0:00

Let's talk about the collateral ligaments

0:02

with the foot in the plantar flex position,

0:05

which we see on our sagittal projection.

0:08

The toe is pointed.

0:11

Now that we've proven that to you, let's bring

0:14

down our axial T1 and compare the appearance

0:17

of ligaments on the water-weighted proton

0:20

density fat suppression, the T2, and the T1.

0:25

We're gonna start out with our all-important,

0:28

most commonly torn anterior talofibular ligament.

0:33

The anterior talofibular ligament can

0:35

be identified a little more easily

0:38

when you see the talus a bit elongated.

0:42

It looks a little more like an egg.

0:44

It's longer than it is shorter.

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In other words, the AP dimension is

0:50

longer than the transverse dimension.

0:52

So it doesn't really look square.

0:54

That's how you know with a toe-pointed view.

0:57

You're in the lower ankle.

0:59

Now the anterior talofibular

1:01

ligament is not just on one slice.

1:04

It's a continuous structure.

1:06

So it, itself could tear its lower portion,

1:09

its mid-portion, or its upper portion,

1:12

before you even get to the high ankle.

1:15

We're down pretty darn low.

1:16

There's some ligament right there.

1:18

Coming right off the fibula.

1:19

There it is.

1:20

There it is on the T1.

1:22

Now let's work our way up.

1:23

Oh, that's pretty.

1:24

And it's the prettiest, yep,

1:27

you guessed it, on the T2.

1:29

There's a little bit of fluid highlighting it.

1:31

Sure, we can see it on the T1, but

1:33

the discrimination between the gray

1:36

fluid and the ligament, not as good.

1:39

Even on the sensitive, proton density,

1:43

fat suppression, spare, spur, or special,

1:46

the fluid bathes or swaths the ligament

1:51

so that you don't see it quite as well.

1:53

We're still seeing the upper portion,

1:57

now we see it a little better, as a

1:58

line, or as a band. The highest portion

2:02

of the anterior talofibular ligament.

2:06

Now let's go back down for a moment.

2:08

Because whenever you have, uh, an ankle

2:11

sprain and you injure this ligament, the

2:14

next maneuver that you have to make is

2:17

to look at the calcaneofibular ligament.

2:20

And with the toe pointed, wow, that's exquisite.

2:24

There it is, forming the floor of the

2:26

peroneus fossa going right to the fibula.

2:29

Yes, you see it best on the T2, but pretty

2:32

darn good on the T1. And pretty darn excellent

2:36

on the proton density fat suppression.

2:39

So the plantar flexion view affords us a

2:41

real advantage there for that ligament.

2:45

The roof of this tunnel is formed

2:47

by the peroneal retinaculum.

2:50

The superior retinaculum above the ankle joint,

2:53

the inferior retinaculum below the ankle joint.

2:56

Right over here, this triangular-shaped

2:58

tissue, a little gray on the T1, gray

3:01

here, and dark on the T2, this small.

3:04

Thorn or fibrous ridge helps secure the peroneus

3:08

brevis and longus inside this tunnel whose

3:13

floor is formed by the calcaneofibular ligament.

3:17

So if you've torn the calcaneofibular

3:19

ligament, your next maneuver anatomically

3:22

is to check these two tendons and to

3:24

check the securing retinacular structures.

3:28

Well that only leaves us with one more

3:29

collateral to go, the one that never tears.

3:32

And that is the posterior talofibular

3:35

ligament, which you learned also has an

3:38

inferior transverse component that is best

3:41

seen in the coronal projection and beyond

3:43

the scope of assessing this projection.

3:47

So this defines the three key ligaments in

3:52

the axial projection with the toe pointed, or

3:55

in plantar flexion, which gives us our best

3:58

view of the calcaneal fibular ligament.

4:01

And even though we did really see the anterior

4:04

talofibular ligament very well, typically,

4:08

the neutral position is better for that purpose.

4:10

Now what about the high ankle?

4:13

The high ankle does very well

4:15

in the plantar flexion position.

4:16

Let's go up to the high ankle.

4:18

Now that we have the bony structure

4:22

seen as a square, we know for sure,

4:26

absolutely, we're at the high ankle.

4:28

Also a change in direction.

4:30

The low ankle has more of an arched

4:32

course and a more oblique course.

4:35

The high ankle has more of a

4:36

short, straight, stubby course.

4:39

So we're already into the high ankle

4:41

anterior tib fib ligament, and for sure,

4:44

when the bones become square, we're now

4:47

in the anterior tibiofibular ligament.

4:52

Inside, between, the tibia and fibula, will be the

4:56

syndesmotic structures, including the syndesmotic

4:59

membrane, there it is, which is variably

5:03

perforated for vessels and nerves, and then when

5:05

we get into the back, the bones are still square,

5:08

we're seeing the posterior, Tib fib ligament.

5:13

By the way, the high ankle is an intercalary

5:16

structure which tears from front to back.

5:18

So you never tear the back

5:20

without tearing the front.

5:21

You never tear the middle

5:23

without tearing the front.

5:25

Anterior tib fib ligament, syndesmotic

5:28

membrane, and posterior tib fib ligament.