Okay, so I'm going to give a presentation on avoiding errors and oversights and imaging of upper extremity trauma. Now, the objectives of radiologists, well, my objectives, not those that are assigned by administrators, but the first is to make a diagnosis, not just to write a report, but to make a diagnosis. I'm committed to that. The second, avoid embarrassment. Don't overlook anything that somebody else is going to point out to you because that's rather irritating. And third, stay out of court. I have yet to receive a subpoena that hasn't ruined the rest of the day. So these are my objectives when I'm interpreting radiographs. To prevent errors, you need to obtain the appropriate radiographs, know where to look, and know what you're likely to miss instead of just worrying about it because there's certain things that people do miss, and then look for it. Don't just sit there like the internist and gaze and think about lunch and expect to get better with time. You have to be focused on what you're doing. In appropriate radiographs, in general, without oblique views, you can miss eight plus or minus fractures, percent of fractures. So if you don't mind missing eight percent, then don't get the oblique views. But if you don't get them, then you should realize that there's a risk involved. So let's start with the hand. Here's the fractures of the condyles may be missed on PA and lateral views. And here's the case. And oblique views are required. And as you can see here, there's the fracture, which is clearly or not so clearly seen in the other projections. I love obliques, as you'll see. Now, ballplayer injuries. Bowler plate avulsion fractures and baseball mallet finger. Bowler plate avulsion fractures. The bowler plate is a thickened structure on the bowler surface of the joints, of the interphalangeal joints. It's firmly attached to the distal joint. And when you hyperextend, you can either fracture, avulsion fracture, as shown here, or just tear off the bowler plate itself. And here is a small avulsion. Now, here is a 12-year-old boy who hurt his finger playing ball. So you know already what you should be looking for. So you should be looking for bowler plate avulsions with such a history. And you look there, things look pretty good. Not seen on the PA lateral view. But bowler plate avulsions may be seen only on the oblique view. And here, you've got to look more closely. Unfortunately, we have ways to do that now. So you mag it, and now you can see this small bowler plate avulsion, which was not evident otherwise. Baseball mallet finger, stub finger, as shown here, flexing the distal interphalangeal joint, may result in an avulsion of the extensor tendon or a little fracture. You get a flexion deformity of the DIP joint, which is characteristic of this injury. But only 25% of the baseball fingers have an actual fracture. So while this is the classic appearance that one would see with flexion of the DIP joint, most of them won't have that. So they'll look like this, where there's no fracture here. So what are you thinking? Well, can you do that? Shake yourself and try and get there. You can't do that. If you can't do that, chances there's something wrong with it. And the fact is that in this case, it's abnormal. And there's an extensor tendon avulsion without a fracture. So, can you do this? That's pretty hard, I'd say. So what's this called? It's called a boutonniere deformity because the Frenchmen were in charge of orthopedics and rheumatology during the 19th century and named these things. So it was called that, a boutonniere deformity. And the reason for that is there's the lateral slips of the extensor tendon form here, and then there's a central slip that attaches, as you can see, on the middle phalanx, and it tears, and that allows the joint to flex between those two lateral slips there. So the joint then, over time, rises through the central slips and is flexed. So the deformity looks like that. Now, the clinical course of disease is insidious and onset, so you don't see it right away. Often overlooked at initial injury. Slow progression of deformity over time. It's shown here. A 42-year-old woman who had been injured five years previously. But, you know, procrastination is one thing, but today's the day, right? So she came in to see about this. And here's one injured three years previously. Obviously had good care because there was a phalangeal fracture, which had an open reduction, internal fixation. Now, adjacent injuries of digits often occur, and now you see the adjacent one. It's actually flexed here and clearly flexed here. And now we see it in the lateral view, and it's a boutonniere deformity, and there's the little fragment that was pulled off three years previously and overlooked at the time of the initial injury. The wrist. Examination of the wrist. I feel these four views are essential. You get a PA, a PA with ulnar deviation, a lateral, and an oblique with 45 degrees pronation. The PA with ulnar deviation is called the scaphoid view, and I think they're essential and should be obtained at the time of injury. Fractures of the waist of the scaphoid. Seventy percent of scaphoid fractures occur in the waist. The fractures of the waist may be only seen on the scaphoid view with ulnar deviation, so they're so common that the scaphoid view should be obtained routinely. So here's a 37-year-old man who fell off a roof, and now with ulnar deviation you see the fracture, which was barely perceptible in the other view, so you just get it routinely. Here's one where a woman fell on the outstretched hand and hardly see anything there, but you get the ulnar deviation view and the fracture becomes evident. So that's why I feel that you ought to get this view routinely in all carpal trauma. Here's one. Red is no evidence of fracture dislocation, but the scaphoid view was not obtained at that time. So two weeks later he was reexamined, and they did get an ulnar deviation view, and there it shows that, which is a widely displaced fracture. As you can see, oops, this should be avoided, obviously, and can be avoided if you get that view. The distal tubercle of the scaphoid is fractured 8 to 20% of scaphoid fractures. Distal tubercle on the palmar surface is on the palmar surface of the distal pole of the scaphoid, and in the PA view the tubercle underlies the distal pole of the scaphoid as shown here. In the oblique view it's seen in profile, and most distal pole fractures are avulsion fractures of the distal tubercle. So therefore you must have oblique view to see the tubercle fracture, and when you do you can see it here, which you can't see it on the other view. So here, young woman, clear, but you see there's the fracture shown in the oblique view on the distal tubercle. The proximal fractures are often difficult to see, and like that, what the devil. So now, if you see something like that, you should be seriously concerned about the presence of a fracture. So you get the MR, and then you can identify the fracture with certainty on the proximal view. And the proximal portion is shown here. This one, 18-year-old man, I read as negative. I read it. That was an osteoidium, so we'll forget that. Here's what I was looking at, because I'm so serious about this. And I thought, damn, maybe that's something. I don't know, Lee. Of course, I'm always looking for something. So I get into arguments with myself, just like you do. Should we obtain another view or do something differently? And unfortunately, I didn't. I just let it go. And then three months later, they came back for a CT and demonstrated that there was a proximal fracture. And so what I should have done is we should have done it at the time of the initial injury, but I talked myself out of it. You talk yourself out of most of those things rather than you talk yourself into them. That's a natural tendency. You should just order it and be done with it. What's the worst thing that could happen? It's normal, right? That's it. So there, it's better to see it than put somebody through three months of wondering what was wrong with their wrist. All right, and the elbow. Fracture of radiohead and neck accounts for 60% of fractures. You need 10 to 15 degrees of external oblique to identify subtle fractures of the radiohead. Here's a 25-year-old man, pain on supination and pronation of the forearm. If they have pain on supination and pronation of the forearm, they got a fracture of the radiohead. So there, the external oblique. Now you look and you can see the fracture, which is not evident on the PA view. So you really need that view. Now sometimes satisfaction is search. Here's a real fracture, a comminuted fracture of the radiohead. And what should that suggest? Well, a comminuted fracture of the radiohead is associated, maybe associated with an Essex lopresti fracture dislocation, which is a combination of a comminuted fracture of the radiohead with disruption of the distal radial ulnar joint. And we see the distal here. You can see there's the joints displaced, the ulna displaced posteriorly. And this is, of course, associated with tears of the interosseous membrane. It's an extensive injury. Now here's, well, there's a joint effusion. And there's a large piece of bone over the radius. But I can't tell where it's from. That's not a very good report, actually. People won't be too happy with that. So what is that? This is a classic injury. And you can see the radiohead real well, better than usual. And you see there's no joint surface here. And you can see that structure right there. So this is a rounded fragment over the radiohead, a loss of the articular joint surface of the capitellum. The capitellum is missing from articulating with the radiohead. This is, therefore, a fracture of the capitellum. And if you can put that down, fracture of the capitellum, they can go to Sergey Brin and Google it and find out how to take care of it. And, of course, the way to take care of it is this. But if you're dealing with people who aren't familiar with this injury, this could be a problem. So you can identify it with certainty. Now the shoulder. Anterior dislocations are common. Ninety-five percent of dislocations easily recognized. This one proved irreducible, so we obtained a CT. And there you can see in the CT that the humeral head is impaled on the glenoid, forming a Hill-Sacks defect. External rotation plus impaction. Then when you reduce it, this is before reduction. Actually, this is a case we were doing an arthrogram, and it dislocated during the arthrogram. And then we said, would you mind, sir, if we went to the CT and got a CT on this? And he was very kind, and we did that, and then we reduced it, then went about our study. So it's amazing what people are willing to let you do. So anyway, that was it. Anyway, so there's the Hill-Sack defect posterior and laterally at the level of the coracoid. Now, anterior dislocation. Again, the Hill-Sacks of the humeral head. You see it in external rotation. You see this line and a loss of the articular surface lateral to it. The normal, there should be no line, and the articular surface should be contiguous. So here is how that occurred. There. This was described by Pidlitz in the German literature in 1925, and clearly depicted here. Now, so I was always worried about these lines, and now this boy came in and tested me. I saw this in the internal rotation, a line. I said, what the devil? What have we got here? Well, that's the epiphysis. We know that. So there. So I say, seek ye with the eye of faith. You've got to believe. You have to believe. So I said, I think, don't let the fear of being wrong rob you of the joy of being right. So we did a CT on this kid, and here's what showed up. He has a Hill-Sachs lesion at the level of the coracoid, and more particularly, look at that large anterior fragment of the glenoid rim. So what happened here? Well, he had a transient anterior dislocation, which resulted in these injuries, but he relocated spontaneously. So that was an important observation and came about fine. Now, posterior dislocations. Uncommon, 4% of dislocations. First sign of seizure disorder. Common cause of malpractice suits. Diagnosis missed by the first observer in 40% to 60% of cases. So not to worry, because therefore it meets the standard of care. I wrote that, and I got letters from legal authorities about that. I shouldn't be saying that, but anyway. So there are three phases of posterior dislocation, as I know. One with a wide joint, all fixed in internal rotation, and the joint is wider than 6 millimeters, as you can see here. And then the second kind is with a trough line or a reverse heel sac, as we'll come to know about it, as shown here. And then the third is with fractures of or about the lesser tuberosity. So we'll go through them quickly here. Here's two fixed in internal rotation, and the CT demonstrates clearly the posterior dislocation. Now, this was a trough line. We wrote the paper, and I still hadn't thought of some clever thing to call it, and we ended up calling the line a trough line. And then after I gave a talk like this, somebody came up and said, Hey, Lee, you should have called that the liability line. Then nobody would have forgot about it. But I didn't. Now, on internal rotation of the normal head, you see there is no line. You shouldn't see any line. And if we look now, you see an anterior dislocation has this set of findings laterally, and posterior dislocation has a medial. They're sort of mirror images. So that's why you call one the heel sacs, and now we started to call the other the reverse heel sacs. And I think that will catch on. Okay, posterior oblique view is very helpful, and we used to get it routinely because we had missed some posterior dislocations, and this was a big help, and it showed us fractures of the anterior glenoid rim. Now, here's a person who came with a frozen shoulder. The posterior oblique view demonstrates overlap of the head and the glenoid. Well, that's obviously abnormal. I would hope most people would recognize that. And so then the CT was obtained, and it demonstrated the reverse heel sacs defect and the periosteal reaction from stripped periosteum attached to the labrum. So it had been of long standing, and it was a frozen shoulder because it just couldn't move. So here, plus fractures of lesser tuberosity as shown here, and here, internal rotation, wide joint, lesser tuberosity fracture. And so you do it this way, internal rotation, and you break it there, and it looks that way. But sometimes you break it with a bigger piece like that, and it looks more like this, which can be very confusing. And it tends to obscure the joint, so you can't see it so well. So this internal rotation, the joint is wide, and so this is a posterior dislocation with a large fracture in front of it. So we call that the osseous veil or shaggy rag sign of posterior dislocation. Now sometimes you have comminution, which is shown here, and you don't see the joint well, but you see other fractures about the humerus. And this indicates a complex fracture dislocation of the shoulder, fractures about the lesser tuberosity, the head of the humerus, and either the surgical neck of the humerus, which CT will show you quite well. And thus endeth the lesson. So, let's start, since we're talking about avulsion fractures this morning, with the definition of avulsion. A tearing away or forcible separation of attached or anchored tissue. Nobody knows what the prevalence is. I was given the knee to talk about, and in the knee, it's not an uncommon situation to encounter in evaluation, since there has been increased participation in sports by us old people, but remember that avulsions are not uncommon in adolescents also, because they have weak apophases and their ligaments and tendons are stronger than their ICS insertion sites. There are a bunch of different sites that the avulsions can occur from, ligaments, tendons, the joint capsule. I tried to count the number of sites in the knee that were available for avulsion injury. There are at least 18, probably more, that are at risk for avulsion injuries. Some of these injuries may look benign, and it is important to remember that they have significant pathology underlying these somewhat benign-looking fractures, and often the patients need consultations with orthopedic surgeons. There are a bunch of different ways to organize them. I'm not going to go through all of this. This is the way that I've organized these for the lecture. Capsular avulsions, ligamentous avulsions, and tendinous avulsions. The Sagan fracture is probably the best known of the avulsion fractures at the knee. It was first described by the French surgeon Paul Sagan in 1879. It is an avulsion of the lateral capsular ligament, the posterior fibers of the IT band, or the oblique fibers of the fibular collateral ligament, or a combination of these. It occurs two to five millimeters below the articular surface, and MR imaging should be performed to assess for ACL tears and medial meniscal tears. So here's an example of the Sagan fracture, pretty easily seen if you're looking for it. And then the coronal recon CT shows the small avulsion fracture and the donor site here in the lateral aspect of the tibia at the capsular insertion. Here's another one. They all look pretty much alike, and then on the MR done in this patient, you will see the minimal separation here of this avulsion fracture. An MR in another patient with a Sagan fracture shows the mid-substance ACL tear associated with it. ACL avulsion fractures of the tibial eminence are caused by forceful hyperextension or direct blows at the femur with the knee inflection. The fracture fragment may be subtle, but keep it in mind, particularly in young, adolescent athletic children. Associated abnormalities include, in 40% of the cases, meniscal collateral ligament and capsular injury and osteochondral fractures. Now the ligament is often intact, so no ACL graft is needed in these patients. The lateral image of an athlete injured in a soccer game shows a large effusion, and then if you look very closely, there's a triangular-shaped fragment here, donor site here in the anterior tibial eminence, representing the ACL avulsion fracture. Sometimes you can be lucky and get a slightly oblique lateral view, which puts that triangular-shaped fragment in better perspective for you, and it can be very difficult to see this on the frontal view, but here's an example of it here on the frontal radiograph. Sagittal recon CT showing that triangular-shaped avulsion injury with the donor site here, and then of course on the CT, that coronal evaluation, that fracture is going to be much better seen. Here's another example, sagittal T1-weighted MR showing the avulsion fracture. The ligament is intact, maybe a little bit of increased signal intensity within the ligament, and here on the coronal scan, you can see the minimally displaced avulsion fracture with the bone marrow edema, and these are the pivot-shift bone contusions of the lateral compartment. This is a soccer injury in a 28-year-old. This one is a little more subtle, but they all kind of look alike. Triangular-shaped fragment, donor site here, and on the sagittal MR, you can see the intact ligament with the extensive bone marrow edema here in the tibia with the minimally displaced avulsion fracture. The good thing about these, if there is a good thing, is that these are often treated with cannulated screw fixation. Here is diagrammatically what that looks like, and then here are two images, frontal and lateral views of the knees, showing a treated ACL avulsion. PCL avulsions are almost always at the posterior tibial insertion site, very rarely proximally. It's from a direct blow to the anterior tibia with the knee inflection, more common in motorcycle and automobile accidents, the dashboard injury, but can be seen with severe hyperextension in athletics. It's the most common isolated PCL lesion, and the physical exam sometimes has trouble detecting a posterior cruciate ligament injury. And again, often arthroscopic or open fixation is successful with a low complication rate. These are easy to see on the lateral view. They're a little easier to see than the ACL avulsions. Here is an avulsion fracture at the PCL insertion. Here is another one showing, again, a triangular-shaped fragment. Here it is on the sagittal reconstruction CT, showing that it's minimally displaced, at donor site being down here. And then on the frontal view, posteriorly, you can see this avulsion injury. Here is an MRI, sagittal T2 Fatsat MRI, showing the triangular-shaped avulsion fracture, intact PCL, donor site here in the posterior aspect of the tibia. And here on this coronal T2 Fatsat image, you can see the minimally displaced fracture here at the insertion of the PCL, representing the PCL avulsion. The good thing, again, is that with cannulated screws, these can be tacked down without needing a graft of any kind. Two different patients showing the post-surgical effects of that. MCL avulsion injuries are the most common knee ligament injury. Forty percent of all knee ligament injuries are MCL injuries, and it comprises eight percent of all athletic knee injuries. These are the highest-risk activities. The mechanism of injury is excessive valgus stress with a direct or a direct blow to the MCL. They can be at three different sites, and I'm going to discuss it in this order. First of all, let's look at the MCL anatomy. The MCL is a very thin structure, only about a centimeter and a half in width. This is on the gross specimen. The coronal specimen shows the origin and the insertion about five to seven centimeters down on the medial tibia of the MCL. And then on this gross specimen, you can see the deep fibers of the MCL, which are basically the meniscofemoral and meniscotibial ligaments, also called the coronary ligaments, and the superficial fibers here. Specifically demonstrated on this T1-weighted coronal MR study. An MCL sprain, of course, does not have the avulsion factor associated with it. This is a sprain. There's periligaminous edema. The ligament is intact. And here's another example of a partial tear of the proximal MCL with periligaminous edema. Again, the ligament is intact. Here's an example of what's been called the steata lesion. It's an MCL avulsion at the proximal origin of the medial collateral ligament. And when you get that, you get a significant amount of bone marrow edema, as in this case in another patient, showing the avulsion fracture here of the MCL with, again, the MCL sprain. Distally, the ligament can avulse, but that's uncommon. But this is an example of an MCL avulsion distally. You can see the serpiginous retracted MCL. And here's another one where the superficial fibers have been pulled away from the proximal femur, and then the deep fibers also are pulled away in this avulsion injury. When this happens, and often people aren't treated for this because it is a minimal injury, there can become ossification of the medial collateral ligament. This is called a Pellegrini steata lesion, named after an Italian surgeon, A. Pellegrini, and a German surgeon, A. Steata. So you can see the ossification here on the frontal radiograph, and this can be seen quite easily on the CT. On MR, this can be somewhat difficult. Here is an example of you can see the difference in signal intensity here in this Pellegrini steata calcification, as opposed to the ligament itself. And here is an almost completely ossified ligament from prior trauma, the Pellegrini steata lesion. The reverse Sagan fracture may be very subtle. It's an avulsion of those deep fibers of the MCL that I told you about, that generally occurs from external rotation with valgus stress, and it's more common in MVA injuries or knee dislocations, and less common in athletics. The MRI is needed for the commonly associated injuries, and I told you at the beginning that there are often other injuries besides these subtle fractures. Medial meniscal tears, PCL injuries, which can go from intrasubstance degeneration or partial tear to avulsion, and MCL disruption. So here's this tiny little, you know, looks pretty unremarkable fracture fragment here off the medial tibia in one patient. Here's another patient showing the reverse Sagan fracture. On the coronal proton density, or T1-weighted MR, you can see the avulsion fracture here at the deep fibers of the meniscal tibial ligament. And one more case, looking very similar to the other cases, showing the medial meniscal tear associated with this reverse Sagan, and the PCL avulsion fracture. So whenever you see this small little fracture fragment, it is important to do MR imaging. The extensor mechanism has a lot of avulsion injuries associated with it. We'll start with the superior patella avulsion fracture at the quadriceps insertion, usually from intense quadriceps contraction. Here is one that is minimally displaced and comminuted, and here's another one that is substantially displaced, and you can see the thickened quadriceps tendon above that. The inferior pole can also show avulsion fractures. This is two different patients. You can see the transverse, minimally displaced avulsion fracture at the origin of the patella tendon. Here's another one here, smaller fragment, with thickening of the patella tendon. On MR, it's a pretty easy diagnosis. You can see the minimally displaced oblique fracture of the inferior pole of the patella with increased signal intensity within the patella tendon, and here on this same patient, you can see the minimally displaced fracture itself with the avulsion and the thickening of the patella tendon. There's also bone marrow edema anteriorly. This could have been from an anterior direct blow. The patellar sleeve avulsion lesion is a form froust of this avulsion fracture, and it's from, again, sudden quadriceps contraction. There may be chondral or osteochondral lesions of the inferior pole. This occurs in younger patients, and it's important because this displaced fracture may actually, over time, form a second or duplicate patella. So here's an example of the patella sleeve lesion in two different patients, the plain film or the radiograph here showing it inferiorly. Looks like the non-displaced patella fractures that I've just shown you, but it's in a younger person, and you can see the fracture extends up anteriorly and obliquely here, and here's one on the MR imaging showing the fracture here of the – this oblique fracture of the inferior patella, the patella sleeve avulsion fracture on the T1 and T2 weighted images. Avulsion fractures can also occur in the tibial tubercle. They're uncommon. They're, again, most common in adolescence. Basketball is the most common sport that we see these in. The mechanism of injury, as you might imagine, is a violent knee flexion against a tight quadriceps contraction or a violent quadriceps contraction against a fixed foot. There is a classification system that I didn't actually know of until I put this talk together if you want to look up the Ogden classification system. These are easy diagnoses, right? The patient comes in with intense anterior knee pain, and you can see this avulsed tibial tubercle here in this patient that was injured in basketball, and this one was another, and I think this was a soccer injury that this person was injured in. CT shows this quite nicely. It doesn't add a whole lot to the diagnosis, and then MR imaging can show the edema associated with this and the slight widening of the anterior tibial tubercle interface with the anterior tibia here and here on the T1 weighted image. You may also get avulsion fractures of the medial patella facet, since we're talking about patella. Here is a sunrise view showing this avulsion fracture of the medial aspect of the patella, and in this same patient, you can see the fat fluid level here, the bone marrow edema in the medial patella facet, the sprain of the medial patellofemoral ligament or medial retinaculum, and the small avulsion fracture here. The way I notice these, and you can almost always notice them when you put up the images, if you see this huge bone contusion on the lateral femoral condyle, then you got to go look real hard for the bone marrow edema of the patella and potentially the avulsion fracture from transient patella dislocation relocation. Here's a more subtle fracture here, and then in this patient, you can see the bone marrow edema, the small avulsion fracture, and the sprain of the medial patellofemoral ligament or medial retinaculum. Chronic stress on the inferior pole of the patella, generally in adolescence, can result in Sending-Larsen-Johansson syndrome, which is a patella traction tendonitis. Here is an example of that. This is different than the acute avulsion, because this is usually from chronic pain, and you can see this small little ossification here on the inferior pole of the patella. Here is an ossification of the inferior pole that is healed to the inferior portion of the patella. And then this one had symptoms, and you can see the edema within Hoffa's fat pad, the small ossification here of the proximal patella tendon in these two patients with Sending-Larsen-Johansson. Now when the major stress is at the distal aspect of the patella, you get Osgood-Schlatter disease, which is from chronic repetitive stress or trauma, and this may be seen in adults also, and that is a fragmentation or ossification of the tibial tubercle and the distal patella tendon, as demonstrated in this case. It can be an acute finding. This is acute Osgood-Schlatter syndrome in an adolescent athlete. You can see the bone marrow edema here in the tibial tubercle, the edema in Hoffa's fat pad, and the thickening of the distal patella tendon. This is also seen here in another patient. This is two different patients, adults, showing Osgood-Schlatter disease. I just mentioned this as an incidental finding when I see it on adult radiographs, because generally the patients are not symptomatic with this disease in their later life. An avulsion fracture of the fibular head is also called the arcuate sign. It's an important indicator of posterolateral instability. There are three different ligaments that insert here. You can read those as well as I can say those, and the mechanism of injury is a direct blow to the anteromedial tibia with the knee inflection. Physical findings may be subtle, but this is important to recognize, because if not treated, then the ligament reconstruction, if there is an ACL tear, may fail because of the posterolateral instability. So here is an avulsion fracture here of the fibular head, the arcuate sign. And here is another patient with the MR features of that. Easier to see, a little bit easier to see on the MR, here's a minimal avulsion fracture here of the head of the fibula, which you can see here on the coronal T2 fat-saturated image with a little thickening of the fibular collateral ligament. Avulsion fractures of the iliotibial band are rare injuries. They're usually from a pure varus force, and they're usually associated, as many of these are, with other injury, especially ACL tears. Sometimes they can be easier to diagnose on MR imaging. I would have thought that this would have been an arcuate fracture or a fibular head fracture. But then when you do the MR in another patient with the same injury of a fracture, avulsion fracture of the iliotibial band, you can see this is at the insertion of the iliotibial band, although it looked like it was from the fibula. And here is another example of that, where the fragment is displaced pretty proximally. Here's the donor site for that fracture. Avulsion fractures of the semimembranosus tendon, the semimembranosus is part of the posterior medial corner, which is composed of, in addition to the semimembranosus tendon, the posterior joint capsule and the posterior oblique ligament. The insertion sites of this are the infraglenoid tubercle of the posterior medial tibia, the posterior joint capsule, and the posterior horn of the medial meniscus. It's most common in athletic injuries. There are three major mechanisms of injury, external rotation and abduction of the flexed knee varus force applied to the flexed knee valgus force to the tibia. And it is very difficult to diagnose, in fact, probably impossible to diagnose on radiography. You need MR to show that. And here is an example of the avulsion of the semimembranosus tendon posteriorly. The avulsion fracture of the biceps tendon is very uncommon. It's a disruption at the lateral collateral ligament. You can see a little fragment of bone here, which is better seen on the coronal MR study. You can see the avulsed fracture here. In summary, we have reviewed most of the common knee avulsion injuries encountered in clinical practice. There are at least 18 sites for these to occur in the knee. There might be more. Be on the lookout for these lesions, especially in the adolescent athlete. They originate from either the capsule, the tendon, or the ligamentous insertion site. They may be from acute or chronic stress, and it's important to diagnose because many of these lesions need an orthopedic surgeon for evaluation. And I'm just gonna go through these last two slides to say thank you very much for your attention. All right, thank you so much for coming. My name is Omar Awan. I'm a musculoskeletal radiologist at University of Maryland. I'm thrilled to be part of this panel here with some of the people that I look up to, like Dr. Rogers, Dr. Pope, Dr. Rosenberg. It's great to be here. So in terms of definition, so I wanna first start off with a question. We don't have audience response here, but maybe we can do just by a raise of hands here. So there's three statements here that appear in a report. I want you guys to tell me which one would be incorrect in the dictated report. So how many people think that A is an incorrect statement, evulsive injuries of the sartorius in a six-year-old male by a raise of hands? How many think that that may be an inappropriate statement? Okay, almost no one, okay. How about B, evidence of traumatic avulsion of the apophysis in a 17-year-old female? How many think that's, okay. And how about findings consistent with avulsion of the adductors in a 20-year-old male? Okay, how many didn't vote? Okay, that's the vast majority of you. Okay, all right, great. So it's actually A, and we'll talk a little bit about why this is not an appropriate statement. So in terms of an avulsion, I think Dr. Pope kind of explained this as well, but just to refresh you guys, an avulsion is really an injury of a tendon or a bone, or quite frankly, both, right? Where are they at the tendinous attachment? Okay, and it's usually due to a traumatic event from myotendinous contraction. Again, this image was taken from STAT-DX. The apophysis is an accessory ossification center that does not contribute to the length of a bone, okay? And apophysitis, which is sometimes used in, you know, in the pediatric literature is inflammation of the apophysis. The important thing to remember is, is that cartilaginous apophyses do not avulse, right? So until it becomes ossified, that's when they avulse, right, so when you say that a six-year-old is suffering an avulsive injury of an apophysis, that doesn't make sense, right? So please don't, if a six or five-year-old is presenting, that's not an avulsion injury, okay? So please remember that. Pelvic apophyses, in general, don't ossify until about 14 or 15 years of age. Now, there's obviously exceptions. In some people, it ossifies, you know, some of the apophyses are at the age of 12, 11, but certainly not at the age of five or six, right? And a lot of these apophyses don't fuse until the age of 25 years of age, okay? So that's an important point to remember when you're using the specific term avulsion, okay? That's very important. In general, pelvic fracture, avulsion fractures in children accounts for about 13 to 15% of fractures in children, okay? They're usually due to eccentric muscle contraction. So, you know, typically when I talk to my residents, I talk about, you know, doing, going to the gym and doing a bicep curl, right? So when you're curling, you know, when you're doing a curl, this is concentric muscle contraction, okay? That's not when avulsion injuries occur. Avulsion injuries occur during this phase, eccentric muscle contraction, when the muscle is lengthening, right? Because that makes the, you know, myotendous junction very vulnerable to injury as you're releasing the weight, right? You're lengthening the muscle there, right? So that's eccentric muscle contraction, okay? So now we're gonna talk a little bit about anatomy. This image was taken from the radiology assistant online. So in order to talk about avulsions, you have to know where the tendons are attaching, right? That's the key, that's the key. So, you know, the iliac crest, you know, a lot of the abdominal musculature, like, you know, the external oblique, internal oblique, transverse abdominis insert onto the iliac crest, the anterior superior iliac spine, that's where the sartorius and also the tensor fasciae latae insert. The direct head of the rectus femoris is where the anterior inferior iliac spine, that's where that inserts. The indirect head inserts actually on the supraacetabular region, or the indirect head of the rectus femoris. The gluteus medius and minimus insert onto the greater trochanter. So the medius inserts onto the posterior superior and the lateral facet of the greater trochanter. The gluteus minimus inserts onto the anterior facet of the greater trochanter. The iliopsoas inserts onto the lesser trochanter. And then you have hamstrings that insert onto the ischial tuberosity. By that I mean the medial head of the gastrocnemius. I don't know why I'm drawing a blank. So the hamstrings, excuse me, the semimembranosus, the semitendinosus, and the biceps femoris are the ones that insert onto the ischial tuberosity and the adductors insert onto the pubic symphysis. So now let's do a case-based review of the most common avulsion injuries. And this is question number two. So let's poll the audience here again. Let's try to do a little better on this question here. So what's the most common site of avulsion in the pediatric population when we're talking about the pelvis and the hip? So by a raise of hands, who thinks that it's the anterior superior iliac spine? So that would be the sartorius. Okay, so we have, I would say about 20% of the room thinks it's A. How about the anterior inferior iliac spine? So I'm talking about the rectus femoris. That's maybe 10% of the room. How about the ischial tuberosity, which is the hamstrings? Okay, so that's about 20% of the room as well. And I saw Dr. Pope raise his hand, and if he's raising his hand, it's probably correct. Okay, and then who thinks it's D, pubic symphysis? Okay, so yeah, and as Dr. Pope, you know, it's the ischial tuberosity. That's the most common avulsion injury in the pediatric population for the pelvis and the hip. So this is case one. This is a 16-year-old male runner who presents with pain in the buttock region and difficulty ambulating. Okay, and we see here that there's an ossific fragment here coming off of the ischial tuberosity. This is a classic look for what a hamstring avulsion would look like, okay? These are very common in sprinters, cheerleaders, dancers. It's usually, that's sort of how they occur. Typically, these are treated conservatively with normal return to activity in about two to three months. They really only require surgery if there's fibrous nonunion between the fragment and the donor bone, or if the fragment is displaced by more than about one to two centimeters. This is what a subacute hamstring avulsion looks like, and they can look a little scary, right? They can look a little scary because you get this, you know, ill-defined, you know, somewhat maturing heterotopic bone around the, around sort of the ischial tuberosity region. Okay, so this is what a subacute injury would look like, and this is what, you know, and this looks a little scary, too. It might be a tumor. It's not a tumor, it's not a tumor. So it's not a tumor, right? So this, it can be scary. So you gotta love Arnold Schwarzenegger, right? That's one of my favorite movies, right? It's great to see him acting, but this is just a chronic healed avulsion, right? Hamstring avulsion, right? So you have, you know, this, it almost looks like an exostosis, right? It almost looks like, simulates an osteochondroma, but it would be really rare to have an osteochondroma at the ischial tuberosity, right? So this is just, this represents a chronic healed avulsion of the ischial tuberosity here, okay? On an MRI in a different patient, this is what an avulsion would look like, an acute traumatic avulsion, where you have, you know, this is the ischial tuberosity. These are the hamstring tendons here, right? The semimembranosus, semitendinosus, biceps femoris, and you can see all this hyper-intense fluid, right? Which represents hematoma and retraction of the tendons that should be inserting here onto the ischial tuberosity. Okay, so that's an avulsion. This is what an ultrasound would look like, right? So an ultrasound. So this here is the ischial tuberosity, this hyper-echoic bone with posterior acoustic shadowing, and this structure here are the hamstring tendons. Notice that tendons on ultrasound appear hyper-echoic and fibrillar. And then all this anechoic foci here is the hemorrhage or the degree of tendon retraction from the bone to the retracted fibers of the tendon, okay? So this is what a hamstring avulsion would look like on an ultrasound. Moving on to question three. This is a 45-year-old with a chronic hamstring avulsion. You can see that heterotopic bone there adjacent to the ischial tuberosity. What would this patient be likely to develop? Would they be likely to develop CAM impingement, pincer impingement, ischiofemoral impingement, or piriformis syndrome? So how many think that the answer here is A, CAM type, FAI? Okay, no one, okay. How about pincer impingement? No one. How about ischiofemoral impingement? Okay, the majority of us think it's ischiofemoral, and you guys will be correct, very good. All right, so ischiofemoral impingement, because anything that's narrowing that space, right, between the lesser trochanter and the ischial tuberosity, right, may result in edema within the quadratus femoris muscle, right? And that's exactly what that fragment of bone was doing. Okay, moving on to case two. This is a 13-year-old female with pain after kickboxing. Notice that we have a fragment of bone that's been displaced sort of inferior laterally from the anterior inferior iliac spine. As you know, that's the site of the attachment for the direct head of the rectus femoris, okay? So that represents a straight head avulsion. This is another patient that also has the same thing. We have a fleck of bone adjacent to the anterior inferior iliac spine, because this is one of the rectus femoris avulsion. These are much less common than hamstring avulsions, okay? And they usually occur from forcible extension at the hip, typical in kickers, jumpers. Okay, that's usually the mechanism of injury. And these people return to athletic potential even sooner than hamstring avulsions, typically about five to six weeks, okay? This is what an MRI would look like in some of these patients. You'll have T2 hyperintensive meridema along the anterior inferior iliac spine, okay? You can have some edema at the tenonous attachment of the rectus femoris as well, okay? That's consistent with a rectus femoris avulsion. Moving on to case number three. This is a 63-year-old male presenting with left hip pain, okay? If you take a good look at this X-ray, you may notice that there is some model lucency around the lesser trochanter. There's no avulsion. There's no avulsion right now, but there is a little bit of model lucency around that lesser trochanter right there, okay? One year later, we do a CT, and there's a frank avulsive, avulsed fragment of bone from that lesser trochanter, okay? So the question I have for the group here is that what's the next best step in management here? What do you think is going on? Is this, would you do conservative measures? Would you do a malignancy workup? Would you do surgery? Or would you do a steroid injection? How many people by resume thinks that conservative measures would work in this case here, okay? How about malignancy workup for this patient, okay? Looks like at least 60% say that. How about surgery, okay? And how about a steroid injection? Okay, very good. So this is malignancy until proven otherwise, okay? Any iliopsoas avulsion is malignancy until proven. And in fact, this person has an aggressive lesion, right? There was marked model lucency at the lesser trochanter, right? Which should be a tip off for what's going on. So traumatic avulsions certainly do occur in young individuals at the iliopsoas. And those are not associated with malignancy, right? So they're possible, but they are rare. They can cause considerable amount of pain. But in an adult, an adult that's had no trauma, right? Atraumatic avulsions are malignant until proven otherwise, okay? They're malignant until proven otherwise. And I wanna take that a step further because all atraumatic avulsions in the pelvis and hip are malignant until proven otherwise. And that's a concept that, you know, I think even my residents don't completely understand because we all know that it's affiliated with the lesser trochanter and the iliopsoas. But for all the avulsions that I'm talking about today, in an adult, if there's no history of trauma, they should be considered malignant until proven otherwise. And some authors such as, you know, Dr. Bu Mansfield, Felix Chu, Leon Lenchik, who invited us to this talk, wrote about this in AJR in 2002, okay? Said that nearly all atraumatic avulsions in the pelvis and hip specifically, specifically in the pelvis and hip are malignant until proven otherwise. Again, I think that's a very important teaching point for this talk. Okay, this is just multiple MRI images showing an aggressive lesion through the intertrochanteric and subtrochanteric femur. Okay, notice the sunburst periosteal reaction associated with this lesion. Okay, look at the edema that this lesion is inciting, not only within the bone, but within the soft tissues. And you can see frank avulsion of that iliopsoas tendon that is retracted away from the lesser trochanter, okay? Okay, moving on to case number four. This is a 66-year-old female, status post-fall. Notice that we have an axial and we have coronal CT images through the femur. Notice that there's a common muted minimally displaced fracture involving the greater trochanter here. These are uncommon, okay? They're relatively uncommon injuries and they're usually traumatic in nature. And they're usually resulting in a result of sudden directional changes, sudden directional changes, okay? And obviously in children, tendonous avulsions are more common. In adults, osseous avulsions are more common, as you saw in the case that was presented here, okay? And again, if it's atraumatic, you always want to think about malignancy. You always want to think about malignancy. This was a traumatic case, okay? I work at Shock Trauma, which is one of the biggest trauma centers in the world. We see tons of traumatic injuries, okay? Gluteus medius avulsions does have a high association with lateral approach hip arthroplasty. So that's also been described. But when people do a lateral approach for their total hip arthroplasty, that can be associated with gluteus medius avulsion injuries along the posterior superior and the lateral facet of the greater trochanter. This is what a gluteus medius avulsion would look like on MRI. Notice that there's fluid and edema disruption of the gluteus medius tendon that's inserting right here along the lateral facet of the greater trochanter. This is another coronal image showing, you know, edema and minimal retraction of the tendon along the posterior superior facet of the greater trochanter right here. This is a chronic avulsion of the gluteus minimus that's inserting onto the anterior facet of the greater trochanter. Notice that you have a heterotopic piece of bone here along the distal aspect of the gluteus minimus tendon. Okay, this represents, and there's thickening of the tendon with some minimal, you know, faint edema. This represents a chronic avulsion of that gluteus minimus from prior trauma. Moving on to case five, we have a 15-year-old male basketball player who had pelvic pain after going up for a dunk. Okay, so a jumping injury. And notice here that we have a fleck of bone right here adjacent to the anterior superior iliac spine. Okay, that's where, that's the insertion site of the sartorius or the tensor fasciae latae. And just like avulsions of the anterior inferior iliac spine, right, you know, these injuries typically occur in people that are, you know, kicking or jumping. Pretty much forceful extension, forceful extension at the hip. Same mechanism of injury, okay? If we take a look at an MRI on a different patient, notice that there is, you know, frank edema at the insertion site of the anterior superior iliac spine where the sartorius is inserting. Okay, this represents an avulsion of the sartorius, okay, on these axial T2 fat site-weighted images, MRI images. And again, these are usually due to kicking, jumping, forceful extension at the hip, okay? Sometimes these avulsive fragments are hard to know where they're coming from because sometimes they can be displaced pretty significantly, okay? And sometimes a false profile view can help in those cases to figure out exactly where that fragment of bone is coming from. And typically these also heal quickly with conservative management. This is a chronic sartorius avulsion on MRI where you see a frank heterotopic bone that is T1 and T2 hyper intense from the bright marrow, okay? At the typical site of the sartorius tendon, okay, near the anterior superior iliac spine. Moving on to one of our last cases here, this is an 18-year-old football player with groin pain. Notice that we have rarefaction and lucency of bone around the left parasympathetial region, okay? This is the site where the adductor tendons insert. So, you know, the adductor magnus, longus brevis, gracilis, okay? Among others. So these are usually chronic injuries, okay? So, you know, pubic symphysis avulsions tend to be chronic from repetitive microtrauma. However, they can be acute. They can be acute, okay? So typically, especially in, you know, when there's forceful contraction against resistance or when there's a significant twisting injury, typically, you know, when people are playing soccer and two people are going and kicking the ball at the same time, that can result in this type of injury, acutely, okay? And the interesting thing to know about this is that bone fragments, as in this case, may not be seen in this type of injury, okay? There may just be rarefaction of the bone or relative lucency along the parasympathetial region. This is a great, this is one of my favorite MR images of all time. It's just such beautiful images here. So a 22-year-old soccer player with groin pain after forceful kicking. Notice that there's frank and significant and profound intramuscular edema within the rectus abdominis muscle right here, okay? You can see extensive edema within the adductor muscles. And you can see frank retraction of the tendon of the rectus abdominis, which is right here. This is where it's retracted to. And all of these adductor tendons, which all of which should be inserting right here onto the pubic symphysis, okay? You can see the coronal image here showing the sense of edema within the muscles. And then you can see, you know, the edema within the right rectus abdominis muscle here. Okay, this is known as athletic pubalgia, which we're gonna talk about in a second, okay? You can see here extensive edema within the adductor muscle group here with a tendon right here. You can actually see some edema here along the aponeurotic plate at the level of the pubic symphysis. And you can see extensive, you know, edema here along the adductors and the rectus abdominis muscle. Athletic pubalgia is really a clinical syndrome of midline groin pain that's related to athletics, okay? What happens is that the rectus abdominis and the adductor tendons share a common aponeurotic plate at the pubic symphysis, okay? It's sort of also known as a sports hernia. You may have heard that term before as well, a sports hernia, okay? So what happens is that they share a common aponeurotic plate and either of these muscles and tendons can be injured in this type of injury. Treatment is very variable. It can range from conservative measures or it can even be surgery depending on how much the tendons are displaced from the pubic symphysis, okay? This is sort of a nice cartoon from StatDx showing the common aponeurotic plate of both the rectus abdominis and the adductor tendons as they insert here onto the pubic symphysis, okay? This is an ultrasound image of the rectus abdominis muscles and notice that on ultrasound, a normal muscle like this left rectus abdominis should be nice hypoechoic with hypoechoic fibroadipostrands, okay? That's what the normal muscle looks like on ultrasound. But notice here you have some hypoechoic foci traversing through the muscle suggesting partial tearing of that muscle. This is a partial tear of that right rectus abdominis muscle, okay? This is what a chronic avulsion would look like. You can see heterotopic ossification adjacent to the pubic symphysis and anterior to it where the rectus abdominis muscle is coming in and inserting onto the pubic symphysis, okay? So this represents a chronic avulsion with well-cordicated ossific fragments adjacent to the pubic symphysis. Okay, so my take-home points for this lecture are please don't call avulsive fractures in the pelvis and hips specifically in people that are younger than 10 years old. That's not correct because the apophysis has not ossified. It's still cartilaginous at that state, okay? Evulsive injuries are typically due to eccentric muscle contraction or traction on the unfused apophysis, which is the weakest point which is very vulnerable to injury in children and remember in adults any Atraumatic avulsion so any when there's no history of trauma and you start to see Avulsion injuries in the pelvis and the hip always think about malignancy in that case. Okay. These are my references And thank you so much for your attention So I'm going to talk about Ankle and foot avulsion injuries. So when we talk about avulsion injuries typically they're related to inversion injury in the ankle and foot and When we talk about avulsion you may or may not have a fracture on radiographs, right? it may be without bone fragment and CT is the optimal modality of choice for showing those tiny little fracture fragments MRI on the other hand is very useful because it shows you marrow edema at the site of the avulsion and a lot of times That's the clue For you to look more carefully to see that there is an avulsion here The thing to remember is that MRI the edema is very minimal Compared to contusions and I'll show you examples in a second And the other thing to remember is when you have an avulsion fracture with a bony fragment It's usually more painful and it takes longer time to heal than if it is without it so just to emphasize the point about avulsions versus other injuries Such as contusion or fracture so with avulsion you have minimal marrow edema And that is at the ligament tendon attachment while contusions is a large amount of edema and site of impaction So here we have an example This is a tear of the anterior tibiofibular ligament at this level here And we see that there is some marrow edema, but not a lot of marrow edema compared to this person who had an inversion injury with contusions along the medial aspect of the ankle and you have a lot of marrow edema in the medial Malalus in the talus and even in the sustentaculum tali So this is just something to remember Another example of the same thing you have a fracture here of the medial malalus actually with a patient with a menstrual nerve injury And you could see the marked marrow edema at the medial malalus as we see here But the patient also has a tear of the anterior tibiofibular ligament And when you look see how minimal the marrow edema is So just something to remember that avulsion injuries have minimal marrow edema on MR But they're useful because the edema is useful for us to help Okay, so now if we look at avulsed ankle ligaments the most commonly avulsed ligament is the anterior talofibular ligament as we see here and Second most common is probably the anterior tibiofibular ligament This is in the hind foot area and all of us are familiar with this You see this very well corticated ossification. The point is to remember it's not an acute Injury, and we see you could see it also on MRI and this is along the course of the anterior talofibular ligament and here we see the same patient and we see this very nice well corticated ossification within the Substance of the anterior talofibular ligament so most of the time these are Asymptomatic, but they can cause pain they can cause decreased range of motion they can cause Patient to present with anterolateral impingement syndrome so you can have Some pain with it and occasionally they will excise it the thing about excision is that you have to be very careful Not to disrupt the ligament as you extrude that ossification Now this is a little bit more subtle And what we're seeing here if you look at the x-rays you can easily dismiss this But there is actually a tiny little avulsion fracture here and obviously it was missed because the patient did go and have an MRI and Here is the avulsion fracture here and notice by the way there is soft tissue edema But notice that the minimal marrow edema in the tibia so just something to remember This is again a subtle injury 25 year old with twisting injury. I Worry that we miss these Often if you look at the AP you're not sure if there is anything going on Fortunately or no bleak view you actually see this fracture line here And this is what we call the adult to low fracture right? And that's we could see it here on the CT again Obviously was missed so we got a CT on it and here it is and this is really a pull of the anterior Tibiofibular ligament we call it either adult to low in adults and juvenile to low in children Which is really a salt of three Okay, so moving further distally We have the 63 year old post twisting injury, and we see a lot of soft tissue edema distal to the fibular tip and we see this this is a Fracture comminuted fracture of the anterior process of the calcaneus By the way fractures of the anterior process of calcaneus you would think you would see them best on foot films But a lot of times you'll be surprised you see them best on the AP view of the ankle And when you look at the lateral view, I'm not sure but I think there are fracture fragments here But I am having a hard time telling for sure and this is the CT in the same patient You see actually the comminution of the anterior process of the calcaneus and you see a concomitant injury Of also an injury at the cuboid and here is the anterior process of calcaneus fracture Now this is another patient same thing a lot of soft tissue swelling here And then you see this tiny little fracture fragment here right again a fracture of the anterior process of calcaneus It looks very benign right you wouldn't worry about it too much But when you look at the lateral view you actually see that you also have dorsal talon avicular Ligament avulsion and in reality, this is an indication of Shapard joint injury. So Shapard joint injury a lot of times you'll have injuries of the anterior process lateral injuries as well as medial injuries and Basically, what happens is it's a spectrum of an injury, it's usually an inversion injury again With low energy trauma when we call Shapard mid-tarsal sprain It can be isolated But it may be associated with lateral collateral ligamentous injury and basically what you have here is you get Distraction laterally and then you can hear a fracture of the anterior process of calcaneus Sometimes an avulsion of the cuboid. Sometimes it's concomitant and basically it's an avulsion of the dorsal Calcaneus cuboid ligament, maybe bifurcate ligament Maybe the extensor digitorum brevis Which I'm not showing in this picture and then because inversion injuries will often have Happen with plantar flexion You're also going to get an avulsion of the talon avicular ligament right here as I've shown you in the last case You may also get an impaction of the plantar talar head and you may get Medial injuries impaction compression injuries So if you look at this drawing here, basically what happens is you get these distraction forces here With avulsion fractures here and then you get the impaction here, which is a plantar flexion dorsal Talon avicular ligament and impaction injuries either on the talus or on the avicular So if we look at this case similar findings, right there is some soft tissue swelling here But a lot of soft tissue swelling here and we see this tiny little fracture fragment here interior process of the calcaneus and It looks very benign, right? But we do the MR and we see the marrow minimal marrow edema at the dorsal calcaneal cuboid ligament disruption, but we also see an impaction fracture of the navicular So just keep that in mind Not all of them will have that but some of them will And I magnified the x-rays for you just so you could see and I guess in retrospect You could see this fracture line here and there is that navicular fracture But in retrospect another patient all the patient again a fracture of the interior process of the calcaneus We can see the avulsion of the talon avicular ligament dorsal talon avicular ligament here is the avulsion again laterally at the anterior process of calcaneus of the dorsal calcaneal cuboid ligament and Also, this patient has an avicular injury So just remember Schapard's injuries can look benign can start here, but they progress here So look very carefully at that dorsal talon avicular ligament and at the navicular Moving on This is a 30 year old with twisting injury and we see this soft tissue swelling and whenever I see soft tissue swelling in the dorsal aspect of the midfoot Along the metatarsals assuming the patient is not a heavy patient I always think about and I look carefully did I miss a stress fracture on the AP views? Or do I have a Lisfranc joint injury and indeed in this person? We do have a Lisfranc joint injury and we have here an avulsion fracture, right? coming off the base of the second metatarsal and this is along the course of the Lisfranc ligament and We call that the flex sign. So we have this little fracture fragment here and this is the flex sign so just to review the normal anatomy the Lisfranc ligament has three components. There is the dorsal which is the weakest There is the interosseous which is usually we see it very nicely on short axis as well as on the long axis And then there is the plantar one, which is usually not seen so nicely on short axis But we can see it often on the long axis going back to that patient that I showed you before This is the retracted ligament with the fragment superimposed over it and you could see the edema at the donor site of the Base of the second metatarsal and a little bit of edema here and when you look at the short axis you don't see any of the ligaments and you see all this edema right here and This is another patient you're looking at this here and this patient had Obviously does have the widening here It doesn't look like you have a step-off and then question mark is this a fracture fragment right here? And this is another fracture fragment here So does this patient have a less frank joint injury? Yes from the widening, but not so clear Is this a fracture fragment but on the CT that's very obvious, right? So here is a fracture fragment and you can see that now the CT shows you more fracture fragments, right? You have intercranial form ligament avulsions and another little avulsion here So CT is very useful for all these tiny little avulsion fractures, which really they're not going to do anything about But it kind of confirms the injury. Here is the flex sign right at this level But if you had an MR, you'll probably see a lot of marrow edema in this area You may not see the fracture. So this frank joint injury We also call it a midfoot sprain unlike the mid tarsal sprain and this is an axial loading it's often under diagnosed because they can reduce Spontaneously and if one thing I want you to get from this lecture is you need weight-bearing films, especially in the ER To make sure that you're not missing these type of fractures and why do we care? Approximately 50% of them if underdiagnosed or misdiagnosed will develop premature arthritis And they may even develop loss of the longitudinal and transverse arches So you really need to treat it immediately and just Before I move on from the Lisfranc, is this a Flex sign raise your hand if you think this is a flex sign So nobody is raising their hands very good. I don't know. It's because you're tired or because But anyway, this is not this appears well corticated, right and it's also dorsally located, right? So remember the ligament the D is deeper It's gonna be here. You will rarely the interosseous ligaments It will rarely get a flex sign that is so dorsally displaced Actually, I've never seen them and this is just the inter medial tarsum. You don't want to confuse that with a flex sign So moving on we have here two different patients a tiny little avulsion appearing very benign here at the distal fibula tip Here in another patient a little bit bigger fragment. You would think well, this is not very important. Why is this important notice? However, a lot of soft tissue swelling here. But what is that soft tissue swelling? so these tiny little fracture fragments are path pathognomonic for superior peroneal retinacular injury and superior peroneal retinacular injury is going to be associated with peroneal tendon Dislocation. So here is another case 32 year old woman Post fall and we see this large fragment. This is a larger fragment here again It doesn't look too serious But when you look at the MR You could see that there is stripping of the superior peroneal retinaculum here is the fragment and here is a piece of a torn peroneus brevis, which is laterally subluxed and A different patient here is a fracture fragment here, right? And here is the fracture fragment here and we see the peroneal Peroneus brevis dislocation. By the way for those of you who are still awake, and I appreciate that if you are There is a much more serious fracture here. Anybody sees it? So there's actually a tail and neck fracture Tail and neck and tail of body fractures to me are very scary because they're so easily missed but there's a fracture right here So basically superior peroneal retinaculum holds the peroneal tendons in place behind the distal fibula and with sudden dorsiflexion You can have these violent peroneal contractions and you can dislocate your peroneal tendons It was first described with skiing But you could see it with other Athletic endeavors and you don't need to know this classification at all This is actually a new classification the one classification But basically just to remember that the ligament doesn't always a vulse off But a lot of times it gets stripped off and allows those peroneal tendons to dislocate here You could see it Stripping as well as a volition fracture and when their volition fracture is big the ligaments not only to get dislocated But they can also get entrapped. So it's something you want to recognize so moving on to These two cases So these are two different patients 53 year old courtesy of David Rubin and a 61 year old courtesy of the Harvard Rosenberg So what do these two have in common? So both of them actually Reflect a volition of tendons. So this is a well corticated ossification this is the volition of the peroneus longest tendon with proximal migration of the Asperonium and this is an avulsion much less common of the posterior tibial tendon with proximal displacement of a type 2 accessory navicular So going back to this case here We see the ossification well corticated and we actually see that also on the lateral view which is proximally retracted There's nothing that else this could be when you see this well corticated ossification here. It has to be approximately displaced Asperonium and here we see the peroneus longest dislocated. I mean displaced and Torn of all stuff and here is the fracture fragment right here This is another patient less clearly seen a lot of soft tissue swelling and we see this ossification here You could think that this may be a fracture of the anterior process of calcaneus But when you have when you look at the oblique you see that this is very well corticated So this is approximately displaced Asperonium I couldn't see it on the lateral view but on the MR Definitely you see the wavy retracted tendon and you see the empty groove You know the cuboid tunnel groove and empty groove here with some friction related Meridema compatible with proximally displaced peroneus longest So moving on This is a 69 year old post-eversion injury so with eversion injury you have a pull of that posterior tibial tendon and you may have a fracture of the navicular tuberosity as we see here. This is the insertion of the posterior tibial tendon and This is Can be part of the nutcracker Spectrum So you get that strong pull of the posterior tibial tendon you get the navicular fracture and you get these impaction injuries of the anterior process of calcaneus and of the cuboid as I said Described as nutcracker injury and then going back to our first patient that I showed you and I showed you that approximately displaced us Type 2 accessory navicular and here it is again, and it's sitting probably somewhere here and Here you see it proximally displaced and This is the posterior tibial tendon attached to it. So you have approximately a valsal posterior tibial tendon with disruption at the synchondrosis and And finally, my last case is this fracture here of ulcer and fracture of the greater tuberosity of the calcaneus and we see it here and Healed later on and this is how they can present and it was described mainly in diabetic patients That have weaker bone, but we know that it can happen in osteoporotic patients And we know we can also not that common But we can see it in athletes and it's related to strong concentric contraction of the gastrocnemius soleus muscle complex more fancily, less fancily just Achilles tendon with forced dorsiflexion these usually can cause Skin injury and ischemia and you usually need to repair them with fixation So basically I covered lateral ligamentous injuries, syndesmotic ligamentous injuries We went to Schapard's joint injury, Lisfranc joint injury, retinacular injuries and then tendon dislocation Peroneus longus, posterior tibial tendon and Achilles tendon. Thank you very much

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