 We welcome you on this Sunday morning for the Indian Radiologist Journal Club. This is something which we were doing almost every month last year, where we used to take one article with relevant topic. And one of our experts used to review that article for the next one hour or so, to get into the details of those articles, include their experience into it and also show a few cases relevant about it. So continuing the same thing we have started the Journal Club this year as well and we'll have it every Sunday morning, which will be the first Sunday of every month and morning 10 to 11 a.m. And for this we have with us Dr. Chathali Parik and the article she is going to take is post-aromideal corner of the neglected corner. Dr. Chathali is a well-known speaker on, especially on Indian Radiologist Forum. Her videos are the ones which are like and subscribe the most. So she is one of the most popular speakers and we have been learning MSK with her. She is consultant radiologist for Pulse Chain of Diagnostic Centers and she has done her fellowship in Musculoskeletal Diagnostic and Intervention Radiology at Innovation Imaging Mumbai. She has received Dr. Aran Goyal Ghul Medal for best paper presentation on MSK interventions and she was also selected as one of the best speaker at RADAC speaker competition of radiology review course. So we welcome you Dr. Chathali and over to you. Thank you so much Dr. Mithusha for this wonderful introduction. Good morning to all of you. I hope my screen is visible. Yes. At the outset I would like to first thank the Indian Radiologist team and Dr. Mithusha for this wonderful invitation. I know this is a bright Sunday morning and most of you would be having better plans for the Sunday morning. So I would like to I will try to keep this session short and not extended too much. Without wasting any time, let's begin with the session which is the journal that we're going to discuss is predominantly concentrating on the posterior medial corner. Now, why I have mentioned it as a less discussed corner. First of all, we do not report a lot about the corners in our day to day routine life for the knee joint. So you've got a posterior lateral and a posterior medial corner. However, in recent times, there has been awareness of the posterior lateral corner and we are putting it in our reports which is helping the orthobots. But posterior medial corner is again something which we are not looking at all in our day to day practice that corner is also important for the orthobots for the stability of the knee. So we are going to today discuss about this corner. The article which we are predominantly concentrating on is the posterior medial corner of the knee, the neglected corner, which has been published in Radiographics in 2015 and written by Ryan Lindquist and Ital. Another similar article that we have is the posterior lateral and posterior medial corner injuries of the knee, which was published in MRI clinics of North America in 2014 and written by Daniel Gager and Ital. The reason I'm not predominantly or primarily discussing this article is because it covers both posterior lateral and posterior medial corner. So anyone who's interested in understanding both of these corners from the basics, this is a really good article. But for today, we are only concentrating on posterior medial corner of the knee. So posterior medial corner, before I start, what I'm going to do is first I'll be explaining the anatomy on the slides. Then I will be switching over to a normal anatomy scan. Then we will discuss about the posterior medial corner injuries again on the PPT slide. And then again, I'll switch back to the abnormal scan. So I'll be switching my screen between the PPT slide and the DICOM viewer so that we can look at the scans as well. So posterior medial corner has got five components. So we've got semi-membranosis and its expansions, posterior oblique ligament or the POL, oblique poplite ligament or the OPL, posterior medial joint capsule. And the fifth component is varying between the articles. So there is still a bit of research that has been going on about the components of the posterior medial corner. And the fifth component, some articles mentioned posterior horn of the medial meniscus, whereas some articles mentioned menisco tibial component of deep fibres of medial collateral ligament. Now, what do I mean by deep fibres of medial collateral ligament and what is the menisco tibial component? I'm just discussing this part of, sorry. So these are the four major components which we will be looking at. And since we won't be discussing medial collateral ligament too much later, so I might as well just show it to over here. So we all know that medial collateral ligament. So we've always been looking at this outer structure of the medial collateral ligament, which we very well see on the coronal images of MRI scan. The outer long linear structure, which is seen on a single image, those are actually the superficial fibres of medial collateral ligament. You also have the deeper fibres of medial collateral ligament, which is relatively shorter ligament. It has got two components. So it goes from the medial femur up to the medial meniscus, which is the menisco femoral component. And then it goes from the medial meniscus to the medial aspect of tibia, which is the menisco tibial component. So there is a deeper fiber of medial collateral ligament besides the routine superficial fibres of medial collateral ligament whose injuries we are reporting in day-to-day life. Now it has been said that the menisco tibial component of the deep fibres of medial collateral ligament is also one of the component of posterior medial corner. However, some article suggests that it is not a part of the posterior medial corner, but it is just one of the structures that supports the posterior medial corner. Okay, so what exactly is posterior medial corner to begin with? All the area that is extending posterior to the, so along the posterior margin of medial collateral ligament and the medial margin of posterior cruciate ligament. So the area that is spanning between these two margins is your posterior medial corner. Anteriorly, it goes up to the posterior medial menisco-capsular junction or the posterior horn of medial meniscus. Posteriorly, it goes up to the semi-membrinosus tendon. So from the posterior margin of MCL, along the posterior menisco-capsular junction or the posterior horn of medial menisco-caps, medially up to the medial margin of posterior cruciate ligament and posteriorly involving the semi-membrinosus tendon. So this entire area is my posterior medial corner. Now, again, we look at the diagrammatic image and along with that an axial PD image to understand the anatomy well. So here you can see that these are my superficial, so this is an axial image, an axial diagrammatic image. You can see the nice large meniscus, which is the medial meniscus. And here you can see that this is my medial collateral ligament. So these are actually nothing but the superficial fibres of medial collateral ligament. Just posterior to the superficial fibres of medial collateral ligament, you have your one component which is the posterior oblique ligament or the POL. Now, this POL goes posteriorly and this forms the posterior medial menisco-capsular junction. Further on, when you extend the posterior medial menisco-capsular junction laterally, what you get is your oblique poplite ligament. Behind your posterior medial capsule, what you have is your semi-membrinosus tendon. So these are the structures of your posterior medial corner. So coming on to the PD image, now you can see there is a nice black line that is going, sorry. So you can see there is a nice black line that is going over here. The anterior half of the black line is actually your superficial medial collateral ligament. And the posterior half of the black line is what is the posterior oblique ligament. So this is actually almost at the level of knee joint line where we are looking at the lower most part of the femoral contile. And so this is my posterior oblique ligament. As it goes inferiorly, it will join with the posterior medial capsule of the joint. And here further, there is a lateral expansion that goes from the capsule. This is your oblique poplite ligament. So this is my oblique poplite ligament. This is my posterior oblique ligament. And this is nothing but my MCL. Okay? So this is MCL. Now, here what you see, everybody is aware where to look for the Baker cyst. So what you have is the medial gastrocnemius tendon. And just anterior to it, this is the semi-membranous tendon. And this is where your Baker cyst is actually going to come out, right? So semi-membranous tendon is over here. And what you see, this is your posterior medial capsule. So once again, revising, semi-membranous tendon, posterior oblique ligament. So this is your POL. I'm really sorry. I'm very bad at this. This is my OPL. That is oblique poplite ligament. And this is my posterior medial capsule. So these are the major components of the, these are the major components of the posterior medial corner. And along with that, you can appreciate very well on the diagrammatic representation as well. Now, as you go one step inferior, you can see that this posterior oblique ligament is now actually merging with the posterior medial capsule. Okay? So this is how the posterior oblique ligament will merge with the capsule. This is the semi-membranous tendon. From the posterior medial capsule and the semi-membranous tendon, the structure that will arise is the oblique poplite ligament. Now, semi-membranous tendon itself has got five different insertions or five arms. What are those arms? The first one and the most important one is the direct or the principal arm, which attaches to the tubercle on the posterior medial tibial condy or in the groove just above the tubercle. Next, what you have is the anterior arm. Next is the capsular arm, inferior arm, and the oblique poplite ligament expansion. Now, of these, it is difficult to differentiate the direct arm from the anterior arm on MR images. Next, what we're going to look at is the posterior oblique ligament. As I've already mentioned, it is just posterior to the MCL origin arising from the adductor tubercle of femur. There are some variations in the origin of the POL, but it is more or less close to the adductor tubercle. It runs posterior inferiorly and attaches to the posterior medial capsule and the posterior horn of medial meniscus, just as we've shown before. So, again, just another diagrammatic presentation so that you can understand the POL very nicely. So, here, this is my MCL in black and this yellow dotted line, what you see, so this yellow dotted line is my POL. You can see the black dotted line is actually nothing but the capsule of the joint and the POL will eventually go and merge with the capsule of the joint on the posterior medial aspect, right? So, this is how it is going to go and merge with the capsule over here. And what you see over here, this is my semi-membranosis tendon. OPL arises from the capsular arm. So, I've already told you it arises from the semi-membranosis. So, it actually arises from the capsule or arm of the semi-membranosis tendon and its lateral expansion. It goes superlaterally and attaches to the fabula or the posterior lateral joint capsule or plantaris muscle. So, now, just let's go back and look at a normal anatomy scan. So, let's just look at the normal anatomy scan and understand the anatomy better. So, now, I hope my screen is visible to all of you. So, here what we see is this is an axial PD image, okay? I'll just take a sagittal fat-saturated image also. So, this is actually my medial femur, my medial tibia, my anterior and posterior horn of medial meniscus. And what you see over here, this is my posterior medial meniscocapsular junction area and the posterior medial corner area, right? Now, let's understand the anatomy so the coronal image will be more like a scout for you so you can understand at what level we are looking at. So, now, here, as we are going from cranial to caudal, okay, this is my medial femur and what you see, this structure over here, so you can see there is a nice black structure, a long black structure over here, okay? The anterior half of the long black structure is actually my medial collateral ligament. The posterior half of the long black structure is actually my posterior oblique ligament. So, this entire long black structure, you can just divide it into half. The anterior half is the medial collateral ligament, the posterior half is the posterior oblique ligament. Now, when you correlate on the coronal images, so what you see this entire structure, this is nothing but my superficial medial collateral ligament, okay? And as I go posteriorly, now what I see over here, this is not the MCL, it is actually the posterior oblique ligament. So, you can see this is my posterior oblique ligament, this is my posterior oblique ligament, this is my posterior oblique ligament, and now it will go and merge with the capsule in this region. So, as I go below, okay, you can see that how this posterior oblique ligament is nicely merging with my posterior capsule. So, this is my posterior medial joint capsule and it's nicely going and merging with the posterior medial joint capsule. Now, again, we go up, so here what we see is the, now let's look at the second component. So, this is my medial gastrocnemius and what you see over here, this is my semimembrinosis tendon. Now, again, as I'm going inferiorly, okay, before reaching up to the joint line. So, here if you'll see, we are still above the joint line, we're about almost a centimeter or so above the joint line. You can see that there is a small black structure that is separating out from the semimembrinosis tendon. Now, this is the capsular arm. So, this nice black structure which is going towards the capsule, this is the capsular arm of the semimembrinosis tendon and if you'll see, it will go and join the capsule in this region. Now, as you go inferiorly, okay, so this is my main tendon, this is my capsular arm. Now, as I go inferiorly, I've already told you that the anterior and the direct arm are not well differentiated on an MRI. But, let's try whatever we can make out. So, here, again, I'm going up, okay, at this level, so you can see this is my semimembrinosis muscle, myotendinous junction and this is the semimembrinosis tendon. Now, as I go over here, you can see there is a nice groove, okay. So, there is a tubercle over here and a nice groove over here and the tendon is going and attaching on the tubercle and the adjacent groove. Now, let's come down to this level. So, as we go from ancient, the two arms are there. So, this is all the rest of the arms and this is the capsular arm. As you go inferiorly, it actually forms a wider fan shape structure, okay, which goes in attaches like this. Now, of this fan shape structure, what you see, this is my this is my direct arm which goes and attaches into the tubercle. So, see, it's well nicely coinciding. So, this is my direct arm which is attaching to the tubercle and the adjacent groove. What you have is few fibers are going anteriorly. So, these are this is my anterior arm of the semimembrinosis tendon. So, my direct arm, okay, let me just label it so that you guys don't get confused. So, this is the direct arm. This is the anterior arm, okay. Now, as I go inferiorly, you can see there are few thin fibers which are extending inferiorly. These are actually difficult to appreciate but they go deep to the POL. So, this is my POL and the MCL and they go deep to it and they will attach just above the MCL region. So, there are thin fibers that go down and this is nothing but my inferior arm, right? So, again, we come come back up. Let me label this also, okay. So, this entire thing as we go back up this is my semimembrinosis tendon, okay. As you go inferiorly, you can see that an arm is coming out of the main semimembrinosis tendon going towards the capsule. So, this is my capsule around. As you go further anteriorly, the entire semimembrinosis tendon becomes like a fan shape structure. What the tendon that attaches onto the tibia posterior medially in the posterior medial tubercle and adjacent groove. This is my direct arm. Few fibers will go anteriorly and attach to the anterior aspect of tibia. In fact, these few fibers, what I'm talking about that go anteriorly are better seen on a coronal image. So, here you can see this nice or void black structure over here. So, this is nothing but my anterior arm. So, these structures that are going anteriorly is actually the anterior arm. Anterior arm normally has some hyper intense signal inside it because of the magic angle artifact. So, this should not be mistaken for a tendinosis or a tear. Similarly, because of the fan shaped attachment, you can see that there is some intrinsic linear hyper intense signal over here. You can very well appreciate that is again because of the fan shaped attachment and should not be mistaken as a tear and few fibers extend inferiorly and this becomes the inferior arm. So, now we have discussed POL, we have discussed semi-membrinosis tendon. Now, let's look at the OPL or the oblique popliteal ligament. So, this is my capsular arm. This is my posterior medial capsule. This is the posterior medial menisqua capsular junction and what you can see this black line going all the way circular line. This is nothing but your posterior horn of medial menisqua. So, this is the posterior medial junction or the capsule. Now, this structure that you see that is coming out like this, this black structure is which is actually nothing but going along the capsule like the thickening of the capsule. This is your OPL. Now, OPL actually traverses all the way to the top. So, it actually goes superolaterally and attaches somewhere to the posterior posterior lateral femoral or the adjacent fabula. Now because it is traversing from medial to the lateral aspect it is not only an important component for a posterior medial corner but it is also an important component and provides stability to the posterior lateral corner as well. So, this is my oblique popliteal ligament. So, we have discussed all the major components. So, again, revising quickly, we have going from top to bottom. What you see first is your posterior oblique ligament behind the MCL. As you go inferiorly, you begin to see the semimembrinosis. We have discussed all the arms of semimembrinosis. As you go inferiorly the posterior oblique ligament will join with the posterior medial junction or the posterior medial capsule. From the capsular arm and the posterior medial capsule, what arises is your oblique popliteal ligament. So, once we have discussed with the anatomy now let us just go back to the prapavapoint presentation and look at what is the importance of these structures and why are we actually reading them in the first place. So, what are the functions of posterior medial capsule? The first thing is let us discuss about semimembrinosis because semimembrinosis is the main dynamic so it is the main dynamic stabilizer of the posterior medial capsule. The rest of the stabilizers that is your ligaments, they are actually the static stabilizers whereas semimembrinosis being a tendon it is a dynamic stabilizer of the posterior medial corner. It causes internal rotation of TBR during flexion. Another important job is that it pulls out the posterior horn of medial meniscus during flexion and prevents its injury by compression between the medial femoral and TBR contact. So, if you would have noticed the direct and the anterior arm they actually go behind the posterior medial capsule and insert on to the TBR. Plus, it also has a capsule expansion. So, semimembrinosis tendon has got some insertions on to the posterior medial capsule. The posterior medial meniscus capsule junction in turn is attached to the posterior horn of medial meniscus. So, whenever there is a contraction of the semimembrinosis which happens during flexion of the knee, it will put a traction on the posterior horn and pull the posterior horn further peripherally so that it does not get squashed between the medial femur and medial TBR during flexion. That's how it prevents the posterior horn medial meniscus injuries during flexion. Now, what are the functions of the posterior medial corner as a whole? Now, PMC is actually taught in extension and lacks in flexion. We can see the PMC structures, in fact the posterior oblique ligament and everything very well because we perform the knee MRIs in extension position and they are actually taught in extension. It is an important stabilizer for valgus stress in extension. So, the important thing is that in extension it is an important valgus stress stabilizer. By valgus stress means what is valgus? Your distant limb is actually going away from the midline which means that whenever there is a valgus stress, in fact, even if you try to just put a valgus stress on your knee, there is a stress that is felt along the medial compartment of the knee joint. So, it actually stabilizes against the valgus stress so that the medial compartment does not open up whenever there is a stress on the medial side of the knee. It is lax inflection so per se it does not have or it does not provide a lot of stability in case of a flexed knee. Hence, MCL becomes the primary stabilizer of valgus stress inflection. So, in an extended knee besides MCL even your PMC is an important stabilizer for the valgus stress whereas in the flexed knee it is predominantly only MCL which is a primary stabilizer for the valgus stress. What is the use of this knowledge? Whenever there is a medial compartment knee pain what the orthopath is going to do is a valgus stress test or an abduction stress test. Now, this valgus stress test is nothing but the orthopath is going to apply a valgus and an abduction force on the knee joint. This is done at 0 and 30 degree flexion. If there is opening up of the knee joint which indicates that there is valgus instability in at 0 degrees it is because of the MCL at 30 degrees it is because of the MCL injury. So, as we know the inflection MCL forms the primary stabilizer of the valgus stress. So, in 30 degrees it is the MCL which is injured if there is a valgus instability if there is no valgus instability at 0 degrees which means in extension it indicates that your PMC is intact. But if there is a valgus instability even in extension it indicates that added to MCL even the PMC is injured. So, that is how you can differentiate between the valgus stress and abduction stress between the MCL and PMC injuries on the valgus stress test. I will just repeat this again. So, in valgus stress test you apply the valgus stress on the knee joint inflection that is 30 degree flexion and in extension. If in extension there is no instability it means that your PMC is intact. But if in extension there is valgus instability meaning there is opening up of the medial knee joint space on valgus stress it indicates that added to MCL there is also PMC or the posterior medial corner injury. Other functions of PMC is that it is a secondary stabilizer for anterior translation. So, obviously we all know the primary stabilizer is nothing but your anterior cruciate ligament. It acts as a secondary stabilizer for anterior translation so it can provide anterior stability in ACL deficient means. So, this is important most of the times whenever the ACL sorry, most of the times whenever the ACL is torn you will get anterior instability. Some patients however we found that they have found is even in ACL deficient needs there is not much of an anterior instability which is because the PMC is actually now acting as an important stabilizer and preventing excess of anterior translation. It also provides it also prevents excessive posterior translation and similarly hence it can provide posterior stability in posterior in ACL deficient needs. So, three important things it is an important stabilizer for the valgus stress particularly in extension. It is a secondary stabilizer for anterior translation and is useful to provide anterior stability in ACL deficient needs. It is also a stabilizer for posterior translation and can provide posterior stability in ACL deficient needs. So, this is what are the functions of the PMC. Now, so what is the bottom line? Why are we learning all of this stuff? This is because PMC injuries if not repaired can cause ACL or ACL graft failures. So, just like what you heard about posterior lateral coroner, why is posterior lateral coroner important to be addressed? Because if the patient is undergoing an ACL or a PCL reconstruction surgeries and if the posterior lateral coroner is not addressed there is a risk of graft failure in the future. Similarly, if the patient is undergoing ACL and PCL graft repair and the PMC injury is not addressed, it can result into graft failures. Because as we have seen it is a secondary stabilizer both for the anterior and posterior translation. Okay, so PMC injuries, isolated injuries are rare. So, isolated injuries are rare. What we usually get is PMC is injured with other ligaments like ACL, PCL and your MCL. Whenever there is a PMC injury it can result into chronic valgus instability in extension. For obvious reasons it is an important valgus stress stabilizer in extension. It can also cause another instability pattern which is called as the anterior medial rotatory instability. Okay, it sounds complex but it is not. What happens is, there is instability of the TBR so there is external rotation and anterior subluxation of TBR relative to the femur. If you can understand it is actually anterior so it prevents valgus stress and it also prevents excessive anterior translation. Now if the PMC is injured obviously the knee will start going outwards so there is the TBR will start going outwards so it goes into external rotation and there is obviously anterior translation will also happen so there is anterior subluxation of TBR relative to the femur. Patients who have symptomatic AMRI, they usually have both MCL and PMC injuries. So and patients with symptomatic AMRI will almost always have the POL component as injured. Other components are also injured but it is found that POL is almost always injured whenever patient has a symptomatic anterior medial rotatory instability. So as I have told you again AMRI is caused by injuries of both of these. Now what happens is why again this is important usually isolated MCL injury meaning nothing else is injured it's only the medial collateral ligament which is injured. These patients are usually treated conservatively but whenever there is simultaneous PMC injury there is increased chances of developing a symptomatic AMRI and hence these patients actually require surgical management. So this is again important only MCL injury is usually treated conservatively but the treatment changes to a surgical management if there is an associated PMC corner injury because there is increased chances of development of anterior medial rotatory instability and because of the development of AMRI there is some instability in the medial compartment of the joint and it eventually results into an early medial compartment OA. So this is again a take home point that why we need to address PMC injuries one is we've already discussed that if not repaired it can result into graft failures another thing so this is when the patient is undergoing surgery but we need to add something else in the surgery whereas the second point is where actually the plan was conservative but now the plan has become surgical because along with MCL there is a PMC injury and it can cause symptomatic AMRI. So eventually the patient's management will completely change from conservative to surgical. The next thing is similarly you have if there are isolated PCL injuries usually we treat them conservatively because PCL is known to heal very well or remodel very well but if there is a simultaneous PMC injury along with a PCL injury again a surgical management is considered or can be considered in this patient depending upon the clinical examination because these patients usually develop symptomatic AMRI and eventually they will have medial compartment OA. So third point, third important take home point is PCL plus PMC injuries again a surgical management can be considered. So these are the three major reasons that we need to address PMC injuries. Now let's just look at the cases so we are just going to look at a couple of examples of posterior medial corner injury ranging from low grade to high grade injuries so that all if we just get an idea that how exactly these injuries look like. Now most of the information regarding a posterior medial corner you will get on a surgical and actual image. First obviously we look at a fat saturated image so I am going from medial to lateral so basically the reason we look at the fat saturated image is to understand where all which all areas are showing injury. So the most medial most structure this is a very important thing which all of you should actually put a habit of looking at it. This gives a very good idea if there is any MCL and a PMC injury so if I will just put a coronal image over here so here you can see that this image is actually correlating along my MCL and posterior will be my PMC. So when you see a lot of soft tissue edema always go and look at the medial collateral ligament and the posterior oblique ligament in such patients. So here you can see that there is obviously some injury to the MCL and the POA. Now as we go further medially what we see is there is some edema so this is my posterior horn. This is my posterior medial joint capsule and the junction so there is some soft tissue edema in the posterior medial joint capsule and junction and as you go further medially or towards the midline what you see is that there is an ACL there in this patient. The PCL looks intact and then when we go laterally what you have is your posterior lateral compartment or sorry the lateral femurative compartment which we won't be discussing. So here you have so this patient on the first look has an ACL injury there is some soft tissue edema along the posterior medial corner and there is surely some injury of the medial collateral ligament and the posterior oblique ligament which is also a component of the posterior medial corner. So now let's just look at the axial images because most of these structures are well recognized on axial images. So here I have already told you what you see is a nice jet black line. The anterior black line is slightly thicker now the anterior half is your MCL the posterior half is your posterior oblique ligament. Now we have seen we have seen the normal images and it's actually pretty thin so this is how thin this is how thin it should be the posterior oblique ligament should be as thin as this. But here what you see is that it is thickened there is hyper intense signal within and also when I come over here I can see that there is a lot of soft tissue edema. So I know that at least there is some load to intermediate grade posterior oblique ligament injury obviously there is injury to the fibres of the medial collateral ligament with soft tissue edema. As you go inferiorly again you can see that there is some edema in the posterior medial junction or the posterior medial capsule. So here I can see that there is edema in the posterior medial capsule. So there is at least low grade injury of the posterior medial meniscus capsule junction the posterior horn of the medial meniscus looks pretty okay. And now let's look at the, I'll just get this out. So now let's look at the semi-membrinosus tendon so the semi-membrinosus tendon in fact looks pretty okay. So there is not much of an injury. This is, as I've told you, do not label this as a tear. This is nothing but the magic angle effect of the anterior arm of semi-membrinosus tendon. So the semi-membrinosus tendon looks okay. And finally what you see is your posterior, sorry, your obliquial ligament which also looks pretty much okay. Always go on the sagittal fat saturated images and look for any edema in this region. So there is not much of edema that is there okay. So in this region, this is my posterior oblique ligament and that there is not much of soft tissue edema here. So this is a pretty normal sorry, this is a pretty normal oblique peculiar ligament or the OPL. So coming down what all stuff this patient is having one is obviously the most important is that the patient has an proximal third ACL tear besides that the patient has low to intermediate grade injury of the posterior oblique ligament or the POL. There is some low grade injury of the posterior medial meniscocapsular junction with some soft tissue edema. So added to ACL injury this patient also has low to intermediate grade, sorry besides that this patient also has low grade medial collateral ligament injury at the femoral attachment. So you've got a full ACL tear, you've got a low grade femoral attachment MCL injury and you've got low to intermediate grade posterior medial corner injury particularly involving your POL and your posterior medial junction capsule. Okay, so this is the first scan, I hope all of you are clear with this. Let's go at the look at the second scan now. Okay, again we look at first only the fat saturated image to understand the structures that are injured. Now this, I'll just open a coronal so that you understand which will act like a scout for all of you. So just look at this image, okay, use this only for a scout. So here I'm coming from all the way from the periphery and look at the amount of soft tissue edema that is there. Okay, so we are this is the bone. So this is where my MCL and my POL is supposed to be located and you can see that there is a lot of soft tissue edema here. So I know that there is at least intermediate to high-grade injury of the MCL and POL. I can make that judgment just on this one image. Now as I go further immediately, sorry, further towards the midline, what I can see is that my posterior medial cap, meniscus capsular junction is also showing a lot of soft tissue edema. Okay, this is where my semi-membrinosis is inserting. There is some soft tissue edema in the semi-membrinosis direct arm insertion as well. So you can see this is my nice tubercle. This is a small groove. So this is the at least there is some low-grade injury of the semi-membrinosis and as I go here, you can see that even posterior to PCL where there is a some amount of soft tissue edema. So there is at least a low-grade OPL injury. Now besides that, the most important thing is that the patient has a PCL evulsion fracture with an intermediate-grade ligament injury itself and obviously there is a full thickness ACL tear. You can see the ligament fibres are flipped over here. So this I'll show you well on the PD image. So here you can see that there is a nice PCL evulsion fracture with an intermediate-grade PCL injury. There is really no fibres that is attaching. There are no anti-accruciate ligament fibres that are attaching at the femoral attachment. So it's a full-thickness ACL tear and you can see that the ligament fibres are actually flipped in the anterior intercondylar notch. Now let's look at the coronal images. So again, we are going from anterior to posterior. This is my MCL. You can see there is an injury here. In fact, there is a full-thickness tear of my superficial fibres of the MCL. So there is a full-thickness MCL tear. Now let's put the actual image so you can understand at what level we are looking at. So this is the site of injury. Now this is the entire MCL and POL. You can divide it into half. So this is my MCL. This is my POL. Now what I am looking at is the POL. And you can see that there is a high-grade tear of the POL as well. This is a high-grade tear of the POL. So this patient is actually not only having a near-full-thickness or in fact a full-thickness tear of the superficial MCL, but there is also a high-grade tear of the posterior oblique ligament. As you go down on the axial images, you can see that the posterior oblique ligament is injured here. Also the capsule is not looking good. So this is the menisco capsular junction. It is thickened. We have already seen that there is a lot of soft tissue edema in the menisco capsular junction. So there is an intermediate-grade posterior-medial menisco capsular junction. Injury on the axial images you can get magic-angle artifact here, but this is surely not a magic-angle artifact. We have already seen that this coincides to the injury. So there is a low-grade injury to the direct arm of the semi-membranosis tendon and along with that this is my capsular arm and this is my OPL. So here you can see that there is a low-grade injury of the OPL as well with a lot of soft tissue edema in that region. So here there is a lot of soft tissue edema. It's not a tear. It's just a low-grade injury of the OPL. So now summarizing, we have a full-thickness ACL tear at the femoral attachment. We have a PCL-evalgent fracture at the tibial attachment. We have a full-thickness proximal third-fibre stare of the superficial MCL. We have a high-grade tear of the POL. We have intermediate-grade injury of the posterior-medial menoscope capsule adjunction. We have low-grade injury of the direct arm of semi-membranosis and we have no-grade injury of the OPL. So it's practically involving all the components of your posterior-medial corner. So while putting in the impression, you not only have to mention about your ACL, PCL, and MCL injury but you also need to tell them that there is at least intermediate to high-grade posterior-medial corner injury. This patient will undergo an ACL graft repair may or may not undergo a PCL-evalgent fracture fixation but this patient will surely need an ACL graft repair and if the posterior-medial corner is not addressed, this patient can land up into a graft failure in the future. So this is how you need to correlate everything and put it together in your report. Now let's go for the third quiz quickly. Since now you've understood everything, I'll be just running a bit fast. So looking at the sagittal images again, the medial aspect, this is my MCL, this is my POL. You can see very nicely, this is my MCL, this is my POL. MCL is showing at least a low-grade injury. POL looks like an intermediate-grade injury at least on this one image. As I go further towards the midline there is a posterior-medial meniscocapsular junction injury. In fact, this patient also has a ramp lesion. So you can see that there is a discrete fluid signal in the posterior-medial meniscocapsular junction. So this is nothing but your nice ramp lesion. Okay. Your semi-membranosis over here looks okay. So not much of a semi-membranosis injury and as you go further towards the midline, the OPL also looks pretty much okay. So there is not much of soft tissue edema, so obviously not a intermediate or a high-grade OPL injury. Let's look at the axial images. So here, as I told you, the MCL is just going to be like a low-grade injury. If you look at the coronal images also, so what this nice black structure that you see going all the way through and through, this is your MCL. Okay. Now, if I go slightly posteriorly, you see a lot of injury over here. This is not your MCL. This is your posterior oblique ligament. So in fact, MCL is a low-grade injury but your posterior oblique ligament is intermediate to high-grade injury. So you can see the entire thickness of the fibres is involved. It is not a tear, but it is surely injured. It is almost three times the normal thickness. So MCL is a low-grade. POL is intermediate to high-grade injury. You also have posterior medial menoscope capsular junction injury along with ramp lesion. I am looking at the semi-membranosis. Already on sagittal, we have seen that it is normal. Even on axial images, we have seen that it is pretty normal. This is magic angle effect of the anterior arm. You can see the direct arm is pretty good and normal. And also your OPL looks okay. So it is mainly your that obviously this patient had an ACL tear. So to summarize, ACL tear, along with that you have a low-grade MCL injury but an intermediate to high-grade POL injury. Intermediate grade posterior medial menoscope capsular junction injury with posterior medial menoscope capsular junction tear which is your ramp lesion and your rest of the components of the PMC corner are good. So next, let's look at the next case. Again, we are looking at the sagittal FS images going from going from periphery inverse. Again, from the peripheral image I can identify that MCL is at least an intermediate grade injury and my POL is at least intermediate to high-grade injury. Now let's go towards the midline. So here obviously there is posterior medial corner injury okay. Besides when you go towards the midline, you can see that probably there is some low-grade injury of the semimembrinosis but not the tear or a high-grade injury, some low-grade injury of the semimembrinosis. There is obviously some intermediate grade injury of the OPL and besides that what this patient has is an avulsion fracture of the PCL. So this is a nice avulsion fracture of the PCL with a very low-grade injury to the ligament itself. ACL per se is not torn, may be a low-grade injury but surely not a tear. We'll confirm that on a surgical PD image. So actually the in fact the ACL looks pretty good. So ACL is not torn, low-grade PCL injury and a PCL avulsion fracture. Now with this let's look at your posterior medial corner on the axial images. So we've already pretty much diagnosed everything about the posterior medial corner. What we're going to do is just confirm our findings. I'll just open a coronal image along with this. So here now what we see is this is my MCL injury. So if you see now in this case I'll just first show you the coronal images. This is what is your superficial and deep fibers of MCL. So here this is my superficial fiber of MCL. There is intermediate grade injury at the femoral attachment of superficial fibers of MCL and what you see over here this is your deep fiber of MCL. So this is my medial meniscus ok? What is this? is your menisco terrorists .. this is my menisco femoral component going from the medial femur this is my menisco femoral component going all the way from the femur to the meniscous and this is my menisco tibial component going from the menisco to the tvia. So if you see that menisco tibial component is like in intermediate grade is in fact the full thickness tear. So this patient has about intermediate grade superficial MCL injury but a full thickness tear of the deeper fibers of the menisco femoral component. So this is the MCL now as we go. So this is my intermediate grade MCL intermediate to high grade because deeper fibers is actually a high grade injury and as you go posteriorly what you see this entire thing is your POL. So you can see the POL is actually a high grade injury. It is really thickened okay so nicely thickened POL and here also you can see a lot of soft tissue edema in it. So high grade POL injury and the rest what we've already discussed is your meniscocapsular junction injury with a ramp lesion. So here this is my so this is my meniscocapsular junction injury as I go further inferiorly okay. This is my capsular arm so this is my actually OPL. So you can see that there is a low grade injury to the OPL as well okay. This is also my OPL and there is some soft tissue edema in this region. So you can appreciate the soft tissue edema adjacent to the OPL. So it's like a low to intermediate grade OPL injury and as you go inferiorly you can see that there is some edema in the direct arm of the semimembranosis here you can appreciate it. So there is a low grade semimembranosis insertion injury as well. So this patient to summarize has a PCL avulsion fracture with a low grade PCL injury. This patient has intermediate to high grade MCL injury particularly involving the deeper fibers of the MCL intermediate to high grade POL injury along with that this patient also has a posterior medial meniscocapsular junction injury okay. Here you can see this and along with that a low grade semimembranosis injury and an OPL injury. So putting all of this together it is somewhere like an intermediate grade posterior medial corner injury because everything else is low grade except for POL which is a high grade injury. So it's putting all together it becomes an intermediate grade PMC corner injury. So again this patient will require as we've already told you this is a large PCL fracture so they may actually go and fix the PCL fracture because it's a huge fragment if they want to it is not slide it is not too much displaced. So again the management is between conservative versus surgical but if there is a lot of intermediate instability because intermediate root injury instability because this patient has an MCL tear which may require a repair and this patient has a PMC injury along with a PCL injury this patient may go for a surgery instead of a conservative management though your PCL evolution fracture is not displaced too much. Okay let's look at the last case now again from the peripheral aspect here you can see that my MCL is looking good so maybe it's a low grade injury because there is some soft tissue edema but POL is surely injured like a low to intermediate grade injury there is a lot of meniscal contusion so even the posterior horn of my medial meniscus is involved okay there is posterior medial junction injury which is like a low grade and what you see is that the semi-membranosis tendon is almost like an intermediate grade contusion. So again it's not a tear but it's more thickened so you can see that this is like an intermediate grade semi-membranosis tendon contusion and as you go over here may be a low grade OPL injury but not too much of an OPL injury. So further on what you can see is that your PCL is intact maybe a low grade at the TBL attachment but importantly there is an fragmented evolution fracture at the anterior cruciate ligament insertion. So here let's look on the axial images again so as I told you even on this image that MCL looks to be a low grade injury so you can see the fibers of the MCL are looking good is that there is a soft tissue edema around it so this is like a grade one injury or the sprain this is more of like a grade two injury where there is signal within the POL as well as there is thickening of the POL okay semi-membranosis as you go down you can see that there is edema within the direct head of the semi-membranosis and this is nothing but your intermediate grade semi-membranosis tendon contusion and over here you can see the OPL is not much injured so the OPL looks pretty okay right so this patient also has a intermediate grade posterior medial corner injury because there is an intermediate to high grade sorry there is an intermediate grade POL injury as well as a semi-membranosis tendon contusion so both static and dynamic stabilizers are actually injured in this patient. So this is how we need to put everything about the posterior medial corner in the reports you may not concentrate a lot on the low grade injuries of OPL and all but you need to really mention what is the status of the PMS of the POL and the semi-membranosis tendon and the posterior medial joint capsule this is really important to be put forth in the report and obviously as a whole the posterior medial corner what is the status of it we need to mention in the report. So now let's go back to the slides again for a last couple of slides so now there are mimics of posterior medial corner injury every edema in the posterior medial corner is not a posterior medial corner injury so please get a decent injury a decent history look for other ligament injuries because isolated PMC injuries are rare what can be the mimics of PMC corner injuries ruptured baker's cysts paramanical cysts pesansidine bursitis so here what you see is that there is a lot of soft tissue edema over here okay there is so you can see the whole posterior medial corner there is a lot of soft tissue edema in and around it but what you closely observe is there is some fluid over here okay and then you go on the next image you can see there is a small baker's cyst and it's actually nothing but a partially ruptured baker's cyst because of which there is a very baker's fluid leakage which is causing this reactionary soft tissue edema in the posterior medial menisco capsular junction so this is nothing but your partially ruptured baker's cyst next what we have is the another case where you can see that there is fluid and edema something like a cyst in the posterior medial menisco capsular junction again this is not a PMC injury if you closely observe this patient has a horizontal tear of the posterior horn of medial meniscus and this is nothing but the paramanical cyst third patient where there is a lot of soft tissue edema in the posterior medial menisco capsular junction but along with that there is a lot of fluid so if you'll see this is nothing but a pest tendons and there is a lot of fluid that is actually tracking along the pest tendons so this was nothing but pest answering bursitis when you go more towards the midline these are my pest tendons and what you see now there is not much of edema in the menisco capsular junction this fluid is nothing but the normal fluid in the posterior medial joint recess but otherwise there is no soft tissue edema in the posterior medial menisco capsular junction so this was nothing but a case of pest answering bursitis so the take home points is posterior medial corner is an important corner and its injury can change the management of the patient so we need to report them in our reports why it is important one thing is PMC injuries if not repaired can cause ACL or TCL graft failures if along with MCL isolated MCL injury there is also PMC injury it can cause symptomatic anterior medial rotatory instability and may require surgical management so again the management is going to change from conservative to surgical and along with PCL injury if there are PMC injuries the management may change from conservative to surgical PMC injuries again it is very important for us to report because we can see them on the MRI so we can really help the orthopods in their surgical or conservative management basically in their decision making we play a very important role so always look out for the posterior medial corner and make sure that you correlate well with other ligament injuries do not report any soft tissue edema in the posterior medial corner as a PMC injury isolated injuries are rare but if you see a multi-ligament injuries or if you see ACL injury or MCL injury please make sure that you've looked at the posterior medial corner along with your posterior natural corner and reported them in their report thank you thank you Dr. Chatali for this informative discussion and the way you explain made everything very clear and look easy for this very important corner of the knee there are few questions one is are ramp lesions limited to medial meniscus or can occur laterally as well no ramp is by definition it is a posterior medial meniscus capsular junction in fact we have discussed ramp lesion in the radiology journal club in previous year as well which was discussed by another speaker ramp is one to one and a half centimeter of the posterior medial meniscus capsular junction whenever there is a tear in that junction we call it as a ramp lesion on the posterior lateral aspect you do not have a proper meniscus capsular junction what you have is the popularity of meniscal fascicles and the ligament of wrist work so these provide stability to the posterior horn of lateral meniscus and what we develop in them is the wristburg rib tear on the lateral meniscus where the tear is present in the posterior horn along the ligament of wrist work and this is also seen in ACL injuries so ramp is posterior medial wristburg rib is posterior or posterior lateral meniscal tear okay and the next question is in what image in finding a knee MRI should we start suspecting the PMC injury apart from the graft failure of pre-op cases so all the ligament injuries that's what I've told you in the last slide all the ligament injuries are ACL your PCL your MCL injuries or multi-ligament injuries you need to look out for your posterior medial and posterior lateral columns right and this last question like low grade intermediate grade and high grade is it like low grade is spring intermediate is a partial tear and high grade is a complete tear is this a universal terminology basically kind of yes but we don't use it in the report okay what we use it as basically what you're saying is right low grade is g1 high grade intermediate is g2 and high grade is g3 but if you see a moderately thickened or I mean I've shown you a couple of images where the POL was very much thickened okay but you can't discreetly appreciate a tear but still that goes into a high grade injury okay so it is more on an eyeballing if you just see mild thickening of the ligament with perilligamentous edema that's a low grade injury if you see some thickening some intra substance hyper intense signal within the ligament and perilligamentous edema that's an intermediate grade injury partial thickness tear you always put it as an intermediate grade tear and you can give a percentage thickness that is involved which will give the orthopod a better idea like if it's less than 50% thickness or if it's more than 50% thickness so broadly speaking g1 g2 g3 is low grade intermediate grade high grade but high grade does not always mean a high that it has to be a complete tear there can even be a high grade injury where the ligament is really thickened a lot of hyper intense signal the fibers are mushy and you cannot identify them thank you Rokchadali once again for taking these doubts as well in detail so I think with this we can conclude today's journal club and it was really informative it will be shared on our youtube channel by Indian radiologist so you can revise these later on and make your reports even more importantly crisp for the referring physicians