0:00

There's a 20-year-old male with

0:02

"syndesmosis widening".

0:06

And so, unfortunately, the history is a

0:08

dead giveaway, but that's the real history.

0:11

Let's evaluate the way I would normally

0:13

evaluate if I was sitting by myself,

0:15

and I put up the sagittals, usually hand

0:18

in hand, fat-weighted, water-weighted.

0:20

And I focus mostly, initially, on the water

0:23

weighted image because it's like a bone scan.

0:26

We're looking for hot spots.

0:27

We've got an effusion.

0:28

And in that effusion is a glob.

0:31

The glob is not sharply defined or

0:34

dark enough to represent the body.

0:37

That glob, in a young person with

0:40

an injury history, should tell

0:42

you you got blood in the joint.

0:43

So you're immediately suspicious

0:46

that something serious has happened.

0:48

Then as we scroll back and forth, the

0:52

next thing that should strike you is this

0:55

edema in the posterior malleolar region.

0:57

And now, game over.

1:00

Now you know you've got a high ankle

1:02

injury, and this is known as Volkman's sign.

1:06

So now your job is to assess the

1:11

type and nature of the ankle injury.

1:13

Are there other fractures?

1:15

But clearly, what type of

1:17

ligamentous injury do you have?

1:19

And as soon as you see this Volkmann's

1:21

sign, you know you have at least a

1:23

component of a high ankle injury.

1:26

Now that may be accompanied by a low

1:28

ankle injury, but almost certainly, with

1:31

virtually 99 to 100 percent certainty,

1:34

you've got an element of a high ankle injury.

1:37

Let's keep scrolling and see if there

1:38

are any other ancillary findings.

1:41

And the answer is, not really.

1:43

You know, there are no other

1:44

fractures to really tip you off.

1:47

And what types of fractures am I looking for?

1:49

I'm looking for fractures of the anterior

1:53

fibula, or fractures of the anterior tibia,

1:56

where the other syndesmotic ligaments are

1:58

found. This area is known as the Chaput,

2:03

tubercle, and this area is known on

2:06

the fibular side as the Wagstaff tubercle.

2:12

So if we had avulsion fragments or edema

2:14

in these areas, this would further lead

2:16

us into the realm of high ankle injuries.

2:19

But this is the most reliable, and this one

2:22

already tells you you've got a high ankle problem.

2:25

So my next maneuver is to go to the axials.

2:28

Now, I want to point out that the way this

2:30

exam is done is in neutral positioning.

2:33

So it wasn't specifically done with

2:35

the foot plantar flex to look for

2:36

the tendons, and that's appropriate.

2:39

Although, you have to be aware that your

2:41

tendon analysis is going to be a little

2:43

bit hampered by magic angle effect because

2:45

the tendon is going to curve a little more.

2:47

But that's not necessarily

2:49

why we're doing this study.

2:50

We're doing it to assess the complex severity

2:54

and complications of an injury to the ankle.

2:58

So now let's look axially and let's start

3:02

out low where the tail is kind of looks

3:04

like an egg or it looks like an egg.

3:08

You're right in the heart of the anterior

3:11

talofibular ligament, which is the most

3:13

common ligament to tear in a low ankle sprain.

3:15

And it is clearly not normal.

3:17

It's too gray.

3:18

It's too fat.

3:19

It's even gray on the water-weighted image.

3:22

Is it ruptured?

3:23

No.

3:23

Is it sliced and retracted?

3:25

No.

3:26

Is the posterior talofibular ligament torn?

3:28

No, it never tears.

3:30

You have to get hit by a truck and

3:31

dislocate your ankle to tear it.

3:33

It doesn't tear.

3:35

Okay, so we know we've had a low ankle injury.

3:38

Let's keep scrolling.

3:40

We'll get up a little higher into

3:41

the higher fibers of the low ankle

3:44

of the anterior talofibular ligament.

3:46

And they still look a little rugged,

3:48

especially as we get towards the Wagstaff

3:52

tubercle, the anterior tubercle of the fibula.

3:56

Still very, very swollen

3:58

with lots of edema and fluid.

4:01

Now, let's keep working our way up higher.

4:04

And now we're really in the heart of the Wagstaff

4:07

tubercle where the syndesmosis, the anterior

4:10

tib fib ligament, has begun, right there.

4:14

And where is the connection between the high

4:18

ankle bones, between the talus and the fibula?

4:23

It's not present.

4:24

It's filled with shredded ligament and blood.

4:28

That's all we see.

4:30

Normally, we should see a

4:31

very discreet line here now.

4:33

It looks something like this.

4:35

Easy to spot.

4:37

Let's keep going up higher.

4:40

Let's keep working our way up higher.

4:42

We get up higher, and there is a

4:44

little bit of interosseous tissue here.

4:48

Some of that may be related to some

4:50

crossing vessels or some residual ligament.

4:53

But the higher we go, the more swollen

4:54

it gets, and the wider it gets.

4:57

Now, normally, this space up higher

5:00

should be about 2 millimeters.

5:01

I'm not going to measure it right now, but

5:04

it's clearly more than two millimeters,

5:05

but the measurement doesn't really matter.

5:08

Because you're able to directly visualize

5:10

this area, as I'll show you coronally in a

5:12

minute, and see that the interosseous is torn.

5:16

Now, the tears of the high ankle

5:18

occur in an intercalary fashion.

5:21

In other words, they occur

5:22

from anterior to posterior.

5:25

So you can't tear the posterior

5:27

without tearing the anterior.

5:29

So the anterior tib fib is torn.

5:32

They're interosseous.

5:33

Is torn and swollen.

5:36

There again is our Volkmann sign or

5:39

our Volkmann fracture in the back.

5:42

And then the posterior tib fib ligament,

5:45

which should also be a nice line.

5:48

It ends as a little stub.

5:51

So all three components of the high ankle kaput,

5:57

not shepherd kaput, they're gone.

6:00

Volkmann sign.

6:01

Anterior tib fib tear, interosseous

6:03

tear, posterior tib fib tear.

6:09

Now let's go back to the low ankle so we can

6:11

complete our responsibilities in this case.

6:14

Let's go down low.

6:16

We've already said that there is an injury

6:19

to the anterior talofibular ligament, the

6:21

most important component of the low ankle.

6:24

It's swollen, transected.

6:27

So there's been a low ankle sprain.

6:30

And remember, this ligament is like a sheet.

6:33

It has length from top to bottom.

6:35

So you can tear the lower fibers,

6:37

or the upper fibers, or all of them.

6:39

But in a high ankle injury, it's generally

6:41

the upper fibers that are injured, and the

6:43

lower fibers tend to look a little better.

6:45

Let's see if that's the

6:46

case here as we go down low.

6:48

Not really.

6:49

The lower fibers are swollen.

6:51

The upper fibers are swollen.

6:53

So the whole anterior talofibular

6:56

ligament has taken a hit.

6:57

But it's not transected and retracted.

7:00

So your next question is, "Okay, well

7:01

what about the calcaneofibular ligament?"

7:04

Well, here's a little tip.

7:06

You can't tear the calcaneofibular ligament

7:10

without tearing the anterior talofibular ligament.

7:14

So if you're having trouble seeing it, you

7:17

might as well just assume that it's intact.

7:20

In other words, if you can't see the

7:21

calcaneofibular ligament, don't say it's torn.

7:25

Say that it's poorly visualized due to

7:27

technical limitations, but likely intact.

7:30

Well, let's see if we can spot it.

7:32

It forms the floor of the peroneus tunnel.

7:34

There it is right there.

7:36

It comes off the calcaneus and

7:38

it goes towards the fibula.

7:40

And it's pretty hard to follow

7:41

it all the way to the fibula.

7:43

Here's the fibula.

7:46

Let's see if we can spot it.

7:48

That's probably as far as we can

7:49

get it, but it's pretty straight.

7:51

It's pretty delicate.

7:53

And if we go to the coronal projection

7:55

now, there's our coronal, T1.

7:58

Here's our coronal water weighted image.

8:01

There is the origin of the CFL.

8:03

That's pretty cool.

8:04

And it's nice and straight and it continues

8:07

to be straight and admittedly I cannot see

8:09

it go on to the fibula as I move posteriorly.

8:14

But there's no swelling there, so I'm just going

8:16

to assume, because the anterior talofibular

8:19

ligament is not ruptured, that it's intact.

8:22

And indeed that is how the case was read.

8:25

Now, oh, there's more.

8:28

You are probably wondering, well, you know that,

8:30

that tib fib area is kind of hard to see axially.

8:34

Yeah, it's swollen.

8:35

Yes, it's fuzzy.

8:36

Yes, it's widened.

8:38

But can I actually see the interosseous

8:40

membrane or the interosseous ligament?

8:42

You sure can.

8:43

There it is.

8:45

It's big.

8:46

It's fat.

8:47

It's bloody.

8:47

It's swollen.

8:48

It's gray.

8:49

It's not black.

8:50

There's edema tracking up

8:52

between the tib and the fib.

8:54

So what if this is widened?

8:55

Okay, it's widened.

8:57

It shouldn't be widened.

8:58

But you now have MRI to directly see the ligament.

9:03

Now, if you just looked at the

9:04

most narrow space on a plain film,

9:09

especially if you were able to look axially, that

9:12

space would be no more than 1 to 2 millimeters.

9:14

This is certainly more than 1 to 2

9:15

millimeters, more like 5 millimeters.

9:18

Now, on the plain film, you were always

9:20

taught that the tibia and fibula overlap

9:23

at the ankle mortis, at, just above the

9:25

ankle mortis, by about 6 millimeters.

9:27

So that's a, a cardinal plain film sign

9:30

you might use for a, for a core exam.

9:33

But with MR, you don't really need

9:34

that anymore, because you have

9:36

direct insight into the ligaments.

9:40

A couple of other things that just are,

9:43

are relevant to conventional radiography.

9:45

There's a little clear space here between the

9:48

plafond and the medial malleolus and the talus.

9:50

That's usually about a millimeter.

9:52

You don't really need to measure that, although

9:54

you can see in this patient with a serious

9:56

ankle sprain that the plafond looks excellent.

10:00

There's no widening here, and

10:01

there's no osteochondral defect.

10:04

Another important aspect of your responsibility.

10:08

In this high ankle sprain case.

10:12

What are some other measurements you might use?

10:14

Well, sometimes on plain film, we look at

10:17

the horizontal axis of the dome of the talus.

10:23

And then we look at the tib

10:25

fib angle relative to that.

10:27

You'd have to bring this one

10:28

over a little bit, say to here.

10:30

Then we'd measure this angle.

10:32

And we'd see if there's any tibio talar

10:34

alteration in the relationship of this angle

10:39

and the relationship of the tibia to the fibula.

10:41

Is the fibula elongated?

10:43

Is the tibia retracted because of

10:45

the loss of interosseous stability?

10:49

That's probably passé for MRI, but

10:51

that's a plain radiographic measurement.

10:54

Finally, the mechanism of injury.

10:56

How does this happen?

10:58

Usually the patient is pushing off.

11:01

The foot is in slight plantar flexion.

11:04

Now in the typical ankle sprain,

11:07

you're not quite as plantar flexed.

11:09

Usually in a neutral position.

11:11

And it's a simple inversion.

11:14

Or you might be slightly plantarflexed,

11:16

and it's a simple inversion.

11:20

The more dorsiflexed you are, the

11:21

more likely you are to have fractures.

11:25

The more plantarflexed you are, the more

11:27

likely you are to have ligamentous injuries.

11:31

The more plantarflexed you are,

11:33

and the more external rotatory.

11:36

In other words, you're plantarflexed,

11:39

your foot's in the turf, and your foot's

11:40

And then you turn, so that there's

11:42

external rotation on the foot and ankle.

11:46

That's when you see high ankle sprains.

11:49

This, an intercalary, three part, high ankle

11:53

sprain, a tif, anterior tib fib ligament,

11:57

interosseous, right here, and posterior

12:00

tib fib ligament, all torn, along with a

12:05

sprain with swelling and bleeding, into the

12:08

low ankle, anterior talofibular ligament.