Ankle and Foot Ultrasound - SD

Introduction to Ankle and Foot Ultrasound

Hi, I'm Nandu Raul.
I work at Thomas Jefferson University Hospital
and I'm talking about the
musculoskeletal ultrasound.
We've been doing it for about 12 years
and we were one of the first ones
to start musculoskeletal ultrasound.
And we will go into the ankle
and foot ultrasound, for the lecture
and, we'll continue with that.

Okay, we'll talk about the ankle and foot ultrasound today.
If you've been listening to musculoskeletal ultrasounds,
one of the biggest thing to remember in terms
of technology is you need a high frequency pro,
which is going anywhere from 10 to 14, preferably something
that goes up to 14 or 15, but also goes down to like 10
or maybe eight because you need that for deeper structures.
You can visualize muscle tendons, bursa joints,
skin, most of the other structures.
The good thing about ultrasound for musculoskeletal is
that you can use that to compare with the other side.
There's no technical limitations for musculoskeletal,
as you would see like in doing an
abdomen or something else.
If you're looking at the tendon,
most tendon have elongated appearance,
and I'll show you a couple of pictures for that.
And they have these parallel fibers,
and here's an image of a tendon,
where you can see nicely hypoechoic fibers going from the
top end going towards the bottom.
Most tendons appear this way because of the fibers,
and what you have to be careful when you're scanning is
to make sure that you're scanning at 90 degrees from the
probe, because otherwise you'll get a darker image,
something that's called as phy.
And this outlines the border
of the tendon from the top and at the bottom.

I've kept this image intentionally.
If you look at the image on the left,
it shows you a much detailed picture.
And the image on the right was about few years ago,
I would say almost not few, but 10 years ago when
we started doing ultrasounds.
You can see the image quality wasn't as good
because the probe technology changed quite a bit.
We could still do the work,
but a big difference in terms of detail,
of the tendon imaging that you can see.

Anatomy and Scanning Positions

If you're looking at the scanning positions,
the best thing we found for the ankle was
to have a patient live prone,
and this is the edge of the table,
and have the leg hang down from the patient's,
from the table's bottom end, that helps you
to scan the posterior part, the medial and the lateral.
And then you can also compare with the other side.
If you look at the anatomy, this is a picture
of the cross section of the, of the ankle.
And this is kind of reversed intentionally
because the picture in the book was the, the wrong way.
What you want to see is the posterior part
of the tendon, which is the Achilles.
Then we look at the medial portion of the tendon
of the ankle, which is the, these two tendons,
and then we'll go to the lateral.
And so that's the prone position.
And then what you would get is you would get the
anterior portion of the tendons
or the ankle that you can have the patient set up.
So there's the posterior, there's the medial,
there's the lateral.
And you can see in that same prone position,
you can see pretty much all the tendons.
So there's the posterior part.

Achilles Tendon

Let's first look at the Achilles tendon.
And what you're looking in this portion is
that's the probe position you want to have.
And that's the calcaneum.
So the insertion of the achilles going to be on the calcan.
Here's a schematic
representation of what we are looking at.
We'll be looking at this tendon up here,
going onto the Achilles,
and then we'll see what the ultrasound picture looks like.
So this is the same pictures that's shown here.
The patient is lying prone,
and what you're doing is you're putting the probe
where the green line is,
and what that gives you is gives you a beam that goes,
shoots through the achilles
posteriorly as it's shown in this picture.
Yeah, there is the probe, that's
where the achilles tendon is and that's
what the tendon would look like.
So there's the prob again, and there's the achilles tendon.
You can see the nice fibers very well.
And what you see underneath this bright portion is the
calcan, which is the bone on which the Achilles inserts,
and there's the calcaneum over there.

Apart from looking at the Satch portion,
you also wanna look at transverse.
So what you do is turn the probe 90 degrees to the portion
that you're scanning, and you should be able
to get a 90 degree view of that same Achilles tendon.
Now, when you do that, sometimes the probe
is gonna be bigger than the ankle.
So what you will have is a dropout on both sides,
and that's normal to have it.
And here's the picture that shows in transverse
and there's the achilles tendon.
And as I said before, here's the dropout that you see
that just that the probe is not in
contact on these two areas.
But other than that you can see nice
fibers through the Achilles.
And also what you see is the tendon is oval shaped.
What happens is most normal tendons appear oval.
And that's something to remember no matter
where the tendons are because once they start
to get inflamed or swollen,
the tendon tends to become more round.
This is even before the tear happens
or other pathologies happen.
If it's a very subtle change,
it's going to be more circular.
And also this looks bright.
Most pathologies in musculoskeletal when they have
pathology, they look dark, which is hypoechoic.

The text material,
what I showed you is basically telling you
what I, I'm speaking.
So this is just for your reference.
What you also get when you have a tear, like I said
before, here's the area of a tear
where the normal fibers are missing.
And what you see here is the hypoechoic area or darker area.
And you can see the tendon is so much thicker.
What you see underneath here is the white portion.
This is just the fat that's usually the fat is usually
underneath it and it herniates through that tear.
So it's normal sometimes to see a bright area within a tear
that just something called as a kegar fat.
And this is the same thing seen in transverse.
There's the transverse, there's the fat underneath it,
and there's the normal tendon on the left side.

Something else to remember when we look at the tendons,
remember we always talk about tendon pathology,
but also it's important to remember something that goes
around the tendon, which is the tendon sheath.
So sometimes the patient can have pain or symptoms,
but the tendon might be fine.
It's just the sheath around the tendon that's inflamed
and the inflammation usually appears hypoechoic or dark
or black because usually there's a little bit of fluid
or inflammation and that's what you see up here
and you can see it's around the tendon.
Most tendons have sheath,
tendons like Achilles don't have a sheath.
So that's something to remember.
And here's another example of an achilles tendon.
You can see the tear in between.
There's a long axis of the tendon, you can see
how thick this is and it's hypoechoic or darker,
and then you see tears in between.
Now even this part is not normal because it's dark.
The same thing seen in transverse.
Again, the transverse tendon, you can see how it's more over
or more round as opposed to oval.
And what you see here is they're again a tear,
but again, this part is also not normal.

Now, sometimes when you have inflammation,
what you can find is there's increased flow on color doppler
or as in as in this case power doppler.
In this patient there was a very small tear,
that came up with this patient was actually a
Philadelphia marathon runner.
In fact, she actually won the
Philly marathon the year before.
And what we found was she had this pain on
that achilles tendon on that side,
and when we scanned her,
what we found was this inflamed flow
and there was a small tear that was present there.
All this is basically body's ability to heal
and kind of get to that tear.

What you can also find sometimes is chronic changes.
What it means is you could have tear that might have healed.
So it's important to remember
that when you compare sometimes to the opposite side
and you find something that looks like a pathology,
it's important to compare if the patient has pain or not.
If the patient doesn't have pain, it means
that something very chronic that the patient had problem
before and now it's gone
and the tendon may not go back
to like a totally normal tendon, like as if it was normal.
There's some residual effect left from that tendon.
Same thing again. Here you can see there's a transverse,
here's the hypoechoic area that can mimic pathology.

The other thing to look posteriorly apart from the achilles
tendon, which we just saw, is the what's called as a roc
bura, and that's the bura that's present there.
It's a very small bura that you can see on ultrasound.
Normally it's about two to three millimeters.
And what you see in this case is a very subtle anti echoic
area or what's called as a hypoechoic area.
So what you see is there's the bursar on the anatomy
and there's the bursa on the ultrasound.
This is a normal fluid to be seen,
but this should be very minimal.
It should not be very thick.
If you have a bures
or retro calculator bursitis,
this thing is gonna be inflamed.
And here's an example. There's the rare area
that's inflamed, that's the bura that's inflamed.
And you can see this bursa is pretty thick
and inflamed, so the patient can have a bures
and have pain just from the fluid
and the inflammation in the bursa.

Posterior Tibial Tendon

The next tendon we'll look at is the posterior tibial
tendon,
which is the second most commonly injured tendon,
after the Achilles and also a very major or a big tendon.
The tendon is situated on the medial side.
There's the medial moola, so the bony landmark
that you can feel on your feet, on your or on your ankle.
And right behind it will be the posterior tial.
Tial is posterior or posterior tial,
and the next to that will be the flexor digitorum.
The scanning position is the same.
You go from the posterior part of the ankle
and move medially and there's the medial moola.
So if you actually feel on your ankle,
you can feel this bony structure
and you just go on top of it, that or posteriorly
and you want to scan more horizontal.
One of the mistakes people make is when they scan,
they go sideways into the tendon and they don't see it
because the tendon is in that groove.
And once you have that image,
what you see is a pretty nice beautiful tendon there,
which is the posterior tial.
And you can see again how the landmarks are very nice
hyperactive fibers, very uniform
and sometimes you'll see hypoechoic areas on both sides,
and that's just a normal sheath
around the tendon, which is normal.
And these fibers should be normal.
They should not look dark
and they should not look disruptive.

What we do with this tendon, going back
to the anatomy picture, is you wanna follow this tendon all
the way up to the insertion onto the bone.
That's called the navicular.
And we don't follow all the other tendons
because very few of them tend to have pathology distally,
but this one we do because we found quite a few
of them have pathology.
And what we found was here's the distal posterior tibial
that's going in and inserting onto the navicular.
Now if you see this fibers, they're all horizontal,
but as they come in you find that this kind of spreads out
and this is normal appearance
because what is happening in this 90 degrees from the top is
missing in this case
because the tenderness from there move up the
tendons from there, move down.
And what you're getting in this case is not a very perfect
picture, but that's normal also,
if you notice there's some fluid there
and that fluid is normal to be present,
we find sometimes in ankle ultrasound there are areas
where small amount of normal fluid is seen
and that's even documented on MRI.
It shouldn't be too much
or it shouldn't be too, uneven From the opposite side,
this is the posterior tial, the same tendon in transverse,
we can see it's about two to two
and a half times the size
of the flexor digitorum, which is next to it.
And there's the medial moola.
So you can see how tightly in the groove that thing sits.

Here's an example of a pathology.
If we look at the normal and now we compare the pathology,
this tendon looks okay,
but as it comes further up,
you can see there's the tear going
through the posterior tibial.
And what you also see is this darker and thickened area.
This is the inflammation.
So there's definitely a tendon tear
and also some inflammation or tendonitis up here.
Another example of tendon pathology there is the posterior
tibial you can see is hypoechoic and it's inflamed
and you don't see the normal, category of the fibers.
Same thing again, posterior tibial tear.
Some of the fibers appear okay,
but for most part it's very thick and flamed.
Maybe there's some fluid around the tendon.
Here's an example in transverses,
the same posterior tibial on
what you're seeing up here, this is the tendon.
What you see in between is the tear.
So the tendon appears like it's split into two
and it's like a linear tear going through the, the tendon.
There's a flexor digit room,
which is much smaller and normal.
Another example of a tear.
Now this tear is more near the insertion.
Remember we said we usually follow this tendon on the
insertion to the n navicular bone.
And what you're seeing up here is the inflamed tendon,
which is hypoechoic.
Same thing again in transverse,
in inflamed tendon looks dark.
You can see, you don't see the bright fibers
that you're normally used to seeing in a normal tendon.
Some similar example.
This part of the tendon looks fine,
but as you go further up, you can see this part
of the tendon is torn.
And you can see around this is the edge of the tendon.
You can see around the tendon there's some inflammation
which is hypoechoic.
Same thing again, distal.
There's the proximal end, there's the distal end,
and you can see those normal fibers
that should be going along if they're missing.
This is the hypoechoic area, which is tear at the insertion.

Flexor Digitorum Tendon

The next tendon we look at is the flexor digitorum,
which is right next to the PTT.
It's about half to one third of the size.
We don't see too many pathologies with this tendon.
There's the posterior tibial
and the scanning position is the same.
You scan vertically, scan more near the ankle,
and here's the tendon that you see posteriorly.
Again, this is a normal tendon.
Like I said, you don't see too many pathologies
with flexor digitorum.
Again, in transverse there's the flexor digitorum,
there's the posterior tial, just so the shows the comparison
of the size between the flexor digitorum
and the posterior tibial.

Flexor Hallucis Longus Tendon

The third tendon to imagine on the,
on the medial side is the flexor lysis.
Initially we didn't look at this normally,
but we have had times when we found a pathology
that was actually missed on MRI, the patient came in
with a pain on the medial side
and they thought there was a cyst
or maybe the patient had DVT.
And what ended up happening was when I was scanning this
patient, what we found was something much more deeper.
So if you look at this patient here,
there's the flex flexor lysis
and you can see how inflamed it is.
The reason we found this was when I was scanning the
patient said the pain was not very superficial,
it was much deeper, and the flexed hallus
is a much deeper tendon.
So here's an example and I'll show
you the normal for comparison.
You can see this inflamed.
There's all this fluid and that's the tendon there.
And here's the comparison.
In transverse, there's the transverse tendon.
You can see it's inflamed, there's a tendon
and you can see all this fluid around.
And if you look at the normal side, there's the normal,
you can see in comparison that it looks much smaller.
There's no fluid around the tendon,
and this tendon has that nice echo texture
and bright spots that you see, which is normal.

Lateral Tendons: Peroneus Longus and Brevis

Once we're done with the medial side,
what we now do is we go to the lateral side,
which is on the, this is the lateral side,
there's the lateral maus.
And now we are looking at these two tendons that go parallel
to each other behind the lateral moss.
Now you can follow that up
to the insertion at the fifth metatarsal if you want.
For most part you're looking at this area
and what you find is when you're scanning again,
the scanning position is the same.
There's the lateral aspect of the tendon.
You can see how the patient is lying comfortably.
You looked at the posterior, you looked at the medial,
and now you're looking at the lateral side.
And if you look at the bone landmark, that's the lateral eo.
So you want to be in that groove when you scan.
And what you see in this case
are two tendons on top of each other.
That's the peroneus longest.
And the vis, which is deeper, if you go back
to the anatomy picture, you can see
how they lie on top of each other.
On the medial side, they lie side to side.
So when you see them, you appear, they appear side to side
and you have to visualize one tendon
and then the other on this side, when you scan from there,
you see both these tendons in the same plane.
And that's what is happening there. This part is a long way.
You can see there's a little bit of division there.
And then this part is the BVIs.
You can look at them in transverse
again in that same groove.
And what you see is there's the tendon in transverse.
So there's the longest on top brevis at the bottom,
and sometimes this has been called as a pair of stack
of pancakes because they lie on top of each other
and there's the lateral moles at the bottom.

Now, what you're looking for in this case, apart from tear
and inflammation, is something else happens on the lateral
side that's a little different from the medial.
You can get a subluxation of this tendon.
And subluxation is basically when the tendon from there goes
over the lateral moles
and goes, goes to the opposite side on this end.
So you don't want the tendon when the patient flexes the
knee to go on the opposite side.
And here's an example of the permanentes long vis.
You can see there's the tear
and there's the brevis, which looks a little bit okay.
Here's again an example of the brevis at the bottom,
which looks nice and bright, but the longest is hypoechoic
and there's also some fluid there.

This is basically a colorized image.
There was a technology that came few years ago
and people thought maybe, this might help
to identify a pathology much better
because your eyes are more sensitive to color image.
Unfortunately that did not turn out to be true.
We did some blinded studies with people
and then turned out we gave a bunch of studies
that were colorized
and some of them were actually colorized on a machine
and some were colorized using Photoshop.
And we found that unfortunately
that technology did not hold true.
Even though you can see the darker
areas better on color.

The other thing that can happen is on the lateral side
there's the ous longest
and brevis, sometimes the longest can hit the brevis against
the bony landmark posteriorly
and it can actually split the tendon into two.
So instead of seeing just two tendons,
now you're looking at one, two, and three.
And what you're looking at the bottom is basically
a brevis that's split.
So this is a split tear for other brevis
and that's the pathology, whereas the longest looks fine.

Anterior Tibial Tendon

What we do next is once we start finishing the posterior
aspect of it, we go anteriorly.
So what you want to do is have the patient sit up now
and look at the anterior TBL L tendon.
What ends up happening usually is you, we look at bunch
of tendons anteriorly,
but we focus more on the anterior tibial tendon.
Now there's, if you look read in the literature,
they say that there's not as many pathologies
with anterior tial tendon.
But we did find quite a few of them.
And part of the reason they say you don't have
as much pathology, it has good vascular supply.
We've had a couple of examples when the patient came in
with a tear, here's the normal anterior TBL tendon.
And if you look at the pathology, here's an example
of a pathology where the tendon is inflamed and torn.
And what you find there is the an echo,
echo hyper echoic area.
Here's another example of a patient who came in
with the anterior tial tendon tear,
and you can see how thick this tendon is.
This patient actually had been to like three
or four different doctors and was almost 76 years old.
So nobody thought that she had any pathology.
They all just thought she had arthritis
and they asked her to take some medicine, go home,
and she came to us for a, one
of the different studies we were doing
and it was more of an RSD patient that we were scanning.
But she came in thinking she might have RSD.
And when I scanned her,
what we found was here was an example of a torn tendon.
And she did have history
of trauma except she didn't realize she had it.
What this patient was actually doing was she was
76-year-old and had started going
to a gym about five or six months ago.
And what she did was basically, tore
that when she was doing extension exercise
and didn't realize that that was causing it.
And then she stopped going to this gym.
Here's the same image in transfers.
There's the anterior tial tendon, there's the lysis,
there's the digitorum, and you can see how big this tendon,
it's circular and it's hypoechoic.

Other Structures in the Ankle

Plantar Fascia

Apart from the tendons,
there are a few other structures you can look at in
the ankle.
One of the popular one is obviously plantar fascia.
This is at the bottom of the foot
and you can almost see it in all the patients.
Sometimes these people say, oh, it's too hard
to see plantar fascia because you
know, it's too hard to identify.
But I can tell you, we can almost see it
in every single patient.
What you see basically is there's the plantar fascia,
there's the insertion on the calcan,
and what you want to do is you want
to scan from the posterior aspect
and try to find this portion of the fascia.
That's the one that has more pathology.
The pathology can be focal or it can be diffused.
The focal it'll be up here or the diffuse.
What you can also do is you measure the thickness of it.
So there's the calcaneum, there's the plantar fascia,
and what you're looking at in this case is a nice normal
fascia that's about two to three millimeters in thickness.
And there's the insertion.

In an inflamed fascia,
either you will have a focal inflammation
or you'll have a diffused inflammation
where the whole tendon is inflamed.
And here's an example of a plantar fascitis
where the numbers in terms of thickness almost double.
And here's an example of a plantar fascia.
You can see from the top, here's an inflammation.
You can see how thick this tendon is or fascia is,
and it's also very hypoechoic.
So that's definitely a, a, a generalized, plant
of fascia or fascitis.
Here's another example of a person who came in.
And you can see there's the plant of fascia.
In this case it's a little bit over the calcan.
You see this an echoic area.
This is where the patient was hurting.
If you look at colored doppler
or powered dopplar, sometimes you
can see increased flow there.
And this is because this is an acute inflammation
and most acute inflammation tend to have increased flow.

If you compare the left to the right, here's an example
of the plantar fascia that looks abnormal.
There's the normal fascia that's
it shows nice fibers within.
In fact, not only that, when the,
when I was scanning this foot, I asked the patient
where it hurts and she said it hurts
more on the medial aspect.
And this is a transverse image of a fascia
with the medial aspect of the tendon.
And you can see how the patient, where she points
to the pain is the area where the inflammation is.
And that's confirmed by ultrasound with the powered Doppler.

Anytime you see powered doppler, I always try
to confirm it with pulse doppler.
You wanna make sure it's not just an artifact,
that you're looking at.
And here's again an example of a plantar fascitis.
You can see in long axis how thick the fascia is.
You can see the numbers, it's almost twice the size.
Normally it's two to three millimeters.
And what you see up here is about almost six millimeters.
And here's an example where you confirm
that fascia is a flow with actually doppler
and you can see an arterial flow
because, so you know that
that's a real flow that's coming in.
Here's a normal fly fascia
and you can see it's about three millimeters.
So you can definitely think this is thinner.
And then we, when we saw earlier,
there's the one with an abnormal.
You can see it's like twice the size.
Even though few millimeters might not mean much,
but when it goes from three millimeters to six millimeters,
that's almost double the size.
So it's definitely something to remember.
Here's an example again on the opposite side
for the plantar fascia
and transverse, you can see there's no flow
because this was an asymptomatic side
and there's a symptomatic side again with increased flow.

Foreign Bodies, Fractures, Morton's Neuroma, and Gout Tophi

There are other things you can see
with ultrasound in the ankle.
One of the things we have had very good luck
with is the foreign body.
Most of the time when you have foreign bodies,
obviously you know that the foreign bodies, if it's metal,
it'll show up on x-ray.
But if it's wood or if it's glass,
or some other material that won't show up on x-ray,
ultrasound can be very good.
And what you see in most of those cases,
you see something that's very bright.
The good thing is over a period
of time there's an inflammatory reaction to the foreign body
and you get this hypoechoic area around
that just an inflammation.
So what you're seeing in this case is the
inflammation around the foreign body.
This is the foreign body.
This patient actually came in in one of our practices
and what we did was under ultrasound
guidance, we removed it.
She was actually on pain for quite a few weeks
because they had missed it.
They had taken part of the foreign body out,
but the small area that was there was left behind.
And you can see nicely on ultrasound.

There are other things you can look at.
This is the toe and this patient came in
and she had stopped her toe against the coffee table.
And what we found was, you know,
so I said, you know, you can come in.
She actually was one of our coworkers.
And I said, just come on in, we'll take a look.
Here's a normal toe or the bone
and here's the bone that you see on the fifth toe
that you can see there's a fracture there.
And obviously this was very well seen on ultrasound also.
There was a lot of inflammation at the top of the fracture.
And here's again an example of a fracture
that you see very well on ultrasound.
She was in a lot of pain and she was gonna ignore it
because she thought it hopefully was just a stu toe.
But she does have a fracture.
There's some flow there
and you can see this is the fifth toe.
There's flow, the place where there is no fracture,
you can see there's no flow.
Here's an example again,
looking at the soft tissue over the area,
you can see there's so much flow
and inflammation even on transverse.
You can see how that circular area of a bone is broken
'cause that's where the fracture was.

You can see Morton's neuro on ultrasound very well.
Morton Turro is something that happens between the third
and the fourth of, and it's basically a inflammation
or neuroma coming from the nerve.
On a normal ultrasound, you may not be able
to see the nerve, but when you have the neuroma,
you can scan from the planter aspect.
And what you can do is you can push from the,
from the dorsal aspect and scan from the planter aspect.
And what you're looking for is there's the nerve
and there's the inflamed neuroma.
And what you see is this is the nerve up here
and there's the neuroma that you see very well.

There are other things you can see.
Here's an example of when we did this for the first time.
We had no idea what this patient had.
The surgeon said this patient in
and said that the tendon looks fine,
but the patient does have a lot of pain on that side
and he wanted us to find out what that was.
And turns out when we saw this, like I said this,
there was very few things reported in the literature
and what it turned out, what this patient outta history
of gout and what these are, what you see up here is our gout
or tophi crystals.
And what you see in between is a
tendon that's totally normal.
So in this case, in fact, there was an added incentive
because the surgeon said to us
that if you tell us what's wrong with this patient,
I'll send you all my patients.
So it was a good intensive to look at it.
And turns out now many people have reported
that now some people even do injections
or serial injections that you can flush the tophi crystals
out, from that area where it,
where you can see them on ultrasound.
So this is sag. Here's an example in transverse.

Conclusion

Okay? That's pretty much it for the ankle ultrasound
and the tendons that we can image.