Ultrasound of the Foot and Ankle - SD

Introduction to Foot and Ankle Ultrasound

The foot and ankle complex is incredibly complex
and people need to really be guided by patient symptoms.

I don't wanna go ahead
and cover everything in foot and ankle.

I need everyone to be aware of the fact that there are
so many structures that are possibly affected.

I'm just gonna cover the major structures,
and the major,
things
that can potentially go wrong in the foot and ankle,
but again, at all areas of ultrasound, you need
to expand your study according to patient symptoms.

That's really important to be aware of.

Plantar Aspect: Plantar Fascia

We'll start with the plantar aspect.

I'm gonna ask our patient just to curl her toes underneath
and stretch out the bottom of her foot.

I'm going to look at the plantar fascia.

You can see here the calcaneus,
the heel pad above
and the medial insertion of the plantar fascia.

Here
Again, a standard measurement for the plantar fascia is
around sort of three or four millimeters.

Anything more than that, you're starting
to get into plantar fasciitis
or thickened,
plantar fascia.

But this looks, this looks beautiful.

Again, make sure you scan the insertion side to side.

You may need to go to a transverse section.

Again, looking at that calcaneus in transverse
with the plantar fascia insertion, overlying the top.

Again, something to be aware
of in musculoskeletal ultrasound is an atrophy
that we mentioned on an earlier talk.

If your transducer varies even slightly, even just three
or four degrees from perpendicular, you can see how,
koic the structures become.

Again, this is indicative of fa fasciitis,
or tendonitis tendon tearing in other
areas of the foot and ankle.

It's really important to make sure you maintain
that perpendicular scanning plane.

Make sure the entire area appears echogenic,
and again, the heel pad slightly hypo hypoechoic.

On top of that, if this starts to look koic in any way,
or if it demonstrates increased blood flow on power doppler,
you can start to be concerned about,
an inflamed heel pad
or edema in the heel pad, which is,
something
that's relatively common,
particularly in athletes.

Again, just going back to a sagittal section
over the calcaneus.

Again, pushing out into wide scan just to get that
extra amount of information either
side of the perpendicular.

Again, beautiful looking plantar fascia here.

Attachment here, normal.

Again, you can see the, a nice atrophic effect,
of this very, very proximal portion of the plantar fascia
as attaches onto the calcaneus.

But you can see as you heel toe back
and forth that that fills in and becomes echogenic.

You can see that that's perfectly normal
and that's just hype.

The hypoechoic area is just artifactual in this case.

The plan of fascia extends all the way
through the arch of the foot.

Again, making sure you scan side to side,
we're looking at this structure here, nice
and smooth and continuous.

If it's interrupted by a hypoechoic ovoid structure at any
of its, at any point along its length, you can be suspicious
of a plantar fibroma.

Some patients feel them in the bottom of their feet
because you can see how superficial the plantar fascia is
reaching as it becomes more distal.

So much so that sometimes people feel these fibromas,
it's quite hard structures underneath,
their fingertips
and that it feels like sometimes
that they're walking on pebbles.

That's something to be aware of clinically.

Again, making sure we follow this structure all the way
distally comes right up.

Superficial as we reach the toes at this point, it starts
to spread out and it attaches across to each toe.

The best way to look distally at the plantar fascia is
to go back to the calcaneus as your landmark.

Again, heel, toe the probe to make sure that you fill it in
so it's nice and echogenic.

This is its proximal insertion.

We're gonna head down the foot into the arch.

You can see the plantar fascia here.

Let me just put calipers on so I can delineate
that a little bit better for you.

That's the structure we're looking at.

Again, 2.9,
millimeters, perfectly normal,
but you'll see as we move distally, if you look carefully,
it's going to start to branch out.

This is the plantar fascia here.

I'm heading down the foot, I'm into the arch now.

You can see it's starting to become more ovoid as opposed
to more spherical.

As I keep coming down, it's
spreading further and further out.

It's becoming thinner, it's coming closer to the top
of the surface until we get all the way down towards the
toes and you can see how spread out it becomes.

It's really important to make sure as you assess,
particularly in this transverse section,
that your eye scans all the way medially
to all the way laterally
and doesn't just stay focused on that central portion
of the plantar fascia
because you can have quite,
extensive
and distal fibromas sitting right out either side.

It's really important to,
be aware of that.

Achilles Tendon

While we're at the plantar aspect of the foot,
we'll go ahead and we'll take a look at the Achilles tendon.

We're headed now to the back of the heel.

Again, you'll see a different aspect of the calcaneus here,
this echogenic lines, again being representative of bone.

We just zoom this up so we can see a little more clearly.

And again, you can see the, lemme
Get rid of this, The fibrillar pattern of the tendon
stretching right out
and attaching onto the top of the calcaneus here.

Again, be really wary of musculoskeletal ultrasound
of a nicer trophy heel toe, the probe.

Make sure you get rid of this hypoechoic area.

If it doesn't disappear, then you can start to be suspicious
of tearing or tendinosis.

But again, really make sure you have a dedicated effort
to fill in those,
blank areas of echo
before you,
become suspicious again,
the approximal,
measurement for achilles tendon,
you don't want it to be,
more than about
10 millimeters or so.

This is,
way below that. Perfectly normal.

You can see here deep to the achilles tendon.

There's a small fat pad here
and this is an area where fluid can collect in the
retrocalcaneal bursa.

Sometimes if that becomes fluid filled, it
can become inflamed
and it will light up on power doppler if that's the case.

Always make sure that you put power doppler on
that bursa back there.

And again, similar to plantar fascia, make sure that you
scan all the way medial to laterally
covering the entire aspect of the tendon
and follow it all the way up into its muscular insertion,
more proximally in the calf.

Again, you can see as we stretch more proximally,
the Achilles is gonna bow down
and start to get a little deeper
and start to blend into its muscle.

Here again in
ultrasound, assessing everything in two planes,
we're gonna go back to the distal insertion
and we're going to look in a transverse plane.

Now again, be aware of a nicer trophy.

Make sure you heel toe the probe.

Getting rid of all this blackened artifact here.

Make sure you're at 90 degrees.

And again, little bit
of fluid in the retrocalcaneal bursa here.

Again, little bit of fluid is quite normal.

Just
as a cushioning effect on the tendon power doppler.

Again, just making sure that there's no hyperemia
surrounding that small amount of fluid.

We're gonna extend slowly
proximally into the calf.

Again, be aware that the achilles tendon is quite an ovoid
structure, so make sure
that your eye doesn't just affix in the center
portion of the tendon here.

Make sure that you really are assessing out laterally
and medially, making sure that you're,
covering all aspects of the tendon.

Again, as we move proximally,
you'll see the achilles tendon start
to spread over its muscle.

Quite normal. We just take it off the zoom
so we can appreciate that a little more effectively.

You can see the tendon gets really wide over the top
of the gastro deemus muscles there at the back.

You can see it gets really thin proximally
stretching all the way out.

Something to be aware of too sometimes that,
when the achilles tendon tears it is, or a muscle in fact,
or any tendon tears, it can be associated
with a fluid collection.

Something to be aware of just sitting
underneath the achilles tendon.

Just stay really cognizant of any fluid
that might be in the area.

Into the gastric emus muscles.

We come now medially, laterally soleus underneath
and the achilles tendon is completely gone.

Now we know we've covered its entire length
'cause we're up in the muscle bulk again,
just scanning down one more time,
being really sure we've covered the entire area.

We've been sure to put power doppler on.

We've checked that retro calc bursa
all the way down
Distally.

Medial Ankle

Let's go ahead now
and have a look at the medial ankle.

If we can ask our lovely assistant here
to roll up onto her left side
so I can see the inside of the ankle.

Looking medially in the ankle now
starting, 10 centimeters or so, recording,

Starting about 10 centimeters
or so proximal to the medial malleolus,
taking a wide approach here
to what's called the tarsal tunnel, similar
to the carpal tunnel in the wrist, but in the medial ankle.

We can identify a number of structures here immediately.

They call these tendons Tom, Dick and Harry at the back,
and that's a nice way to remember it.

The posterior tibial tendon flexor digitorum longest tendon,
and the flexor lysis long longest tendon.

At the back in between the tendons,
you'll see the tarsal itself made up
of the posterior tibial nerve.

With that typical honeycomb appearance of a nerve
with all its punctate hypoechoic spheres in there,
you can see the posterior tibial artery.

When we go back to live, you'll see that pulsating away
and the paired posterior tibial veins next to it.

Something to be immediate, immediately aware
of in the medial ankle is that tarsal tunnel complex.

Again, let me just highlight where we're looking.

This area here, similar to the carpal tunnel in the wrist,
anything that's going to intrude on space in this area
is, a likely cause of pain and tingling in the toes.

Anything that's impinging on that nerve,
whether it be soft tissue neuroma,
whether it be a ganglion cyst,
whether it be varicose veins, all these things are
relatively common to see in the tarsal tunnel.

Something we need to be aware
of when we're assessing that region there.

Just something to be aware of.

You can see stretching out above the tarsal tunnel.

Encapsulating it is the ret ulu looks a little bit like a
ligament extended right over the top there.

Again, you wanna make sure that that's intact
and creating a superior margin over the tarsal tunnel.

It, it can become interrupted, it can become discontinuous
and you can get fluid collections here.

Really important to make sure you assess
the ret aum lying over the top here.

Posterior Tibial Tendon

Let's go and focus on our tendons.

Now let's look at the posterior tibial tendon.

First of all, there's the guy right at the top here, right
Here.

Again, we're gonna start quite proximally
and we're gonna follow it all the way down.

Again, heel towing as we go.

Making sure it stays nice
and genic as it goes around the malleolus.

It can be difficult again, underneath the re macular
that you can see here, following it all the way down
distally, you are looking for any fluid
around the tibial tendon.

You can see here there's a little fluid here, quite normal.

It's quite a, inferior structure in the body.

Fluid can collect here normally again, be sure
to put the power doppler on, make sure it's not associated
with any hyperemia or inflammation.

Continue heel towing until you see the tendon fan out
and attach distally.

This is it in sagittal.

Now distally tendinosis is quite common
at its distal attachment.

Something to be aware of. Little bit of fluid here.

Again, quite normal and a nice fibrile tendon above.

I find tendons of the ankle, easier to assess
initially in the transverse section
and then to come to a sagittal to make sure that you sweep
through medial to lateral.

But, I find transverse a good place to start.

Heading back now, approximately in the,
in the tendon complex,
you see here flexor digitorum longus with its muscle.

Flexor Digitorum Longus Tendon

At the back we're gonna do exactly the same thing.

We're gonna start proximally
and we're gonna follow that tendon distally,
heel toeing all the way, making sure it stays nice
and genic

Again, following it all the way down distally
and then coming to sagittal
and following it back up.

Flexor Hallucis Longus Tendon

Flexer lysis longus at the back
because of its depth is a little more difficult
to define at times, but again, it's important to be aware
of the echogenic tendon here
and it's more hypoechoic muscle around it,
which can be a good landmark.

It's obviously a lot larger than the tendon itself.

Sometimes it's easy to isolate the muscle
and then really focus your eye a little bit more
superficially to the tendon here.

It sits back in its calcaneal groove back here
below the tassel tunnel.

We're gonna follow flexa lysis again,
heel towing all the way down
through its muscle to the groove

There It's here all the way underneath the foot.

There's the flexoral as longest
as the name suggests, flexes the big toe.

You need to come all the way down now to the big toe.

You can see Flexoral is here above the sesamoid
all the way down and attaching onto the big toe
distally if you like, at this level.

Sometimes it helps to do provocative maneuvers.

If, people are getting,
pain when they point their toes
are quite common in ballerinas,
you can just have the patient flex their toe back
and forth, see if they can reproduce their pain
and watch the tendon move back and forth in its sheath.

You wanna make sure it's a nice smooth gliding motion
and there's no bunching
and no fluid collection, which can be indicative
of teno synovitis

and then the major structures medially.

Lateral Ankle: Peroneal Tendons

Let's go laterally. If we can roll over
the other way so we can see the outside.

Now we're almost done. Laterally we're going
to be looking mostly at the peroneal tendons.

There are paired tendons that share a common sheath,
the peroneous brevis and the peroneous longest.

Peroneus longest is the more superficial one,
the bigger one here, proximally

peroneous brevis is the one at the back here
with the peroneous brevis muscle.

Similar to that flex alysis tendon muscle complex.

It looks similar muscle at the back, nice
and hypo coic the more echogenic tendon next to it.

The way I remember which is, which is peroneus brevis B
for brevis and b for bone brevis is closer
to the bone than long is, that's how I remember it.

There's something to keep in mind if you think like me.

Again, I'm gonna follow brevis
and longus down around the malleolus.

You'll see here underneath there's a number of fibers
that stretch out medial to laterally
between the fibula and the calcaneus of the heel.

This is the calcan fibula ligament.

It's a nice and thin, nice and genic, perfectly normal.

It creates a bit of a couch for the peroneals
to sit on as they roll over the top.

That's just something to keep an eye out for.

As you head more distally with the peroneals,
you can see they stay paired as they head down the ankle
and they start to branch off just distal to that malleolus.

At this point you're gonna have to make a decision as
to which one you're gonna study first.

Let's go with brevis, this guy
following it all the way down
till it attaches onto the metatarsal.

Again, just looking at that distally in sagittal coming all
the way down from proximal, expanding out
and attaching onto the metatarsal.

That's peroneus. Brevis Come
Metatarsal The fifth metatarsal.

We come back up to where they started to separate.

This time we'll follow pers long as it dives down
into the tunnel, following it deep headed down,
still deeper, bringing your focus down,
making sure you keep all your parameters is with the tendon.

And again, in sagittal you can see it
the longest diving deep here.

Again, I find,
looking at these tendons more proximally in transverse,
it gives you a good overall view, first of all.

And it also is, is good to orientate yourself as
to which of the peroneals
or which, how it associates
with the calca fibula ligament that we looked at.

And then heading to sagittal for more information.

That's the way I would recommend it's done.

That's It. That's just a
basic overview of foot and ankle.

Again, a lot of things to take in all at once,
but again, they're the major things
to be aware of in the foot and ankle.

And that's it.