0:00

Okay, we're going to talk about the

0:02

tarsometatarsal joint, and that discussion

0:05

is going to focus on the Lisfranc

0:07

joint, the Lisfranc ligament named

0:10

after Jacques Lisfranc de Saint Martin.

0:14

These are injuries that are either high-impact or

0:17

low-impact, and they're actually divided as such.

0:21

A high-impact injury would be due to a greater

0:24

energy force like a motor vehicle accident, and

0:27

these are termed Lisfranc fracture displacements.

0:31

Thank you very much.

0:31

You can also see a lower-impact injury in sports,

0:35

and these are typically called Lisfranc injuries

0:38

or midfoot sprains, but there's quite

0:40

a bit of crossover, and it's not uncommon to

0:43

see, you know, big people playing sports where

0:46

they get stomped on, or they have a twist on the

0:49

grass or turf producing a Lisfranc type of injury

0:52

that can either be low-impact or high-impact.

0:55

So they're not so easy to divide

0:57

up by just visual inspection.

1:01

The Lisfranc fracture displacements are

1:03

about, um, uh, 50 percent of the time

1:08

responsible for post-traumatic degenerative

1:11

midfoot arthritis in the athlete.

1:14

Lisfranc sprains are really tough to

1:16

detect on physical exam and on imaging.

1:20

They're a source of big-time morbidity.

1:23

In fact, almost 20 percent of all athletes,

1:27

whether they're 15 years old or 30 years

1:29

old, high school, or a professional, are

1:33

not able to return to their sport after a

1:37

mid-level to high-level Lisfranc injury.

1:40

In one study, 25 percent of all

1:43

Lisfranc injuries were missed or

1:45

appeared normal on initial radiographs.

1:48

And in my experience, that number

1:50

is probably higher than that.

1:52

It's probably closer to 40 or 50%.

1:55

On weight-bearing radiographs, Lisfranc

1:58

injuries may not be visible initially.

2:00

They can sometimes take up to

2:02

six weeks to become apparent.

2:03

Initially, with the swelling, the midfoot may

2:06

be stiff, but you don't actually see separation.

2:10

And even on the classic or cardinal weight-bearing

2:14

views, it may take a bit of time for that splaying

2:18

to occur between the base of the first and second,

2:21

which used to be the hallmark of diagnosis.

2:25

Now, if we look at the midfoot, there

2:28

are three metatarsal bases that have

2:31

sort of a trapezoidal morphology to them.

2:35

And you can see that the base of

2:36

the second metatarsal is recessed

2:40

between the third and the first.

2:44

And it sits directly adjacent

2:46

to the second cuneiform.

2:48

And we're going to label these.

2:49

We're going to give them labels C1, C2, and C3.

2:53

And then we're going to label

2:54

this M1, M2, M3, M4, M5.

2:57

And of course, we have the cuboids.

3:00

Now this configuration, that is kind of

3:02

a little bit like a Roman arch, confers

3:05

stability to this arc right here.

3:08

And you're going to better appreciate the

3:09

arc in the short axis or axial projection.

3:12

But I want to point out Lisfranc ligament complex.

3:16

Now I'm on the dorsum of the foot.

3:19

This is known as the dorsal Lisfranc ligament.

3:23

The Lisfranc ligaments go from C1 to M2.

3:27

This one's kind of stubby.

3:30

Then let's flip it over and go to

3:31

the plantar aspect of the foot.

3:33

So we're on the underbelly of the foot.

3:36

That's C1, M2, the plantar

3:40

portion of the Lisfranc complex.

3:43

So you might say, okay, there's a

3:44

dorsal, there's a plantar, well, which

3:47

one's the Lisfranc ligament officially?

3:50

Which one's the main ligament?

3:51

The answer is neither.

3:54

The main ligament is the one that's in between.

3:57

So it's under this one and it's over this one.

4:01

And it also is going to be short and stubby.

4:04

It's between those two.

4:05

I've just drawn it in in red.

4:07

And because it's short and stubby,

4:09

when you bisect it, it doesn't retract.

4:13

It's almost like you slice a stick of

4:16

butter, but the butter doesn't fall apart.

4:18

All you see is a line through the butter

4:21

stick, and that's what happens when

4:24

you have a tear of what we call the

4:26

proper interosseous Lisfranc ligament.

4:29

So we've got a dorsal, we've got a plantar,

4:32

and in between we've got, not drawn, a proper.

4:37

Then we've got some other lesser ligaments.

4:39

C2M2 ligament, also known as a tarsal metatarsal.

4:46

We also have a C1M3 ligament.

4:51

Now these plantar ligaments are a little

4:53

skinnier, and they're a little longer.

4:56

So, when they tear, they may retract.

4:58

Unlike our main, proper Lisfranc

5:01

ligament, that doesn't really retract,

5:04

because it's stuck in a very small space.

5:07

But when you lose that proper ligament,

5:09

and you use, you lose these plantar

5:11

ligaments, You've got big problems.

5:14

Obviously, there's another

5:15

tarsometatarsal ligament drawn in here.

5:18

So, Pearl, you're looking at an MRI.

5:22

You're looking at a stir, fat suppressed

5:24

sequence, or a spur, or a spare, or a special.

5:27

Very water emphasized.

5:28

And you see high signal at C2,

5:32

C3, the cuboid, M4, M3, M2.

5:36

You better think Lisfranc ligament injury.

5:39

Otherwise, you and your patient

5:41

are going to be in trouble.