what that knee looks like. Have you already started to go through osteoarthritic changes or not? So some of the surgical options which I'll discuss in some deeper more detail. One is just a simple debridement or a chondroplasty. One is a marrow stimulation, otherwise known as micro fracture which I'm sure everyone's heard about. Osteocondroautograph transfer, otherwise known as an oats where you take some cartilage from one area of the knee and move it to a damaged area. And then a version of that would be if we use cadaver tissue, if the damage area is too big, we can use an osteocondrolalographed. Autologous chondro-plant implant, chondrocyte implantation is where we take some of the cartilage out, we send it to a lab, grow it out, grow normal cartilage out from your own chondrocytes and then have a second surgery to implant it. And then there's a couple others that I will discuss as well. Now, I've been talking about the knee and in fact, most of the research that's been out there is for these cartilage defects in the knee and it's by far the most common. But I want to, these principles can be to apply to any joint in the body. They are doing a lot of these types of surgeries in the hip and ankle as well. Less commonly in the upper extremity, just because it's not weight bearing, but certainly we've done micro fractures in shoulders and it's been, these principles can be used elsewhere. So the decision making process about which one of these surgeries to do is complex. And if you talk to a hundred different orthopedic surgeons, you might get a hundred different answers. But there are some general trends and consensus among some of these different treatment options that I'll discuss. I think the biggest decision is deciding first whether to do surgery or not. And I think we've, as we've outlined earlier, but once you decided that you're gonna do surgery, then I talked to them a patient about, are we just gonna clean this up and do a chondroplasty or are we gonna do a bigger surgery to try to regrow the cartilage? And then from there, it depends on where it is in the knee, what kind of activity demands the patient has, how big is the defect? Is it six millimeters by six millimeters or is it 25 millimeters by 25 millimeters? Those are very different types of defects with different kinds of treatments involved. And also a surge in preference. Obviously you need to be comfortable with any of these options for it to be successful because some of them are quite technically demanding. I understand that I don't think anybody on this call is a surgeon, but I think a lot of you may have had some interest in this or have heard of some of these surgeries that are done. So I just wanted to give a brief overview and also some pictures just to show you what these surgeries are and how we do it. And it might help explain to patients as well. So as an overall, the cartilage restoration tends to work pretty well. It's very, very challenging to do research on this for a lot of reasons. First of all, it's not that common of a procedure. Secondly, it's hard to find two cartilage lesions that are exactly alike. They might be in different parts of the knee. You can't really compare a directly compare a lesion in the trochlea or the patella to one of the femoral condyle. They all have different sizes. The patients have different demands. Some patients might have been missing meniscus, some may not. So there's just so many factors that it's very challenging to follow. And also we have a really robust animal studies that are robust results in animal studies, mainly because we can actually do second surgeries or biopsies of the cartilage and look at that afterwards. And obviously for, you know, there are some studies in Asia back in the 90s or I think 2000s where they would do second look arthroscopies and just take a small biopsy. But that's not done in the United States. And it's, you know, for obvious reasons that's not commonly done. Despite all of that, about 870% of patients are pretty, have had significant improvements and are very happy with the results. And the results tend to last for 10 years or longer. Although the relative improvement tends to deteriorate with time for many of these techniques. But usually there's no right answer in that there's typically for a given defect there could be a couple options. And there are poison cons to each option what we're talking about. Overall, these kinds of treatments in the patellofamoral joint, that's the kneecap in its groove, tends to not work as well. And that's probably because there's a lot more shear forces with that, with the knee inflection and extension. And there's also a tremendous amount of load on that area. In fact, the patella has the thickest cartilage of anywhere in the body just because it has to from the amount of forces that are involved. So again, this is just the same picture that I showed earlier. So on the left is a nice young highland native cartilage that's not damaged. And on the right is damaged cartilage. So we're not able to... So in an ideal world, we'd be able to completely recreate what we have on the left. Now, a chondroplasty is another way of saying we're just going to clean up that cartilage lesion. So just having a flap in itself can be symptomatic. So I'll use that same analogy I had, I have a like a hangnail. So, you know, it can catch on your clothes, if you, and it can tear, get bigger, and it could just cause some problems. So often, if you just take out a nail clipper and trim that off and smooth it out, the rest of the nail, that usually solves the problem. And just like a hangnail, we can't get this to heal. So really just trimming it out and smoothing it out is how you treat it. And so if you look at the bottom left here, that's an example of ephemeral condyle cartilage flap. It's a partial thickness, didn't go down to bone. And then after I cleaned it out, we'll do that with a combination of a biter or a shaver. And you see on the right-hand side, this is a pretty small lesion, probably about five millimeters, but that no longer has that flap. And that patient actually did very well and that's all they needed. And even for the bigger lesions, this patient, the one on the right was actually a medical student that I treated years ago. And he, you know, he was 21 years old and had this very diffuse cartilage damage throughout the trochlea. And a lot of you may ask, why? Why did he get that? And I have the same question. He was just, he didn't play any, you know, college sports. He plays occasional, you know, pickup basketball. But there's definitely a lot of research coming out about cartilage genetics. Some people just tend to have heartier cartilage. And I will admit, I don't know why, but there are, I've definitely seen 50-year-olds that run five marathons a year that have perfect cartilage where other patients like this or even younger have their cartilage just seeming to fall off for lack of a better term. And I definitely think genetics plays a factor. But so this patient to the left, as big as that defect is, we decided as a first surgery just to clean it up, do a chondroplasty, and it's been years, and he actually is completely pain-free. So that's all we needed to do for him. So first of all, the advantages are it's a very quick and easy surgery. It typically takes 20 minutes or so. It's a very easy rehab. I let them put weight on it right away. Typically it's a four to six week full recovery to get back to all activities. It's inexpensive. You can do it at a surgery center. So there's a lot of attractive features of this type of surgery. Now you're still gonna have missing cartilage there. We're not attempting to regrow cartilage at all. But we're trying to see, hey, if we clean it up, get rid of that flap, is that gonna take care of the problem? Oftentimes it does. There was actually one of the more prominent cartilage surgeons in the country presented his research at a meeting a couple of years ago, showing that of all these big cartilage defects where he first step would be to clean it out and then they would say, all right, well, if you're having pain in the future, come back and we'll do the big surgery. Only 50% of the patients ended up needing another surgeon. So this can certainly work a good percentage at the time. And but what if it doesn't work, you know, or there are some patients that just want to have a more definitive surgery. And the goal of some of these surgeries is to try to regrow cartilage, try to move cartilage around or try to fill in that gap to give some protection and actually treat the problem. Well, one of the most common treatments that's been performed throughout the country over the past, sorry, throughout the world over the past couple of decades would be bone marrow stimulation, otherwise known as microfracture or drilling. So I'm sure many of you have heard of microfracture. And what that is, is we were going to clean out any kind of peach fuzz who are a little bit, whatever cartilage is left, get down to bone, make sure that the edges are nice and clean so that you really have a clean quote unquote pot hole. And then we use a mallet and alls to create a couple holes or small channels to the center of the bone. Now, why do we do that? Well, the access is the bone marrow. The bone marrow is actually very rich of healing factors. There's bone marrow derived stem cells which can differentiate into cartilage. So the theory is that you make these holes and that everything, and then I have a depiction here, we're gonna clean everything up, clean out the calcified cartilage layer, which is that last layer to get down to subcontral bone. We're gonna use a pick here that you can see at the bottom left corner to get down to the bone marrow. And we make really pretty small holes and we separate them out. And then if everything goes well, it's gonna, first of all, that pot hole is gonna, I seem to say in pot hole, I'm sorry, that's how I describe it to patients, that cartilage defect is gonna fill with the bone marrow contents and there's gonna be many regenerative factors, including stem cells in there that's gonna form a clot. And then over time, the hope is that it differentiates into cartilage. So you can do this with either microphone, the traditional microfractures you use in all like this, but more recently, we've been using drills. The thought is that the microfracture kind of compacts the bone edge and kind of it almost looks like the edge of a crater where you have a little area of raised bone on the sides of it. So a drill can help just make a cleaner channel, but no one's really proven that one is better than the other. Either way, it is a pretty tough rehabilitation afterwards. We are trying to get these stem cells to turn on that switch to become cartilage and not bone. So it's actually, the thought is that you wanna move that knee as much as possible so that the knee knows, so that those cells know that it's a joint, but you also don't, I mean, this is just gonna be a blood clot more or less at first. So you don't wanna be putting too much weight on it or any stress. So really for six to eight weeks, it's moving the knee as much as you can and keeping your weight off of it. And that's really important. These continuous passive motion devices, otherwise known as CPMs, you can see that in the bottom left corner here, that will actually move the knee for you. And the recommendation, the traditional recommendation was be aware of those for about six to eight hours at a time. And the thought is that that can stimulate chondrogenic differentiation. But this is a very slow healing process. To get that blood clot to turn into cartilage, that can take up to, that can take years and at the very minimum six months to a year till we let patients start running and doing certain higher impact activities. Now, as you can imagine, that's a much different rehab than just the chondroplasty that we mentioned. So that's why one of the reasons the chondroplasty as a first line treatment is often an attractive option for patients, especially when it works about 50% of the time, as I mentioned. But this certainly can be helpful. So advantages, it's easy to do. All you need is that mallet or drill. So if you're doing an arthroscopy and it's of maybe a bigger lesion or a deeper lesion than you think, you can always just easily just do that. And it takes about five, 10 minutes. It's inexpensive. You don't have to put in any implants. So it's an expensive type of treatment. And it's relatively speaking, it's fairly straightforward. And even people that don't specialize in sports medicine that have just done an orthopedic surgery or residency can do it. Of course, technique, proper technique is important, but those are some, but not very difficult. Some advantages, disadvantages are overall the outcomes are very good, especially the first two years, but the results and outcomes tend to deteriorate after two years. It's still better than what you were before surgery, but they do go down. The results are also not as good for bigger lesions. The initial descriptions before we had other options was up to four centimeters squared defect. Now that's a very large defect, four centimeters squared. That's the majority of the weight bearing surface. So I don't think there's hardly anyone that would really do a microfracture at that size anymore. In general, we try to keep it less than two centimeters squared, but in all reality, I think anything greater than 1.5 centimeters squared or so you're really probably better off doing some of the other cartilage restoration procedures. So the next one I'd like to talk about which also has a longer track record is osteochondral autograph transfer. I know that's a mouthful, we call it oats. That's what the technique got. That's what the set that we use is called, but that's what it's also been known to be referred as. And what it is quite simply is we take a piece of cartilage connected to the bone. We basically take a hollow core cylinder and we core it out from a part of the knee where you don't really put much weight on. And then we move that entire unit to the damaged area. So to the cartilage defect. So if you look at the right of our screen, you'll see the side view of that is gonna be what we call the donor plug. So we've taken this unit out. And the benefit is we have, this is basically the only treatment we have, we are using completely normal cartilage from that own patient. So that's gonna have that perfect histology that we found. It's gonna have a perfect connection to bone. It has nice healthy bone and we know bone, even though cartilage doesn't heal, bone likes to heal as we know. So bone will heal the bone. So if, and then we're gonna move that to an area that is concerning that that's a more important part of the knee versus basically a weight-bearing aspect. And I'm gonna come back to the slide in a sec, but we show you here, this is from the Arthrex website. This is the set that's commonly used. Again, I'm not endorsing any brand names at all. But this, if you look at the left part of the knee here, those holes there, those are areas where you don't really put any weight on. So when you're putting, standing, you're not putting any weight in that area. And it's more or less too far to the lateral side of the knee for the patella to put weight on. So that's an ideal place to take it. Now, and you can put multiple plugs into a bigger lesion as you see here, and that's called mosaicplasty, but in general, that's not really performed much anymore. But as you can see, the big downside is there's a limit, there's not, your knees weren't created with a lot of extra cartilage areas that aren't important. So you're kind of limited on size to about one centimeter. And that's really the maximum size. You can't take a couple plugs, but if it's a really big defect, you're not gonna have enough to take. But this is just a patient case example of, so bottom left, that is the cartilage defect. After we took, we cored out the bone and the cartilage. And so the right is after we've transplanted cartilage. So as you can see, that more or less looks like a normal cartilage right there. So this is one of my favorite cartilage procedures. Overall, it has excellent results. And this is the one area where we do have some good research where they did a randomized study where comparing oats to microfracture. And it had pretty significantly better results, better results with regards to pain and getting back to sport compared to microfracture. It also heals quicker. We don't have to slow them down as long and we can get them back to running quicker. So this is certainly an attractive option in the right patient. As I mentioned, I think I talked about all of these advantages, but you can have some pain from where you took it, the donor side, it's actually not that common. People do pretty well. I don't really, typically complain of pain there, but they can. And really the size is a big limitation. Now, if you have a really big area like this, then it's too big and you have to use an osteocondrol allograft. And that's where we take a cadaver knee and to basically do the same process. We have to send an MRI so they can match the size. But we do take, it is a fresh frozen cadaver bone with live controsight. So the downside is you only have about two weeks to get it in the knee. That can be logistically challenging. But here's an example. As you can see, a huge lesion. This is most that you just don't have enough of your own to take, but you can get a similar type of outcome if you use the cadaver tissue. The big disadvantage is very expensive. You might be waiting for months and then all of a sudden you get a phone call. Hey, you need a surgery with a long rehab in two weeks. So that's a downside. So all of those that I just mentioned are by far the most common that are done now. That probably represents about 80, 90% of the cartilage surgeries that are done out there. So some of the hot new things out on the market, I'll go over, but they have very limited data. So one is articulated at juvenile articular cartilage and that's where it comes from a juvenile donor with the thought that there is more healing potential and higher concentration of condro sites. Basically it's minced up, chopped up cartilage that you glue into the defect. So the downside is it only has a two week shelf life. So if you end up not using it, it can be a big cost to the hospital. It's very expensive. You need to order it ahead of time so you can't just decide to do that when you're in the OR and there's really limited data to support it. Another implant that I've used is a mesh cryopreserved articular cartilage. So instead of having to order a cadaver knee, this is a cryopreserved mesh, but it does have a condro sites and it is an articular cartilage. So it has a two year shelf life and you can implant that and usually we'll do that in addition to like a micro fracture. And so I'm getting a little late on time. So I'm gonna try to go quickly through this last section. And then ACI, this is not commonly done as much anymore, but used to be very popular. It's where you grow out cartilage into a sheet. So what you would do is two surgeries. The first surgery, you're in there, you might do a condroplasty and you take out a little piece of cartilage from an unimportant area. It goes to the lab, they grow out your condro sites. So you basically will be able to inject current condro sites and those are the cells that cartilage are made out of. The big downsize is it's not normal. You're not gonna have that normal zonal architecture of cartilage, it's just, it's gonna be disorganized. This is how you would do it. You would put on a membrane, you would sew it on and then you can see here is in the syringe you would inject the condro sites. And nowadays they have something called matrix or Macy which basically comes already, the cells are already in a scaffold that you just suture on. So the problem is this is very expensive. It's very expensive. It is two different surgeries. Okay, sorry about that. And it hasn't been shown to be any better than the other, any of the other treatments. So the final section, cartilage tissue engineering. This is just a show, I mean, I just Googled this yesterday and I Googled, it's PubMed and yesterday 15,000 results. So this is extremely hot topic. Being able to regrow cartilage is kind of the holy grail of orthopedic surgery in sports medicine. So the lots of current cartilage research especially using stem cells because they can turn into cartilage. So you can get that through adipose derives, the adipose derives stem cells that you find in fat can actually turn into cartilage, bone marrow derived. There's a lot of promising animal studies. But the problem is in the United States the FDA doesn't really limit to how we can manipulate and use these stem cells. So in other parts of the world, particularly Asia they're much more advanced than we are. And then tissue engineering is really gonna be the future here to be able to regrow the different zones and the specific try to recreate that highland cartilage. 3D printing is also a very exciting new direction. So the implant must be stable, cost effective, safe and be able to clear the FDA restrictions. I just wanted to show some of the research I've done with John Fisher who is the chair of bioengineering at College Park. And he's been 3D printing some of these scaffolds and he's figured out a way to attach certain molecules to the scaffold that can give healing and cause it to turn into more of a normal cartilage structure. So the study we did was using aggregate because it's a main proteoglycan component of native cartilage. We did surgery on 14 rabbits tested micro fracture with and without this bio functionalized cartilage as you see here on the right hand side it resulted in much thicker cartilage. I don't know if you can fully appreciate this in this side but on the top left is the healthy cartilage the micro fracture and some of the other treatments didn't work that well but in the top right with our new scaffold you're able to at least the best out of all these groups that regrowing some of the healthy cartilage. You can see it in these as well. So final thoughts, these are cartilage lesions are very common variable clinical presentation. There's a lot of it's more of an art treating these in the science. So we do whatever we can to give them symptomatic relief but if we have really identified that a certain cartilage defect is symptomatic there are some good treatment options. I would say good but not great. So we still all these options that I mentioned tend to wear out with time. Mainly because other than the oats that I talked about none of them are normal cartilage. So certainly I think tissue engineering offers some really exciting new opportunities. I'm continuing that line of research with Dr. Fisher. I'm trying to use a 3D printed scaffold that we can shape to that patient's specific defect. So again, thank you very much. Sorry if I didn't leave enough time for questions but I can certainly answer some before one o'clock and I'm happy to stay here a little bit longer as well. Here at the University of Maryland we've developed a huge center for sports medicine with a multi-blisciplinary team and not only a bunch of orthopedic surgeons but non-operative sports medicine specialists as well physiatrists, athletic trainers, physical therapists and we're in all different locations. So we're happy to work with you if you're for any patient, athlete or not. Thank you very much.