Sonography of the Pediatric Hip and Spine - SD

Introduction

Hello, I'm Michael d Pietro.

I'm a pediatric radiologist at the CS MA Children's Hospital in Ann Arbor, Michigan, and a professor of radiology at the University of Michigan.

Today I'll be talking to you about pediatric musculoskeletal ultrasound pertaining to pediatric spine and pediatric hip and the spine.

We'll be talking about the assessment of the spinal canal and detection of the occult tethered cord.

And in the hips we'll be talking about two topics. One is developmental dysplasia of the hip, and the other is the child with a painful hip related to hip joint effusion.

Since I'm from University of Michigan, I guess it's appropriate that I wear this.

So we're talking about sonography of the pediatric hip and spine, or as you might paraphrase it, the bottom line with hips and spine, starting with pediatric spine sonography.

Pediatric Spine Sonography

The reason we're doing it is primarily screening for occult tethered spinal cord.

And what I'm presenting is based on 25 years personal experience. I've had doing this.

When we talk about the hips, primarily we'll be talking about the detection and follow up of developmental dysplasia of the hip, and then also the child with the painful hip with joint effusion and the use of ultrasound to diagnose the effusion and if necessary, to assist in aspirating fluid from the joint.

So now we'll begin in pediatric spine sonography, regarding screening. Who gets screened, when do they get screened, why and for what purpose and how do you do it? And these are the topics that will be discussing.

It's actually sonography of the pediatric spinal canal rather than of the spine per se.

So we'll be looking at the spinal canal and its contents really throughout the, using ultrasound and especially in regarding musculoskeletal ultrasound orientation and technique are paramount and it's very important.

And much of the talk is really gonna be centered around orientation so that you realize where you are, where you should be, what you should be looking for.

The transducers that you wanna use have to be the appropriate ones, which means that they should be at a high frequency and high resolution.

Other features that can be very helpful are the extended field of view, and I've found dynamic cine loop storage to be invaluable, especially in dealing with children who can sometimes be moving targets.

Indications

Now the indications for the spinal canal sonography is generally to rule out the occult tethered spinal cord.

Now, what leads the clinician to think that this may be a possible entity in this child? It can be a back mass, which is midline or near the midline.

It can be a skin covered cyst.

It can be a cutaneous anomaly, which we'll discuss in a moment.

One of the common ones is a dimple and children with imperforate anus or anal atresia have a high incidence of occult tethered cords and they usually get screened.

And this example, this shows you a nice correlation between the ultrasound image and the MRI image.

It's an older study, but the ultrasound was done first and then the clinician just wanted confirmation.

But this is quite typical what you're scanning from the back.

The patient is lying prone, usually over a towel roll or a pillow.

And this is the lumbar canal.

The arrowheads are showing the spinal cord coming down farther caudally in the canal than it should.

And then you can see it's invested with this mass, which is consistent with the lipoma.

So the lipoma is tethering the spinal cord and the correlation with the MR, we can see the lipoma and then on the dorsal aspect of the cord and the low lying cord is really a perfect correlation.

This was in long axis. Now in short axis, the same thing.

You can see the patient is prone, here's the spinal cord here.

Notice how it's even sort of flattened.

And he faced on its side, where the lipoma is against it, just like you can see here on the MR.

So this is just an example to show that you can get very good correlation, especially when you're dealing with neonates or very young infants.

Normal Anatomy

Some of the normal anatomy in this extended field of view image.

You can see you're up in the lower thoracic upper lumbar area.

You can recognize the lumbosacral junction just like a lateral radiograph and the sacral canal.

And then the cauda equina.

And what you're seeing is the tip of the conus medullaris and all these echogenic are they rootlets in the fibers of the cauda equina.

These are the backs of the vertebral bodies, these echogenic structures here, these U-shaped structures are osseous portions of the spinous processes.

If you don't have extended field of view, if you have a steady hand and stay away from the caffeine, you can do the little trick that people often use in an OB ultrasound where you do a split screen and just be very careful how you fuse the images together.

But you get the same effect.

And in babies and neonates and very young infants, you get this exquisite panoramic view of the lumbosacral canal, as you can see here, to identify the conus, which we see in greater detail in long axis and the roots of the cauda equina.

And then also in short axis, you can see dorsal roots and ventral roots.

And this is the little tip of the conus corresponding to this area right here.

And that's what you want to localize and identify where it is in different portions of the thoracolumbar canal.

You can see how the spinal cord looks different at different levels.

It's nearly a circle and throughout most of the thoracic level, when you get down to low thoracic upper lumbar, it gets larger.

These are all at the same magnification.

You can see the roots of the cauda equina around this portion of the cord.

As you get further down, you see the tip of the conus and the roots of the cauda equina.

And then once you're below the cord, all you see is the cauda equina.

You can see roots on one side and roots on the other side.

And this area here is the spinal canal.

You can see the dura outlining it here.

And the vertebral bodies are all on the ventral aspect of this image.

This diagram shows you sometimes the conus tip almost looks like a little spider, and you can see it here with dorsal roots and ventral roots.

This is vertebral body. Here's a picture that we saw before.

We're seeing roots at the tip of the conus, and as you get further down, you can see all the roots of the cauda equina.

So it's important to recognize them and to know them for what they are.

Now in this movie loop, I'm gonna show you a short axis view where you're sweeping from the spinal cord down into the cauda equina, just as we discussed.

So you can see how when you start out, you see the cord, and as you go more caudally, the cord disappears, so you know where the tip of the conus is and where that is in relation to the location on the back.

Here's the kidney over here for orientation.

Same thing in long axis, the back of the vertebral bodies dura dura osseous portion of the spinous processes and cartilaginous portions here.

And as you can see, we're sort of sweeping from side to side, which you can see the spinal cord and the cauda equina quite nicely.

This composite view shows you the lumbosacral canal, cauda equina, sacrum, lumbar.

You can see the lumbosacral junction, the thecal sac extending to the upper sacral level.

If we go caudally, this is what the cauda equina appears like.

It has some low level echoes within it, not yet ossified.

And then these are the sacral elements that we're seeing here.

And sometimes if you're having trouble figuring out how deep you wanna be and where you should be in orientation, it helps sometimes to start with the sacrum and find it, and then work your way from there.

You find the lumbosacral junction.

You can see the back of the vertebral bodies.

It's almost like a lateral radiograph where you go from lumbar to sacral and you can see the thecal sac coming down here.

And then the fluid ends at S2.

And these are roots of the cauda equina that we're seeing here go up a little bit higher into the lumbar level.

You just see nerve roots, you go a little bit higher.

We see the conus just as we saw it in the spinal cord.

And its characteristic central echo complex that you can see as a line coming right through the middle.

Now, you might have noticed on some of the images that the spinal cord was oscillating.

This is a normal feature.

We may not see it in newborns, but in my experience, usually by about six weeks of age, you usually see it.

This is more popular in Europe to document the oscillation, but you can really just see it quite nicely here.

And this, it bounces as you see here with the heart rate.

And then in short axis, you can see it here.

And this is a normal feature.

Technique

So again, as we had mentioned, technique is crucial.

The most important aspect of technique is to get adequate flexion of the spine to separate the posterior elements, and that usually means putting a towel roll or a pillow underneath the baby.

Sometimes I'll even do the baby sitting and then they fall forward a little bit.

But if you don't have adequate flexion, you're not gonna see anything.

Abnormal Examples: Tethered Spinal Cord

A few abnormal examples, this is a useful definition of a tethered spinal cord from a pediatric neurosurgeon and it's self-explanatory and basically that the cord is tethered and pulled.

And then with this mechanical stretch on it, neural function is impaired and you really do not want the child to get to the state where this occurs.

And it makes sense because as the child grows the spinal cord is not able to ascend relative to the growth of the spine, it's gonna be pulled tighter and tighter.

So some of the children with occult tethered spinal cords may not present neurologically with any neurological impairment initially, but as they start to grow and lengthen, they do very often this spinal cord is not only down too low.

So here at the lumbosacral junction, L5 S1 level, here's spinal cord right here.

It's an older picture, but it shows you it's going down into the sacral area where it should not be.

Not only is it too low, but it's often eccentric within the canal.

I call it the low down stuck up appearance.

Here's another example you can see up in the low thoracic, upper lumbar area, and then it continues further and further and it's eccentric within the canal.

Cutaneous structures are probably the most common reason, cutaneous abnormalities why pediatricians refer children to us.

And the most common one is the dimple hemangiomas.

In the lower back area where there's a deficiency of the skin called aplasia cutis, a dermal sinus, a hairy patch, and a subcutaneous lump, subcutaneous lipoma, all have increased possibilities of having an occult tethered cord.

Now, the dimple, a lot of children have a little tiny pit or dimple that's way down by the coccyx in the butt crease.

And over the years we've seen that those little coccygeal pits, if it's just a very simple dimple, especially if you could, the pediatrician can see the bottom of it, have little or no yield.

And many places have ceased doing screening ultrasound for tethered cords in those children.

But if it's away from that area, yes, they should be scanned.

So here's a picture and you can see this dimple up here.

This is definitely one that has to be investigated, but if this dimple were way, way down here and you had to separate the butt cheeks to see it, those have very low yield in many places.

Don't do them. If the pediatrician orders it, we do it because lots of times there's apprehension and the family is really concerned about it.

So this is a fairly simple test to rule this out.

And imperforate anus, whether it's a high one or low one, they all have a possibility of having an occult tethered cord and we look at them.

So what are the aspects of the low down stuck up cord? It's low because it's too caudal within the canal.

It's eccentric within the canal, often dorsal.

And usually we see something that is tethering it, whether it's a lipoma or a thick filum terminale, fibrolipoma.

We may also notice that those oscillations that we saw become damped and less as you get closer to the area of tethering.

Now, how do you know where you are in the spinal canal? There are various ways we can do it and to assess exactly what our lumbar level is.

But in my experience, most tethered cords are obviously low. And this I don't really have to be as concerned about.

But some of the things you can try, you can identify the lowest rib and then move medially and call that T12.

This is in quotes because you may not know if the child has 13 ribs or 11 ribs, so that may be off.

You can identify the lumbosacral junction just like you do on a lateral radiograph.

You can count back from the sacrum and assume that there's five sacral elements.

That's an assumption that's not always true.

You can find the end of the thecal sac where the fluid ends in the canal.

We know from myelography that's usually at S2.

If you use all of these different signs and they all keep giving you the same level, then it's gonna be correct.

But again, as I had said in my experience, most tethered cords are obviously low, so I don't have to worry about it.

A newer one we've been trying is that looking at the origin of the psoas, which starts at L1, and here it is in cross-section, and you can identify that.

Nice. Now this is a little bit lower.

The psoas is already quite bulky.

That's the cauda equina, but we move cephalad to the origin of the psoas here and here.

And here's the kidney, there's the tip of the conus and that should correspond to L1 or in the vicinity of L1.

What we wanna do is locate the conus tip in both views.

And occasionally if you're really stuck, if it's in the mid lumbar area and it really is problematic, you may very carefully localize the tip of the conus, put on a radiopaque marker and take a radiograph.

I have found this not to be necessary.

I've only done a handful of these over the years, but occasionally it can help you out if you need to.

So just localize the conus tip in two views, mark it on the skin, put a marker, and take a radiograph and go from there.

A few examples, as is a child. You can see the ostomy.

It's a tethered cord case.

There's an anomalous sacrum presence or absence of the anomalous sacrum might or might not correlate with the tethered cord, but even if the sacrum looks okay, all imperforate anus kids get scanned.

You can see a spinal cord, an older picture, but it's coming way into the sacral canal on short axis.

As you can see, the reason this thick echogenic structure, which is the thick filum terminale, here it is on a cine loop on a newer case, a more recent case, the conus is coming down.

You're down by the lumbosacral junction, way too far down, and the filum terminale should only be about a millimeter or so in thickness.

And this is quite thick.

This is it in short axis right here, and you can see there.

So that was the problem there.

You do have sometimes occult tethered spinal cords that have skin covered, but they're more complicated cases, more than just the dimple.

I just wanna show you how ultrasound can really show detailed anatomy of abnormal cords and septa and roots and areas of fat.

And here's an MR for correlation, but also in looking at the rest of the cord to make sure the rest of it is okay, and here it looks fine, that can be a very useful purpose.

Now I've been talking about occult tethered cords.

Generally we do not scan an open defect such in the child with myelomeningocele or myeloschisis.

And that's not the reason why an ultrasound might be offered or might be requested.

But it really is to assess the rest of the cord.

And this is an example where there's scanning the defect is more caudal.

I'm going from transverse to longitudinal.

And you notice that this cord looks very different than anything you've seen before.

It's dilated and you don't see the central echo complex.

That's because this is all extensive hydromyelia and you can follow it up here, it is in short axis.

You can follow it up the cord.

So looking for diastematomyelia, which is a split in the cord looking for hydromyelia.

These are the reasons why you may examine the rest of the cord in children with an obvious spinal defect.

You can do it in older children, but it's really limited and I generally don't recommend it unless you really get some expertise in this.

And you also have to know your clinician because you may be able to tell them is that the conus where it is and if it's oscillating.

But if they need to know anything more than that, you need an MRI.

And generally most pediatric radiologists, once you're out of the neonatal period or perhaps the first few months of age, they usually rely on MR.

And these are other abnormalities we had already discussed and indications for doing our screening spine sonography.

Pediatric Hip: Developmental Dysplasia of the Hip

We're gonna switch topics now we're gonna look at the hips and regarding developmental dysplasia of the hip.

And once again, orientation to anatomy is very important.

And this is a study which has both static and dynamic aspects.

DDH has people on requisitions and pediatricians will put in clunks and clicks and hips may be lax.

The high association with breech presentation.

If the child also has torticollis related to fibromatosis colli, there's foot deformity such as metatarsus adductus or more extensively a clubfoot or if there's a family history that these children usually get screened.

Developmental dysplasia of the hip really covers a spectrum of abnormalities all the way from dislocated hip to some hip laxity, which as we'll discuss in the neonatal period can be physiologic.

And also the appearance of the acetabular dysplasia.

It has static aspects and dynamic aspects.

This scanning is done from the side.

Now for illustration, the hand is up here, but generally when we're scanning children, we have the hand right on the body holding the transducer.

But this was done so that you can see where we are.

We're coming in from a lateral approach.

And basically a hip is a ball in a socket and normally the ball should be in the socket.

The socket should be well-formed if the coverage isn't very good, if the socket is not as well formed.

You can see this is a nice curved one that covers the head.

This is a shorter acetabular roof.

It's more has more of a slope to it or if the head is outside of it.

These are all features that we're gonna be looking at and discussing.

It takes a little while to get used to the orientation of what we're actually seeing.

And if you compare a radiograph to that coronal long axis view that we were talking about, that view is very much like an AP radiograph of the hip.

Now, since we're talking about infants, the femoral head and the greater trochanter are unossified, and as such do not appear on the radiograph, whereas you will see them on the ultrasound as you can see here.

Three questions basically as the ball in the socket, does it stay within the socket or is there laxity with stress maneuvers? And is the socket well-formed?

If you think of an AP radiograph turned 90 degrees, that is the appearance that you get with the long axis or coronal view of the hip, such as you see here.

And in for orientation, look up in the corner and you can see how we're oriented.

So this is the lateral aspect of the ilium, the osseous acetabular roof, the unossified femoral head, the ossified metaphysis, the unossified greater trochanter gluteal muscles coming towards the greater trochanter.

And you can see that it is a ball and a socket.

Now here's one where it doesn't look quite right, the coverage, a lot of the femoral head is not covered by the osseous roof.

Generally about 50% of it.

If you drop a line down like this, about 50% of the unossified femoral head should be medial to that line.

This is medial, this is lateral, this is superior.

The innermost portion of the acetabulum is here and the head is not occupying there.

So this is a slightly subluxed hip.

Here's one that's subluxed even more.

And you can see where it is. It's out here.

It should be down in here.

And this is one where actually the hip is actually dislocated outside of the acetabulum And the femoral head, the greater trochanter, the acetabulum is down there.

The transverse view is even a little bit harder for people to understand.

And this is the baby that has to be, happens to be in a Pavlik harness.

But regardless of that, this is the orientation and you can see that you're axial or transverse to the baby's pelvis, but still coming in from the side.

And that view is very much similar to an axial CT scan.

If you can keep that in mind, that'll help you to understand what you're seeing on the transverse ultrasound view.

So here's a CT scan of a baby.

This one does have ossified femoral heads as you see here.

And if you again, if you turn that axial CT 90 degrees, that will look the way the transverse ultrasound view appears.

So here we are turning it. This is the pubis and the ischium.

So that's anterior, that's posterior, and that's similar to this view of the ultrasound.

Lateral medial posterior anterior.

Here's part of the femoral shaft, here's the head.

Now this view is not useful for acetabular morphology, but it is good for showing you where the head is in relation to the acetabulum, notice that much of this posterior acetabulum is very cartilaginous in children.

And that's what you're seeing here.

So here's one where the head is out a bit lateral and posterior instead of being down in here.

So it's slipping out this way.

Here's one that it's this is an older picture, but it's out.

More So here's the issue, the portion, here's the cartilaginous posterior aspect of the acetabulum.

This epiphysis, this head should be down in here, resting on this instead, it's gone laterally and posteriorly hips, when they go out, tend to go laterally, posteriorly, and superiorly.

This is the Barlow maneuver. Pediatricians do this.

We also do it during our study, and you're looking to see with pushing like a piston, whether or not the hip goes out of the joint.

Now here it's frankly leaving the joint in this diagram, it could just be subluxing and partially leaving it.

So show you a few dynamic studies.

This is a coronal view.

And you can see here, there's this is a one day old, there's a little bit of laxity.

This head is drifting out a little bit as we push on it, as you saw with the Barlow maneuver.

But at one day of age, this can just be physiologic.

In fact, physiologic laxity can be present for a month or so.

But you'd wanna follow it to see what is going on in this one.

This is another coronal view.

So superior, inferior laterally. This is a one month old.

The acetabulum is here, this head should be down here.

And here I'm trying to reduce it and I'm unable to fully reduce this hip.

This is a transverse view, so lateral and posteriorly.

And this is a seven day old.

And what I'm showing you here is abduction and adduction and hips that are really loose.

When you adduct, when you bring the knee towards the midline, this space will widen here or else the hip will slip out and drift posteriorly and laterally.

This is doing neither. So this is normal here.

What I'm doing is you can see this head, this is also a transverse view.

Posteriorly anteriorly, laterally medially.

And this head should be resting more on this ischium and it isn't.

You can see that it is lax and even when I abduct, I cannot reduce it fully.

So this is more than just physiologic.

This is what you wanna prevent the child with the missed DDH, which can then become more problematic to fix.

And of course, this is appropriate statement, so you don't wanna look at them too early, too often, or too badly, too early is the fact that if in the first week, two weeks, four weeks, that sometimes there can be a little bit of laxity and then you're committed to having to follow them.

So generally I'm not gonna go into all of the clinical indications and what, when you study them when, but if you have a hip that's just perhaps a little bit of laxity, you may wanna wait until about four to six weeks or so.

Let the physiologic laxity go away and then check them.

There's an interpretive pitfall that you can have.

If the hip has a contracture, this is a child.

You can see there's a contracture here, a deformed femur.

Actually, it ended up the head was here, but when the person did the ultrasound, they weren't aware of a radiograph.

And what they were seeing out here, and this coronal view, superior, inferior, this was misinterpreted as the femoral head or as it's really the greater trochanter, the head.

You can't see because of the contracture and the anatomy is all distorted.

That child then had an arthrogram, which shows you that clearly the femoral head is in the proper place.

But that's a well-known pitfall that you should be aware of it.

So when you have children with particular deformities like that, especially like arthrogryposis or proximal focal femoral deficiency, bowed femurs, you should really be mindful of what's going on with the child and what the radiograph shows.

Pediatric Hip: Painful Hip and Joint Effusion

Now for a new topic and our final topic, we're gonna talk about the hips again, but from a different aspect.

Really a joint effusion.

Usually we're looking at a child with a painful hip, and our purpose with ultrasound to identify the effusion to aspirate the fluid.

The painful hip can have multiple etiologies as you read here, but we're gonna be concentrating on these two transient synovitis and septic arthritis ultrasound can also provide guidance to obtain fluid.

Now, instead of ultrasounding from the side, as we did with the DDH cases, the hip effusion is localized from an anterior aspect.

And here in this example you can see the baby supine.

Here's the left thigh, here's the right one, and you're looking, in this case, they're looking long axis right across the front of the hip.

But this is the femoral head and this is the femoral neck.

And this is anterior and inferior.

This is that long axis view.

You can often see the capsule and if the capsule's bulging, that's indicative of an effusion.

You can't always rely on radiographs.

In this case, there is a little bit of widening on this side, but we've had children with effusions where the radiograph looks normal.

And this is the ultrasound on the same child.

And there's marked bulging of the capsule.

This is the metaphysis, the neck of the femur.

This is the psoas, just as in this diagram, The looking over the femoral neck works because here on this arthrogram you can see that the hip joint extends well down the femoral neck.

And that's what we take advantage of.

Looking along this axis, here's that larger effusion that you just saw.

You can also pick up smaller effusions.

This is the abnormal side. This is the normal side.

Very subtle difference between the two of them.

When you compare the normal side with the abnormal, which you should always do, you wanna be sure that the position of the femurs is the same in both of them.

Here's a septic right hip, here's a normal side.

Here's a septic hip with very echogenic fluid, very thick capsule.

And you may say, no surprise that this is a septic hip with pus in there.

You can't always rely on the ultrasound appearance.

This case you could, and this is the fluid that was obtained with staphylococcus aureus.

Here's another example. Very similar appearance compared to the normal side here.

The psoas is bulging and pushed forward by this very echogenic fluid within the joint capsule compared to the normal.

So these findings can be suggestive that it's a septic hip, but they're actually non-specific.

And certainly not seeing these findings do not exclude a septic hip.

Meaning if you see fluid but it looks clear and anechoic that doesn't exclude the possibility that it is septic effusion.

We looked at the possibility with a power doppler with its increased sensitivity to hyperemia could be useful.

We had both a clinical series and an animal study that we did at University of Michigan.

And this is an example.

You take the normal side, you adjust your settings, you just get a little bit of a signal along the bone in the capsule, use the same settings, go the abnormal side, and you can see there's much more power doppler signal.

This was indeed a septic hip.

And what we found was when it was positive it was septic, but there were also cases of septic hip in which the power doppler signal was not increased.

So it's not a perfect study.

Same findings we found with the animals in that when it was hyperemic and increased signal and power doppler that correlated with the septic effusion.

But sometimes early on in the course of the septic effusion, this had not yet happened.

So it has a good specificity but not a high sensitivity.

So if the power doppler is positive for joint effusion, it's likely septic.

However, if it's negative, does not exclude the possibility of an early septic effusion.

If people have also looked at any role for clinical predictors.

And it ends up that even the clinical criteria of one versus the other is not perfect.

You can look at fever won't bear weight, sed rate over 40 white blood cell count and the blood over 12,000 in these two studies.

If all of these factors were positive, it was very likely it was a septic effusion.

If all four factors were negative, it was very likely that it was transient synovitis.

The initial study, which was a retrospective study out of Boston Children's where they looked at many factors, this was almost to 99%, if we're all positive was septic.

And the same amount of certainty if they were all negative.

They then repeated this study, doing it as a prospective.

The numbers were still quite good, but not as good as it was on the retrospective one.

A study from the University of Michigan by pediatric orthopedists showed a high correlation with the C-reactive protein.

And certainly if all of these are positive, it's a very high likelihood that this is a septic effusion.

Now the reason we bring this up is that there's some argument that if your clinical criteria are all negative, perhaps you don't wanna tap that hip because there's a possibility even though we use an aseptic technique that you could introduce bacteria and if they're all positive, you have to go to the operating room anyhow to really clean out the joint.

The aspiration is not therapeutic.

The use of ultrasound is very useful.

And ultrasound guided aspiration in the situation where some of the factors are positive and some of them aren't, then you're dealing like with a 60 or 70% likelihood of septic effusion and you can't let that slide.

You really have to figure it out.

Ultrasound-Guided Aspiration

So how does ultrasound help you with aspirating the fluid? Well, you can identify the effusion in two views, long axis, short axis.

And then as you do here, you just kind of see where you are.

If you wanna just note where you are and if the child's not moving, all of our children are sedated.

When we do this, you just go straight down and you should get the fluid.

If you wanna use ultrasound guidance while you do it, that's fine.

And here's a long axis view and a effusion and you can see where the needle is pushing on the psoas.

It hasn't popped through yet.

And then in this picture you can see the needle coming down, which is in the joint space.

So it's really your choice if you wanna watch while you're doing it or if you just want to set up your coordinates and then do it, whatever you like.

And then you can see here's the needle is in and then post tap, it actually looks pretty normal in that picture.

So they got the fluid out. Couple little caveats.

One thing you wanna be sure of is that you can see the cartilaginous head, here's the femoral head, the cartilage over it.

You can see the psoas and note that not to be confused and thinking that this is a small amount of fluid.

Remember we're supposed to, we should be seeing the fluid coming down over the femoral neck.

So therefore, looking in this area, don't confuse a hypoechoic portion of the femoral head as fluid because it isn't.

You really have to rely on seeing it in the femoral neck.

The other thing which is in this picture is this little echo density here.

Not to confuse that with some kind of debris within the joint capsule.

This is just a posterior reflection of the joint capsule which had been described a few years ago.

Other Diagnoses

Now, could there be other diagnoses And you wanna avoid having tunnel vision.

So for instance, the psoas, as you had noticed, is sitting right on top of the joint.

And if there's a problem there that can present with hip joint pain in this case, you can see there really is no effusion.

But the psoas was really thicker than it should be and didn't look right when patient was scanned a little bit more towards the pelvis, you saw this complex fluid collection.

And then indeed, you can see later there was a CT scan.

This is up in the pelvis now 'cause here's the ilium that this child had a large psoas abscess.

And here's the ultrasound picture that correlates with that transverse CT view that you just saw.

So psoas abscess can be an entity which will present with hip pain.

You can also have psoas irritation from other reasons.

And this is a case that I had a few years ago and went down to the emergency department and this 10-year-old came in but having hip pain for three days and was a small effusion on the right comparison left.

So very small effusion.

And actually you can hardly read this up here because this is history that was not given to us, that this child had a neuroblastoma three years before and with a recently treated recurrence.

And when I was talking to the patient, he said, well actually my pain is even a little bit higher than just in the hip.

So with the ultrasound, I looked north a little bit and going up into the pelvis and here's the psoas, and lo and behold, there's a mass resting right on the psoas and in short axis you see it here.

And actually then as we looked into his record, we realized his story about the neuroblastoma.

Here's a cine loop showing the short axis, ilium iliacus muscle.

Here's the neuroblastoma sitting on the iliopsoas and psoas causing his joint problems and his small effusion, which was probably just sympathetic.

And here it is in long axis going towards the feet, which is up in this direction.

There's the psoas heading towards the hip down here, here, and you can see how that mass sitting on the psoas was irritating it and causing that.

So you really wanna have a focus when you're doing ultrasound, but you don't want to have tunnel vision.

And that's it. And thank you very much.