Hi, everyone. Welcome to our session. Today's session is going to be Fundamentals of Muscular Radiology, which we'll be focusing on the hip. As you guys may have noticed from prior years, we always have one of these fundamentals radiology sessions. And this year will be the hip. We have two really great speakers today, which I'm really excited about. I just wanted to, I think I have a couple announcements, housekeeping things that I'm supposed to say, a reminder participants and faculties to silence their cell phones. An audio recording will be taking place. This course will also be streamed live. A reminder to complete your individual session evaluations as they will help with future planning. A reminder these evaluations are located in the mobile app and on the online agenda. And then a reminder to visit the PM&R Pavilion because they have a lot of interactive resources and educational opportunities. And then also a reminder to pick up your Physiatry Day t-shirt at the member resource center. All right. So let's kick it off. I have no financial disclosures. I'm Jen Sukhum, one of the sports medicine attendings at Cornell. I will be today's moderator. So very simple outline of what we're going over today. We're gonna have a talk on hip X-ray, hip MRI, and then there'll be hopefully a nice 10 to 15 minute session at the end for Q&A. There's a microphone right there in the back if you want to say your question out loud. Also through the app, you can enter your question through there and we have an iPad out here for those joining us virtually or if you just wanna enter your question through there, we'll address those as much as we can at the end. All right. To introduce our two great speakers. So first up we'll have Dr. Peter Moley, who's an associate attending physiatrist at Hospital Special Surgery and also associate professor at Wall Cornell Medical College who will be talking to us about hip X-ray. He's a real expert in this area so we're really excited to have him. And then last but not least here, we have Dr. Marty Lazarus. He is a clinical associate professor of radiology at North Shore University Health System and then University of Chicago Pritzker School of Medicine. He's also the director of the Musculoskeletal Radiology Fellowship there and also a team physician with the Chicago Bears. And then now I will pass it over to Dr. Moley. So, thank you, Jen. I have a little bit of a passion about the hip, and I think that if you speak to anyone who's done a fellowship with me, you'll realize that you'll end up hating measuring x-rays, but hopefully during that time you'll learn something, and I think today hopefully you'll learn a little bit about the assessment of the hip using an x-ray. I have no disclosures. So why do we care? And I think that the hip is a very complex joint. It's a multiaxial joint, so it moves in multiple directions, and its design and morphology are very important in developing what we call like a mechanical diagnosis. So what is the mechanical diagnosis of the hip? And that's going to be super important as you're kind of assessing patients and determining what treatment pathways you want to do with them, and so you should know how to see an x-ray, how to assess an x-ray, and then what would happen based on the x-ray, and then, like anything, the most important piece of seeing a patient is going to be that history and physical. Once you've done that, then you have your MRI as the conformational test to look at the injury patterns that you have predicted based on your history, physical, and radiographic assessments. We're going to go through really radiographic assessment of a hip using an x-ray. So this is my protocol, and we'll go into a little bit of how we come up with the protocol, but the basics of it are I get a supine AP pelvis with crests. So as opposed to what you're seeing for someone who's getting hip replacement where they want to see the distal portion or proximal portion of the femoral, of the femur, we want to get the top of the crests. And the reason we want to do this is we want to standardize how we look at these. And that's going to give us the acetabulum, the hip on an AP view. It's going to give us the superior and inferior portion of the femoral neck, and then we're going to do a lateral view. And the lateral view is going to be what's called a DUN. I used a DUN 45 or a DUN 90, and that's going to show us the anterior and posterior portions of the neck, head-neck junction. And those are very important. Those have been studied. They're superior to the frog lateral, and the frog lateral, the reason of the frog lateral, the trochanter will block that head-neck junction, so you'll miss that. So you want to get an AP pelvis crest, and then you want to get a DUN 45 is what we typically use. Just briefly, in our workups, the MRI is going to be something we want to see, the cartilage sensitivity. And they want to get high-resolution thin cuts. We like proton density because it's going to help us with the cartilage and the tendons and other things around the hip. Finally, in the full workup of a patient who's, you know, surgically, you know, at the hospital, we're going to get a CT scan. Typically, we're going to do a 3D modeling. That's going to give us an idea of the morphology of the hip. It's going to give us volumetric measurements of the containment of the head in the socket. So these are all kind of a radiographic workup. We're going to focus on just the top. So why do you care about doing this? I think it's kind of like the bread and butter of the workup. This is what we're going to use as kind of our template. So if you're going to do an advanced evaluation, if you're going to see people, you want to see athletes, then you really need to have an x-ray as part of your workup because that morphology is going to play a big role in what you're seeing in the patient, what you're seeing for pain patterns, how that affects them. We'll go through, as we do this, a couple of things you're going to see by assessing the hip, a finding, and how that might be in your diagnosis. So today, we're not going to talk a lot about arthritis. We're really going to focus on the athletic hip. So probably normal or abnormal anatomy. We're not going to talk about joint space loss or arthritis. The question is to stand or not to stand. And this is a debate that comes up in a lot of hip conferences in our department. And it really gets down to a functional versus a static x-ray. And in my mind, the way to do these that we're going to compare is we want to have a supine film because I can get the supine film, and I'll show you images of them. But in that supine film, I can set the x-ray up so that everything is equal. And that is harder to do a standing film because your pelvic tilt is going to play a role. How they stand, there might be a lean. So I can, with a radiologist, we can set these up so I can get a good x-ray that I can measure. And then if I was dealing with someone across the country, I'm dealing with someone in Switzerland, or we've got the same patient, we could all say, all right, these are our measurements. These are the basic measurements. So all the studies you see on this are based on certain parameters of a pelvis. And so all the numbers I use, I think we're going to talk about, require that. So if you stand someone up, you lose that. So some of that changes. And there's really some good studies looking at just moving a pelvis around, putting metal wires around it. The other thing to kind of think about in this is just that, aside from standing, is just when we put them down, we also internally rotate their feet about 15 degrees. When I first started, I was like, why do you do that? Well, if you look down below, there's a little schematic. And it looks at how the torsion of the femur. So the femur actually has kind of a twist in it. And so if you look at the middle and think of that bottom being like a bell curve, most people are going to fit in that kind of 15 to 20 degrees of torsion or anteversion. So the red angle is 15 degrees. If you have excessive anteversion, you're in-toeing patient, the patient's knee rolls in, they're going to be 30 degrees, about 30 degrees or more. Or excessive retroversion might be zero degrees. The reason this matters is we're going to get into a little bit of like when people talk about the neck shaft angle, what's the angle there? And so that's going to be great if you have 15 degrees, if you move them in 15 degrees, and it's going to be a little thrown off if you have 30 degrees or zero degrees, right? So that's going to be more of an oblique. So some of those angles, what people talk about, are going to play a role in impingement, and we'll go through that too. So I think I do not do a standing AP. I do do a standing lateral. We'll talk about that at the very end and why I do that and why I think that's it. So there it gives me one functional x-ray and two static x-rays. So this is kind of centering of the beam. So this is a good x-ray. We can see we have ASIS on both sides, the synthesis, and then I've got the coccyx lined up with the pubic synthesis, and the measurement is usually one to three sonometers from that level. So here's good. You look at the obturator frame and everything matches up. This is symmetric. We can start the process of measuring these. So what is a good AP x-ray? Well, we want to have that x-ray, and we want to find certain features on it. So here we see this is the teardrop. Then we see the obturator foramen. Then we see the distance from the sacrum and the coccyx from the pubic synthesis, superior pubic synthesis. We can see that in red, you can see the anterior wall. In yellow, you can see the posterior wall. The light blue is your sore seal or eyebrow, and all those are going to be important in the orange issue line. So these findings I want to see on every x-ray. Now, if it's properly done, they're going to sit in the right place, and then I can assess how those have been seen over the years in multiple studies of how those impart some type of damage or injury to a hip. So this is a good x-ray. I found the right things, and now I can use that as I'm making decisions about the history and physical findings I had and why that might be applied in an x-ray. So here we see not as good an x-ray, but basically just some kind of basic measurements. So line number one is looking at the bottom of the ischium. Line number three is looking at the teardrops. The teardrops come down, and those are going to be important to us because we want to say, well, why don't the patient shift at all a little bit because now we're going to start measuring perpendicular and parallel to that line. So line number four, then, is a perpendicular line to either one or three, and that's going to be through the center of the femoral head. Line number two is a best-fit circle around the femoral head, and then we're going to number five is an angle between number four and five, and that's going to be our lateral center edge angle. They're going to be a lot. We'll talk about that a fair amount, but basically that's an important angle we're going to look at from the spectrum of a hip. Think of a hip spectrum. You're going to have very unstable or dysplastic and very over-covered or impinging hips. And so that, again, bell curves of hips. What are you finding? What are you seeing? And knowing that, are they over-covered, under-covered? How did that affect their motion? Why are they here? What's their pain patterns? All that's going to be important. So here we draw these silly lines, but in the end, it does help us to come up and make a proper diagnosis. So first, this slide here, we're looking at the AP x-ray, and we're looking at its interaction with the femoral head. So we start over on the left, and we can see what we consider under-coverage. So the femoral head and socket, there's not a lot of volumetric coverage, and so that's hip dysplasia. So that'd be a lateral center edge angle of less than 22. The normal center edge is somewhere between 22 and 34, is about normal. We're going to see some people say 25. The numbers can move around, but basically, that's where you want to see coverage. So then we get to the next one, and we can see a little bit of over-coverage. So the femoral head now is basically covered a bit more. There's also, when we look at that source, that eyebrow above there, maybe it's a little flatter than we saw before. We're going to show that and measure that a little bit later on. Then we get more over-coverage. So this is called a profunda hip. The hip is deep. And so now our center edge angle is greater than 39. So now we've got a lot of volumetric coverage, but that has positives and negatives. That's not always good to be over-constrained. So you're thinking about, I want a mobile socket, and now I've got an overhang. And so that can create injury patterns to the labrum, to the femoral neck, and also to the cartilage and some of these deeper hips in the cartilage. Think of the medial side. The inside of the hip can actually take more load because that over-coverage is forcing the head in and causing damage to the medial side of the femoral head. Sometimes you can look at the iliopsoas line. I'm not sure if this works exactly. It does. Iliopsoas line, the head will be a little bit medial of this iliopsoas line here. And that's something people will associate with this deeper hip or profunda. The last picture here, the retroverted, is associated with a socket. So the actual acetabulum is retroverted, meaning instead of being open about 15 degrees, which is similar to what you see in the femur, which is 15 degrees, acetabulum is open 15 degrees because we're going to sit. We're going to bring our femur up. We want some opening. Well, sometimes the actual acetabulum rolls back. And there are a couple of features you can see on this. And this is going to show us, this is called an ischial spine sign, so the ischium. Is I can see the ischium, and I shouldn't see that on a standard AP. I'm also, the lines cross over. We call that crossover sign here with a retroverted socket. The front wall and back wall are almost on top of each other in the center there. And so that's kind of important. So those are things where we're going to talk about, well, that's going to create some conflict between that femoral neck and the acetabulum, and that could be a pain generator. So understanding that is very important in our process of looking at these hips and looking at patterns of degeneration and injury. So why does it matter? We talked a little bit about it. So someone comes in, and you're looking at this undercover dysplastic, that far left center edge angle less than 22, could have anterior pain. And that could be from the overload of our more dynamic structures, mainly being the psoas. It can also be arthritis. If your center edge angle is less than 16, there's a very high prevalence of arthritis in the fourth and fifth decades. So understanding that, you might see someone comes in, a young athlete, and they've got a center edge of 12. That might push you towards treating them or having them see a surgeon for a procedure where you can cover the head a bit more. So that's important. And instability, this kind of generalized pain. You know, why do they hurt so much? This mobile patient with all this pain. Understanding that their socket volumetrically does not cover enough head is why some of that pain is occurring. So the hip is working harder. We can see symptoms anteriorly from that. And also, the lateral pain, you're overloading the gluteus medius and minimus. Oftentimes, lateral pain out there isn't because of weakness or an L5 radiculopathy. Sometimes it becomes the coverage is so low, the hip has to work harder and the muscles around it to keep it centered. When you look at acetabular version, the anteverted socket, so we talked about 15 degrees open like this, well, it could be more than 15 degrees open. You can almost see no anterior wall. So you could see anterior pain there. Again, the dynamic structure is trying to settle down the hip. Also, the retroverted hip has had both pincer-type impingement and you can have posterior pain. Sometimes you don't have much of a posterior wall. So as you're seeing the patient, you've taken this information and you're applying that to your morphologic thing and then a mechanical diagnosis. What's going on? Well, this is a mechanical structure. So how could that affect what I'm seeing? So when you look at x-rays, x-rays do not measure correctly. So if you look at an MRI and you measure 5 millimeters, it's 5 millimeters. But an x-ray is based on the beam length, where you are. Center maybe measures correctly. The beam length could be off. If you're higher up, it's going to be different. So we're going to get some dispersion of that x-ray. So it's very important, actually, to look at ratios. And this is Klaus Siebenrock, who's a Swiss surgeon who's done a lot of work in this area. But basically, he kind of looked at this acetabular coverage. We're talking about the retroversion and diversion. And kind of a quick and easy way to look at these is that he came up with ratios. So this is the anterior-posterior coverage. This index is there. And basically, the easy way to look at it is r equals the radius of the head. And your anterior wall should be about half the radius. So the number he came up with was 0.4. And the posterior wall should be about the radius, so 0.9. So if you look at just an x-ray, I was going to look at my 10,000. Before I start measuring, what's my 10,000-foot view of that? And the first thing I want to say is, OK, the posterior wall is covering half the hip. It's covering 3 quarters or not. And I want to look at that. And it's kind of an easy rule. So when you look at it, is the coverage correct on the acetabulum? Or do I see an ischial spine? And the anterior wall is too much. I don't see much of the posterior wall. So this is going to help, again, when you're looking at these hips. And I think that's always think about in your x-rays. You can't compare x-ray to x-ray. Just look at ratios a lot of times. It's very helpful. So the next thing we're going to look at is a little bit of what we call the interplay between the femoral neck and the acetabulum. So what happens when you get past the head? What's going on in the neck? This is where we're going to see cams. We're going to see pincer. What's happening at that head-neck junction? So the first thing we do is we see the cam down there. So on an AP, actually, it's a pretty good AP. I've got good coverage, good joint space, the head's relatively spherical. Typically, I tell the patient, I want a round, spherical head and a narrow waist. So the waist, the neck should come down almost like a light bulb. But when we do our elongated femoral neck here, what you're going to see is that the now we've got this bump right here. So that's a cam. I get kind of I think how we describe things is important. So a cam is a cog. It has to be convex to some degree. If you like cars, a camshaft has little cogs on them. They open up and they allow the gas and air into your cilter. So basically, this is truly a cam. Sometimes what you'll see is that it's very flat. And I would say that's a decreased offset. And we'll talk a little bit about that. But basically, here we see this interplay between the femoral neck and here first is a cam. The next is what we're going to see most commonly. It's kind of a mix. We have a bit of a crossover up top here. We also have this reduced offset and this high alpha angle. So in most literature, the alpha angle greater than 50 is kind of where people have decided, well, that is a reduced amount. And we'll go into drawing that alpha angle in a little bit. But that's kind of an important thing to see. So here I've got both. I've got a little bit of the rim of the acetabulum. I've got a little bit of the head-neck junction. And there's a conflict between the two of them. That can cause an injury pattern. And we can predict those injury patterns on MRI and everything else if we have an idea of what we saw in the X-ray and we listen to our patients. The last two are looking at a little bit at the head-neck junction. So the first one is a varus. So it's less than 125 degrees right there. And the second is valgus. So it's steeper. These have some application. Certainly, the varus hip is an impingy hip. A lot of times, it's impinging actually on the anterior iliac spine and or on the ilium. So that hip, that steeper angle, brings the trochanter up. And there are certain features associated with that. And then the valgus hip is a very mobile hip because it has very little constraint. The trochanter isn't coming into play. But it's a hip that's a very high-load hip. It's a hip that takes a lot of load. We call it static load that no matter what you do, that angle puts more load. It's associated with early arthritis. So seeing that is good. But as we said at the very beginning, remember, we had our feet and they're twisted. So what happens when they're both varus and or we think they're varus, but they're retroverted in their socket or in their femur. So what happens there? Well, I'm not getting it on FOS. I'm getting a little bit of an oblique. So an easy way to take care of that, we're looking at that. This is kind of a measuring of the neck shaft angle. So here we have this measurement. We've got our best fit circle. We've gone down the center of the femoral neck. We've gone down the center of the femur. And we come up at an angle, assuming you're at 15 degrees. But that's not always true. So kind of a quick and easy way to do this is that if you take a line and you draw it from the top of the trochanter to the top of the trochanter, that should sit in the center of the femoral head. And the reason that matters is that that's the ideal location. And that we can kind of steal from our colleagues in arthroplasty. If you see a replaced hip done correctly, it will always have the trochanter, top of trochanter in the center of the femoral head. And that has a lot to do with the mechanics of gluteus medius and how the hip functions. So they've done tons of biomechanical studies where we can take the native hip and apply back from that. That's super important. And a way to look at it is if I draw that line and the center of the femoral head is below the line, then you have a valgus hip, right? So the center's high. The line's below it. So I've got a steeper angle. And that doesn't matter how much version they have. We know that that's going to be true no matter what. And then I can also, if I draw the line and the line is above the center, then I've got a varus hip. So looking at that's going to be important because those are going to affect patient early arthritis. It can affect their trochanter. It's going to affect impinging the trochanter, so trochanteric pelvic impingement. It's going to affect the function of the gluteus medius. All this from an x-ray. And this is as we're going through the different features. So how do we measure, say, a center edge? You leave nothing else today. You can measure center edge is kind of important. So basically, you get a good x-ray, all right? Good AP with CRES. And then we draw a best fit circle around the femoral head. If you're using any PAC system, this is pretty readily available. We even have these ortho tools now that can help us out. And we can get all these measurements with a few. It's clicking on different areas. So it's automated a bit more, which is kind of nice. But basically, draw a best fit circle. We used to use protractors to do this. So it's possible no matter what you're doing. But that was on film. So we draw that. And then we draw a line. So I like to use the teardrop. So we have a line from there. And I've got a perpendicular line to that that goes from the center head up. And then I draw a line to end to the sword seal. And that gives me the number of about 27 degrees. That's a normal coverage. That's a normal acetabular coverage. So very good. And we can now apply that in our patient. The next thing we're going to do is what's called the tonus angle or the sore seal angle. So that, I take that same tear drop to tear drop, I then draw a line parallel from the medial portion of the sore seal or the top of your acetabular right here. So the sore seal is this, the eyebrow. So I'm going from here, here, then you come up and I get an angle there. And so that angle is going to be important because that angle is going to affect what we talk about in different types of impingement and what we talk about for stability. So normally that tonus angle sits between 2 and 10 degrees. And that's a component of dysplasia. So when you look at greater than 10 degrees, that's one feature of dysplasia, something called a Sharpe's angle that kind of applies that using a different measurement. There's also a fear index, which is an index looking at the angle between the tonus angle and also looking at the physeal scar. And that's been validated in many studies. That's your tweener instability. You've got 22 degrees of coverage or 21 degrees, are they stable, unstable. The fear index has been very helpful to help that. And then also on the other side, if it's less than 2 degrees or even negative, that's going to be creating some pincers, some pinching of that. And those types of injuries, you can apply that in your MRI. A pincer injury is more of an injury of impaction, the labrum is going to hit on the femoral neck different than it can. So how do you measure the femoral head-neck junction? Well now we've got our DUN 45, our elongated femoral neck view. Again a best fit circle is drawn. We then draw an angle down the shaft and then we draw an angle to where the femoral head-neck junction breaks off of our circle. So now we've come to the end of the circle here, we've drawn this and we get an angle of about 52. So we would call that a hip that does impinge. Now I wouldn't personally call that a CAM because the next measurement I'm going to do is I'm going to look at what's called the offset. So the offset is going to be from the top of the femoral head and then along the anterior portion of the femoral neck. And that should be about 10 degrees. So this patient has a reduced offset. And so that the alpha angle and offset interact with each other. Some people would say, oh they're a CAM, but they have a reduced offset. And so that again is going to cause a problem as that femoral head-neck junction comes into the socket here, okay. So when you look at this x-ray here, here we've got a few things going on. This has got a large CAM, okay. And then we have actually a negative sore seal. So we've got that mixed picture. Well, the CAM doesn't stop the femur, the femoral head going into the joint. The CAM comes into the joint. So this guy, Michael Lunig, a Swiss surgeon, and he would call that an inclusion injury. Think of that, my knuckle coming into the joint like this. And what that's doing is wiping away the cartilage at the junction of the labrum. And so we want to, you know, that head-neck junction is going to be important. So looking at that, we're going to say that damage might lead to early arthritis. So where does that make a difference? As we said, the CAM with inclusion, the motion loss, labral tear, and early arthritis are things we're going to see. The pincer is more of an impact injury with labral blunting and motion loss. Just quickly, today in the world of hip arthrosis, in hip world, in replacement world, in spine, everyone's kind of looking at these pelvic parameters. I'm not going to get too far into this. But understanding that if you draw, you look at the angle of the sacrum, you draw a line down to the center of the femoral heads, that's what's called the pelvic incidence. That pelvic incidence, the number is equal to your lordosis. And then the pelvic incidence is sacral slope plus pelvic tilt. So the tilt is going to be a vertical line, and that should go right through the center. In most professional athletes, it does. But in our patients, it goes anywhere from like 40 degrees to zero degrees. And so that's going to affect how the pelvis, so that's a very functional way to look at the pelvis. So on another time, if we get, you know, look into this, it's kind of interesting. And so this is what I'm going to get when I want to do a standing ladder or a more dynamic study and stand and look at how they stand, posterior pelvic tilt, anterior pelvic tilt. How are they standing? How does that affect the hip? So this is all, you know, in conclusion, I think you have to be able to understand how to read these to understand how a hip functions and how the injury may occur. X-rays should correlate with history of physical. If there's no correlation, always look above and below. It's always important in this. Sometimes that's an important thing to look at. So thank you for your time. We're set. Thank you. All right. Next up is Dr. Lazarus. Welcome, everybody. Dr. Suhu, thank you very much for having me. Dr. Molley, that was a wonderful, wonderful talk. We're going to be talking in the next couple of minutes. We're going to be talking a little bit more about what we're going to be talking about in the next couple of minutes. These are the topics I'd like to cover in the next 30 minutes, and they're a lot, but we're going to get there. We're going to start with MRI protocols. We're going to go over the basics. We're going to go over normal anatomy. We're going to go over pathology, which to me is also the indications to order an MRI scan. And specifically we'll have FAI, or femoris tabular impingement, as we just saw so beautifully articulated, specifically with MR arthrography and looking at labral tears. And then we'll go on to other entities such as avascular necrosis, stress injury, gluteal tendinopathy, osteoarthritis, just to touch on that, osteitis pubis, and ischiofemoral impingement. So, MRI protocol, what should you be expecting from your radiologist as far as what kind of scan or study do you want, or sequences do you want? And for a plain or non-arthrographic MRI, normal ones you get every day at work, straight axial, coronal, and sagittal images in the T1 and T2 planes, and that's really what you need. And we'll talk momentarily more about T1 and T2. And by the way, I apologize ahead of time if any of this is too basic or too advanced for all of you. I'm sure there's variability in the audience here, but hopefully by the end of the 30 minutes you'll all be able to be very familiar with a lot of what I'm going to be talking about. So for an MR arthrogram, and not everybody does MR arthrography, specifically at certain places out east, it's not always done. But we do it at our place, and if you want to do that, you'll do extra imaging sometimes with oblique coronals, oblique sagittals, and double oblique, what are called double oblique imaging, usually parallel and perpendicular to the opening of the joint. So MRI basics. If there's anything you take away from this 30 minutes, it would be this. The difference between T1 and T2. T1, on T1-weighted images, fat is bright. So the subcutaneous fat we see here is white or bright, and on T2, it's dark. Sorry about that. And on T2, it's dark. Also notice that fluid or pathology, and most pathology in the human body does have extra water content. So because of that, we'll be able to see it real nicely on T2-weighted pulse sequences, and not so well on T1-weighted pulse sequences. So you'll see, so you'll see that there's dark area on the T1-weighted sequence here, where there's pathology, and then white area on the, sorry about that, on the T1-weighted pulse sequence here. Also notice that the anatomy is much more visible on T1. So we have high resolution on T1. We have decreased resolution, relatively, on T2. So your job, when you're looking at these scans, is to find the abnormality on the T2-weighted pulse sequence, because it'll show up like a Christmas tree. And you'll find out where the abnormality is on the T1, because it's got a higher resolution. So you'll want to integrate these two types of scans in your mind to find what the pathology is, and where the pathology is. So let's go to hip anatomy, because anatomy is 90% of the battle with MRI. It truly is. So these are actually coronal T1-weighted pulse sequences, as if you're looking at the body from the front. We know it's T1, because the subcutaneous fat is white or bright. We also know we're anterior here, because we see the pubic bodies. The muscles are going to be these gray areas, and we can see the muscle attachment to the pubic bodies, specifically the adductors here, and specifically the adductor longus. Here we see, also anteriorly, the iliopsoas muscle. On the right, now, we're more posterior. We know it's posterior, because we see the different components of the iliopsoas. We see the iliacus muscle on the right, and the psoas muscle on the left coming together to form the iliopsoas. We also see, at this level, the gracilis dropping straight down the medial aspect of the thigh. We see the quadriceps musculature, specifically here, the vastus lateralis, and the rectus femoris muscle as well. And we see the superior pubic rami. If we go a little bit further, posteriorly now, we're in the line of the hip joint itself, and the femoral head, neck, intertrochanteric region, subtrochanteric region, and greater trochanter. And now we start to see tendinous attachments to that greater trochanter at this level. Tendons are dark or black on these images, because they have a total lack or near total lack of water content. Also you see the obturator internus and the obturator externus musculature in this image as well. The image on the right, you see a sagittal image, as if you're looking at the patient from the side, like a lateral x-ray. You're looking at this patient from the side. We know it's T2, because we see subcutaneous fat is dark. The circle is about the greater trochanter, and we see this dark tendon attaching to the posterior superior facet of the greater trochanter, representing the main head of the gluteus medius. Now let's go to axial images. On these axial images, they're T1. It's like cutting through the body like a sausage, T1, because the subcutaneous fat and the marrow fat is white. On this particular image, we see the superior pubic rim again. Then we see the anterior and posterior acetabular rim. And then on the right, we see some musculature in cross-section. We see the sartorius in front of the rectus femoris muscle. And now we see the adductors, the adductor longus, brevis, and magnus in cross-section. Now if we go to the left again, we see the three different facets of the greater trochanter. We see an anterior facet, a lateral facet, and a posterior superior facet, onto which the gluteus minimus, the lateral head of the medius, and the main head of the medius insert respectively. Now if we go a little bit lower to the level of the lesser trochanter, we look again at our sartorius to find our way anteriorly, rectus femoris behind, and now we see the tensor fasciae latae at that level. Also we see the proximal hamstrings at this level originating from the ischial tuberosities and the inferior pubic rami. And back to the left, we see the actual ischial tuberosities isolated. And then finally, we'd like to look inside the joint. And what we do is we do MR arthrography to look inside the joint. The reasons you might be wanting to get an MR arthrogram of the hip would be these, labral tear, cartilage defects, loose bodies, and synovial abnormalities. So here we're looking from the front again. So this has to be a coronal image, and the marrow is white. So this is a T1-weighted coronal image. But the thing you have to realize here is all this white stuff is the contrast or dye that we injected into the joint. So this is an MR arthrogram. And this outlines beautifully this triangular black-shaped structure with a sharp apex representing the acetabular labrum. This is where the money is. Now we go to a sagittal image. Again you're looking at this patient from the side, and you see outlined beautifully, these two triangles of the anterior superior and posterior inferior acetabular labrum. You also see the femoral head beautifully outlined by contrast or fluid, a nice circle here. But you also get the morphology of the acetabular labrum really well here as well. So it's this C-shaped structure, and it's actually tipped over about 45 degrees. So the opening is anterior and inferior. Now back to a coronal image. Again contrast is the white material. And we see this dark structure represented as the ligamentum teres dropping down from the fovea of the femoral head down to the transverse ligament. Also notice here there's this thickening or condensation of the distal capsule here. This is called the zona orbicularis. This is a normal structure. We shouldn't worry about it when we see it on an MR arthrogram. And finally an axial image. Again beautifully outlining the femoral head with the white contrast material. In this particular case, you see the anterior and posterior acetabular labrum again, nice sharp with very good apices. And then we're cutting through in cross-section the ligamentum teres in front and the pulvinar fat right behind the ligamentum teres on this cut. All right, so let's go to the fun stuff. Femoral acetabular impingement, it was beautifully described in the last 30 minutes. We'll take a look at it now from a different perspective. Again, as we know now, it's a mechanical conflict in its most basic form between the femoral head-neck junction and the acetabular opening and or rim. It's a precursor to early osteoarthritis, which is why it's really important that we catch this as early as possible. The labrum and or the cartilage at the rim are damaged. It's kind of controversial as to which comes first. And it is oftentimes amenable to arthroscopic surgery, another reason that we need to find what's going on as early as possible. So it's also important to understand that patients who have an acute injury have a better prognosis than those who have an insidious onset. So if a hockey player comes to your office and says, three weeks ago I got checked into the boards and I felt a crack in my hip, that athlete will have a better prognosis than somebody who comes to your office and says, I've been having increasing pain for the last two years. I'm not really sure what happened originally. Also it's important to note, and Glick and Sampson showed this about 15 to 20 years ago out west, that if you have significant osteoarthritis radiographically, arthroscopy results are significantly reduced. In other words, if you have significant arthritis on the plain film and you do arthroscopy, they tend to go on to a new hip earlier than if you didn't touch them at all. So the presence of osteoarthritis radiographically is important. So what are we looking for on the MRI scan? As we've seen before, we're looking for a spur or bump at the lateral femoral head-neck junction. We're looking for that loss of concavity. We're looking for a labral tear or labral degeneration. And we're looking for articular cartilage tears. So here's the MR representation of really what we were looking at the last 30 minutes or so. This is an oblique axial image. And here we see a nice lateral femoral head-neck offset, nice concavity or sigmoid shape at the femoral head-neck junction. And that's in contradistinction to this image here in which you see the bump or bony excrescence at the femoral head-neck junction anteriorly and the diagramic representation on the right of the bony excrescence abutting the anterior acetabulum, the labrum, as well as the cartilage. So there are two types, as we now know, CAM and pincer. I'm going to really be focusing on the CAM type today for time purposes. And that basically is an abnormal femoral head-neck junction, usually a bony excrescence as a spur, as we've been looking at. And it will strike the acetabular labrum, oftentimes in hip flexion. And it can cause a labral tear, usually anterior superiorly, or chondral labral cartilage tears, delamination or flaps. And that's what we're going to be looking for. And by the way, before I go on, everything I'm talking about today, we were just discussing this. You should be looking at the scans yourselves in your offices. So you certainly can take the word of somebody reading them for you, the radiologist. But it's really better if you are looking at and feel somewhat comfortable the images of your patients. I think it's really helpful. And you can talk with the radiologist about the scans as well, if you know something about them. So the alpha angle now, we've looked at it on the plain films. How do we do it on an MRI scan? We can do it for any type of image. And that's important. We can do it on the plain films, as we looked at. We can do it on an MRI scan. We can do it on a CT scan as well. Most radiologists are going to be using the MRI scan for the alpha angle, as we do at our place. And off of the oblique axial images, initially anything greater than 50 degrees was abnormal back in 2002. That's been increasing kind of steadily ever since. It was up above 57. Some people go above 60 is abnormal. Some people go as high as 63 degrees is abnormal. Now how do we get the normal alpha angle? Same way we do on the plain film. So we take this oblique axial image. We draw a best fit circle around the femoral head. We bisect the femoral neck to the midpoint of that circle for one limb of the angle. And the other limb goes to the inflection point between the femoral head and the femoral neck. That's our alpha angle. Pinscher type, as we also discussed, it's an overcoverage issue of the acetabulum, giving you an abnormal tonic angle or abnormal acetabular index. It can lead to anterior, posterior, or a combination of labral pathology. And it's also associated with multiple congenital abnormalities such as developmental dysplasia of the hip, coxa valga, and coxa vera. So what are you looking for to say that this is a torn labrum? You're looking for multiple different things. Number one, blunted morphology. Number two, extension of contrast into the labrum itself. Number three, extension of contrast at the chondrolabral junction, at the interface, or just displacement of the labrum. And for degeneration, which is a very different picture actually than an acute tear, you look for an enlarged or abnormal morphologically, abnormal labrum morphologically. You look for irregular margins, an abnormal intermediate intrasubstance signal intensity. And here's an example of a normal acetabular labrum and a normal chondrolabral junction at the site of the arrow. The contrast, the white material, is not going into this triangle base at all. And that is different from this image right here, where you see the white contrast going into the substance. So this is a partial, non-detached tear of the acetabular labrum here at the chondral labral junction. This is a 27-year-old wide receiver with bilateral hip pain. And you see on the right, on his hip, contrast material entirely through the base of the acetabular labrum. So this is a detached, non-displaced, full-thickness tear of the acetabular labrum on his right side. On the left side, you see that there's contrast also through the base of the labrum, representing a tear. But you also see that there's early cyst formation, or what's called a paralabral cyst. And this takes time to form. So if you're looking at this, you realize that this is more of a chronic injury on the one side, where it's more of an acute injury on the opposite side. If we move on, sorry about the image on this one, but it's a very different looking labrum in this particular case. We see it's smallish, irregular, marginated, and there's fluid within the substance. This is more of a degenerative tear of the acetabular labrum. It loses its normal triangular shape, and it loses its normal sharp apex. Also look at the CAM morphology at the lateral femoral head neck junction. And then finally, a really bad image, but it's the most beautiful demonstration I've ever seen. It's a sagittal image. You're looking at this patient from the side on T2. And you see this curvilinear line going entirely from the front to the back of the labrum, filling contrast material with a massive acetabular labral tear from anterior to posterior. Let's move on now to a different topic real quickly. Osteonecrosis, or AVN of the femoral head. It is the most common site, most likely due to a combination of poor blood supply and high axial loading forces. Typically affects adults under 50 years of age, and it will present with hip, thigh, groin, or buttock pain. Typically, you'll see it anterior superiorly, involving the articular surface anywhere from the 10 o'clock to the 2 o'clock position. And causes are many, as many of you know. Trauma, steroids, alcohol, smoking, SLE, HIV, chronic renal failure, diabetes, and pregnancy are just a few. And MRI is the most sensitive way to look at this thing and most specific. And what are you going to look for on these scans? Well, you're going to look for what's called the double line sign. And it's a secondary hyper-intense line between the normal marrow and the ischemic marrow. And when you do see this, it's highly specific for AVN. So once you see this, you're done. You know the diagnosis. Also, you'll have different signal intensity on an MRI proximal to that double line, depending on the age of the lesion. So let's take a look at a couple cases real quickly. Image on the left, this is an axial image, like we're cutting through the patient like a sausage. We see it's T2 because the subcutaneous fat is dark. Now we see the serpiginous geographic circular area of signal abnormality, or this white line. And it's anterior superior on the left. It's a dark line on the T1 weighted image on the right. This represents avascular necrosis of the femoral head. The one other thing I'd like to point out in this case is you see on the other hip. It looks dark throughout the entire thing. You don't see the subconval bone. And that's because this is a collapsed femoral head. This is essentially an end stage hip. And when you see this, it's pretty difficult to determine what the initiating cause was. And we'll talk a little bit more about that momentarily. Here's another classic appearance of avascular necrosis. We see the serpiginous geographic lines within the anterior superior aspect of the femoral head. And that is AVN until proven otherwise. And here you see the classic double line sign. You see the black and then the white within the subconval portion of the femoral head. Let's go on real quickly to stress injury. Gradual onset of groin or hip pain is how it usually presents. It increases with activity and weight bearing. And it's more common in females. And what's important to us, especially when we're looking at these cases, is it is seen on the compressive side of the femoral neck or the medial side more frequently. And the important thing here also is that there's a risk of propagation throughout the femoral neck to total collapse. So what are we gonna see on an MRI scan? If you're looking at your patient who's a marathoner, for instance, you'll see a continuum from reaction to response to fracture on the MRI. And the most important finding you'll see is bone marrow edema. And it will be on the compressive side of the proximal femur. And that will be increased T2, decreased T1 signal. And oftentimes you'll start, you'll see the earliest signs of a stress fracture far medially, and that can extend if the patient continues their activity to a complete fracture. Oftentimes what'll be really helpful if you're looking at the MRI scan to help you diagnose that there's a stress injury is there'll be periosteal edema adjacent to the cortex. And that'll let you know that just beneath the cortex there's some type of either stress response or stress fracture. So here we go. Here's a 39-year-old female marathoner with hip pain. And you see this crescentic white area in the compressive side of the proximal hip. But if you look real closely, you also see that there's this white area along the periosteum that lets you know that there's something going on right underlying the cortex. And in this particular case, there's no fracture that we can see here. So this would be a stress reaction or stress response. And that's in distinction to this 30-year-old female marathoner. And these are the exact same images I showed you to look at T1 versus T2. And here you see rather extensive bone marrow edema within the compressive side of the proximal femur here. But you also see the earliest vestiges of a stress fracture starting at the medial or compressive cortex. And if that isn't enough to stop the athlete, we get a 39-year-old female with acute pain in mile 10 of the marathon. And of course, she didn't stop running. And now we see this very impressive stress fracture going over 50% of the diameter of the medullary cavity of the proximal femur. We see all this surrounding bone marrow edema as well. So this is a big time stress fracture. And this is just one enlarged image to show you that MRI is really good for diagnosing fractures. Everybody always asks me, Dr. Lazarus, what about CT? Should we get a CT on this patient? MRI is really good for any kind of marrow abnormality, including a fracture. And this is a blown up image here of a intertrochanteric proximal femur with the greater trochanter up near the arrow here. And this is a motor vehicle accident actually. And you see the comminuted fracture outlined really nicely on the MRI scan in the greater trochanter extending to the intertrochanteric region. So let's go on to the next topic, which is gluteal tendinopathy. It's a continuum from mild tendinopathy to full thickness rupture. You can have partial tears, you can have complete tears. You can have associated bursitis. And I think this is important here. I think everybody kind of uses trochanteric bursitis as a catch-all phrase for this. But technically there are three separate bursae around the gluteal tendons and beneath each of them. So you'll have actually subgluteus maximus, subgluteus medius, and subgluteus minimus bursae. And they're separate things. So on an MRI scan, what are you gonna see? As always, we see increased T2 signal intensity within the tendon representing tendinopathy. And if that continues on, you can see partial thickness tears. And that would look like either thinning of the tendon or fluid within the substance of the tendon. And then of course, if that continues on, you'll see full thickness tears in the distal aspect of the tendons with fluid in a gap. And if you see fluid, you're done also. You know it's a full thickness tear if it's cutting straight across the entire tendon. So let's go back real fast to anatomy. We're looking again at the body from the front. So these are coronal T1-weighted pulse sequences. Just take a little bit closer look at some of the tendinous attachments. And we see here this black structure extending to the greater trochanter representing the piriformis tendon. And below that is the obturator internus tendon leading to the obturator internus muscle. Also on the right, now we start seeing this vertical tendon attaching to the greater trochanter. And that's the lateral head of the gluteus medius. And if we go posterior now, and on the right we're looking sagittally and posteriorly. From the side, we see the main head of the gluteus medius attaching to the posterior superior facet of the greater trochanter. And on the left, we see in a far posterior image, the vertical tendons of the main head of the gluteus medius attaching to the posterior superior facet of the greater trochanter bilaterally. So that's the anatomy. And now here we see a coronal image, and we see the white substance within the tendon itself representing tendinopathy. So this is early gluteus minimus tendinopathy, no tear at this level. And that's in contradistinction to this case where we see the same image on the right. On the left, we start seeing fluid within the tendon itself representing interstitial or early partial thickness tearing. And if that isn't taken care of, of course, we end up with what we're looking at here, which is a full thickness gap within the distal gluteus minimus tendon filled with fluid. But you also see fluid in the subgluteus minimus bursa. So this is a full thickness distal rupture of the gluteus minimus tendon with associated subgluteus minimus bursitis. And finally, lousy image, but the best case I've ever seen. The gluteus minimus is completely ruptured and flapping in the breeze here, pulled off of the greater trochanter. We see subgluteus maximus and subgluteus minimus bursitis all over. And here's an isolated collection of fluid simply within the subgluteus medius bursa outlined posteriorly by the main head of the gluteus medius tendon here. So this is isolated subgluteus medius bursitis. I'm just gonna go real quickly over osteoarthritis because a lot of our patients, including athletes, and when you see a lot of athletes, you realize that they get osteoarthritis at a very early age. So you will be seeing this a lot with the athletic population. Here we see some of the hallmarks of osteoarthritis, which is joint space narrowing, subchondral sclerosis, and subchondral cystic change. We don't have a lot of osteophyte formation on this one. But taking a look at this on a macro level on an MRI scan, what can you see? Well, we see a lot of fun stuff. We see this curvilinear black line representing subchondral sclerosis within the subchondral bone plate. We also see this extension of an osteophyte about the acetabulum. And if you look on the other image, we see subchondral cystic change. So these are the things that you expect to see with osteoarthritis on a macro level. And on a micro level, if we see in the joint, say with an MR arthogram, we see some different things. We see a great view of a markedly abnormal acetabular labrum here. We see no longer any triangle at all. We see contrast within the substance of the labrum diffusely. We also see loose bodies in the dependent portion of the space, and we see spur formation laterally. And remember, osteoarthritis is a bone-forming proposition. It forms bone, whether it's sclerosis, whether it's loose bodies, whatever it is, it is going to be bone-forming. And we get to see that really nicely on the MR arthrography. And here's another case. You see complete loss of articular cartilage, superior laterally on this patient. We see some gray area here where there actually is cartilage. And we see again, markedly enlarged acetabular labrum with degeneration and tearing within the substance. And you see on the right, near complete loss of articular cartilage from the arthroscopic image. And finally, again, I alluded to this before. This is a collapse of the articular surface of the femoral head with all this edema throughout the head, neck, and inner trochanteric region. And when you see this, you realize that this is an end-stage hip. Whether it's from AVN, whether it's from arthropathy, it's extremely difficult to determine. So let's go to the one subject that I just find really interesting. And it's difficult to clinically diagnose sometimes. So we'll talk about osteitis pubis a little bit. It's clinically diagnosed by the presence of groin, pubic, or lower abdominal pain, and the presence of pain to palpation over the symphysis, the superior ramus, or the adductors. And it's seen in sports oftentimes with a lot of lateral movement, kicking and twisting and shearing forces, such as soccer, such as mixed martial arts. And there's gonna be stress because of that shearing force across the symphysis, and that'll lead to weakening of the ligamentous restraints and increased mobility across the joints. So you'll have chronic traction on the pubic ramus from the adductors, from the gracilis, and from the conjoint tendon, which is the rectus abdominis and adductors over the pubic bodies. And that'll lead to disruption of the substance within the joint, what's called the fibrocartilaginous disc, and we'll take a picture of that momentarily. And that'll lead to secondary osteoarthritis in these patients, oftentimes young athletes. So you'll see sclerosis, cyst formation, and erosions. You'll see osteophytes peaking superiorly, and oftentimes impressing upon the base of the bladder. And so here's a schematic diagram with first the muscle attachments. You'll see the adductor longus, brevis, and magnus coming off of the inferior surface of the pubic body and rami medially. And now if we look at the symphysis itself, you see within the central portion that there is a disc, and at the superior portion there's a superior pubic ligament. And that is a weak point within the whole construct. So you'll see disc protrusion in these athletes superiorly towards the base of the bladder because the superior pubic ligament as well as the posterior pubic ligament are the weak links in the envelope that surrounds the symphysis. So what are you gonna see on an MRI scan in a patient with osteitis pubis? Most frequently, and the thing you really need to take away today, is you'll see bone marrow edema on one or both sides of the symphysis within the pubic bodies. You'll see stress fractures, and you'll see what's called the secondary cleft sign. The secondary cleft sign is similar to an annular tear in an intervertebral disc. And it's basically an extension of that joint space obliquely towards one side or the other, wherever the symptomatology is referable to. And you'll oftentimes see fluid within both the primary and secondary cleft as well. And you'll see increased T2 signal intensity which will extend into the proximal adductor muscles. And basically what the secondary cleft sign is is tearing of the proximal adductors. So let's look at a couple cases real quickly. Here you see increased signal within the adductor, longest musculature representing a strain. We also see abnormal signal within the pubic body on the left representing osteitis pubis. In this particular case, it's a collegiate fullback with osteitis pubis, and you see bilateral bone marrow edema within the pubic bodies. And this is the classic appearance. But we also see some other things that go along with it. And here you see a linear dark signal line representing a stress fracture within the right pubic body in addition to the bilateral osteitis pubis. And now we have a coronal image. Again, you see herniation of that disc material with swelling extending to the base of the bladder. And that's really helpful to figure out exactly what's going on in these particular cases. Also look at the origin of the adductor tendons coming off inferiorly. Here we have a secondary cleft sign that I was describing to you. And here you see the line extending to the left which was the side that this patient was symptomatic on representing the secondary cleft. And that comes from the joint space itself. And if you look closely, you see the disc herniated into the base of the bladder in a cephalad direction with associated spur formation. Now we have a 25-year-old professional soccer player in this particular case with bilateral osteitis pubis. But you also see bilateral linear white lines here representing bilateral secondary cleft signs with bilateral partial adductor tears. Again, look at the extrusion of the discal material towards the base of the bladder with the osteophyte formation. And if you look on axial and coronal images, you actually can see the weakened posterior and superior pubic ligaments extending towards the base of the bladder. And here, last of these, we see abnormal signal within the distal aspect of the right rectus abdominis muscle. And we know this is a T1-weighted pulse sequence because subcutaneous fat is white. So we have fat replacing the muscle down here, meaning that there's been a chronic conjoint tendon rupture with secondary fat infiltration. And lastly, let's go on to ischiofemoral impingement real quickly. It's a cause of posterior hip pain as well as groin and thigh pain. It's narrowing of the space between the lateral aspect of the ischial tuberosity and the medial aspect of the lesser trochanter commonly seen in middle-aged to elderly females. And it results in compression or impingement of the quadratus femoris muscle. And so we're looking for edema within the quadratus femoris muscle on an MRI scan. Over time, you'll get fatty atrophy and replacement of the muscle itself, and you can get irritation of the sciatic nerve leading to sciatica also. It's important for everyone to realize, though, that not everybody that has narrowing of the space has symptoms. And that's important because you wanna see abnormality in the muscle itself before you're calling this ischiofemoral impingement syndrome. And here's how we measure for this. We look at the medial cortex of the lesser trochanter, the lateral cortex of the ischial tuberosity, we measure that. We go from the medial cortex of the lesser trochanter to the proximal hamstrings, we measure that. So we have a ischiofemoral and a quadratus femoris space. There are a bunch of different numbers I could throw out to you. I don't think it's important that you know any of them, and they're constantly changing, and they change with the positioning of the patient also. But if you can just recognize when these spaces are abnormal, it's really helpful on these scans. So here's a case with left hip pain, and you see this dumbbell-shaped white area in the region of the quadratus femoris muscle representing marked edema in this patient with ischiofemoral impingement syndrome. And the case on the right is more subtle, but still definitive, and you see the whitish or grayish area still within the muscle itself. And on the opposite side, the quadratus femoris also has subtle edema. And if you look at the space, the ischiofemoral and quadratus femoris spaces, very, very narrowed. Okay, to summarize, basic knowledge of T1 and T2 is critical. Anatomy is 90% of the battle. Interarticular pathology, in my mind, is best seen with MR arthrography. And there are a whole bunch of different pathologic entities that can be similar clinically. So if you're aware of all these, it really helps if you're looking at your MRI scans on your patients. Thank you for your attention, everybody. Thank you. All right, thank you. I think we have a few minutes for questions, if anyone has any. You can also put it through the chat feature in your app, if you have any. Or I know people are rushing to your next session as well. Yes. Are you asking what percentage of patients have gluteus medius tendinosis on MRI? Yeah, that's a great question because a lot of them have abnormal signal in the gluteal tendons and there have been a few studies that have come out recently within the last five or seven years, I'd say, that show that especially in the older population above 65, there's a lot of false positive MRI scans of gluteal tendinopathy in patients who are asymptomatic. So I think as you get into the older population, that percentage of positivity on MRI scan is going to rise and you really have to use your clinical acumen as far as putting it together with the MRI findings. Anyone else? Yes, come on up. You can use that mic right there. First off, thank you for your talk. I just wanted to ask, is there any utility using ultrasound for gluteal tendinopathy before MRI or do you go straight to MRI? That depends on who's ordering the scans, I suppose. I think that we usually go to MRI. We have occasionally had people ask us for ultrasound of the gluteal tendons, but a lot of times they'll do it in their offices if they have that capability. So I think what you want to do if you're thinking about using this is start to take all your MRIs and then scan all your tendons. There's a lot of user variability with the ultrasound, look at the tendon, and I think a lot of people, you know, I see people come into my office and they're like, someone did an ultrasound, they said I have tendinopathy, I need to have a PRP injection, and it's like, why don't we do rehab first, let's look at this, that's pretty common. So having tendinopathy as you age is very common. So while ultrasound I think is very sensitive and very good for tendinopathy, as we're getting into the gluteus medius, depending on the patient's size, you're going to lose a little bit of your resolution as you're going down. So I think if you're going to do that, I would get kind of comfortable, I would see MRIs, I would scan them, I would look at pathology, and then first and foremost, you know, deal with patients, what's their symptomatology, and have they rehabbed properly first before any kind of intervention. We have one question here from the virtual audience. How much arthritis is too much to make a patient not a great candidate for hip arthroscopy? Are early cartilage changes on MRI significant? So that's a good question. You know, the numbers typically when you're looking at it is a tonus two, which means you have cystic changes in the acetabulum or in the femoral head, a joint space less than two and a half millimeters if you're looking at x-ray, and then you get kind of like the MR gestalt feeling about the surgeon and what they're going to do. But I think those are kind of the hard and true ones are, anything, a tonus two or greater or less than two and a half millimeters of joint space is generally too much arthritis. Yeah, I would agree with that. I mean, also, you know, I think you have to take into consideration the type of patient, the age of the patient, their activity level also, and that'll go into the decision making, I think. Great. Another one from the virtual audience. What is the sensitivity for finding a labral tear without contrast? So as seen in HSS, it's about 90%. So it depends on your imaging, how you do it, but Doug Mintz, MITZ, and Hollis Potter did a study looking, comparing MR arthrography and non-arthrography in, and looking for labral tears, and they're about 90% sensitive. So it's pretty close depending on the imaging you have, the quality. That's all going to be very dependent in where you are, who you're working with. Yeah, I mean, those numbers are great numbers. You know, I, they are great numbers, and I still think, you know, I'm comfortable doing MR arthrography with a slightly higher percentage than that, and my eyes aren't quite that good, and I think the work that they do at HSS is wonderful as far as the quality of every single study, and I think that's the advantage. Yeah, get to know your radiologist, talk to them on the phone, and figure out what they like to do, because that's going to be the most sensitive. So, you know, you tell them, I don't want arthrography, but they don't, you don't get the same kind of sensitivity, the MRs aren't done the same way, and they're not as comfortable, you're not going to get the same results. So find what your centers around you do, and try to work with them in getting the best, like, imaging you can with the people you're working with. That's the most important thing. Do you also use dynamic MSK ultrasound to diagnose ischiofemoral impingement? So you can. We went through a phase of it, and we were doing a number of them. There are some technical aspects, it's quite hard, patient size, positioning, it gets into that. I think we've pushed away a little bit from ischiofemoral impingement in that there isn't a treatment process, we rehab them, we work on abductors, we, you know, typically, you know, you're going to look at a patient who's got a valgus femoral neck junction, and averted, is your most common patient. That's going to put the trochanter, the lesser trochanter back towards the ischium, and so you've got your patient population, and corrections, you know, Reinhold Ganz did a study looking at taking off the lesser trochanter and attaching the psoas complex to that, and that's interesting, but it's rarely done. So I think that we've done less ultrasounds because we've had less interventions, and we've done more rehab, and again, we're looking at morphology design of the hip, and that has been relatively successful. Yeah, I agree. We don't do that at our institution. You know, I think everyone's pretty comfortable with the MRI scans, and you can say they're very sensitive with very subtle cases, and I can't speak, certainly, for referring physicians or clinicians who have ultrasound units in their offices, but as far as from the radiologic perspective, we have not been asked to do that. And then do you definitively need an MRI when treating people with FAI in order to kind of send them to a surgeon, or can you, do surgeons usually just use an x-ray and can make that decision? So, I'll give you the HHS experience. Yeah. Yes, you do, because I think in the end, the damage of the joint is very important. Understand how it's occurred, what you need to do, and the health of the cartilage. Sometimes you can be surprised. Sometimes in two and a half millimeters, then you get an athlete, a young athlete, professional athletes will have more cartilage loss than you could ever imagine, and so I think you do. I mean, I think the proper workout for a hip arthroscopy is an x-ray, MRI, and a CT. I think you should do all if you're going to go and embark on that, because the complications of not doing enough can be catastrophic. It's not something you do well on your second, certainly not on your third. You kind of look at like three strikes and you're out, and look back and found that the third arthroscopy does not do well. So, you want to do it once right, so get all the information ahead of time. Yeah, that's 100% agreement right there. I think every one of our referring physicians wants an MRI scan on these, especially if you're talking about high-level athletes who have a $40 million contract they're worried about. You want to know everything that's going on inside their joint, so the only way to really do that is to order an MRI scan. Any other questions? Yep. There's a difference between what's called increased signal intensity on T2, which is kind of a whitish thing, versus fluid signal intensity. You can always look, actually, if you're not sure, if you're looking at fluid in a tendon, look at the bladder, and if the bladder is the same signal as that, that's fluid, that means there's a tear. If it's not fluid, it's not a tear. And that's the best way to determine. Anything else from the audience? All right, thank you. Thank you so much to our speakers today.

hip anatomy

radiology techniques

hip pathologies

x-ray views

MRI protocols

T1 weighted images

T2 weighted images

MR arthrography

ultrasound limitations

hip arthroscopy

clinical practice