Okay, we'll try to cover a one-hour topic here in 10 minutes. So I'd just like to thank other ROC members and the ROC leadership, as well as two mentors back at Boston Children's, all of whom have been instrumental in my and many of our understanding of this complex condition. So in terms of the treatment algorithm, one concept I'll try to pass on is that really it's quadrants of care. So there's stable and unstable and skeletally immature. So the non-operative treatment, the only place for non-operative treatment is really in that skeletally immature subgroup with activity modification, weight-bearing protection, and mobilization. There's not great agreement on what algorithm there for non-operative treatment. But we know 50% to 60% should heal, but that's a pretty high number that don't heal and then go on to surgery, which is OCD drilling, as the skeletally mature will do upon presentation. So we're really talking about the unstable OCDs, which actually have similar treatment principles between immature and mature. So regardless of age, though, one wants to be thoughtful about the growth plates. The second concept is really, this is a disease of subchondral bone first. So cartilage problems occur only secondarily to more advanced bony problems. So for the immature, you have a biologic problem in terms of unhealthy bone, but you don't have a mechanical problem until it progresses to instability, where it's bone and cartilage problem and it's both the macroarchitecture, so it's a mechanical and biologic problem. Deciding on instability is important. It can be tough to differentiate. So these review and imaging studies are important to understand the principles. We're all familiar with a breach in the fracture line. So that's the most common and sort of simplistic version of instability. But of course, there's a rim of fluid signal intensity, as well as breaks in the subchondral plate. And then cysts are important as well, both multiple cysts, which can be small, or a single cyst greater than five millimeters. All of these are signs of underlying instability from the MRI. And then we use arthroscopy to corroborate or definitively diagnose instability. Though it's important to differentiate mobility from stability, because instability comes from both MRI and arthroscopy. So our immobile lesions from our classification system are the cue ball shadow and wrinkle in the rug. There's some debate as to whether the wrinkle in the rug, which is a rare lesion, is unstable even if it's immobile. But we're really talking about the locked doors, trapped doors, and craters. Craters will have a hefty five loose body in the joint as well. So our technical treatment decisions really relate upon the approach, arthroscopic versus open. The debridement of the backside of the lesion in the bony bed. And then our choice of implants, metal versus bioabsorbable versus newer technology in terms of suture and suture anchor type fixation constructs. And then bone grafting. Where do we get it and what type of bone graft? There's a bunch of different implant constructs or fixation constructs, including even mosaic plasty and bone sticks to stabilize lesions. But really we're talking mostly about metal screws versus bioabsorbable implants. In terms of when to open the joint, I consider that the same question as when to do deep curatage. It really depends on the presentation of the lesion at the time of arthroscopy. So if it's a locked door, I feel the standard of care is in situ fixation and drilling. You'd have to do damage to the cartilage, which is really what you're trying to preserve to get to the backside of the lesion unless you use retroarticular techniques. And then a trap door, basically 100% of the time in my hands, gets an open deep curatage or burring and bone grafting plus drilling and fixation. However, a few years into practice, I discovered this isn't always an easy calculation because there are many things in between. So you can have fissures or openings in the lesion that are part of the lesion. And so I came to develop sort of an approach, which is 50% of the circumference of the lesion. If the cartilage is compromised, then I'm willing to take down a little bit more cartilage to get to the backside of lesion. Otherwise, I'm doing more damage than I want and I'm doing in situ fixation. But 50% of the circumference or greater, I think warrants an open approach and getting to that unhealthy bone on the backside. In terms of fixation implants, the bioabsorbable options come in bio screws, darts, and tacks. And then our metal screws can be headless compression or variable pitch screws in a variety of designs. The bioabsorbable, in a systematic review with Matt Malusky, we found that 11% of these cases will have unexpected surgeries needed from either synovitis or migration or breakage of these screws. Sometimes even well after it's healed, the shaft will reabsorb and the head will come loose and it really is just a quick arthroscopy or waiting on that patient for their synovitis to settle down. Here's an arthroscopic case of it hiding under the anterior horn of the meniscus. Submeniscal implants are very difficult to find. And so here's a case that we'll just show of a bioabsorbable implant fixation. We're assessing the lesion, the stability, and as well as trying to characterize is this a locked door or a trapped door. And we see there's really no breach in the cartilage. So we'll move towards in situ fixation here. Here's our cannula for a bioabsorbable tack. We'll drill and then feed the implant down the same cannula, compressing the lesion. And multiple implants were placed in this case. One tip with these or important trick is that many people put them into the cartilage almost like a button on a mattress. But if there's good subchondral bone beneath, you want that head buried well below the cartilage surface. And so part of the implant breakage and migration may come from people not putting it quite deep enough. You'll feel the difference in pitch when it engages the subchondral bone below, which enhances compression as well as minimizes the chance that the implants are going to be an issue. So here's a case of screw fixation. And this is a similar locked door case where we'll palpate the margins of the lesion, ensure there's no gross fissures or openings. There may be a bit of instability behind the insertion of the PCL or PCL synovium here, but we can't, along the articular surface, easily access the backside of the lesion. So I'm going to move towards fixation in this case. So here's a screw fixation example. I started with bioabsorbable implants and then was a participant in a healing study looking at a lot of metal implants, fixing these, and was impressed with the healing on some of those cases. So moved to metal and have actually moved back just because of some of the challenges of the removal cases. It can be very difficult. You can't get an MRI with the stainless steel reliably. Even the titanium screws give off enough artifact to not necessarily assess your healing well. And so despite the downsides of the bioabsorbable implants, I feel that the challenge in removing the screws, sometimes doing more damage than you wanted, are considerable. So here's six months later after screw removal with healing of his lesion. And so the key was changing his unstable lesion into a stable lesion and then stimulating it to heal with in situ drilling essentially. Here's a case of a trap door where clearly there's more than 50% of the circumference that has a breach. And so we'll try to get bone graft in there, but it's a tricky technical case because you don't really have access often on the side of the notch. So you choose superior or inferior or go through your other portal to get to the notch. That's autograft taken from the distal femoral metathesis and fixation of multiple bioabsorbable implants. What about when to convert to salvage or cartilage resurfacing, i.e. when is an unstable lesion unable to be fixed? Well, our mechanical threshold is really it should either be a hefty stage four or five, a trap door or a crater. And then our biologic threshold is really inadequate or negligible bone on the backside of lesion or cartilage that's inadequate or not worth saving, either macerated, frayed, fibrillated. So here's a case on the trochlea with multiple loose bodies and poor looking cartilage. So this really needs to move towards cartilage resurfacing. So I've debrided this, assessed for size in terms of oats and then a mosaicplasty to replace this cartilage on the lateral aspect of the lateral trochlear ridge and also realigned the patella slightly to offload that area. And then when to attempt questionable fixation. So when to try the Hail Mary. So Minn-Coker and Lau-McKelly have a study showing most of the hefty five lesions they fixed successfully healed. There's a little bit of sclerotic rounding of this more chronically loose body in the trochlea but debriding the backside. They unearthed some bone there and felt it was reasonable for fixation for this two by one centimeter lesion. So in terms of the best salvage or cartilage resurfacing options, oats may be the best for 20 by 10 millimeter or smaller lesions. We're not sure about donor site morbidity but I've had minimal issues with that. And if one is concerned about that, there may be a role for off the shelf osteochondroallograft plugs in your donor site if your recipient site is the priority. Macy is a good option for the larger lesions where you can't use oats. Maybe best for patellar and trochlear. Remember OCD is a bone problem first so most of these require the sandwich technique if you're going to go with Macy. And then if it's too deep, maybe that sandwich technique can't hold up and restore the, you know, the articular surface on a subchondral level. So osteochondroallograft may be the best for that. And there's significant subchondral bone involvement. The literature is somewhat limited but Bugbee has suggested a failure rate of 5 to 10 percent at five years. That may sound pretty good, 85 to 90 do well. But what happens when you have a failure that you've done on a 15 year old, so they're 20 years old, you've burned some real bridges by reaming their subchondral bone. Your only options really go into a larger OCA. Here's a case of an oats with a loose fragment and a more involved area on the lateral femoral condyle. So this was a two-plug construct that healed well on MRI. It's his own bone as well as restoration of his own cartilage with pretty minimal donor site morbidity. This is anterior to the meniscal zone, the weight bearing zone, and lateral to the zone. Here's a case of an OCA reamed out from a large lateral femoral condyle lesion. Here's a graph prep with the workstation and a pretty large lesion here inserted into the lateral femoral condyle with a CT scan suggesting good healing at six months. So in summary, know the signs of instability both on MRI as well as what to look for arthroscopically. Follow the principles of instability treatment, which is to stabilize an unstable lesion with your fixation choice. Stimulate healing on the deep level, usually transarticular, though retroarticular may be just fine. Curatage I'm in favor of with autologous bone grafting whenever there's access or an option to do that. But be realistic about when instability won't work. It's a bone and cartilage issue. So know the risks and benefits and try to be facile if you're going to treat these at a high volume with at least two of the three major resurfacing techniques, though many work. Thanks very much. Great.

osteochondritis dissecans

treatment algorithm

skeletally immature patients

instability

imaging studies