Sonography of Developmental Dysplasia of the Infant Hip - SD

Introduction

Good evening.

I'm Henrietta TLAs Rosenberg from Mount Sinai Medical Center in New York City, and I'm going to be speaking about sonography for developmental dysplasia of the infant hip.

Sonography has revolutionized the evaluation of developmental dysplasia of the infant hip.

Learning Objectives

The learning objectives for this presentation is that when I'm done, you should be able to list the risk factors for developmental dysplasia of the infant hip.

Describe the protocol and technique for performance of dynamic hip sonography in infants and how to measure the graph angles.

You should be able to recognize the ultrasound appearance of the normal hip, the subluxated hip, and the dislocated hip, and be able to list when to perform sonography of the infant hip.

Definition and Incidence of Developmental Dysplasia of the Hip (DDH)

In the past, dislocation was the term that was used for abnormalities of the infant hip, but in 2010 we used the descriptor of developmental dysplasia of the infant hip, which is meant to include all aspects of abnormalities in the development of the hip, including dislocation, subluxation, and dysplasia, whether or not it occurs prenatally or postnatally.

The reason that this term was developed is that it really more accurately describes the pathogenesis of DDH.

It's known that some children develop DDH during the first months of life after birth and it helps to eliminate placement of blame on the pediatrician or the neonatologist.

When a child develops DDH beyond the neonatal period, the incidence of DDH is approximately 1.5 in a thousand infants, the incidence is up to about 6%.

When there is a family history of developmental dysplasia, particularly in a parent or a sibling, there is a four times the incidences of DDH in female babies compared to males.

And although I don't like talking about litigious issues, we have to be realistic in realizing that 10% of lawsuits against pediatricians are because of mist, DDH.

And so it's become very important not only in the care of the child, but in the preservation of the pediatrician's reputation.

Clinical Evaluation of the Hip

Evaluation of the hip clinically is part of the routine physical examination of a newborn.

And during the first year of life at the periodic checkups, the doctors are looking for asymmetry of the skin folds.

They may notice that there's shortening of the thigh, particularly in babies who have a superior dislocation.

There may be limited abduction of the hip.

Usually it will be less than 70 degrees when there is concern.

And in the normal baby there's about a 10 degree flexion at the hip and at the knee.

In babies with DDH, there may be loss of this normal flexion.

Clinical Tests: Ortolani and Barlow Maneuvers

Two of the tests that are done clinically in the evaluation of the baby's hip are for the purpose of determining whether or not a sublux or dislocated hip can be reduced.

And the other test is to determine if the hip is unstable.

So let's begin with talking about the ani reduction test.

This was actually determined in 1937 by Dr. Ani who determined that by taking the hip and abducting it and externally rotating it, that a hip that was unstable would create a clunk as it's passing over the bony acetabulum into the region of the center of the acetabulum as it is being reduced.

This is basically difficult when the baby is crying and the baby is not relaxed.

So having a way to see this during real time observation with ultrasound is extremely helpful in determining whether or not the clunk or as we often hear it called the click is significant.

Clicks are probably just due to stretching of the ilio sous tendon, but no one's going to turn away a baby who has what's described as a click and rather than a clunk, for the ultrasound.

The other test that's done is the Barlow dislocation test, which was described in 1962 by Dr. Barlow.

And basically this is the test that is used to detect instability of the hip so that the knee is adducted and there is a pistoning maneuver that is done where the head of the femur has some gentle pressure against it by pushing the hip posteriorly and letting it go to see whether or not there is a sense that the hip is unstable.

Risk Factors for DDH

Now there are several risk factors for DDH and the mechanical factors are usually related to restricted space in utero, the so-called fetal packaging deformities.

They are seen when there is maternal prima parody.

First baby could be that there's less amniotic fluid than normal.

Sometimes a baby is growing inside a horn of a bicornuate uterus and the space is quite limited.

And if the baby is extremely large, there may be a problem with a packaging deformity.

And so the baby is not in a position in utero where it's possible to have the hips flexed so that there is appropriate formation of the acetabulum around the femoral head.

And then there are other problems that may be seen in babies who are having problems with restricted space in utero, particularly congenital torticollis where the baby is born with the head tilted toward one side, they may have foot deformities such as a clubfoot or a calcan varis deformity.

One of the most important mechanical factors that may be a risk for DDH is breach presentation at birth.

There is a 25% risk in babies who are born after being in a breach position.

About 3% of deliveries are breach and about 30 to 50% of patients with DDH have a history of breach delivery.

As we can see from these pictures of various infants, when the legs are extremely extended, it can be a problem in terms of promoting dislocation.

The hips and the knees are quite extended during a breach birth.

And the extreme flexion during the breach delivery causes contraction of the ilio sous muscle, which promotes even further dislocation.

Another factor is when people swaddle their infants and it's well known that there's a higher incidence by about 2.5 to five times what we see in, the other populations in the world amongst the Native Americans and lap landers where they actually tie the babies into a papoose with the hips and the knees extended.

By putting the baby in that type of appliance, it is contradictory to, I have to go back.

I'm gonna do this whole slide again. Okay.

Another risk factor is swaddling infants.

It's well known that in the Native American and Lapland of populations where the babies are actually tied into a position where the hips and the knees are extended with no flexion at the hips, that there is a 2.5 to five time the incidents of DDH than in other populations.

Other mechanical factors are neuromuscular abnormalities, babies with spina bifida who have considerable spasticity, the same in babies with arthrogryposis, and then the reverse in babies with Alos Danlos where they have quite a bit of laxity of the hips.

And it said that there is a higher incidence of DDH in babies with juvenile scoliosis.

One of the most important factors in DDH is when excess estrogen causes the block of collagen maturation due to the impairment of the cross linkage of fibrils in the joint capsule as well as in the cartilage, and therefore in babies until the estrogen effect decreases after birth, which takes usually within the first four to six weeks of life to be significantly decreased.

Enough to note that there is no longer physiological laxity of the hip.

Pathophysiology of DDH

Now the pathophysiology of DDH is developmental and it's quite a complex etiology in some babies.

The developmental problem is because there's a shallow cartilaginous acetabulum in this situation, there's poor structural support for the femoral head, and so the head moves and stretches the supporting ligamentous structures.

The other situation is when the acetabulum is adequate, but there are lax ligamentous supports.

And so excess motion of the head causes deterioration of the acetabulum, which can progress to DDH.

Historical Imaging Methods

Now up until 1895, when x-rays were discovered by Dr. Rein, there was really no way to make the diagnosis of congenital hip problems except by clinical examination.

And initially when x-rays were developed, it was possible, and we still do this at times when indicated in older babies, we will get x-rays with the hips in a neutral position and also in a frog lateral position to try to determine if the head of the femur is normally aligned with the acetabulum and what the shape of the acetabulum is.

Only in the very young babies, there's no ossification of the femoral capital epiphysis, and so we really cannot determine whether it's formed properly.

And often there are challenges in deciding if the hip is normally aligned.

A long time ago, stress views were attempted by abducting the thighs about 45 degrees, and internally rotating them and getting an x-ray in that position to determine if the hip under stress was subluxed or dislocated.

Certain classical landmarks, lines and measurements were established as criteria for plain film diagnosis of DDH.

First of all, it's important to look at the acetabulum to decide is it round, is it shallow?

Is it steep? It's important to look at whether or not the ossification centers in the femoral heads are formed, and if they appear symmetric because there may be a delayed ossification in the side that has developmental dysplasia.

The head generally doesn't ossify until about three to six months of life.

Now the lines that were developed are meant to help the imager know whether or not the head of the femur is appropriately located.

So the first line that's drawn is a horizontal line that goes through the cartilage parts of the pelvic girdle, the tri radiate cartilage between the iliac bone and the isim.

And this line is drawn horizontally.

Remember H for GaN rhina, H for horizontal and then perpendicular to GaN rhinos line.

A line is drawn through the superior laterals aspect of the acetabulum.

This is called Perkins line.

Remember P for Perkins and P for perpendicular.

And this should form an X with the horizontal line GaN reers, the head of the femur should be seated in a position that will allow it to be demonstrated or projected if it isn't yet ossified overlying the medial inferior quadrant formed by the intersection of GaN rhino and Perkins line.

So on this side we see it looks normal on the other side, if we were to extrapolate where the femoral head would be, it's obviously not in the medial inferior quadrant formed by the two lines.

We also look at acetabular angle and we do that by drawing a line through the tri radiate cartilage, the hi and rhino line, and then a line that passes through the superior lateral and the inferior medial aspect of the acetabulum.

And if you wanna remember one number that basically will be an average of males and females.

Just remember 27 degrees is approximately the most that we should see when we measure the acetabular angle.

And here we can see how steep this acetabulum is compared to this nice little rounded acetabulum on the left side.

And it's obvious that the angle is over and above what it should be.

The other line that we look at is S sheen's line, which we draw along the medial femoral neck.

And it should form a continuous arc with the undersurface of the superior pubic bone and then come along the lateral aspect of the inferior pubic bone.

So it goes around from the neck to the superior to the inferior.

And in the normal situation, it's a continuous arc.

In the abnormal situation, we can see that there is disruption of she's line.

So let's look at an x-ray.

Here we have an x-ray of a young baby who has no acidification yet in either of the femoral heads, and we can draw gin reiner's line, we'll draw the Perkins line perpendicular.

And as we look at the left side, we see that the head would be appropriately seated in the medial inferior quadrant formed by these two lines.

On the right side, however, we see that that head is superior, laterally displaced.

Contrast Arthrography

Well moving on in history.

By the 1960s contrast, arthrography became part of the imaging armamentarium and it really was helpful to be able to evaluate the femoral head to look at the S tabular contours.

Under fluoro, it was possible to see whether the hip was unstable and also to try to do a reduction maneuver under fluoro.

And if indicated, the patient could be placed into a spike.

A cast could also see the soft tissue abnormalities around the hip.

But this is invasive, and so this is not ideal for the children.

It requires ionizing radiation.

There's a risk of infection and hemorrhage when injecting contrast into the joint.

It requires anesthesia, sedation, and it's certainly impractical for serial imaging.

Computed Tomography (CT)

Well then in the seventies, CT came along cross-sectional imaging that allowed the bony detail to be demonstrated.

It wasn't invasive and it was very helpful in looking for the late diagnosis of DDH when the treatment wasn't satisfactory.

It could be done as we see here with a patient in a cast and was useful to determine the centricity of reduction after closed reduction, but we couldn't see cartilaginous structures.

And so it really wasn't ideal for the evaluation of the un ossified femoral head.

The children were being radiated as part of the procedure and they may require sedation in the seventies.

Ultrasound Development

Realtime ultrasound was developed late in the seventies and finally in the eighties.

Dr. Graf on the other side of the ocean in Austria developed articulated arm scanning while on this side of the Atlantic, Dr. Harkey at DuPont Institute showed how we can use ultrasound of the hip during real time observation without radiation, without puncturing the hip joint, no contrast, no sedation.

And with this technique we could see a detailed evaluation of the cartilaginous femoral head and demonstrate the relationship of the head to the bony as well as the cartilaginous acetabulum.

So for the first time, we had a dynamic exam that we could use during various positions of the hip to determine whether or not the alignment was normal over and above.

Looking at the morphology alone, it could be used during intraoperative guidance, during reduction, and can be used during treatment most easily when the child is being treated with a plic harness or brace.

And then we can use it for serial evaluations in a regular fashion until the hip is appropriately treated.

And there's no longer a need for the harness or the brace.

Magnetic Resonance Imaging (MRI)

MRI is also a modality that has been used for the hips.

It's not ionizing, it's not invasive.

We get exquisite anatomic detail of the soft tissues and the cartilaginous structures and it can be used with a cast.

We can use the orthographic effect of fluid in the joint.

And with open MR and short bore it is a little bit more acceptable, but it does in young children require sedation and anesthesia and when they get older, there's the problem with claustrophobia.

And let's not forget either that it's certainly not a cost-effective modality and most centers really don't have time to screen hips or with the MRI, the most important thing is to make the diagnosis of DDH early so that appropriate therapy can be instituted promptly to ensure normal development of the hip.

The goal is to prevent long-term complications in these babies so they don't end up like many did in the past before the days of ultrasound with leg length discrepancy, gait abnormalities, pain and osteoarthritis.

Anatomy of the Hip Joint

Let's talk a little bit about the anatomy of the hip joint.

Before we go on and talk about how to do the ultrasound and how to interpret the findings.

There is a bony component to the acetabulum and there is also a cartilaginous component.

Remember, the cartilaginous component has hylan cartilage in it with at the very tip a fibrous tissue component.

We also will look for the joint capsule surrounding the hip joint.

Now we look at the hip with the baby in a horizontal position, but for purposes of just discussing anatomy, I've turned the ultrasound of the hip into the same vertical alignment as this drawing.

So we are looking at the hip from a coronal approach in a longitudinal approach, and we see here the head articulating with both the bony parts of the acetabulum as well as the reradiate cartilage.

So here we have the ileum.

Here's the tri radiate cartilage between the ileum and the isum and the pubis.

And we also see this cartilaginous head with its little dots and lines that represent the cartilaginous rests.

Here's the cartilaginous labrum.

The hylan portion is quite echo eent or somewhat hypoechoic.

And then the tip is more dense because of the fibrous deposition.

And then we have the joint capsule coming around and we have the three gluteal muscles, the gluteus minimus medias and maximus.

Here's gluteus minimus medias and Maximus, the subcutaneous adipose tissue and the dermis.

Here we can see the ultrasound in comparison with an x-ray and see how well we can see the head by comparison on the ultrasound because it shows cartilage beautifully.

And this is where we would extrapolate the head to be along with the gluteal muscles.

Now we're gonna look at the ultrasound in the position that we use during the dynamic hips sonogram.

Measurement of Graf Angles

Before we do that though, I just wanna take a few minutes to talk about how to measure the graph angles because there are orthopods all over our country and in the world who really depend on the alpha angle to help them know whether or not the osseous convexity of the hip is normal or not.

So the first thing we're going to do is just go over the anatomy for a last time in this direction.

This is the hip in a horizontal plane.

So the baby's head is here, the feet are here.

This is the iliac bone, the tri radiate cartilage, and this is the acetabulum.

Here we can see the rounded femoral head, the cartilaginous labrum, the fibrous tip, the joint capsule comes around here and we have gluteus minimus medias, maximus muscles.

Here's the subcutaneous fat and there's the dermis.

So to draw the alpha angle, we're going to draw a line along the iliac bone.

It should be done in a horizontal plane.

And then we draw the line along the osseous convexity of the hip.

The angle that's formed here is the alpha angle, and this should measure greater than or equal to 60 degrees.

The other angle is the beta angle, and most of the orthopods really are not concerned about it.

We know very well that as a hip is sublux or dislocated, it's going to push on the cartilaginous labrum and that angle is going to increase.

But let's look at how we measure it because often you can't get the alpha angle out of your ultrasound equipment unless you do the beta as well.

So we draw a line along the iliac bone and then we draw another one along the cartilaginous labrum.

The intersection of those lines is where the beta angle is.

So the normal beta angle measures less than or equal to 55 degrees.

So Dr. Autograph developed this chart in which we can look across and see the various sizes of the alpha and beta angle and see that as the alpha angle decreases and the beta angle increases, that there is a much less satisfactory contour of the bony roof of the acetabulum.

So that by the time we get down to the type three and four, there is a very steep acetabulum and basically very significant displacement of the cartilaginous rim of the acetabulum so that the steeper the bony part, the more likely that an infant is going to have a hip that is going to require treatment.

Dynamic Hip Sonography

Now this is a picture of Dr. Harkey to whom I'd like to pay tribute as a person who has really made a major difference in the care of babies.

By developing this technique of dynamic hip sonography, it is really a way of using ultrasound as a veritable laparoscope to see the maneuvers that are performed during the clinical evaluation, particularly the Barlow and the Ani maneuvers.

The baby is in a supine or a slight decubitus position.

And during dynamic hip sonography, we are examining the hip at rest and during stress, it's a great way to assess the appropriateness of closed reduction techniques and to monitor the hips during treatment.

Technical Tips

Just a few technical tips before we talk about how to do the examination.

We ask the parents to bring the babies after a three hour fast so that they will be hungry during the examination and they can bring breast milk or formula in a bottle that they can feed the baby during the exam.

So we have the best cooperation that is possible.

We use the highest frequency probe that will allow for adequate penetration of the soft tissues so that we can see down to the hip joint.

And generally in babies who are less than six months, we will use a 12 five linear probe.

Whereas if they are larger and particularly after they're six months of age, we'll use a curva line nine four megahertz and at times a line nine three megahertz.

We do need foot pedal capability on the equipment so that we can use one hand to position the hip and the other to scan.

It's probably the only time, at least for me, when I'll scan with my left hand because I have to switch as I get to the right side of the baby.

So I can scan with my left and maneuver with my right and not have to cross my hands one over the other.

Do be careful of getting wet.

Just open one side of the diaper at a time.

Examination Protocol: Transverse Neutral View

So now let's talk about how we do the exam.

I like to start with a transverse neutral view, which I use to determine the relationship of the head to the as tabula.

Now bearing in mind that there is a slight flexion of the hip and the knee, we pull the leg down as much as we can without causing any discomfort to the baby, and we place the transducer perpendicular to the length of the side of the baby's body.

What this allows us to do is to see the femoral head right over the tri radiate cartilage.

We often get these little ring down artifacts as we're scanning.

So here's the head, here's the isum, here's the pubis.

And this has been described as a lollipop on a stick when you can actually draw your line right through the middle of the femoral head.

If you like golf, you can think of it as a golf ball and a tee, but the line that's drawn through the as tablum in the region of the tri radiate cartilage should go right through the middle of the femoral head.

Now I'm gonna show you some video clips and actually the clips that you see of the person scanning or the hands of Dr. Harkey. And he was kind enough to allow me to get a VI clips made from a video that he made a long time ago when he first started teaching people how to do dynamic hip sonography.

So to get the transverse neutral view, we placed the transducer along the side of the baby's hip, noticed a little bit of flexion at the hip and the knee.

And in order to find the hip, you can slide the transducer up until you get to the point where you actually see the head of the femur.

And as you can see, it's coming right up through the middle of the head of the femur.

If we draw a line through the tri radiate cartilage has the little ring down artifact.

So these are images that we've gotten using our linear 12 five probe.

Transverse Flexion View

Now for the transverse flexion view, we flex the hip, we flex the knee, and I'm scanning here with the probe perpendicular to the length of the baby's body.

Notice the baby is being fed during the exam and we look for the head of the femur always attached as it should be to the metathesis.

And then inside the acetabulum, in the normal situation, there is a U-shaped cup that the head appears to be seated in.

And notice that in the normal situation, the head is in contact with the acetabulum.

So here's the head, here's the metathesis, and this is the isum.

Nicely seated.

In doing this particular transverse flexion view, we see the baby has been turned a little bit to the right and we're scanning perpendicular.

This is the Ani as Dr. Harkey comes out with external rotation and abduction, and this is the Barlow maneuver, a gentle maneuver with the knee adducted medially with this pistoning posteriorly.

And this is what it looks like on the ultrasound.

We can see the metaphysis.

Here's the lum, and this is when the external rotation is done.

And notice during the Barlow maneuver that there's a little motion of the hip, but it certainly is stable.

And then as we abduct an externally rotate during the ani maneuver, it's perfectly normal.

Abnormal Findings in Transverse Flexion View

Well, in the situation when a baby has subluxation and then we look at the transverse flexion view, we see a change in the alignment.

Instead of having a nice U-shaped cup, the bony density in the region of the metaphysis forms a V-shaped structure in relationship to the isum, but there is still touching of the femoral head to the acetabulum.

Here's another view, and we can see that with the ultrasound that this is metaphysis, this is the head, there's still touching of the acetabulum, but this head is not well seated in the somewhat shallow acetabulum.

So here we go again, the baby's little bit turned to the right.

The probe is gonna be put along the lateral aspect of the acetabulum, and instead of seeing a nice U-shaped cup, we see that as the head is pushed on, it moves out.

But as we externally rotate and abduct, it comes back into a more normal position deeper in the acetabulum.

Considerations for Ossification

Now back in 1986, Dr. Harkey taught us that the Pacific nucleus, when it develops in the femoral capital epiphysis, that it will create an acoustic shadow.

And if it's large enough, it may create a shadow that can simulate the tri radiate cartilage.

And so in the days before we had adequate probe technology, ultrasound was limited after six months in a full term baby.

And I'm going to devote a little bit more time towards the end of the lecture to address that.

So we go from normal, the U-shaped cup to the V, and then finally with dislocation to an L-shaped configuration, notice that there's no acetabulum at this side of the head of the femur.

Here it is on ultrasound, we see the metaphysis.

Notice the L shape, here's the isum, but the head is not in the acetabulum at all.

This is a very shallow acetabulum.

So now putting the probe along the lateral aspect of the hip, and in this particular case we can see that there is an L shape between the acetabulum and the metaphysis.

This hip is only in a more normal position during abduction and external rotation.

It's totally out of what is a very shallow socket, but we can show that this hip is reducible, which is a very important finding when the orthopedic doctors are trying to decide if a patient will benefit from treatment with a pavle harness.

Longitudinal Coronal Scan

The other view that we get is the longitudinal coronal scan.

It must be done in the standard plane.

And what this means is that in order to be sure that we are scanning in the right plane, we have to identify the straight part of the iliac bone.

We need to be able to draw a line that is parallel with the ground to know that it's the right position.

We should be able to see the tip of the acetabular labrum, and we should see the transition of the iliac bone to the tri radiate cartilage.

Now, when we draw a line along the iliac bone, we should see at least 50% of the head below that line.

So here we have the head, the YY cartilage, the isum, the ileum, and drawing a line along we see that 50% of the head is within the bony socket, which is within normal limits.

Here we can see how that part of the exam is done.

As the baby's hip is flexed and the knee is flexed, the probe is placed along the lateral aspect of the hip, and we are looking for the detail of the femoral head.

We see that when the head has pressure exerted on it that it will show some motion out of the socket, but not more than 50%.

And then during external rotation and abduction, it's right back down where it started.

Remember that in the first four days of life, there is normally about four to six millimeters of subluxation because of the estrogen effect on the joint capsule and the cartilage.

And so these structures are quite soft and loose and somewhere about two to four weeks after birth this phenomenon regresses.

Ideally, it would be great to delay scanning in babies who are suspected of needing sonography because of risk factors until about four to six weeks, although the guidelines tell us that after three weeks is appropriate.

Abnormal Findings in Longitudinal Coronal View

Now let's look at what happens in this plane.

As hips are abnormal, we go from a nicely rounded acetabulum in the normal hip to the somewhat shallow acetabulum in the sublux hip.

And basically what we are looking for as we examine the hip is whether or not more than 50% of the head is outside the acetabulum.

And this is a positive equator sign.

Here we see less than 50% below the iliac line.

Typically when this subluxation, the femoral head will be covered by a thickened stretched joint capsule, and the posterior aspect of the acetabulum is flatter and less substantial than normal.

And at times the limbus or the labrum will be inverted into the hip joint so that it can act as a barrier between the head and the acetabulum.

Notice how thick this fibro fatty tissue is deep within the acetabulum.

This is the venar which is in excess in children who have subluxation or dislocation.

So now as we look at the hip in this baby who is with the hip flexed here, we see that the hip with the stress maneuver actually is moving out of the acetabulum and it's severely subluxed.

But with external rotation and abduction, it comes right back into the socket.

Now with dislocation, there is absolutely no contact of the head of the femur with the acetabulum, it's outside the bony acetabulum.

You can see the inversion of the labrum here, which acts as a further barrier.

So here we have a positive equator sign.

No head below the line. The joint capsules is thick.

The bony acetabulum is abnormally small.

There is no evidence of appropriate alignment.

The head is not seated within the acetabulum, it's displaced laterally.

Most often it's posteriorly displaced and superiorly displaced.

The limbus or the labrum can act as a barrier between the dislocated head and the acetabulum and this thickening of the ponar.

Here's the ultrasound.

In a longitudinal view, we see the head is totally out.

Here's the labrum sitting between the head and the steep acetabulum.

Here's the transverse view showing this lack of alignment and this excess pul.

So here we are looking at the head again in this baby who as we will see is actually demonstrating a totally dislocated head.

There's no contact within the acetabulum until the ani maneuver is done, where the hip is replaced into this very shallow acetabulum.

There's excess pul nar and incomplete reduction.

But the fact of the matter is it is reducible.

And that's extremely important in making a decision as to what to do so far as treatment is concerned.

If you can't reduce the hip sono graphically and demonstrate that, then it is very likely that using conservative type of harness or brace is not going to be successful and that surgical treatment is necessary.

Posterior Lip View

The last view is the posterior lip view, which we can see when we move all the way posteriorly.

We see the tri radiate cartilage.

We should not see the femoral head at that point when there's a dislocation, we'll see the head come all the way back to that posterior portion of the hip joint in babies in which the head of the femur is not in proper alignment.

Here we can see on the left side a nice little femoral capital epiphysis in appropriate alignment with this nicely rounded as tablum.

But if we look at the right side, the head of the femur hasn't quite yet, ossified.

Maybe there's a tiny.here, but this is totally out and we see disruption of shen's line wherever that head is leaning on the acetabular region, whether it's in the right place or the wrong place, there will be a concavity develop around the convexity of the head.

So let's just look at this.

Here are the lines that we know how to draw.

This one is appropriate. This one is totally inappropriate.

And here is the convexity that is called the pseudo acetabulum.

We see with the ultrasound that there's an indentation on the iliac bone in the place where the head is leaning.

This is the baby who has a total dislocation, and here we see that there is a concavity.

Now, notice that I wrote on this image.

By the way, this is the posterior lip, and you can see how far back this is coming.

I wrote, we cannot do ani, which basically is a documentation that this hip is not reducible.

Here's the pseudos tablum or Neos tablum.

Treatment and Monitoring

So in these babies where we can reduce the hip, a positioning device is used called the Pavlo harness, and it's used in babies in whom an unstable hip is easily reduced.

The femoral heads are directed toward the tri radiate cartilage with the hips held inflection and abduction to promote acetabular development, but to allow for movement in a safe zone.

So by putting the baby in the harness, we will be preventing subluxation or dislocation.

We don't do stress maneuvers until it's time for weaning.

And then at the conclusion of treatment, it used to be that plain films were obtained, but now we're doing ultrasound.

When the baby is in a harness, we do get images to show whether or not there's color flow because there is a risk that babies can develop a septic necrosis.

So here's an example, both before and with the color showing that in this harness there is no problem with the color flow within the hip.

Reporting the Ultrasound Findings

So after we get done with all of this, we generate our report, which should discuss the morphology, the position, and the stability of the hip.

So we're gonna describe the acetabulum, if it's round, if it's steep, we're going to describe the femoral capital epiphysis, the OCI nucleus to determine whether or not it is round.

And then we're gonna measure the graph angles.

We'll talk about the position of the head. Is it normal?

Is it subluxated? Is it subluxate during the barlow?

Is it dislocated or locatable during the Barlow?

And is it reducible with the ani maneuver?

Protocol and Pitfalls in Sonography

I wanna take a minute to talk about a little project that we did at Sinai during the past year that we presented at A IUM recently where we talked about the guidelines that have been established by A IUM and A CR in that they describe the value of ultrasound diminishes as the femoral head osfi, and that for patients between six months and one year of age, that radiography becomes more reliable.

Usually by one year of age, the femoral head is sufficiently ossified to prevent good visualization of the acetabulum with ultrasound.

And if the tri radiate cartilage cannot be visualized steno graphically, that radiography is needed.

Well, these are the usual views that are recommended by the A CR and the A IUM.

And they can be for the dynamic standard minimum, either coronal neutral view in the standard plane at rest.

You can validate it with the lines in the angle measurements, or you can do the coronal flexion view in the standard plane at rest and with stress and the transverse flexion view with stress needs to be done.

Now, so far as my protocol, I do a lot more than the standard minimum.

I don't wanna miss anything if I can possibly avoid that.

And so I start with the transverse neutral view.

I go to the transverse flexion view without stress, with stress and with abduction.

And then I do the coronal flexion view without stress.

I measure the graph angles, I do it with stress, I do a posterior lip view with stress.

I do the ani, which you really must do if the hip is subluxed or dislocated.

Now so far as when the baby is in the Pavlo harness, we wrap napkins around the harness so it doesn't get contaminated.

With the ultrasound gel, we get a transverse flexion, a coronal flexion, a coronal flexion posterior lip view.

We get a co coronal flexion with color doppler and we will get an abduction view as needed.

We will not get stress maneuvers until the weaning process begins or is about to begin.

Now there are some pitfalls of sonography.

Certainly inexperience is one of them.

And secondly, the shadowing of the acidic nucleus can be a problem if it can be mimicking the tri radiate cartilage.

So we see here the shadow from the ossification center, but notice that we can also see the tri radiate cartilage.

Study on Ultrasound in Babies Older Than Six Months

So we were concerned that there were babies who were going on and getting x-rays when perhaps in this day and age where we have better probe technology that we could obtain images with a lower frequency probe.

So we decided to do a little study to determine if it's worthwhile to try to examine the babies who are older than six months by comparing the quality of the examination for assessment of hip morphology position and stability in older babies with that obtained in babies less than six months, and to determine if the measurement of the graph angles with the nine four megahertz carline transducer is comparable with measurements obtained with the 12 five linear megahertz transducer.

So we reviewed all the statistics of the hip ultrasounds that were performed at Mount Sinai in New York City from October of 2005 to the winter of 2010.

We stratified the patients according to age.

We had 1,723 who were less than six months and 148 older than six months who were with the oldest 17 months.

And we compared the graph angles in the baby's over six months using the 12 five linear and the nine four curva linea.

And once comparability was assessed, they were done only with the nine four.

We also determined whether or not the lower frequency curved probe allows for sufficient penetration to image in the standard plane in babies over six months.

And so we did dynamic hip sonography in 296 hips with 52 of the 296 image with both probes.

And once the advantages of the nine four were demonstrated, the remainder 236 out of 296 were examined with only the nine four probe.

And I show you a few examples.

Here's the linear evaluation in a baby who was a year old, we see the main bang of the ultrasound beam against the Pacific nucleus and nothing more deep to that area because of the lack of ability to penetrate the structures.

But here with the nine four probe, we can actually see a well-rounded ossified nucleus and we can show it looking different depending upon how we angle the probe.

And we could very easily measure the graph angles.

Here's another one, A little baby who had come in initially with at the age of four weeks with a hip click and we see some subluxation of the hip, which is a little worse with stress and came back at 14 months.

Now walking couldn't see very well with the linear, but as we used the curva linear, we could see very nicely the alignment of the hip and do the maneuvers.

We compared the measurements of the graph angles and they really were not significantly different.

None of them measured more than three degrees differently.

And this is a the baby at eight months, and we could see that there are nicely formed ossification centers that look quite symmetric.

So we found that the graph angles were comparable in 18 of 18 hips measured with both of the transducers.

And so we started using the nine four probe routinely, we found the suboptimal dynamic hip sonography in 52 babies who were older than six months with the 12 five probe, but we were able to get diagnostic quality exams in these babies.

With the nine four, we found that the nine four probe is preferable for the evaluation of the hips in the larger babies over six months and concluded that you can get reliable and accurate information with proper probe technology for evaluation of the hip morphology position and stability without exposing these babies to ionizing radiation or sedation.

Thus obviating the need for plain film radiography and higher tech imaging for the diagnosis of DDH.

There are disadvantages, and that is the challenge of distracting an older baby.

During the sonogram, we will be feeding them, singing, dancing, entertaining them, showing them game boys and videos to try to get them to cooperate.

And even with that, it's not always easy.

They're ready to get up and run away from us.

The other challenge is performing the Barlow and Ani maneuvers in the stronger larger babies.

So we concluded that, dynamic hip sonography in babies older than six months really is worthwhile.

Monitoring Hip Position with Ultrasound

So just a little word before I come to the end of this presentation about the monitoring of the hip position with ultrasound.

If the hip is subluxed, we may not be in the situation where treatment is indicated.

It may just be that we're going to follow the ultrasound exam that we did with a repeat exam in about four weeks.

If the hip becomes stable without treatment, then we don't need to follow it with ultrasound.

If it's in a harness or a brace and the follow up ultrasound is normal, then weaning begins and follow up ultrasound at the conclusion of treatment is appropriate.

If the hip is dislocated, we may actually scan the hip every week until it's appropriately located in the as tablum when the patient is in a pavle harness.

And then once we know that the alignment is satisfactory, we won't be scanning for another three to four weeks.

And when it's articulated properly and it's stable, the weaning process begins with a follow-up sonogram.

Screening Guidelines

At the conclusion of treatment, it's been shown that the clinical screening that the neonatologists and the pediatricians are doing decreases the incidence of late missed presentation of DDH by 50%, but that ultrasound screening detects one third more abnormalities than the clinical exam.

It's also known that babies who have a normal hip ultrasound at birth are less likely to develop DDH.

We also know if we scan the babies too early and the physiological laxity of the hip is significant enough that these babies are gonna be obligated to come back for a follow-up sonogram.

So scanning at the right time is appropriate.

So let's just go through this little algorithm for screening.

If a baby has a normal clinical exam and there's no risk factor, there really is no need to do any imaging.

If they have one of the risk factors that we talked about earlier on in the lecture, we'd preferably like to see them at about four to six weeks.

On the other hand, if there's an abnormal clinical exam, if there is a stable click, the babies will be scanned usually at about two to four weeks.

But if there's any sign of instability, we will scan the baby immediately after birth and certainly less than two weeks.

Summary

So in summary, dynamic hip sonography has become the modality of choice for evaluation of infants, suspected of having developmental dysplasia of the infant hip, or those who are at risk for having it.

It allows for detailed examination of the cartilaginous femoral head and allows for clear demonstration of the relationship of the head to the bony and the cartilaginous acetabulum using the Barlow and the ANI maneuvers during the dynamic hip sonogram, we can assess the motion of the hip and we can examine the babies during treatment.

Of course, if the baby is in a cast, a window has to be cut out of the cast to gain access during the Pavlock harness, it's quite easy to examine the baby, and a brace certainly can be removed to examine the hip.

It's non ionizing, it's not invasive, and no sedation is required.

So thank you for your attention and I do hope this presentation will be helpful to you as you continue your lifelong learning and care of patients.