0:00

Let's start out with our perfunctory views,

0:03

the ones I love, namely the sagittal T1

0:06

and the sagittal, fat-suppressed, water

0:10

weighted image, which is kind of like

0:11

your search and destroy. I hate to call it

0:14

this, but it's kind of your dummy image.

0:16

Because all you have to do is find the white

0:18

spots, the areas of water, edema, or swelling,

0:22

and we have found a big one right here in the back.

0:25

Now this patient has mid-tailor

0:27

and posterior ankle pain.

0:29

So let's focus on the posterior

0:31

ankle pain differential diagnosis.

0:33

What are some possibilities?

0:35

Could have an achilles problem.

0:36

Could have a calcaneal problem.

0:39

Could have posteromedial impingement.

0:41

Could have posterolateral impingement.

0:44

Could have a problem with

0:45

the flexor hallucis longus.

0:48

Could have a problem with the calcaneus

0:50

itself and the way it's shaped.

0:52

Namely a Haglund deformity.

0:54

Could have a posterior osteochondral defect.

0:56

Or could have a manifestation

0:58

of Tarsal Tunnel Syndrome.

1:00

That's a pretty broad differential diagnosis.

1:02

But we've got everything going on in the

1:05

subtalar space in the posterior ankle joint.

1:08

We've got dogs and cats living together.

1:09

Ten days of darkness, the plague, mass hysteria.

1:12

It's all here on this sagittal view.

1:15

I mean, look at what we've got.

1:17

We have capsular swelling.

1:19

We have this funny-looking protruding bone.

1:22

We have a spur coming up from the calcaneus.

1:25

We even have a body floating in

1:27

the back, surrounded by capsule.

1:29

The remainder of the soft

1:30

tissues are massively swollen.

1:34

And to make matters worse, the posterior

1:37

facet of the subtalar space is sclerotic,

1:40

dark, but also edematous, bright,

1:43

and the joint itself is swollen and bright.

1:47

And then we get into the sinus tarsi canal.

1:50

Things are also still a bit swollen,

1:52

but now we're starting to move away

1:54

from our prime area of pathology.

1:57

Now, we want to make sure that the, the region

1:59

of the tibia and the talus is not involved.

2:04

And while there's a little bit of remodeling

2:06

of the posterior tibia, it looks pretty good.

2:08

And most of the inflammation

2:10

is a little bit lower.

2:13

So now it's time to look at our axial projection.

2:15

Let's do that.

2:18

So, on the left.

2:20

And the red boxing trunks is

2:21

the T1 fat-weighted image.

2:23

And the blue boxing trunks, on the

2:25

right, is the T2-weighted image.

2:28

Now you remember, from prior vignettes that

2:30

you probably have trolled through, that the T2

2:33

weighted image is an okay water-weighted image.

2:36

It's more of a modifier.

2:37

But it does do a very good

2:39

job of showing you Intel.

2:41

In other words, what's inside the

2:42

chip, or what's inside your computer.

2:45

And what's inside this

2:46

collection is some gray stuff.

2:49

That's synovium.

2:50

Well, let's keep going, shall we?

2:52

If we want to see bone, what do we prefer?

2:56

The T1-weighted image, of course.

2:58

And look at the back of that talus.

3:00

It is not normal.

3:02

That's the normal signal intensity of the talus.

3:04

The talus is getting rubbed, and buffed,

3:07

and scuffed, and compressed, and irritated.

3:10

It's unhappy.

3:11

It's got an erosion.

3:13

We have a body floating in the back.

3:16

We've got, here's another body, posteriorly,

3:19

floating even further in the back.

3:21

So a very complex pattern of bone anatomy that

3:25

perhaps is more easily seen and I will float the

3:28

sagittal by you in a minute to try and figure

3:31

out exactly what structures we're looking at.

3:35

But we also have another problem up front that

3:37

we'll save for, for a separate discussion, which

3:40

is a big fibular spur, an extensive swelling in

3:43

the anterolateral fibular gutter, but I'd like

3:45

to concentrate right here on the back for now.

3:50

So one of the critical structures to analyze

3:53

in a patient with this, you know, serious

3:55

problem is the flexor hallucis longus.

3:59

So here is the flexor hallucis right here, and

4:03

it's located between the lateral talus process.

4:06

Here, and the medial talus process, here.

4:10

The lateral talus process is the insertion

4:12

site for the posterior talofibular ligament.

4:15

So, if some of these structures start to encroach

4:18

more medially, they can have a rather dramatic

4:21

effect on the flexor hallucis longus, and we see

4:24

this in one of the subtypes of this condition,

4:27

which is called posterior impingement syndrome.

4:30

So, what are those subtypes?

4:32

What I call ballet dancer impingement,

4:35

and chronic repetitive trauma impingement.

4:39

Now, chronic repetitive trauma impingement

4:41

is probably a little more easily manageable,

4:44

uh, if the ballet dancer has a repetitive

4:48

injury than if she's had an acute traumatic

4:50

event where she's fractured her steator

4:53

process and developed, you know, massive

4:55

amounts of edema and injured the FHL.

4:58

So I would divide these up into basically

5:01

acute toe pointing injuries, And chronic

5:04

toe pointing injuries, the chronic

5:06

ones, are a little bit easier to manage.

5:08

Because the ones that are acute,

5:10

they like to go back to a very acute

5:12

activity, a very serious activity.

5:15

And once this deformity ensues, it's very,

5:17

very hard to return them to their original

5:20

anatomic structure and configuration.

5:24

So let's continue on with this.

5:26

Terrible phenomenon in this

5:28

patient of posterior impingement.

5:30

Got a lot of bone disease, got

5:31

a lot of bones in the back.

5:33

Let's talk about what things can contribute

5:36

to this type of posterior impingement, which

5:39

is the chronic repetitive trauma arthrosis.

5:45

So let's talk about the structure that is

5:48

most often associated with this condition,

5:51

and it is called the os trigonum.

5:54

The, the Os Trigonum is a structure in

5:56

the back, right here, that mineralizes

5:59

at about 7 to 13 years of age, and

6:03

then it fuses at about 1 year of age.

6:06

So it fuses pretty early, but it

6:08

ossifies a little bit later on.

6:11

And when these become really large, and

6:14

they have fused, and they point out,

6:17

they're known as steator processes.

6:20

10 percent of the time, it persists

6:23

as a round, separate structure.

6:25

called the Os Trigonum ossicle.

6:29

That Os Trigonum ossicle, especially if

6:32

it's big, can produce, and is responsible

6:36

for many cases, of posterior impingement

6:39

syndrome in repetitive toe pointing athletes.

6:43

So we've got the separate ossicle, this is not.

6:46

We've got the attached ossicle

6:47

with the big process, this is.

6:51

We've also got a big process, a big steator

6:54

process, that sticks out that breaks right

6:57

here, that's called a shepherd's fracture.

6:59

That's another cause.

7:01

We've also got big posterior tuberosities

7:04

and spurs coming up from below.

7:06

Oh, we have that too.

7:09

So we have this big process.

7:11

It's not fractured, but it's thinking about it.

7:14

We have this coming up from below.

7:16

And finally, if you have a really

7:18

downslope tibia that comes down with a

7:20

hook, it too can contribute to a fracture.

7:24

Posterior Impingement Syndrome.

7:26

We don't have that.

7:27

And finally, the last thing

7:28

that contributes to it, Bodies.

7:30

Do we have that?

7:31

You bet we do.

7:32

There's a body right there.

7:34

So out of all the things I've mentioned,

7:36

we've got at least three of them.

7:38

We've got a body, we've got this weird upward

7:41

spur coming up from the calcaneus, crunching

7:44

the structures in the back, and finally

7:46

we have a large, lateral, tailor process.

7:50

And you can see that funny

7:52

looking process right here.

7:53

And it's starting to break.

7:55

There's a little bit of irregularity right there.

7:58

So it's starting to break off and eventually

8:00

will mature into a Shepard's fracture.

8:05

Now, let's talk about, you know, the

8:07

differential diagnostic considerations.

8:10

And I want to focus on one in particular.

8:13

One that, that often goes, uh,

8:16

unrecognized and is not commonly discussed.

8:19

And is commonly misnamed.

8:22

So a lot of your colleagues will look at the

8:25

Medial malleolus after an ankle sprain, and

8:28

it'll be swollen, and they'll call it a tear.

8:32

Now when you invert your foot, basically what

8:34

you're doing is, you're doing this, right?

8:37

When you have an ankle

8:37

sprain, you have an inversion.

8:40

So you're inverting it this way.

8:42

So what happens is this bone swings up

8:44

against your deltoid, and it crushes it.

8:48

And it gets swollen and contused.

8:52

Now, you don't want to read that as a tear.

8:54

We also don't repair those.

8:56

But here's a problem.

8:57

If it stays irritated and swollen and becomes

9:01

synovitic, that swelling then starts to dissect

9:05

posteriorly towards the medial process right here.

9:10

So this area then becomes swollen

9:12

and dissects towards that area.

9:14

Here's your deltoid right here.

9:16

This is your deltoid.

9:18

So it's gonna swing back and it's

9:20

gonna start to affect the structures

9:22

near the medial tailor process.

9:25

And what's near it?

9:26

The FHL.

9:28

That's called Medial Posterior

9:30

Impingement Syndrome.

9:31

But we're dealing with Lateral

9:33

Posterior Impingement Syndrome.

9:35

So either one can come over and start to crunch

9:38

and crush and entrap the FHL, producing a

9:42

major problem for any toe pointing athlete.

9:47

But this one is Posterolateral

9:49

Impingement Syndrome.

9:52

In keeping with our differential

9:54

diagnostic list, The Achilles is fine.

9:57

There was no coalition.

9:59

The patient had nothing going

10:00

on in the tarsal tunnel space.

10:02

And there was not a posterior

10:04

osteocondyl defect of the Taylor dome.

10:07

So we've eliminated a lot of the other

10:08

differential diagnostic considerations.

10:11

And we make the diagnosis of

10:13

posterolateral impingement syndrome.