Sonography of the Pediatric Spine and Hip - SD

Introduction to Spinal Canal Ultrasound

Hi, I'm Mike DiPietro, pediatric radiologist at the University of Michigan. I'm a professor of radiology and of pediatrics. Today I'm gonna be talking to you about spinal canal ultrasound, which I've been doing for almost 30 years. The emphasis of this talk is basically how I do it. Rather than showing a number of various different cases and entities, which I've done at other times, this is really gonna emphasize on basically how to perform the study. I hope you'll find it useful. Thank you.

Spine ultrasound, how I do it, this is a talk I presented at the Society for Radiologists and Ultrasound in October, 2014. Another line could be, what's the line on the spine, some tips for good picks. You can see from the start that although it's often referred to as spine sonography or sonography of the spine, it's really of the spinal canal now. Now let's begin.

Disclosures and Background

I have no disclosures to make, and I've been doing this for almost 30 years, and I give credit for getting me interested in. This was a pediatric neurosurgeon, Dr. Joan Venice, who has since passed away, but she was a pioneer in pediatric neurosurgery. I think she might've been the first woman pediatric neurosurgeon, if not perhaps even the first or one of the first neurosurgeons. One day, in the evening, a little bit late after work, she saw me in the hallway and said, did you ever think about using ultrasound to look at the spinal canal? We just went from there. It was a great collaboration. I learned a lot. It was very interesting. I always state this for young people who are earlier in their careers, to always keep your eyes and ears open. You never know when some opportunity might arise.

Indications: Occult Tethered Spinal Cord

Most of the cases are done and the studies are done to look for the occult tethered spinal cord. Features of that are that the spinal cord is low. The conus medullaris is more caudal than it should be. It's often eccentric within the canal. For that reason, I coined the expression called the low down, stuck up spinal cord. You will find a lesion that caused the tethering, such as the things you see before you lipoma thick filum terminale lipoma. Another feature is that the cordal oscillations of the cauda equina, which I'll demonstrate, will sometimes become damped and reduced as you approach the area of the tethering.

These old pictures from the literature, you can see that this the baby has a small hump at the top of the back. This is not the same trial, but this could very well be the same depiction. You can see the spinal cord is low coming down to the lumbosacral junction, and that there's a fatty mass in this case. There's also the hairy patch, which that could really match that. This is a case I did back a number of years ago, which is almost exactly a representation of this. This is the spinal cord. We're down at the lumbosacral junction, and you can see this echogenic fat, which then the arrowheads are showing a hump on the lower back just like this. Although even this is far from being state-of-the-art ultrasound for the present time that it is, still even this vintage image really shows you the information and is a clear representation of what you see in this drawing.

Here's a case that was a little bit later, though, still an older image in which you can see that the ultrasound represented here in long axis, which actually preceded the MR. You can see the spinal cord is down low in the canal. The this is invested here with the fat. This is the lipoma. Really later on an MR was done, which it showed exactly the same findings. I like to show this case again with earlier ultrasound. I don't think this is any greater than perhaps seven megahertz. You could still see things quite well and in short axis. This is a nice depiction because this is the spinal cord here, which is hypoechoic. In this picture, here's the lipoma. Notice how on this side, this, which is actually the right side, that the spinal cord is rather flat, which matches exactly what the appearance that you see on the MR.

Technique for Performing Spinal Canal Ultrasound

Basically, what this talk is about is how do I do it? How do I get these studies? What's some tips for getting successful studies? Most of it's gonna be about getting it. There's also gonna be some discussion about how you word the report, and basically then how you actually show it and depict it and present it to the clinicians.

As with any ultrasound, and especially in musculoskeletal and pertinent also to spinal canal, being aware of your orientation and having a clear orientation on the image and technique is of utmost importance. We use appropriate high frequency transducers. Most of the time they tend to be linear array. There's some features which are a little bit newer, like the extended field of view and the ability to store dynamic cine loops is actually very helpful, especially in children, which might be moving targets for you.

Basically, the most important thing with the technique is, as I've found over the years, is that you really have to get the child adequately flexed to separate the posterior spinal elements. You'll see, and if you are successful in doing that, you can actually use ultrasound to look at the spinal canal much beyond in older children than what is conventionally taught and mentioned. Images are obtained from the back on the dorsal surface. Your ability to use ultrasound is because the posterior elements are less ossified in kids than they are when you're older, but you still need adequate flexion to separate the elements.

This is an extended field of view image, which now we have it. But at the time that we didn't have this feature where I was working, so this is from Ally O'Hare at Cincinnati Children's, and you can see how you can, you're seeing the low thoracic and lumbar canal. This is the lumbosacral junction, very much like you'd see in a lateral radiograph, how you're going from lumbar to then sacral. These lines down here are the backs of the posterior aspects of the vertebral bodies. These are the spinous processes are in the midline. They look like upside down U shape. There's the dorsal dura, the ventral dura. This hypoechoic tapering structure kinda looks like a carrot is the spinal cord, and then normal tapering the conus medullaris and these echogenic kind of hair-like structures extending down or the cauda equina. If you don't have extended field of view, you can use the old obstetrical ultrasound trick, which is basically you just do a split image and you just have a very steady hand and you can line it up. You scan down to here, and then you pick up where you left off, and you can accomplish the same thing.

Very important to locate the conus medullaris. As you just saw, it has a tapered shape, and these are the roots of the cauda equina. You wanna see it to localize the tip in both long axis and in short axis. Here it is right here. These are dorsal roots, and these are ventral roots. Now, I tend to, on my short axis, have this as the patient's right side, and this as the patient's left side, you can do whatever you want as long as you're oriented and you realize it. I do that because usually I'm over here on the patient's left, I'm reaching across. I found that it has helped me in some complicated cases where you're seeing something and there's some asymmetry, and then I'll realize, oh, was that on the right or the left? Then I remember that, yes, I was reaching across the child's back and spending a lot of time on the far side away from me, which is therefore the right side. So I tend to have it that this is the right, and this is the left.

Patient Positioning

Really you can almost have any position of the patient, but the most critical thing is that the back is adequately flexed. Very often the patients are prone and it can, and you may put a pillow or a towel roll or something under it to facilitate flexion of the back. Actually, sometimes if you elevate the head and the upper body a little bit, that can promote distension of the caudal thecal sac. These are all techniques that you may be familiar with for any of you that do myelography. You wanna a nice distended caudal thecal sac to which inject the contrast. So this is basically the same principle as that. You may have the child sitting, and then of course you want them to bend forward or fall forward, or if they're just a little infant, they may be falling forward anyhow because they haven't yet achieved the ability to sit up straight. Sometimes it can hold the child over the parent's shoulder, kind of, I call it the burping position, as though you're gonna burp the child after the child had been fed. I'm gonna show pictures of all these positions. Or you may put the child in a lateral decubitus position so the patient is recumbent on his side and as though you're gonna perform a lumbar puncture. So any of these views will work. Sometimes I'll do a few of them. But as long as the back is adequately flexed, that's the most critical feature.

Here's some examples. Now, this child is already four months of age, and you can see that she's exploring her world. She has her head up, she's able to lift up her head and neck. She's actually arching her back in the wrong position. This is gonna be very difficult to scan. You can see you're trying it, but then what you would like to do is get the back flex a little bit better. You may put some rolls underneath the abdomen to kind of get the back to open up a little bit more and flex a little bit more. The burp position, the trial is kind of held up over the shoulder sometimes if the trial is a little bit anxious, although the young infants don't usually act that way, but it can be comforting the kid to be over the parent's shoulder, and then they will kind of naturally just drape themselves over the shoulder and flex the back. That can be very helpful. Also the parent and the child or feel more comfortable because they have control over things. You can see here as we're scanning in both long axis and short axis to the body, the sitting position can work and actually the child has to be supported. 'Cause the child might fall over and you want them to fall a little bit forward with flexion. The lateral decubitus posture can work. So the child's on his or her side, but again, you wanna make sure that you flex the back somewhat to open up the spinal elements.

As with any time with flexion, and this is a warning to pediatricians in performing lumbar punctures, you wanna be sure that you don't have a small infant and you're so vigorous with your flexion that you actually make it hard for the child to breathe. You certainly don't want that to happen. That amount of flexion is not necessary. You can see here that how we're scanning with from the side, and this is actually from a top down look here, the child's still lateral decubitus, but I've photographed it from the top to show getting the short axis view. Of course, this is a view that won't work because you have no access to the back.

Normal Anatomy

Look at some normal anatomy now. This is the view that you saw, the combined image going from the low thoracic into the lumbar area. Then you can see the posterior aspects of the vertebra start ascending in the picture, kind of like an escalator going up. That's usually your lumbosacral junction, very much like a lateral radiograph, dorsal dura, ventral dura, these white lines conus medullaris. Here you can actually see the central echo complex. You can see the roots of the cauda equina coming off. You see the spinous processes back here. Some of the black that's on the tip of the spinous processes, like here and here. Here is actually the cartilaginous tips, kind of like the dorsal of a shark that you're seeing there. But that's because the ossification is relatively low, that enables you to get these really nice pictures in these young babies.

Just to reiterate, the position of the conus medullaris is very important, and you wanna make sure you've localized it in two views, seeing about long axis. In short axis, some appearances of the spinal cord as you look at the canal. Most of the emphasis is around where the conus is, but I often tend to look at the entire spinal canal. I'm not demonstrating a cervical here, but notice, and these are all at the same magnification. I haven't changed it, but notice how the thoracic cord is circular, but tends to be smaller than the low thoracic and lumbar cord, which is still kind of circular, but almost like a kind of a box shape. Then it starts getting smaller again and tapering as you get down to the conus. Then the cord is gone, and all you have are roots of the cauda equina.

Other things you can see, especially in the thoracic, you can see these horizontal lines in the nine o'clock position and in the three o'clock position, these are the dentate ligaments. Using the one or two o'clock position, 10 or 11 o'clock position, seven or eight. Four and five o'clock positions are usually where you're actually seeing the root dorsal and ventral roots coming off the cord and extending down. You can see them quite abundantly in this picture. Of course, as you get lower, this is just the tip of the conus and the dorsal ventral roots are quite striking here. They are here just below the conus. Then as you go lower down in the canal, you see fewer and fewer nerve roots because they're being given off to the body. Sometimes the appearance of the tip of the conus almost kind of looks like a spider here that you're seeing in this drawing. Here's an example here, and again, more just with the roots at the cauda equina.

Now in this movie loop, which is done in short axis, and you can see you're just coming down. So you see the hypoechoic cord in the center, then you see it getting smaller as you're coming more caudally notice for orientation, you can see the kidney on the left side of the on your left on the screen, in which the way I image that actually is the left kidney. This is just showing you that you're going from the cord down to the tip of the conus and then into the roots of the cauda equina. This is the same area in long axis. You're seeing coming in and out of the picture, the spinous processes, the hypoechoic tips of the spinous processes. You can see all, they sort of look like the dorsal of a shark white line. That's continuous long hair. That's the dorsal dura continuous white line down here, the ventral dura, the backs of vertebral bodies. You can see the tapering conus and the roots of the cauda equina.

Okay, now we're gonna go on, this is just a still picture in which you can notice on this combined image that the black, which is the cerebral spinal fluid, the thecal sac, really doesn't go all the way down the spinal canal. We'll talk more about that in a moment. As you come down, you can see the ascending vertebra, kind of like an escalator. These are sacral elements. Then you get into these hypoechoic areas beyond the sacrum. These are actually elements of the coccyx. You should see a rectum right in front of it, right opposing it, lumbosacral junction area, we're down in here. Again, you can see the thecal sac, and then it ends. This is the sac itself tapering. I'll mention in a moment how that's an important landmark. You sort of in the mid lumbar area, and you're just seeing roots of the cauda equina all in here up by the conus, just as you saw before, nice normal tapering. Again, you can scan the entire canal, but most of them, the requests are to rule out an occult tethered spinal cord.

Definition of Tethered Cord

So what is the tethered cord? This is a definition that I really like it, it really says it rather concisely. Don Regel was head of pediatric neurosurgery when I was at the Children's Hospital, Pittsburgh, in the mid seventies. I think this is a nice quote and it explains exactly what it is. We're really, look, we're gonna really, in imaging, look for the abnormal caudal position of the cord, and showing evidence perhaps that is being stretched, which we'll see with some diminished oscillation. You already saw this statement before the tethered cord because of its low caudal and eccentric, which is often dorsal position. I like to refer to it as a teaching thing, low down, stuck up spinal cord. Again, usually we see something that's causing the tethering now in this longitudinal picture.

So the patient's head is towards your left. I'm kind of scanning slightly from left to right, but pretty much in the midline, you can see the hypoechoic tip of the conus medullaris. However, look at where it is, it's way down by the lumbosacral junction. The tip of the conus should be probably no more caudal than about L three, the mid lumbar level. Most of 'em are around L two, L one, L two very often, sometimes at L three. But this is definitely low. Not only is it low, has a reason for the tethering. This is a very thick echogenic filum terminale. This is a patient who has anal atresia in peripheral anus. All of those children get scanned as a screen for a occult tethered spinal cord, more don't have a tethered cord than do, however, the incidence of tethered cord is much higher than in the general population. So they should all be evaluated at some point.

This is in this static image, this is in short axis. There's the thick echogenic filum terminale, which really normally should be no more than in one or two millimeters. This is much thicker than that. Again, with the conus position, you know that this is a tethered cord. So at some point, this will have to be released. It's not necessarily an emergency right at the moment to be done. They'll do the some of the rectal work first, but at some point, that's gonna have to be addressed.

Another feature besides the abnormal position is, you notice that the damped cauda equina oscillations. So in this picture, which I've shown, and basically a cine loop on the top, we would do, it's also shown on an M mode, which is popular in Europe. You can actually see right through where the line is. It's just showing you that portion of the image and how much motion is occurring. Notice how this, in short axis, notice how it's bouncing up and down. This bouncing is a normal feature, oscillation. But a couple of things. One is that you might not see such brisk oscillation in the very, very young infants and neonates. I don't know why that is. I think usually by about six weeks you see it. The other thing is you may see oscillation still present, although the cord is tethered, and it could just be that it hasn't been pulled taut yet. Eventually it will become damped. Or what you'll see is that as you get closer, more caudally to the place of tethering, that the oscillations will become less, and they'll become damped. You may go up a little higher away from the tethering, maybe in the low thoracic level or whatever, and you may see almost normal oscillation, and you can see that you're kind of higher. 'Cause actually seeing the child's lungs over here as he's breathing, you might notice that.

Determining Vertebral Level and Conus Position

Okay, so basically the conus tip low, yes or no, we have to determine that, you wanna see it in two views. Well, how do you determine where the vertebral level and there are some landmarks. You can just palpate the lowest rib I've found and then just kind go across horizontally from there. That's often around L two. If you're scanning the child, you may just know by your scanning that you're in the high lumbar canal. So actually assigning a number might not be that critical. You can use the lumbosacral junction, which we've shown in a few examples already. Identifying that very much like a lateral radiograph, the caudal end of the thecal sac, I've shown you, and I'll show you in a moment how that really fits in as a landmark. Again, if you're actually doing the scanning, you can just look at the patient's back and have a sense of where it is.

People have asked me, do you ever just put a marker on take a radiograph? Very rarely. I did do it for a study some years ago. But as far as I, clinically, it's rarely necessary. But if you do, make sure that you know exactly where the tip of the conus is in both long axis and short axis, put a mark on the skin, then put the marker and take your radiograph. You have to be very precise about it.

Alright, you can look at the lowest rib, and then you have to go out laterally over the kidney, find the lowest rib, which you can see there with the shadowing and the left side of the picture. Then stay there, and then just come towards the midline. Then you can assign that as T 12. Now, T 12 is in quotes because not everybody has 12 sets of ribs. It could be actually T 11, or it could actually be like a T 13. So again, it gives you an approximation and you can check one side and the other side, right and left lumbosacral junction, you can look at that and notice how the orientation of the vertebra change from being horizontal again, to like ascending towards the transducer, like an escalator, so that you could call that L five. That S one, you could count backward from the sacrum. Of course, that's assuming you have five sacral elements.

Now, the end of the thecal sac is an interesting one. The spinal canal goes all the way down to the end of the sacrum, but the actual CSF, the cerebral spinal fluid and the thecal sac usually ends at about S two. That's been known for years from myelography. I think it's a fairly reliable sign. So you've heard a couple of ways to do it. The only thing I can tell you is that if you've assigned a vertebral level, looked at it with all these different ways, and you keep getting the same assignment like L one or L two, it's probably right if multiple methods are giving you the same number, if you're getting some variation. Well, again, there could be some anatomical variance, as I said, for instance, the number of ribs that the child has. If you're in a tough spot and it's necessary, you can always put the marker on. But I found that is rarely needed. If you do, make sure you put it exactly on the conus tip as noted in both views.

What is the normal level of the conus tip? Well, this is a study I had done using ultrasound and then correlating with radiographs was the child was going to get anyway. So we didn't do any extra x-rays on that. But interestingly, really most of them seemed to be L one or L two. Occasionally. Here's one that extended down to L three, but you can see it here. Even we went out over a number of years, and pretty much the average is about the same.

Basically, I don't just worry about people ask me, well, aren't you concerned because the vertebral or the tip of the conus is at L three? Is that a tethered cord? Well, another thing though is that something has to be tethering it. In my experience, most spinal cords that are tethered are obviously low. I mean, they're down by the lumbosacral junction like you saw on that child early with imperforate anus. Usually it's not that subtle. The second thing is you have to find something that's tethering the cord. I think keeping that in mind will help you from going astray on this. So basically, if you have a spinal cord tip of the conus, it's maybe marginally whether it's low, but everything else is normal. Is that tethered? Well, it might not be, especially around L three or so can be normal. If it's tethered, there should be a reason for the tethering, and you should be able to see that. So you have to put it all in context. Again, in this case that you saw, not only is that conus tip low down by the lumbosacral junction, but there's a reason for it with a thick filum terminale.

Another method that you can use to corroborate with the other ones. This was suggested to me by one of my colleagues, Dr. Larry Kons, is to use the origin of the psoas. Now, the psoas muscle originates all along the lumbar vertebrae, as you see, but the top of it is at L one. It's been designated as so in anatomy books. But we did a study using patients who are having basically total spine MRs. To see if it really held up clinically. 'Cause sometimes pictures, anatomy books may really just be based on one or two corpses from years ago. But it ends up that it does hold up. So it's another sign that could be used.

Now, this isn't a plane that you're not gonna really use for the spinal canal sonography, but you can see the top of the psoas here. You see, this is actually a renal shot, and that should be L one. But you can see it actually in the way that we will image for the spinal canal. Notice this psoas here. This would be the spinal canal here. So if you flip this picture upside down, this is where we're gonna be seeing here. So here's this case, is the right kidney, the left kidney, the psoas, this is the spinal canal. These are roots of the cauda equina. So what I do is I find a picture where the psoas is quite obvious, and then I just march superiorly towards the head until you just barely see it. Then notice what's going on in the spinal canal, and then call that L one, and then just come back down from there and you can see where you are. So it's another way that can help the older child. Now, olders in quotes, because some radiologists consider once you've reached six, seven months of age, there's really no place for ultrasound anymore. You can't do it. Well, that's not the case. I've done spinal canal ultrasound and child that are several years of age. But the older they are, the bigger they are, the more limited your scanning will become. That's what we're gonna discuss in a minute. Really, as we've said before, you really have to get the child flexed to see it.

Techniques for Older Children

I'm gonna talk a little bit about, it's really a size limit, more than an age limit, but usually they go together, techniques for the older child. It's really just an accentuation we talked about already, but we'll discuss that a little bit more. Who orders an ultrasound for older children? Well, in my situation, most of the time these are ordered by clinicians such as pediatric urologists. So here's a very common scenario. The child is having some urological issues, maybe related to the bladder. They're not really suspicious that there's a tethered cord, but they would really like to know, they would be reassured knowing that the conus level is normal. That's really their only question. They don't wanna put the trial through an MRI. So very often if the child can cooperate enough, and you'll see in pictures if I can get flexed enough, I can identify where the tip of the conus is, and I'd probably be able to identify whether or not the spinal cord is oscillating, but basically the conus tip. If it's stone cold normal, and the high up in the lumbar canal, that might be enough information for the urologist. I put in the report that if you need any information other than that, then you have to do an MR.

Notice that, you know, in ultrasound, our spatial resolution is quite good because I can, you can do measurements that you're in the 10th of a millimeter range, which if you wanna sound impressive, instead of calling a 10th of a millimeter, call it a hundred microns, that sounds pretty impressive. But there's no question that if you can get to the structure with ultrasound that the spatial resolution is very, very good. So as the child gets old and larger, the visualization is very, very limited. I found a technique that can help is to go off the midline a little bit through the interlaminar area and then kind of angle in towards the canal. I'll show you a little bit about that, how we do it.

Here's a radiograph on an older child, and you can see I'm off the midline a little bit because the spinous processes are a little bit too difficult to get through. But if you go over by the lamina and you kind of angle in, you can perhaps see in there a bit. I got this idea from years ago, doing myelography in patients that had a lot of midline scar, and to get the needle into the spinal canal, you had to come off center a little bit and then kind of angle in from the side. So I'm really just doing the same thing. Sometimes it helps, but again, what's most critical is that you get adequate flexion.

Here's a girl, she's five years old, she's thin. You can see her spinous processes back here, and we can actually see her canal pretty well, but she really has to cooperate and be flexed for it. I'm just showing the how we're kind of off the midline and angling in, it's probably dramatized a little bit more just so you can see it, but you can see what we're doing. This is from a top down look on the bottom, you know, her head is up here, and then you can see how we're coming in from the side and doing that matching the, that's not her radiograph, but matching the radiograph.

Now, this is an old scan. This is probably from the early 1990s perhaps. This is an 8-year-old, and this is the longitudinal image. You can see though, it's kind of crude, but this is actually dorsal and ventral portions of the spinal cord. This is the back of the vertebral body. This is the like the dorsal dura area, lot of shadowing. This is from a spinous process, which is quite ossified, big shadow. You can look at one level, and then you come down and you don't see any more cord, you just see roots of the cauda equina. So you can infer that the tip of the conus is right here. We'll come back to the images like that in a moment.

Similarly with the transverse, and again, we've exaggerated it some just so you can see what we're doing, where we're kind of off the midline angling. Sometimes this trick can help you. But again, the most important thing is flexion. Now, here's a child a little bit later, vintage ultrasound, but still relatively older. This child is nine years old, weight 65 pounds. They really just wanna know where the conus was. This is coming from the midline, the canal. They're not really seeing a whole lot in there. But when we come in from the side in the short axis view, angling from the left, then angling from the right, you can actually see the cauda equina quite nicely. Then you can scan up and down towards the head towards the feet. You can find the cord and see where the cord ends and where you just get cauda equina.

Now, in this sequence, what we're gonna keep repeating here is a long axis. The head is toward your left, and at the beginning of it, we're seeing spinal cord. Then we're seeing tapered, there's three segments, three levels we're seeing. Then we're gonna see tapered conus medullaris, and then we're just gonna see a hair-like roots of the cauda equina. So when we get back, and I'll just call out to you where we are. So here we go. There's here comes spinal cord, conus and cauda equina. It goes kind of fast. I'll have to do it again. So here we go. Spinal cord conus, roots of the cauda equina once more cord conus roots. So you really, even though this child is at this age, you can really identify where the tip of the conus is.

Now this is the same thing in short axis, again, at three levels. So like pictures we've seen before, you're gonna see the hypoechoic cord in the middle. Then you're gonna see the cord being smaller, which is the conus medullaris going towards the tip. Then you're just gonna see fuzzy roots of the cauda equina. So in a moment, when I get in phase with it, here, I'll call it out to you again, cord conus roots. Here it comes again. Cord conus roots. Once more, cord conus roots.

Reporting and Filum Cysts

Now, how do we word it? The reports? Well, here's a report. We gotta be a little bit careful. Now, this is a common finding. I mean, again, I'm not really discussing a lot of the findings in pathology in this talk, but you'll identify this extended field of view image. Here's the conus medullaris. There's a little bit of separation actually here at the central echo complex. So there may be a tiny bit of fluid within the central canal down here, which is a quite common finding, especially in neonates, roots of the cauda equina. Hairy here. We're well away from the lumbosacral junction. We're in the upper lumbar canal, so that's not an issue. You can see you're going from lumbosacral here, but what's this hypoechoic thing, like great smack in the middle here, just inferior to the tip of the conus. We see these all the time. In fact, I think we more often see them than don't see them. It's really just a product of the higher resolution and the better machines and transducers that we have available. We call it a filar cyst.

Now here's another case, and we'll come back to that in a minute. But here's another case that has one also. But this case is a little bit different. Look at it for a minute and see some of the things we've talked about already. So here's the conus medullaris, but look at where it is. The other one was high up in the lumbar canal. This one is down by the lumbosacral junction. So this is a tethered cord, and there's the filum terminale. Here's this cyst, like within the filum terminale. But this one actually has an issue because this has a filar cyst, but in association with a tethered cord in this case. So that's the difference in these two conus levels. Different. Another feature that's a little different, but we're not gonna go into a big discussion of it, is that this one, actually, the thecal sac actually goes quite far into the sacral canal. We see this once in a while, right there. See, it should have been ending about here, but it keeps going down. Sometimes these are referred to as intraspinal meningeal sacs. Occasionally we see it. But when we're discussing the fact of the little filar cyst where everything else is stone cold normal, some of my colleagues don't even mention it because we see it so often. I will put it in the report because we are seeing it. But you gotta make sure that it doesn't get a clinician unduly excited. Very often what I'll just say, it's a normal variant of common finding that alone an absence of anything else has no known clinical significance showing it, basically getting good pictures.

Case Example: Prenatal to Postnatal Finding

This is a case I'm gonna show you now and kind of the messages just like maybe all roads don't lead to Rome. All ultrasound studies don't lead to MR you know, many of you have probably heard the thing. Well, we're just gonna get an MR anyhow. Or the ultrasound is just the prelude to MRI. Let's get the real study. The MRI. Well, it's not always that case. As some of you that have heard messages from the AIUM, the American Institute of Ultrasound Medicine, their theme last year was about sonography first. I think this is a good example of that. You'll see what happened. It really wasn't a pushing on our part, it was acceptance of the images by the clinician that was kind of striking.

So this is an example of a prenatal to postnatal finding. So this child, and this is the history typed in by the sonographer kid had been seen, they wanted an ultrasound done to follow up on a prenatal finding. This is just the fetal bladder, the child's head's the bottom of the screen, the rump is towards the top of the screen, and that's the fluid-filled white fetal bladder. But then there's another white thing down there also. It was just the anterior to the sacrum area right there. They thought there's some kind of a cyst coming off. Child is born, this is a radiograph, which is unremarkable. I do like to get radiographs. I like to see what's going on with the vertebra. If there's anything that we're seeing with that can be helpful. This was they're look the usual looking at kidneys and bladder, et cetera, et cetera. There's the bladder. There's the very prominent but normal uterus that you see in a newborn girl from the stimulation from the mother's hormones. Here's the low lumbar, the lumbosacral junction. This is the sacrum in the areas you're showing you, like really inferior to the coccyx, which is down here. There's this hypoechoic thing with some low level echoes within it. That's the thing that was seen in utero. Fine, you can do some measurements on it and you can see it. We're showing it in long axis and short axis.

So an MR was ordered. One of my colleagues asked me, well, you know, should we protocol it as a spine study or protocol it as a pelvis study? So we decided, why don't we do an ultrasound and look at it more carefully. 'Cause the other images that I showed really weren't done for the mass. They were really done for the kidneys and bladder. Let's really take a look at it to help us determine what's the best study to get. That's why we did the ultrasound. So we did go up and take a look and make sure that the cord wasn't tethered as they sometimes can be with presacral masses and cysts. Cords not tethered. Nice. Short axis of the conus medullaris, see the hypoechoic center echogenic roots of the cauda equina. As you've seen other examples coming down the lumbar canal, we're still lumbar. These are just roots of the cauda equina. Everything looks normal, getting down by the sacrum. Thecal sac is ending at about S two. Everything looks fine so far. Now we're getting into hypoechoic coccyx and bingo. Here's the coccyx here. Here's our thing that we're seeing, has some low level echoes within it. Basically notice that it really doesn't go cephalad to about S five. It has some areas that are anechoic areas with low level echoes and short axis. It's a little eccentric. This is the hypoechoic coccyx. It's a little off to the side, a little bit, not exactly midline. We use the color and power doppler. Basically there's very minimal internal vascularity, a little bit of vascularity around it. Actually, I had the surgeon come down to take a look at him, and basically he looked at it and he said, okay, that's enough. I can work with that. He really made the decision not to proceed, and he canceled the MR. I think the lesson of this is, I think the pictures were very good, and we took them with a lot of care. The way that they're presented, which I think is important, because it's the clinicians that ultimately really have to accept the images and decide that they can work with them. It gives them a mental picture of what they're gonna encounter in the OR. Surgeon was very happy with him. Basically, we went from there. I like to show this case as an example of how important it's to really get good images. This was removed. It was a mature teratoma. Everything went well.

So really, the points of that case are noted here. As we've discussed, clarity of images and orientation are critical. Now, occasionally, I'm not gonna go into this, but sometimes I actually am asked to do a ultrasound to clarify MR findings. Most of the time it's from the neurosurgeons. Perhaps there's something that's complex, but they have a very specific question for me, and I approach that. After reviewing the MR, and sometimes it can be very, very helpful for them. So sometimes it goes in this direction that again, that ultrasound is needed to help clarify something that's questionable on the MR study or they need some more information.

Summary for Spinal Canal Ultrasound

So basically in summary, how do I do it? You can see carefully and technique is just critical. The major technical point that we've been talking about is flexion and the ways to achieve it. Thank you very much.

Pediatric Hip Sonography

I'll be speaking about sonography of the pediatric hip, specifically about developmental dysplasia of the hip and then about the painful hip and hip effusion. Two aspects of the pediatric hip that we'll discuss are first regarding developmental dysplasia of the hip are also noted as DDH and also about the jaw with the painful hip in which we're usually looking for a joint effusion.

Regarding DDH, this talk will concentrate on providing an orientation to the anatomy, what it is that we're seeing and describing static in dynamic aspects of sonography of the hip. When looking for DDH in regard to the painful hip and joint effusion, we'll be discussing how to identify an effusion and then if requested by the clinician, technique of aspirating the fluid for analysis.

Developmental Dysplasia of the Hip (DDH): Indications and Associations

To begin with DDH, the reasons for DDH are vary the indications and associations. Very often on a physical examination, you'll hear that the trial has a click or more noticeably a clunk at the time of the physical examination, the clinician might note that the hips are lax or loose. There's an increased association with breech presentation, and sometimes the children have other deformities such as torticollis or a wry neck, usually related to fibromatosis colli. The child could have a club foot or less severe foot anomaly, metatarsus adductus. Both of these entities are often associated with a child who might have oligohydramnios and tight fetal packing. Then there is a family predominance of family history sometimes of DDH.

The term DDH is a broad spectrum, which can include anything from a dislocated, non reducible hip, all the way to perhaps some mild immaturity of the acetabulum itself and varying categories in between. As you can see. There are static and dynamic aspects to this entity, which is what we observe regarding the static study. We're looking at the morphology and the position of the femoral head and the maturity of the acetabulum. Regarding dynamic, we're looking for the stability or laxity of the hip dislocatability, subluxability, or if there already dislocated or sublux reducibility.

As with most musculoskeletal sonography and sonography in general, orientation is essential and that is really an aspect that'll be stressed in this portion of the talk. Sonographic technique is also very important and coronal screening and scanning with the coronal plane. Most of the scans performed from the lateral aspect, and you can see that the child is on his side. The position of the child isn't as crucial just as long as you really do maintain the coronal projection.

Now for demonstration purposes, the hand is high up on the transducer, but if we were actually scanning, the hand would be down at the bottom of the transducer, actually in contact with the child, but the hand was removed, just so you can see the orientation. This is the type of view that you might be seeing. Basically, the hip joint is a ball and a socket. The coronal view that is maintained, that is obtained is really very similar to a frontal radiograph. The advantage of sonography that you can see the portions which are not yet ossified, that are cartilaginous and being a ball in a socket.

There's really three essential questions that we address. This is what we address when we're doing our study. This is what I describe when I'm explaining the findings to the parents when we do the study. So first of all, is the ball IE the femoral head in the socket? Does the ball stay in the socket, which is an aspect of the dynamic study looking for laxity. Is the socket well-formed, meaning that is the acetabulum mature? All three aspects are quite important Now, although the coronal view on sonography obtained from the lateral aspect of the hip as you saw earlier is very similar to a frontal radiograph because we're coming in from a lateral approach. The way it appears on the screen is it is as though you rotated the radiograph 90 degrees, as you can see in this drawing. Keeping this in mind will help you considerably to understand what it is that we're seeing.

So in these pictures, that little diagram is in the corner for your orientation. You can see what we see on the sonography is the femoral head. This is the ossified metaphysis. This is the cartilaginous acetabulum of the roof. This is the osseous acetabulum of the roof. This would be seen on an x-ray as well. This is the lateral aspect of the ilium. These are gluteal muscles coming around. You can see indeed the ball is within the socket as you see in this picture.

Now here's one where it looks a little different and you can see that the head isn't as far into the acetabulum. This is the medial aspect of the acetabulum here, instead of being down in here as the other one was, this one is now drifting laterally, and this is some subluxation. In addition, the acetabular roof is a little more sloped, is not quite as straight and horizontal as it was in the other one. So this is a child who's showing some aspects of developmental dysplasia.

Here's one that's even further sublux. You can see the femoral head out here and the greater trochanter here. This is the ossified portion of the proximal femur. This is all cartilaginous acetabular roof, which is actually echogenic and pushed up somewhat. Here's the acetabular roof here, which looks steeper. So you can see in these three examples we're going from normal to a more severe subluxation or displacement of the hip. This one, it's actually outside the acetabulum. Here's the femoral head. Acetabulum is here. Actually this is very far posterior within the acetabulum, which we'll illustrate shortly. This is a completely dislocated right hip. So what would be important here is to see whether we're able to reduce it or not.

So another dislocated, you can head, you can see the femoral head, you can see the greater trochanter. This is the ossified proximal femur. This femoral head, if it were normal, would be way down here, which is much more medial. Again, using this picture as your orientation, and you can see its similarity to a rotated frontal radiograph. This is towards the patient's head. This is towards the patient's feet. This is lateral.

Now here is one where the head is actually pretty well positioned. This is the medial aspect of the acetabulum. This is the greater trochanter. These are the gluteal muscles coming around laterally. This acetabular roof is steeper than it should be.

Now I'm gonna show some anatomy that we alluded to a little bit. If you go very posterior in this coronal view, you'll see this large bulk of cartilage. This is the very posterior cartilaginous portion of the acetabulum. This portion of the acetabulum, you should not see the femoral head at all. If you do see it in that plane, it means that the head is displaced far posteriorly.

Now here's a newborn with actually, if you look at this carefully, you can see the ilium and the acetabulum here and the acetabulum here. Both femurs, even though you cannot see the femoral head because it's cartilaginous, if you drew them in, you could just see that there's no way that these heads are here where they should be. So these are bilateral dislocated hips. This child also has spinal dysraphism, and this dislocated hips at birth are referred to as teratologic hips. But I'm showing you this picture to show you how sometimes on radiographs even, it's very obvious that the hips are dislocated.

Now in this trial's sonogram, this is the femoral head here, which now you can see, and this is the ilium, but you're nowhere near any of the normal anatomy of the acetabulum. This is very posterior just as it was on the radiographs. So you can see here, rotate that 90 degrees counterclockwise and you get this picture. Now in the same child, you can see the femoral head here. This is the very posterior aspect of the acetabulum. This is all that cartilage that we showed. Here it is, the femoral head is right over it. So this is a very posterior dislocated head. This is the transverse view, which we are gonna discuss shortly. But this is anterior, this is posterior, and this is also very much laterally and posterior dislocated. This head should be down here. In a moment you'll see your orientation for those views.

Transverse View for DDH

Now the transverse view, this child happens to be in a Pavlik harness that you can see here, but is also done from the side done from lateral. But the transducer's turn 90 degrees, so it's transverse to the baby's body. The key to understanding that view is very much like an axial CT scan. So you can see what it would look like on a CT. This is the ultrasound. This is a CT scan of a child. He's in a cast is hip, had to be reduced in the operating room. You can see both hips are in, but I'm showing you the analogy of this to the transverse ultrasound view. So if you took that axial CT rotated at 90 degrees, it would look like the transverse view on sonography with there's posterior, there's anterior, there's lateral.

The transverse view when you're first starting out is a little harder to understand. But once you understand the concept and relate it to a CT scan, it makes it a lot easier. So turn the CT scan sideways. This is the pubis. The ischium. Here's the femoral head, anterior posterior, and on a sonogram. This is anterior, this is posterior. This is the part of the ischium here. Here is this posterior cartilaginous portion of the ilium. This is the femoral head. You do not see acetabular morphology very well in the transverse view. That's not why you do it. You really do it for position. But this view equates to this view, and that's right where it should be.

This is a hip that's subluxing a little bit, and this head should be down here more, but it's drifting laterally and posteriorly. This one, this is an older scan. This is the femoral metaphysis. There's the epiphysis. The ischium is here. This head should be way down here. This is drifting quite a bit laterally and posteriorly. So again, we saw this on the coronal view, the very posterior cartilage of the acetabulum. This is what that cartilage looks like in the transverse view. Here's the femoral head. This is a normally positioned one. You can see again the femoral head within the acetabulum Here is right where it should be another picture.

Now in this cine study, this is normal. I'm showing you a transverse view. This is posterior, this is anterior, this is the femoral metaphysis, and here's the head and this is right where it should be. As I'm scanning a little bit superior and inferiorly we're seeing more and less of the cartilage from this very posterior aspect of the acetabulum. But this is right where the femoral head should be.

Now, this is a maneuver where we're abducting and adducting the leg. So when you, you can tell by the position of the metaphysis here. So here we will be abducting in a moment when this looks more ver. There we go, abduction with the knees coming out. Then abduction when this is a little bit more horizontal on the screen and hips that are very loose when you adduct, when you bring the knee towards the midline, the hip tends to slip out a little bit. This hip is normal, this isn't doing anything here. Then what we'll also do is then we'll keep the child abducted, and then we'll push like a piston. This is the Barlow maneuver, and we'll see if the hip goes out or not.

Dynamic Aspects and Case Studies for DDH

So we have a couple of dynamic case studies to show this is a coronal view and this is normal. This is really, here's the ball, here's the socket. You see the greater trochanter coming into the picture. Here's the medial aspect of the ischium. You can see the acetabular roof here, and this all looks normal.

Now, in this one, there's a little bit of laxity. We're still coronal. You can see how this distance here is increasing. As I'm pushing on the hip, it's slipping a little bit laterally. It's not excessive, but there is a little bit of laxity here. Sometimes if the child is really just a few weeks of age, this could fall into the realm of physiological laxity, but you have to follow it. It could be still under the influence of the maternal hormones and which makes the hips a bit loose.

Now, this is another coronal view, so still in the same orientation, superior, inferior, the distance with the medial aspect of the acetabulum is much greater. Here's the acetabular roof, and this is kind of riding on the edge and I was trying to, when I'm trying to abduct and push the hip back in, but I was unable to reduce it fully. This is all useful information for the clinician.

Now we're switching to the transverse view, kind of like the CT scan. Now I'm just doing some abduction and adduction. You can see that the ball is in the socket. There's no widening of this medial space. There's no slipping laterally or posteriorly. This is all normal in this view. The gluteal muscles are coming around from behind and then coming to or over the greater trochanter over, which is just out of the picture.

Now this one, you can see the difference also in the transverse view, but there's a lot of slipping going on here. This space is widening and this is a loose hip. This is what you wanna avoid. You don't want the child to go on and then have a hip that looks like this. The acetabulum is dysplastic instead of a nice cup. This is a very steep roof. Then this head is completely out, and that's what you wanna avoid.

Dr. Harcke is one of the leaders and pioneers in this field, and he warns us about performing this study. It really takes a while to get some expertise and experience, but I'm hoping that this presentation will give you an overview and a chance to get started in this area.

Pitfalls in DDH Sonography

Now, a couple of problems that the common problems, one is regarding the transducer, but not aligned properly so that you really are seeing the true coronal standard plane. What I'm showing you here, this was done intentionally, is that at the beginning of the loop, this is normal right there, nice acetabular roof lateral aspect of the ilium, the ball's in the socket. But if you have the transducer tilted or turned or transposed a little bit incorrectly, it is almost like flying a plane, which Jeff pitch you on roll. All these things can happen to the transducer with respect to lateral aspect of the body. You can make it look very abnormal. You can see if you just froze on that pitch right there, you would think that's a very dysplastic, shallow acetabulum with a steep roof. But it really is just an artifact of projection. So this comes with experience and then hopefully having the proper orientation of mine will help, which will help a lot.

The older patient can be a challenge. Generally, if the child is older than six months, I'll really question why are we doing a sonogram instead of just doing a radiograph. But this is a case that came through and it was a little different. It was an outside pediatrician. It was very hard to track the person down to change the study. So I said, well, I'll just try it. I think we were successful. But it shows you it can be a real challenge. This child's 14 months old. There was some, the toes were going out a bit, and you wanna know if it could be due to DDH. This is the kind of view you get. You can see the real challenge because a lot of ossification is already present. You don't see the acetabulum that, well, here's the femoral head. Here's the acetabular roof. When I did this study, I felt that the head was, the ball is in the socket. The head isn't within the acetabulum. The acetabulum looks fairly normal, but you could have told all this much more easily and quickly on a radiograph.

This is a coronal and just showing how we're trying to define the right planes, but you get the sense that it is in the proper position, but it can really be a challenge in the older child. This was the impression from the report that I explained all this to the clinician. He later called me later on and kind of apologized for ordering this study. But I think we did answer his question, but it was a lot more work than a radiograph would've been. I told him what my feeling was about this. I also usually put in the reports if the parents were present or not, and how much they know, which can be helpful to referring clinicians and knowing what the parents were already told and what their understanding is.

Another area of pitfall that's quite widespread among everyone that does DDH is really regarding if you have a hip contracture or bowing deformity. These cases are not that common, but it is common for them to be misinterpreted. The problem here was that when this sonogram was done, the person doing this sonogram was not aware of the plain film findings. You can see there's a healing fracture. There's a bowing deformity, and then the question is, is the hip in or out? It's a little hard to tell on this radiograph 'cause you don't really know where the femoral head is. If you think it's here, maybe the head is in same thing over here, but let's just see. But this study was done. Now that was an earlier radiograph. This child came around some months later for a sonogram with the challenges of being an older child, as we said. But whoever did it thought that they were seeing this cartilage here with no recognizable acetabulum, and they thought that was the femoral head, and it was completely dislocated. But in reality, it really wasn't because this child then went to the had an arthrogram. What you can see is this is the same hip when the orthographic the contrast outlines a femoral head, which is actually within the acetabulum. The problem was because of the deformity and the flexion contracture. The sonogram was just showing the greater trochanter, which was out here and didn't even show the femoral head because it was blocked by this the ossified femur, which was in the way. That led to the incorrect interpretation of the sonogram.

So these are some of the entities that in which you can, that pitfall can exist. This is proximal focal femoral deficiency. The hip contractures, other kind of bow deformities. In the end, you really have to be aware of what's the clinical story with the child and be aware of the plain radiograph.

Painful Hip and Joint Effusion

Now a new topic, to switch over to joint. Basically what sonography is to identify a hip effusion and then perhaps facilitate aspiration of the fluid for analysis. In some joints in the body, just the radiograph can tell you whether or not this fluid present or not, but that is very unreliable in the hip. So you really do need a sonogram or other study to help you. The trial with a painful hip can be from a multitude of causes. But our question here is gonna be whether or not this trial has a septic hip or a bacterial infection within the fluid, which is really an emergency because if that's not treated properly, this child can then get a very damaged hip, which will follow the child forever, and we might even have to end up with a hip replacement later.

So basically, we're gonna be talking about hip effusion. In contrast to the DDH, instead of coming from the side, we localize it anteriorly. Then whether or not can we tell if it's septic or not? Actually, we're gonna see that our ability to tell based on imaging alone is rather limited.

So now we're scanning from the front and in a schematic diagram, this is superior, this is inferior, this is anterior, and the hip joint extends well down on the femoral neck, which enables us to see a effusion. When there is a effusion, the capsule is bulging. As we're seeing here, this is a radiograph of this hip. There's quite a large effusion here. This is the psoas draped over the joint, and yet on the radiograph, maybe there's a little minimal widening of the space, but that's not a very reliable sign. We've had prominent effusions, which on the radiograph you just couldn't tell the on an arthrogram, you can see how the femoral neck extends, how the joint capsule extends down over the femoral neck. Here's a big effusion. Here's a small effusion in contrast to the normal side here. P represents psoas muscle on all these.

Now, is the effusion containing bacteria, yes or no? Basically we've learned that our ultrasound criteria is really not perfect. You can look at various parameters, echogenicity the fluid, how distended it is, capsule thickness, et cetera. When power Doppler first came out in the 1990s, we used that to see if that would help us. As we'll show momentarily that is also not perfect.

Now, here's a child who had a septic hip. This is the normal side, the abnormal side, the capsule's thick. It is very echogenic. Clinically that's what they're worried about. They got pus with staph aureus, and this makes sense. But we have also have had septic hips where it didn't look anything like this at all. It looked rather clear, so you just don't know.

We did a series of using power doppler to see if that could perhaps help. On the you adjust your settings on the normal side and keep the same settings, go to the abnormal side, and you can see there's a lot more intensity here of the signal. It ended up that if we saw the increased signal that was good evidence, that it was septic, but it didn't work the other way. If you didn't see it, it didn't eliminate the possibility that it could be septic. So you still had to analyze the fluid.

We also had did this with an animal model and really found the same results. You can see here it was a septic hip, but early on when we were producing the septic joint, for the first several hours or so, it really didn't show the inflammatory signs yet. So if it's a little earlier in the course, the power doppler might still be negative. So the bottom line is, if it were positive and power doppler, it's likely septic, but if it's negative, it doesn't exclude the possibility of it.

Clinicians and various centers have also looked at certain clinical criteria, and a study from Boston, two studies from Boston Children's, we're looking at these four criteria. Basically, if all four are positive, it's very likely to septic hip. If all four are negative, is very unlikely, that's a septic hip. At University of Michigan, one of orthopedists also looked at with c-reactive protein, which adds a little bit more specificity to it. But again, these are not perfect studies either. So basically you still have to, clinicians have to use some clinical judgment in trying to figure this out. Once again, this adage comes back to remind us all that the world isn't perfect.

So basically, sometimes you still have to analyze the fluid, and once we've detected it, sonography can be useful to help localize it and then to help obtain fluid. A few ways you could do it. Now, knowing that you wanna go over the femoral neck, you can really do your sonography locate the effusion on longitudinal view, locate it in transverse view right there, and kind of X marks the spot. Then if you don't want to use imaging to actually put the needle in, just go straight in at that point. You should be able to obtain fluid. If you're having trouble, then you could put a sterile cover on the transducer and then take a look and see where you are. Some people actually like to do it under guidance.

Now, this animation from Dr. Shields, who's a well-known pediatric interventional radiologist, uses a lot of ultrasound and he had this made, which really just shows a aspiration of fluid under sonographic guidance. Here's a movie that a case that we did, and you can see the you're pushing on the capsule here, And then in the next movie you can see the needle is present, and then we'll be aspirating the fluid. So this is all the orientation, this is what the fluid looked like here, and after the needle is in, they got this straw colored fluid, and then you send it to the lab and have that analyzed another case where it it's a good bet that that's gonna be septic. But again, this isn't foolproof. We just don't know.

Now this brings up a little caveat. This is gonna refer to the normal side that it had in the last slide, and here it is here. There's two aspects. One regards the femoral head and one regards this little echo right here. So first of all, be mindful in children that they have a lot of cartilage in their epiphyses. They're not like adults with just a little bit of articular cartilage. So I've seen people misinterpret this hypoechoic cartilaginous portion of the femoral head as fluid, and it's not fluid at all. So be mindful of that.

The second thing is that when we're looking for the fluid, we're looking for it down as the joint extends over the femoral neck, you may also see a little echo in the femoral neck right here. You could see this with or without fluid in the joint. If you do see it, don't misinterpret that as meaning that there's debris, echogenic material within the fluid. This is just a posterior reflection of the joint capsule, and it's a normal finding by itself.

So we had a child who came in. This is a typical story which you might see in your emergency department. Here's a radiograph, which really doesn't show that there's any fluid. They did find an effusion, But the person who was doing the sonography also observed that the surrounding soft tissues on the abnormal side didn't look quite right. There's some increased echogenicity as compared to the other side and actually coming up over the thigh. So there was more than just an effusion. There was this subcutaneous layer was all very echogenic, within the muscles there was increased echogenicity. There was some hyperemia in contrast to the normal side where you see your nice normal layers and pennate structure the muscles. This is in short axis. This is an anatomical diagram. You can see the normal side, well-defined muscles forming the quadriceps and abnormal on this side. This is a child that actually had a pyomyositis. This is a cine loop showing that area.

So you don't wanna just have blinders on and tunnel vision when you're studying these children. Here's the short axis, and this could be anywhere in the body that you might see this Other possibilities of an irritable hip that you could come across when you're looking for a hip effusion are many, and I'm just gonna show briefly with this. This is psoas irritation, or a psoas abscess can present just like a infected hip. We really did not find an effusion here, but the psoas muscle looked rather thick. This is a case from Dr. Harcke. Now I'm gonna show it on some CTs for orientation, but you could have done the whole thing with ultrasound. But notice as you're heading up into the pelvis that there's all these fluid collections, and this is all abscess along the psoas.

Now an advantage of CT is a more global picture or an MR could show you also, if you have extended field of view, perhaps you could get a broader field with sonography. But very often sonography is the study that we start with. So we just wanna keep in mind to check along the psoas if you're not getting all your answers just over the hip joint. Here's the sonography in that case, just showing comparable pictures. Well up into the pelvis now. Here it is on ultrasound. So I think the sonography pretty much shows you the extent, but sometimes for the clinicians, the CT or MR gives them a better broad perspective of what's going on.

Another case with an irritated psoas, it doesn't necessarily have to be infection, was a case that I did and went down to the emergency department and saw this small effusion. But in talking with the patient, he said, actually the pain was also going a little bit higher. So I scanned up along the psoas. This history was not given to us at this time that he had a neuroblastoma a few years before. As I scanned up along the psoas, here it is in long axis, there's a mass sitting right on it, and here it is in short axis. That was irritating the psoas. We think the effusion was actually sympathetic. This is a transverse view. Here's the ilium, and there's this mass sitting right on it. This was actually a metastasis that had dropped into the lower abdomen, was growing, pressing on the psoas, irritating it, and giving this child hip symptoms.

You can also see cases where there's a more of a myositis again, or an osteomyelitis. This is a child. Now we're moving to the knee a little bit, but the principles are the same. You can see in musculoskeletal ultrasound, you have your normal layers broken down that we're all familiar with. This is very abnormal, very edematous ill-defined tissue planes, very indistinct tissue planes hyperemic. This is a child that you can see had cellulitis, another case over the tibia, but notice that there's a debris filled fluid along the bone subperiosteal. This is a very strong suggestion that this trial actually has osteomyelitis, which has to be drained in the operating room.

Conclusion for Pediatric Hip Sonography

So basically, in conclusion, in regard to DDH, what we've covered is your just your basic orientation and some of the technique and pitfalls to watch for and with the painful hip. How to identify a joint effusion, some of the problems with trying to tell if it's septic or not septic, and how a sonography can help with aspiration. Then plus some differential diagnoses and other things to be mindful of when you're investigating the hip. Thank you very much.