Sonography of the Pediatric Hip - SD

Introduction

I'm Michael DiPietro.
I'm a pediatric radiologist at the University of Michigan,
and 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.
We're gonna talk about sonography of the pediatric hip.
Two aspects of the pediatric hip
that we'll discuss are first
regarding developmental dysplasia of the hip, also noted as DDH,
and also about the jaw
with the painful hip in which we're usually looking
for a joint effusion.

Developmental Dysplasia of the Hip (DDH)

Regarding DDH,
this talk will concentrate on providing an orientation
to the anatomy, what it is that we're seeing
and describing static
and dynamic aspects of sonography of the hip.
When looking for DDH and 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.

Indications and Associations

To begin with DDH, the reasons
for DDH are varied, 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 breach presentation,
and sometimes the children have other deformities,
such as torticollis
or a rye neck, usually related to fibromatosis Coley.
The child could have a club foot
or less severe foot anomaly, metatarsus abductus.
And both of these entities are often associated with a child
who might have oligohydramnios and tight fetal packing.
And then there is a family predominance
of family history sometimes of DDH.

Spectrum 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 acet itself and,
and varying categories in between.
As you can see, and there are static
and dynamic aspects to this entity, which is what 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.
And regarding dynamic, we're looking for the stability
or laxity of the hip, dislocated ability, sublux ability,
or if there already dislocated or sublux reducibility.

Sonographic Technique and Orientation

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
in coronal screening, and scanning with the coronal plane.
Most of the scenarios performed from the lateral aspect,
and you can hear the 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.
And this is the type of view that you might be seeing.
Basically, the hip joint is a ball and a socket,
and 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,
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,
and is the socket well-formed, meaning that,
is the acetabular mature?
And 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.
And 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.
And you can see what we see on the sonography
is the femoral head.
This is the ossified metaphysis.
This is the cartilaginous acetabular the roof.
This is the osseous acet of the roof.
This would be seen on an x-ray as well.
This is the lateral aspect of the ileum.
These are gluteal muscles coming around,
and you can see indeed the ball is within the socket
as you see in this picture.

Coronal View Examples

Now, here's one where it looks a little different,
and you can see that the head isn't as,
as far into the acid tablum.
This is the medial aspect of the ace tablum here, instead
of being down in here as the other one was,
this one is now drifting laterally,
and this is some subluxation.
And in addition, the ace tabular 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 trca here.
And this is the ossified portion of the proximal femur.
This is all cartilaginous acetabular roof,
which is actually echogenic and pushed up somewhat.
And 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,
and here's the femoral head.
Acetabulum is here. And actually this is very,
very far posterior within the ace tablum,
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 s head,
you can see the femoral head,
you can see the greater trocanter.
This is the ossified proximal femur.
And this femoral head, if it were normal, would be way,
way down here, which is much more medial.
And 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 tro canner.
These are the gluteal muscles coming around laterally.
And 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, very posterior in this coronal view,
you see this large bulk of cartilage.
This is the very posterior cartilaginous portion
of the ace tablum.
In this portion of the ace tablum,
you should not see the femoral head at all.
And 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 ileum in the acetabulum here
and the acetabulum here,
and 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 dermatological hips.
But I'm showing you this picture to show you how,
sometimes on radiographs even, it's very,
very obvious that the hips are dislocated.
Now, in this trial sonogram, this is the femoral head here,
which now you can see, and this is the ileum,
but you're nowhere near any of the normal anatomy
of the acetabulum.
This is very, 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, very posterior aspect of the acetabulum.
This is all that cartilage that we showed.
And here it is, the femoral head is right over it.
So this is a very, 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,
and in a moment you'll see your orientation for those views.

Transverse View

Now, the transverse view, this child happens
to be in a pavlock harness that you can see here,
but is also done from the side done from lateral,
but the transducers turn 90 degrees, so it's transverse
to the baby's body.
And that 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.
His 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 isum.
Here's the femoral head, anterior posterior,
and on a sonogram.
This is anterior, this is posterior.
This is the part of the isum here.
Here's this posterior cartilaginous portion
of the ileum, and 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.
And this one, this is an older scan.
This is the femoral metaphysis. There's the epiphysis.
The issue is here. This head should be way down here.
And 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.
And you can see again the femoral head within
the acetabulum.
Here is right where it should be another picture.
Now, in this sin 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.
And 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 ace tablum.
But this is right where the femoral head should be.

Dynamic Maneuvers

Now, this is a maneuver where we're abducting
and abducting the leg.
So when you can tell by the position
of the metaphysis here.
So here we will be Abducting in a moment
when the this looks more ver.
There we go, abduction with the knees coming out.
And then abduction,
when this is a little bit more horizontal on the screen
and hips that are very, very loose when you add duct,
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.
And then what we'll also do is then
we'll keep the child a deducted,
and then we'll push like a piston.
This is the Barlow maneuver,
and we'll see if the hip goes out or not.
So we have a couple of dynamic case studies
to show this is a coronal view and this is normal.
And this is really, here's the ball, here's the socket.
You see the greater trocanter coming into the picture.
Here's the medial aspect of the isum.
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.
And you can see how this distance here is increasing.
And as I'm pushing on the hip, it
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 fall 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 AST time 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.
And this is all useful information for the clinician.
Now we're switching to the transverse view, kind
of like the CT scan.
And now I'm just doing some abduction and abduction.
And 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.
And this is all normal in this view.
The gluteal muscles are coming around from behind
and then coming to or over the greater trocanter 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.
You, 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 ace tablet is dysplastic instead of a nice cup.
This is a very steep roof.
And then this head is completely out,
and that's what you wanna avoid.

Pitfalls in DDH

And then Dr. Harkey 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.
Now, a couple of problems that the common problems, one is,
regarding the transducer is 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 ileum, the balls 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.
And you can see if you just froze on
that picture right there, you would think that's a very
dysplastic shallow ace tablet 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.
And 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 it,
track the person down to change the study.
So I said, well, I'll just try it.
And 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.
And this is the kind of view you get.
And you can see the real challenge
because a lot of ossification is already present.
You don't see the ace tablum that, well,
here's the femoral head, here's the ace tabular roof.
When I did this study, I felt that the head was,
the ball is in the socket.
The head isn't within the acid tablum,
the ace Tablum looks fairly normal,
but you could have told all this much more easily and,
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.
And 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.
And I told him what my feeling was about this.
And 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 bow deformity.
And 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.
And you can see there's a healing fracture.
There's a bowing deformity,
and then the question is, is the hip in or out?
And 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 was completely dislocated.
But in reality, it really wasn't
because this child then went to the had an arthrogram.
And 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.
And the problem was because of the deformity
and the flexion contracture.
The sonogram was just showing the greater tro,
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.
And 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.
And this is proximal focal femoral deficiency.
The hip contractures, other kind of bow deformities.
And in the end, you really have to be aware
of what's the clinical story with the child
and be aware of the plane radiograph.

Painful Hip and Joint Effusion

Now a new topic to switch overs to joint effusion
And basically with sonography is to identify a HIPA effusion
and then perhaps facilitate aspiration
of the fluid for analysis.
Now, 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, very damaged hip,
which will follow the child forever
and would might even have to end up
with a hip replacement later.
So basically, we're gonna be talking about HIPAA fusion.
In contrast to the DDH, instead of coming from the side,
we localize it anteriorly.
And then whether or not can we tell if it's septic or not?
And actually, we're gonna see that our ability to tell,
based on imaging alone is rather limited.

Identifying Effusion

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 fusion.
And when there ist a fusion, 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 sous 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.
And then p represents sous muscle on all these.

Septic vs Non-Septic

Now, is the effusion containing bacteria, yes or no?
And basically we've learned
that our ultrasound criteria is really not perfect.
You can look at various parameters, echogenicity
of 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.
And 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 capsules thick.
It is very echogenic.
Clinically that's what they're worried about.
And 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.
And 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.
And 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.
And 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 are looking
at these four criteria.
And basically, if all four are positive, it's very,
very likely to septic hip.
If all four are negative, is very unlikely,
that's a septic hip.
At University of Michigan,
when our 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.
And 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.
And 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.
And then if you don't wanna use imaging
to actually put the needle in,
just go straight in at that point.
And 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.
And here's a movie that a case that we did,
and you can see the you're
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
look 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.
You 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.
And 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.
And you could see this with or without fluid in the joint.
And 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.

Pitfalls and Differential Diagnoses

So we had a child who came in.
This is a typical story which you might see in your,
in your emergency department.
And here's a radiograph,
which really doesn't show that there's any fluid.
And 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 penate structure of muscles.
And 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.
And 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
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 sous irritation,
or a sous abscess can present just like a infected hip.
We really did not find an effusion here,
but the sos muscle looked rather thick.
This is a case from Dr. Harkey.
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 s sos.
Now an advantage of CT is a more global picture
or an mark 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 SOAs if
you're not getting all your answers
just over the hip joint.
Here's the sonography in that case
and just showing comparable pictures.
Well up into the pelvis now.
And 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 ssus,
it doesn't necessarily have to be infection, was a case
that I did and down to the emergency department
and saw this smaller 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 s sous.
This history was not given to us at this time,
that he had an neuroblastoma,
a few years before.
And as I scanned up along the s oass,
here it is in lung axis, there's a mass sitting right on it,
and here it is in short axis.
That was irritating the s oass.
And we think the effusion was actually sympathetic.
And this is a transverse view.
Here's the ileum, and there's this mass sitting right on it.
And this was actually a metastasis
that had dropped into the lower abdomen, was growing,
pressing on the solis, 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.
And you can see in musculoskeletal ultrasound,
you have your normal layers broken down
that we're all familiar with.
This is very abnormal,
very emitts ill-defined tissue planes,
very indistinct tissue planes hyperemic.
And 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.
And this is a very strong suggestion
that this trial actually has osteomyelitis, which has
to be drained in the operating room.

Conclusion

So basically, in conclusion, in regard to DDH,
what we've covered is 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.
And then plus some differential diagnoses
and other things to be mindful
of when you're investigating the hip.
And thank you very much.