Thanks, everyone, and thanks, Mark, for his phenomenal work chairing an educational component of our research in OCD of the knee group. I have no disclosures. All my disclosures are on the AOS website. There's nothing directly relevant to this talk. I was fortunate to preside over the ROC group this past year. I just passed off the reins to Carl Nissen. I'll be discussing imaging findings for OCD, and we'll discuss, I think, in the interest of getting you practical information you can get to your practice tomorrow, we'll discuss some genetics in our discussion section at the end, if you like. I'll discuss a little pathophysiology just as an intro, and again, imaging assessment, and cases are interwoven within my talk. So certainly, the early descriptions, as you can see here, oscondrocysticans literally means osteo, meaning bone, chondro, meaning cartilage. Dissecans do dissect or separate. And this concept of parent and progeny bone is one that we came up with to say the progeny is like the kids, and the parents are like the larger area. How do we separate those things? That's just some nomenclature we came up with. And then, in the start of the pathophysiology, breakdown of the normal pathology of endocrinal ossification, and Yuta will get into that more, but just to discuss, we consider the growth plates as a longitudinal growth, but certainly there's a secondary ossification center, and that'll be a focus of where the pathology is and involvement. And the secondary ossification center, you can see, is shown in graphic format there, and the secondary growth plate, if you will. And so, how do we address these lesions? Radiographs can help in screening and diagnosis, look for effusion in loose bodies. MRI, you can see the things that we look for there. CT is not routinely used. Ultrasound, again, not routinely used. It's a limited sonographic window. We'd like to see if things are stable or unstable. The views radiographically, apilateral, notch, merchant, and sunrise view. I use merchant more commonly than sunrise. We like to determine skeletal maturity, and OCD can be subtle. With a small effusion, it's sometimes hard to see loose bodies. Our ROC group did a radiographic feature classification of knee OCD, 45 OCDs. We had seven orthopedists. You can see the reliability studies that we had done. We looked at size and location, this concept of progeny and parent bone, boundary and interface. And I'll just start, run efficiently through this. We look for fragmentation, two or more pieces of bone. Is there displacement, non-displaced, partially displaced, or fully displaced? We look for contour. Is it convex, linear, or concave? We look at the boundary at the interface. Is it indistinct, or is it distinct? We look at density of the progeny or unaffected bone. Is it less dense, the same, or more dense? MRI can help us. It can be more sensitive, and for cartilage changes, those things you see listed here, disadvantages, cost, and they sometimes need sedation. And you can see, obviously, the planes and the slices listed here. Some classic articles by DeSmet highlighted high signal deep to the OCD, articular fracture, cysts, and osteochondral defect. Another by Bruce et al., 33 knees, highlighted T2 high rim and T1 cartilage breach. Senior author DeSmet described 33 JOCD lesions. Some of the findings that we consider specific are this T2 fluid high rim, multiple circumferential cysts, and single cysts of over 5 millimeters, and you see those listed there. Our rock group, and you'd all discuss this more commonly, is looked more intensively at the secondary ossification, secondary growth plate, characterize more the locations, the depth, size relative to the size of the femur itself, and the coronal, sagittal, and axial planes. This is unpublished data, so this is cutting edge. These will be things you'll see published shortly. In terms of comparing that thicken when you get a crush of that secondary ossification center, the OCD lesion cartilage is thicker than the adjacent cartilage. Again, those same things we looked at contour for the plane films who look on MRI. Lower third image is breach in the cartilage, and this fourth is this omen sign that we describe, or high signal within the T1. Oreo cookie sign is this signal on the left where it's high signal, and two adjacent lower signals. The question is, is it fluid, or is that healing fibrovascular tissue? And then in the lower left, is it cyst, or small round cyst-like structures? Are they still filled with fluid or fibrous tissue? And then, so anyway, moving instead of using that cutting edge new, well, based on those established criteria, how does a clinician, and again, you'll get more involved, but how does a clinician use that? How can you use these features on Monday? So we look for craters. Classic example crater that's obvious there. Cartilage injury. So you can see loss and disruption of normal signal at the cartilage interface. This, again, fluid interface that we had discussed, this Oreo cookie shown on the right beneath the cartilage. And do we see cysts? They can be circumferential, or maybe single large cysts. We'd like to distinguish that from physiologic variants, okay? So we have here patient open growth plate, 10 years of age. You can see that cartilage is not thickened at all at that location. It's in the posterior third, no intercondylar extension, no marrow edema. So that's going to be our developing endocondral ossification front, so this false alarm that we see. And again, all these features are going to help us in our algorithm. So I'm not discussing management, just to say, these are the things that help us in our surgical decision making. So case, kind of, these are things that are interwoven. Swimmer, anterior knee pain, physical exam, no effusion, pain with single leg, hopping, medial femoral condyle, OCD, MR shows the cartilage is intact, radiographic presentation, you can see AP, notch, and lateral film. I should spend more time fly fishing, but I spend my time sometimes circling these little areas. And we see progeny, it's not fragmented, no displacement, normal contour, boundary. There's no significant boundary. And the parent is a little higher density. And again, same features there. We can see it, but it's not tremendously prominent. And so we're looking for these concerning signs. Is there no empty crater, no fluid interface, no cartilage injury, little tiny one millimeter cyst. So this is a patient, three months, treated conservatively there for three months, pain-free, six months, remained pain-free, radiographed or improved, and fully cleared back to activities two years later. So somebody who healed a classic OCD. Case two, a multi-sport athlete, anternate pain, limps at times when running. Physical exam pain over the medial femoral condyle, negative Wilson's test. Radiographs from an outside hospital, an MRI. Radiographs at presentation, you can see those are locations listed there. And again, no empty crater, no cartilage injury, no significant fluid interface that we described or cysts. Same features on the proton density image. And this patient at three months, no pain. So therefore, conservative measures. Six weeks later, three months, no pain with hopping, mild tenderness. Radiographs, we weren't happy with. So we said, let's go another six months. And the radiographs were improved, but not perfect. They were restricted. This is a long discussion back and forth. This was my non-operative sports medical specialist. I don't know that I would have, but they returned him back to sports. But at 11 months, intermittent pain with running. And you can see increased sclerosis at that lesion and increased distinct border. And on MRIs, however, no crater, no cartilage injury, fluid interface, or cyst. But the lesion was a little larger. Same features on their proton density image. Surgical intervention, therefore, the patient had no pain. And again, it was returned to one sport, football, but two weeks later, onset of pain. So therefore, at 14 months, had arthroscopy, medial frontal condyle, but for that classic intact lesion, had transarticular drilling. And again, I'm focused on the radiographic management, not conservative. Others will do that. Management at one month post-op. And then now you can see four months resolution. Radiographs showed near resolution of the OCD lesion. Return to full activities. And then again, third case, intermittent pain, no mechanical symptoms. Physical exam, relatively benign. Radiographs, MR. You can see the plain radiographs here at presentation. And I've circled those areas. However, this one does show cartilage injury and rather dramatic that you can see. And there's the T2 mapping, if you like those. I don't tend to use those. And because of that patient's knee buckling, it was brought in. Again, had frayed, friable cartilage. And it was less than one centimeter lesion, therefore, had a marrow stimulation. It was well contained. And our others will discuss other features of those. I'd like to thank you for your time. Happy to answer any questions. I'd like to thank our musculoskeletal radiologist, Ji Win. Matt Grady is our sports medical specialist. And I started the list. I had so many members, Mark and everyone here, and then other RAC members. So I just went back and said RAC group. So I'd like to thank all the members of the RAC group. And happy to answer any questions. Thank you for your time.

OCD of the knee group

imaging findings

radiographic feature classification

management approaches

OCD lesions