So today we are lucky enough to have Dr. Andy Getzen join us to give a talk. Just a quick little background on Dr. Getzen. So he's a sports medicine physician and the clinical director of sports med and the director of the shortness of breath in the athlete clinic out at Cayuga Medical Center in Ithaca, New York. He splits his time between Cayuga Medical Center and Ithaca College where he's been the team physician for the past 23 years. He's initially from New Jersey, went to school up in New Jersey, medical school up in New Jersey at Rutgers, did his family medicine residency at Brown in Rhode Island and then his sports medicine fellowship at Ohio State University. So today he's gonna be giving a talk on an atypical Baker's cyst and this is gonna be a little different this week. This is a prerecorded lecture. Dr. Getzen is traveling at the moment and is in an airport, which is a less than ideal place to give a presentation. So this is prerecorded. He is on the line or on the talk, I should say, and we'll try and stick around if he can for some questions at the end. But that'll be the plan here and we will get rolling here. Okay. Greetings. My name is Andrew Getzen. I'm the clinical director of sports medicine at Cuga Medical Center in Ithaca, New York. We're talking today about atypical Baker's cyst. Let me see now if I can begin by appropriately sharing my screen. Okay. Okay. And away we go. So I've watched pretty much every one of this year's talks in the AMSSM YouTube channel and just kudos to Ryan and Doug for putting together an amazing series. So impressed with the quality of the speakers and the talks. I just wanna thank Ryan for letting me record this talk. There was an excellent talk done last year by Dr. Blake Boggess. We found the AMSSM website. He talked about Baker's cyst. So I'm gonna kind of focus mine a little bit differently. There's also a nice review on how to scan that as part of the ultrasound series done by Dr. Madara Call. That's also on the AMSSM website. And in my talk, I'm gonna do a little bit of a deep dive into just a few topics since we already have that outlined so nicely. Okay. So as I have no financial disclosures and as some objectives by the end of this talk, I hope the attendee will be able to describe the different joint recesses of the knee. The viewer will hopefully be able to explain the character and location of Baker's cyst. They will be able to discuss the role of posterior knee ultrasound for DVT evaluation and finally be able to describe how to evaluate the PCL using a musculoskeletal ultrasound. So this case I'm gonna present is typical in what I see for posterior knee pain that comes to the office, but a little atypical. All the data points don't seem to line up and I'm kind of gonna use this as a vehicle to jump to talk about the posterior knee. So this patient presented with a chief complaint of I have swelling and pain in the back of my right knee and right lower leg for several weeks. And this was a 61-year-old type one diabetic female with initially right anterior knee pain. By the time she had seen me, her pain had moved to the posterior knee and lower leg. This began after she switched her workout routine with her personal trainer. This patient was systemically well. She denied any recent travel, injury or smoking history. She is a diabetic and her blood glucose was slightly elevated. When she developed the swelling, her primary care doctor sent her to the emergency room where she had a normal vascular ultrasound. Upon follow-up with her doctor prior to seeing me, the doctor placed her on cephalexin for possible cellulitis. When I saw her in the office, she was a well-appearing obese female. She was afebrile, blood pressure was just slightly high. Her BMI was 34.8. She was limping in the office and her right knee had quite a large effusion. It was not warm or tender and her range of motion was limited primarily by her effusion to about a hundred degrees of flexion. It was very clear the difference in girth in both calves. We measured them around the circumference of greatest diameter, greatest air, excuse me, greatest circumference. And the right was 50 centimeters and the left was 44. So the image from her vascular ultrasound done one week prior is shown right here. The, if I can get my arrow to point to it, there we go. It shows this patent femoral vein. This was done to sort of the mid thigh level. Then with a normal augmentation with calf squeeze is shown by the specular doctor waveform below. Also on this vascular ultrasound, there was this anechoic irregular shaped structure of popliteal fossa consistent with the Baker cyst. So when I saw her in my office, she had not had x-rays done. So I did some x-rays looking at her standing AP view or actually the left knee or unaffected knee was slightly worse than her affected right, but both show medial compartment osteoarthritis with joint space narrow and osteophytosis and cystic changes. So then I followed up with a lateral view, of course, as part of the series. And we see this, what appears to be gas in the popliteal fossa here. That's one of those uh-oh moments where I didn't think things played where it's exactly as planned. And she's here for a 20 minute appointment. And certainly we're seeing this, what certainly looks like gas, hard to imagine it being anything but gas. And the question is, where do we go? So of course, then we did an ultrasound. This is looking at her mid-sagittal longitudinal ultrasound with the patella showing in the right corner of our screen. And we can see that the suprapatella recess, which moves cephalad from the patella femoral articulation. We can see it's full, it's anechoic, full of fluid. We can see the quad tendon, which is superficial and anterior. We can see this quadricep fat pad. We then see this large femoral fat pad and then femur below. So of course, the next step into this is to assess it in short axis here. And it measures 5.2 down to 1.8 centimeters with heterogeneous for low level echoes here, the multiple foci. And this is in the, I should have said this is of course in the popliteal fossa after I have her flip over to prone. And this gas we should say is, I should say is new compared to the vascular ultrasound done on September 5th, 2020. So the next step is to put a needle in there. So we have to be see what this fluid looks like. And we can see this nice posterior reverberation artifact here. So differential diagnosis is, it looks certainly like septic arthritis is leading candidate, but osteoarthritis with loose bodies. Maybe it's just Lyme arthritis. It's endemic where I live in upstate New York, hematoma, parameniscal cyst. Let's jump right off to talk about the 2021 AMSSM Sports Ultrasound Curriculum and Fellowship on the posterior knee. This is put together by Derek Hall and colleagues. Really did a great job. I think it's a nice update from the 2015 list. In that list, they mentioned evaluating the popliteal fossa, but it was ambiguous what they meant by that. I felt like they meant to evaluate for Baker's cyst, which is the most common reason people come to my office for posterior knee pain. And this actually specifically listed, excuse me. Now, so it talks about the popliteal artery and vein, which we'll talk about the popliteal vein in detail. Talks about many of the tendons and membranosis, semitendinosus, bicep femoris, and down below the popliteus. Now, I don't tend to see a lot of injuries of those tendons, but I think we should be aware and identify how to evaluate them. Talk about the evaluation of Baker's cyst and interval between some membranosis and medial head of the gastroc, which is essential because if it does not come from that location, it is not a Baker's cyst. We should evaluate the sciatic, tibial, and common fibular nerves, posterior horn of both menisci, and then right near there, the posterior tibial femoral joint. And then we'll talk a little bit at depth about the PCL here. Now, I've highlighted it in red here, the structures that we're gonna focus a little bit on, popliteal artery and vein, evaluation of Baker's cyst, and PCL. We're also gonna talk about, as I'll sort of dive into, we'll talk about how to assess if there's a joint effusion. And I've learned by watching this series, I think it's essential. If you're, whatever joint you're evaluating, you need to know if there's an effusion. And so now whenever I look at the elbow, I first assess, is there a fusion? If I'm looking at the ankle, is there a fusion? That is the starting point. And when you look at knee, about effusion in any joint, of course, the fluid will follow the path of least resistance. And when you're looking at the knee, the five most prominent recess are this suprapatellar effusion, which we'll talk about is seen best, the fluid seen best in the knee flexed. There is the medial recess, the lateral recess, the popliteal tendon sheath, which is sort of like the long head of the bicep, in that if there's fluid in the joint, it'll track along that exit point. And then we'll talk in depth about the medial head of the gastroc, semimunosis bursa. This is, over here is my favorite illustration of Netter. I show this to a lot of my patients prior to knee injection to try to explain the concept that when we're putting any kind of medication into the joint, there's really an infinite number of places to enter the joint, anywhere where you're kind of perforating that bag or that balloon. So when they wonder why their pain is medially on their knee, and I'm injecting lateral, I think they get a better sense of that. Now, I think Netter slightly misses with this. He shows this suprapatellar bursa, he describes it, and then shows this suprapatellar fat body, which we might call the quadricep fat pad, which is actually pretty small. It's a pretty small hyperechoic triangle sitting, that's posterior to the quadricep tendon. He doesn't even identify this femoral fat pad, but as we know, we do a lot of ultrasound, but it's actually quite large structure, and certainly in relation, relative to the quadricep fat pad. So let's talk about, you know, how do you know where we should look? And Hahn performed a very nice study where they injected normal saline with contrast in increments of five, 10, 15, and 20 milliliters into the knee joint of eight fresh cadavers. And they looked at it in five different positions, where A was a lateral longitudinal position, B was a midline longitudinal position, C was a medial longitudinal position, D was a lateral transverse, and E was a medial transverse position. And then the incrementing, if we look at the figure to the diagram to the right here, you see it goes from zero, five, 10, 15, 20. And we can see pretty consistently throughout that the lateral longitudinal position, the lateral transverse position showed the greatest depth of fluid, followed secondarily by the lateral transverse position. So really that lateral aspect was the way to go. You can see a greater degree of hypochoic signal compared to the other three locations. And really you can see this as little as five cc's of fluid injected as we, and so again, that's the lateral. Now, if we look at the table one below, what we see here is that now we took the knee at 20 degrees of, it was 20 degrees, some 20 cc's of fluid, excuse me, at full extension and then flex at 30 degrees. And when that happened is essentially a lot of the fluid from there moved from the transverse recesses to the longitudinal recesses. So laterally things stayed about the same, but the midline and medial sagittal both increased and the lateral medial transverse both decreased. So essentially fluid again, moved from the medial to the lateral recesses. Now, this finding of increased fluidness for patellar recess with a knee flex at 30 degrees was supported nicely in a clinical study by Mandel where 18 different European rheumatologists reported on 148 knees. They measured the depth of effusion. And again, this is the three locations where the super patellar recess with the sagittal probe in the sagittal plane, then the lateral with the probe in the transverse plane shown above, and then the medial with, again, in the transverse plane and all of them with anywhere from 15 degrees of flexion to 60 degrees of flexion, that super patellar recess had the greatest depth and particularly was greatest at 30 degrees. So when we're looking at, you know, where should we measure the effusion? And the answer really is the knee should be in 30 degrees of flexion and looking at the super patellar recess sagittally, but it could also be measured in full extension. So sometimes if you're trying to find a different, if you don't see a lot of fluid, check in all planes. So I recommend checking, put the probe, maybe start with it in the midline sagittal plane or midline longitudinal plane, look at it also laterally and medially, then also with the knee extended, right? So looking at my patient, we can see a great deal amount of hypochoic fluid there. So let's flip over to the posterior knee, which is the bulk of this talk. And for position, you want the patient in full extension. This can be accomplished by a towel roll, like we see right here of the lower leg. If you use a pillow, maybe you can put it in the upper thigh, but you really want that. It's helpful to want that knee in full extension. Now, it can be a little uncomfortable if somebody has an injury or a knee pathology. And most of the time you can get by with a linear probe, but you might need a curvilinear probe for a larger patient or if you're looking either at the popliteus or the PCL. So evaluation at posterior knee begins at looking to see if there's fluid in the medial head of the gastroc, semimembranosus bursa. When there is fluid within that bursa, it's called a Baker cyst, named after William Baker, who realized going all the way back to the mid 1800s that these popliteal cysts resulted from fluid flowing out from a damaged knee. Now, the netter illustration here to the right shows that this junction occurs right here at the medial head of the gastroc and the semimembranosus with the semitendinosus on top. On the right where the medial head of the gastroc cut out, you can see here is the posterior aspect of the medial femoral condyle. So you know when you're looking at this for this bursa, you're going to see some of that condyle deep in your screen, in your image, excuse me. And then this is looking at my patient and we can see that here is her large, now I think I have an arrow here, maybe I don't. There's a large amount of fluid back here. Now you don't really know when you look at, by looking at this x-ray, does this fluid come from, is it a Baker's cyst or not? Because you need to see the exit point. Fluid can actually move posterior, it can move cephalad, it can move caudal, we don't really know. Well, these drawings from Lee in 2018 show the axial orientation of the origin of Baker's cyst and really what we should see in ultrasound. So this is the medial femoral condyle right here. And if you go just lateral to it, you're going to see this medial head of the gastroc, here is the semiembryonosis, which is medial to the, is medial to the medial head of the gastroc, you can see the cyst being formed. This is it sort of blown up on the right. Now I love this image, I might change a couple of things. This is the muscle, the medial head of the gastroc, the tendon forms in a sort of a C-shaped pattern on the most medial margin of that muscle. And this cyst tends to sort of have a concave appearance when it gets full, usually wrapping around laterally in the medial head of the gastroc and the tendon. Well, to get a better sense of what this bursa looks like structurally, here's a nice series of pictures by Lindgrom from Acta Radiology in 1977. He evaluated the bursa of 100 autopsy cases and they wound up dissecting 80 knees. Now, A is seen actually from within the knee, sort of looking out at the knee, at the posterior medial aspect of it. And you get a sense of this slit-like opening right here. In B, now you have this probe in the slit. C, this slit is viewed from above, so we're kind of looking down at it. Again, you can see this really teeny slit here. And then D is actually looking from behind and you can see actually the probe real subtly in the bursa right there. This little arrow will show that. Well, Lindgrom also performed histologic evaluations which helped to show why it's structurally more common to develop a Baker's cyst as we age. And this kind of image on top is sadly of a three-day-old that he dissected the knee. And you can see there's a strong fibroelastic cartilage layer here between J, the joint, and B, the bursa. We move down to this image on the left. We're now looking at an eight-year-old child and you can see this synovial membrane is thinner here than it is up and through here. Then this bottom right is looking at 65-year-old. And of course, there's very little, very structural separation here from this septum more than anything between the joint and the bursa. And I think, you know, if you wonder why 50% of people over 50 will have a Baker's cyst when you look at their knees radiographically. And part of it's structurally, and obviously part of it's because of more degenerative changes in the joint that might lead to a joint effusion and subsequent fluid moving back posterior. Well, to start scanning, you can scan from above. I like to begin my scanning from below, looking at the calf muscle. So I initially put the probe in short axis over the mid-calf and we can see the lateral head of the gastroc and the medial head of the gastroc and the soleus, it's a nice orientation point. We then slide the probe medially to center it over the medial head of the gastroc here. We'll then go ahead and slide the probe cranially. And you can see, as we sort of move up this, we're gonna look at the medial head of the gastroc, getting smaller, the muscle tendon forming this medial margin. We get going more, we'll see the posterior femoral condyle. Now, the semimembranosus, which is this large rounded tendon right here, the semitendinosus on top, it is out of plane from the medial head of the gastroc tendon. So this hypoechoic tendon right here, you need to tilt back and forth to go between back and forth and tend to ensure, so this is basically below just tilting back and forth. You can almost see them both in the same plane right now. And if I tilt a little as it's going here, we can see now here's this medial head of the gastroc, this is the semimembranosus, the medial head of the gastroc is forming right here. And they kind of fit together nicely, in my opinion, kind of like a jigsaw puzzle. So you should see them kind of laid together. Just, we can also see if we look right here really closely, we can see that the great vessel, the vessels, the palpiteal vessels sit much more lateral there, really in the center of the knee. Okay. And this is looking from above. So some people like to scan from above. You can actually, usually by the naked eye, see the semitendinosus tendon. So it might be a nice starting point to put your probe in that tendon before I run this sine loop. You can see the tendon sits up here, the semitendinosus, here's the larger semimembranosus as we get deeper into the more, it's going to be more caught onto the lower leg. Let's see, as it begins to go, as we move our way down, all this big muscle will ultimately become this tendon. We now see the femoral, posterior femoral condyle with the articular cartilage. You know how nice that tendon looks. Again, we can toggle back and forth there. Now, these Baker's cysts can have pathology quite similar to the knee joint. So these ultrasound images show this heterogeneous echogenicity consistent with synovitis, possibly right here. We see these hyperechoic pieces in the mix, this hypoechoic fluid, probably loose body sitting through here. While most of these cysts tend to be anechoic, they can be isoechoic or hypoechoic. I think that should trigger the thought of possibly of this being looking short axis and long axis as possibly blood in this, and this is a patient who did have blood in her Baker's cyst. And then these cysts, we should know these cysts can rupture. So the classic story is your patient's walking along and he or she suddenly has this sharp pain in the posterior leg, and then actually they feel somewhat relief after that. So it's important that this is scanned in the long axis from the most cephalad position, the most marginal, most caudal position. And when we see fluid that's extending posterior out of the confines of the cyst itself, we know it's ruptured. It almost always moves in that superficial or posterior to the medial head of the gastroc. And I think that you should know the extension of the Baker's cyst, so deep into the calf musculature, that's uncommon. If that happens, you need to be thinking about other causes. Now, Jacobson's group put together a study where they performed retrospective review of 36 consecutive needs, evaluating for possible Baker's cysts. And they were able to identify, and actually they looked at them with ultrasound and they compared them with MR. And they were able to identify all the 21 Baker's cysts on ultrasound that they saw on MR. But they also identified one perimeniscal cyst and one myxoid liposarcoma, and they thought those were Baker's cysts. But, and so I think it's real important, it's imperative when you're looking for this, that you find that cyst, that you find it right where it should be, which is between that medial head of the gastroc tendon and the semimerosus tendon. But if you look at this structure right here, which is seen on axial proton dense weight MR with FATSAT, that there's no extension of this large, which is in fact, this liposarcoma, no extension coming from this area right here. So that would be cause for further concern. Well, the next structure evaluates the popliteal vein. When people come to my office to post their knee pain, they almost always are concerned about having a blood clot and they almost always wind up having a Baker's cyst. Now, the popliteal vein is shown right through here in this netter illustration, a helpful mnemonic to remember, if you're thinking of the anatomy of where it lies is serve and volley next ball, where S is the semimembranosus or tendinosis, serve and is the artery, volley is the vein, N is for next, and ball is the bicep femoris, right? So serve and volley next ball. Now we know with ultrasound, we can always, of course, follow the structure back cranially, so we'll be able to know our cephalad, so we'll know where we're going. Now, this popliteal vein is formed by three veins that are distal to, it's formed by the, you can see on this posterior view of the right leg by the common femoral vein, by the posterior tibial and the anterior tibial, and they join together, the popliteal vein then ascends, cephalad and pass to the adductor hadis between the two insertions of the adductor magnus to become the femoral vein. Well, barring from POCUS 101, here's a card that shows how to evaluate the deep veins, the legs to exclude a DVT. They're showing the patients evaluated in the supine position with hip and external rotation, knee and slight flexion, they're showing the probe evaluating all of the veins, the veins are compressed till they completely occlude, so you don't see any vein left, and if you can completely compress that vein, you know there's no clot in the vein. The second row here shows deep venous thrombosis pathology, and the third row they show are basically false positives. Well, since clot propagates from distal to proximal, another option, instead of compressing all of the veins, using, but is to use two-point compression, we're just evaluating the popliteal vein and the femoral vein. Chris did a really nice study in 2010, where he basically took 10 minutes to show a group of 47 physicians, I can just find my pointer here, 47 physicians who did a meeting of two exams, they identified basically all 46 DVTs of 200 patients who presented them with possible DVT. Okay, so this is one of my favorite studies, this is a large study by Bernardi that was in JAMA 2018, they evaluated 2,465 patients that were referred to 14 ERs in Italy with suspected DVT, and they randomized them to two groups, one group was the typical venous ultrasound, where you compress every two centimeters through every vein, the second was two-point compression, where they looked at the popliteal vein, and they looked at the femoral vein. They then also, for the two-point compression, they did a D-dimer, and if both the popliteal vein and the femoral vein were devoid of clot, and the D-dimer was negative, they considered that they were done. If the D-dimer was positive, they then repeated two-point compression a week later, and then they follow up on all these people three months later, and they found essentially, they determined they were able to pick up the exact same number of clots, and the outcome was identical. Now, of course, it's a little more arduous, and there's a possibility of having to repeat an ultrasound, but most of the people that I see in my office with posterior knee pain, I wanna see them back in about two weeks anyway, so it really would not create an extra burden of an additional visit. Now, I'm not saying that all sports doctors should be doing two-point compression to rule out DVT, but if they're able to make their decisions based on their comfort level, I think there's certainly some data to support them being able to do it, and I would say that this Wells criteria, for those who are not familiar with it, it really is able to give you a pre-test probability by identifying particular predisposing factors that would increase the likelihood of somebody having a blood clot, so if you can use that as well, that might put you at a greater comfort level. So let's talk about looking at it. An ultrasound of the popliteal vein, you wanna put the probe, you wanna slide somewhat laterally since you've already just been looking at that medial head of the gastroc, some embryonosis, this is one of the few times where I'll hit the dual key in my ultrasound machine so I can have a side-by-side comparison, and I'll first measure the, I'll take an image in short axis, looking at the popliteal vein and the popliteal artery, I will then hit update, which jumps to the image to the right of the screen, and then apply compression to try to completely obliterate or completely compress that popliteal vein. If you can completely compress it, you know there's no clot there. How hard do you compress? You almost wanna have that vein itself compressed. Here's a video showing it. Excellent. So here, so you might need to have a little bit of knee flexion to increase venous return, and then this is sort of a little bigger view to show how you can completely compress that. So you know there's no clot there in that vein. Great. Looks like it's gonna happen twice. For the femoral vein, I flip people over, have them supine, now I usually do this at the end of my exams, not flipping people back and forth, and again, two-point compression with the vein shown, with the artery and vein shown, and now the vein's fully compressed. Next thing to look at is the popliteal artery. As you remember from Cervin-Volynek's ball, it's gonna be either medial or somewhat deep to the vein or somewhat basically anterior to the vein. You wanna be able to see it in long axis and in short axis. This is with Doppler applied, so you can see it pulsating. Here is it in long axis. Notice that the width is consistent against higher length. Now here is an aneurysm where the size of the diameter is 1.5 centimeter, with normal being 0.7 to 1.0. Here's another example of a popliteal artery. You can see how this anechoic or hypoechoic vessel is irregular in shape with fluid outside the margin of the artery. Here is it with Doppler above, and you can see to the right, in short axis again with Doppler, you can see that there is clearly a flow outside of the lumen here. Medial meniscus should be evaluated in short axis. It shows up quite nicely as this hypoechoic triangle between the posterior medial femoral condyle and the tibia, deep to the medial head of the gastroc. Should not see hypoechoic clefts or cysts such as this parameniscal cyst to the right. The lateral meniscus should also be evaluated. It's much more difficult because of the popliteous muscle going over the top. You might have to drop your depth of your probe here. Again, it's in the long axis looking at this. The last structure I'm gonna discuss in depth is the posterior cruciate ligament. This posterior cruciate ligament, this is looking at a netter image here. This is looking at it from below. Looking up at it here is the lateral femoral condyle and the origin of this PCL, the medial aspect lateral femoral condyle. It runs pretty much almost vertically. Now we're looking down at it in this image right here and attaches by itself the most posterior portion of the tibia, its own little shelf there. You can see in this view right here, it's just, the origin is just medial to the articular cartilage and runs almost straight up and down. I love this picture, this dissection by Allotamin. You can see the two bundles, the anterior medial and the posterior lateral. And the proximal portion is actually sort of perpendicular to where we are going to put the probe. So it's quite hard. Here's actually the probe coming in as close. So we're not really able to visualize that due to anisotropy. What we're gonna look at is the posterior half or two thirds even, where it sits on this nice shelf. You can see it slants down in posterior. And you can see that as it goes more caudal or more distal, that it's actually more posterior. You're gonna need to kind of toe in a little bit. Classic mechanism injury that we see is where the knee flexed and the PCLs is actually fully taught at that point in time. And anterior force is driven into the anterior, posterior force driven to the anterior tibia that then in turn pushes it backwards. It was a nice study, South Korean study by Cho and colleagues published in Radiology in 2001, where they evaluated ultrasound findings of normal and acutely torn PCLs. And what they found is that this is, they put the probe just in the similar position I just showed you. And this drawing shows it quite nicely. The ligament sitting on the shelf, they found three things. One is that the posterior border of this ligament between the ligament and this fat layer was heterogeneous and irregular as opposed to being sharp. That there was a heterogeneous echoes in the PCL. And the third thing is that the width of it was greater than one centimeter in the injured people. So the probe, where do you put the probe? It's parasagittal with the cephalad portion of the probe being slightly medial. You may need to toe in a little bit. Sometimes you gotta use a curvy linear probe. Here are a couple of PCLs with a linear probe. These are some of my nice volunteers who've got awesome calf muscles and not a lot of adiposity, so it's easier to see. Notice this PCL sitting on the shelf. It's even more crisp, this PCL right here is hypoechoic, quite thin and sitting right in that shelf. Now, this is the MRI of a college football defense lineman who fell on a flex knee. You can see this piece, I'm taking this T2 image that it's signal is heterogeneous and bright signal here. And this is a partial tear. Now I do wanna comment that he is a little more adiposity that is anterior or deepest PCL and we'll see that in his ultrasound next. So this ultrasound is not the easiest to see because I had to drop to a curvy linear probe because he's such a big guy. But if we look at the affected right knee, what we can see, you see this fat below, here's the PCL, but we also, excuse me, this is the tibia, I apologize. You see this wavy, wide PCL, somewhat heterogeneous echo, whereas opposed to the unaffected side, it's really quite crisp, right? The nice thing about most humans is you have that side to side comparison. Again, one of the advantages we have with ultrasound is you can just scan the other side. So I'm gonna just do a briefly comment. We should be able to look for the nerves, that sciatic nerve bifurcates with the common fibular or peroneal nerve that tracks laterally and superficially just medial to the biceps femoris to go quite superficial around the fibular head and dive back anteriorly below the peroneus longus. The tibial nerve then dives deep and follows the palpateal vessels. You can see them right here. I think I might've actually have videos right here. I do. Just for time, we'll let them run kind of rapidly through here. This is the sciatic nerve. You're gonna see the common fibular nerve break off here. For more detail about these, I do direct you to Dr. Blake Boggess' talk with this nice job. This follows around. We actually lose this classic honeycomb appearance when it gets real superficial right there, but we'll see it again as it begins to dive back down. This is the posterior femoral condyle. We'll see the fibula coming into view momentarily. You can see it there. Okay. And then it moves forward. This is the tibial nerve. We'll see as it breaks off. Notice that's gonna follow the vessels that can kind of lead you to know where it is, but that's quite deep. So you need to tilt your probe as you move down in it and follow it. But you want to see it in long and short axis. Muscles and tendons. I'm just gonna put one slot up here, but we should be able to see all these all the way down to insertion. And again, due to time, I'm not gonna go into it. Ultrasound report, patient access, study date, examination was the right posterior knee indication. You always want to have that, the right posterior knee pain and lower leg swelling. Put your comparison studies, the machine, the probe, you guys can read all this. And the findings were a large amount of fluid. Suprapatellar recess. Popatil cyst was measuring 5.2 times 1.8 centimeters. I apologize, it's in the axial plane with heterogeneous, low-level echoes and multiple foci of bright reflectors corresponding with evidence of gas in the cyst on radiographs. This gas was new compared with the September 5th, 2020 vascular ultrasound. It's actually increased in size. The popatil vein was fully compressed. The popatil artery was normal. Comment on all those muscles that we can see, the menisci and the normal, the sciatic tibial and perineal nerves. And the impression, constellation of findings are consistent with the presence of septic arthritis and based on findings of gas in the popatil cyst. Now, so let's jump back to the case here. So of course I put a needle into there to assess that fluid. It came out looking like clear joint fluid. Did not look particularly concerning to me. Gram stain showed a lot of white blood cell counts, but no organisms. I have a Sagittal View MRI, enhanced contrast MRI because my radiologist wanted to get one just to see could this be something that could, you know, to give us more information of something else going on. And we find this large, of course, this Baker cyst that had ruptured and subcutaneous edema, dyspnea, which certainly would account for the increased leg swelling. The fluid didn't grow anything out. It had no blood cultures at five days. MRSA and MRSS was negative based on PCR. There was no crystals. There was no organism of gram stain. There was no white blood cell count. Shift, no left shift. So she had, following her up, she had decreased swelling over a few days to weeks. I had her see an infectious disease who did not feel the knee was infected. So we had this one data point of this gas in the popatil fossa, which certainly for all indications, you have to think it's an infection, but she was well and she did, you know, certainly possible that the Keflex for a possible salivary saliva, but you can't imagine that's gonna cure a joint infection. So after we knew that, excuse me, the infectious disease, doctor did not feel there was infection. The patient felt comfortable to have a joint injection. So I put Triamcinolone, Marcane, and Lidocaine. Her knee really continued to get better. She turned to working on their trainer and she did not become systemically sick. So I appreciate your time. I'm sorry this was a little bit longer than the 30 minutes I was shooting for. I'm happy to share any of these articles with you. And if anyone wants, and I'm happy, hopefully I'll be there to listen to the Q&A at the back end as I'm driving to the airport with my daughter. Okay, thank you. All right, so great job, Andy. That was well done, super comprehensive. So thanks for doing that. I think you're still, yeah, you're still on. All right, I just have a couple of quick points to make for the sake of time and I'll let everybody get out of here. You know, Andy made a great point about starting his scan. You know, we have these protocols and I think they're helpful, but we really need to approach these patients with a clinical question and think about what we're scanning and why we're scanning it. So like Andy mentioned, you know, for almost any sonographic evaluation, I'm gonna start with the evaluation of the joint, even if this is, you know, a very clear-cut soft tissue, you know, potential pathology, I'll start with the joint. We can get a lot of information. You know, obviously we can't, you know, see much inter-articulately, but we can, you know, see synovitis or an infusion or loose bodies. And so we can get a lot of information from that. So I always start with the joint eval, just like Andy mentioned. And then the other comment to make, you know, not every mass, and I can't say this enough, not every mass in the popliteal fossa is a Baker's cyst. I can't tell you how many times I've had a patient, I probably get three or four a year, that's, you know, referred over for a quote-unquote Baker's cyst and has had three or four unsuccessful palpation-guided aspirations back there. And we take a look with ultrasound and it most certainly is not a Baker's cyst. And, you know, we've caught a couple of folks with various malignancies back here. And, you know, you have to really convince yourself that you see a stalk from that quote-unquote cyst coursing directly between media-headed gastroc and semi-membranosus before you stick a needle in there. And if you don't see that, you know, I would strongly encourage folks to not plunk a needle because bad things can live back there. Yeah, that's what I got. Let's see, if anybody else has any questions, just unmute yourself and yell at me. Otherwise, if not, let's see, I got a comment here. So Will Douglas says, thanks for a fantastic talk. Could you repeat the best resource for learning how to perform DVT studies? Andy, you wanna take that? Absolutely, so during my research, POCUS 101 was a website that I found very helpful. It had that card there. I think those articles were helpful. You know, the reality is, you know, we're back there. And as I said in my talk is that people come to see me and they're always worried about a blood clot. And just get used to, I would tell everyone has the skills, just get used to, every time you're looking at the posterior knee, just compress that papatial vein. It's not too challenging. And all you have to do is flip that patient over and get one of the femoral veins. Yeah, we don't have... I think you got cut off at that very last second, Andy. Oh, sorry about that, yeah. And then, you know, again, I think two-point compression is gonna be the way to go. And my suspicion is that this will become part of our future guidelines. It's such an easy thing to do. We're looking at that area. So I would encourage people go to POCUS 101. I think it's taught. I've never taken a point of paralysis on course, but I think it's taught in all of those courses. And I think it's taught in all of those courses. I think it's taught in all of those courses. So I think that's something maybe, and now we're adding the trauma section to our guidelines in 2021. So I think that we'll all be probably doing this going forward. Yeah, I agree with that. All right, well, thanks, Andy. Thanks everybody for joining. That was, like I said, very comprehensive, very well done. And I appreciate you recording that. I know you're probably about to take off here any minute, but thanks again. Quick housekeeping point to make, because of the holidays, again, we're gonna have a decent little break before the next talk. So we reconvene after the new year. So on January 7th, Dr. Ryan Hubbard is gonna give us a talk on a distal ulnar collateral ligament rupture. So with that, happy Friday, everybody. Have a great weekend, happy holidays, and we'll see you in 2022. Thanks again, Andy. Thanks everyone.

3rd Edition, CASE 31

3rd Edition

Knee

Baker's cyst

Dr. Andy Getzen

sports medicine

ultrasound diagnosis

posterior knee pathologies

DVT evaluation

knee pain

clinical protocols