0:00

Another surgical indication as we consider injuries

0:04

to either the radial collateral

0:06

or ulnar collateral ligament in this case.

0:09

Moving back to the thumb here in the coronal imaging plane,

0:12

you see the proximal detachment

0:14

of the radial collateral ligament

0:17

and you move into the axial imaging plane

0:20

and look at that, uh, capsule or failure.

0:23

Here you're seeing the radial collateral ligament

0:25

and the distortion of the capsule that extends all the way

0:29

to the dorsal aspect of the metacarpal fall andal joint.

0:33

When we have extensive dorsal involvement of the capsule

0:37

of the radial collateral ligament failure

0:39

or the NAR collateral ligament failure,

0:41

those would also be considered indications for surgery.

0:45

Just too much of that capsule being abnormal for us

0:49

to consider conservative therapy and that it would scar down

0:52

and end up with a stable articulation.

0:57

Here in looking in the sagittal imaging plane, uh,

1:01

as we look at the metacarpal phal joint,

1:04

you can see fluid within the articulation.

1:07

As you look at the proximal family,

1:11

the low signal intensity cortex, you see

1:13

that it's discontinuous at its palmer extent as well

1:17

as along the articular surface.

1:20

While this MR Image clearly doesn't have the resolution of

1:24

ct, this is definitive binding

1:28

or diagnosis of a non-displaced fracture.

1:31

We can also see the palmer subluxation of the base

1:35

of the proximal phx.

1:36

Here you see the distortion

1:38

and tearing, as well as partial detachment

1:41

of the palmar plate.

1:43

Here we can see the proximal capsular attachment, that

1:46

and near normal position.

1:48

So in this case, we're easily able to identify

1:51

that non-displaced fracture as well as partial detachment

1:56

of the palmar plate with traumatic remodeling and tearing.

2:03

Let's move now to a different part of the thumb,

2:05

and that's going to be at the trapezial metacarpal joint

2:08

or the first CMC similar to the shoulder.

2:13

This articulation has a very wide range of motion,

2:16

and I think all of us are aware

2:18

that when we have broad range of motion

2:21

stability can ultimately become an issue

2:24

because of loose ligament capsular structures

2:27

and the ability for us to easily

2:29

injure these soft tissue stabilizers.

2:32

So we can have this in both the setting of trauma

2:35

or degenerative change.

2:38

So true to Dr. Resnick's classic teaching.

2:42

Let's review the anatomy in detail.

2:45

As you look at this illustration,

2:46

you're considering the first CMC from its dorsal aspect

2:51

here, looking at the trapezium base of the first metacarpal,

2:55

this ligament called the dorsal radial ligament.

2:58

As we move ulnar,

3:00

we're looking at the poster oblique ligament,

3:02

and then of course, here,

3:03

the inter metacarpal ligament at the base of this first

3:07

and second metacarpals.

3:10

Now let's look at the palmar aspect of the her CMC,

3:14

the ulnar collateral ligament,

3:16

and then we have the structures, the deep

3:19

and superficial anterior oblique ligament, true

3:23

to their names, deep closest to the articulation,

3:26

superficial, closest to skin surface.

3:29

So now let's look at these

3:32

structures from an MR imaging standpoint,

3:35

a sagal image now here taken

3:37

through the carpal metacarpal articulations,

3:40

looking at the dorsal aspect of the CMC,

3:43

there's your dorsal radial ligament

3:46

coronal imaging plane coming all the way

3:48

to the dorsal aspect of the CMC.

3:51

This is a very robust structure.

3:53

You see it nice and thick here in both the sagittal

3:57

and the coronal planes.

4:00

Now remember, look at our diagram.

4:02

You just saw the dorsal radial ligament.

4:05

If we move ulnar, we're going

4:07

to encounter the posterior oblique ligament.

4:09

Here's a dissection.

4:11

Consider this similar to a coronal imaging plane.

4:13

Looking at the dorsal aspect of the articulation,

4:17

here's the base of the first metacarpal.

4:19

There's that substantial thick dorsal radial ligament moving

4:23

to the ulnar extent here that, uh, that clip is look right

4:27

underneath the posterior oblique ligament.

4:29

So now in the sagittal imaging plane,

4:32

we've moved from dorsal to a more ulnar position,

4:35

and here you see the poster oblique ligament in both the MR

4:39

image as well as here in the specimen photograph.

4:42

This also, as you can see, a fairly thick

4:45

and robust structure, inter metacarpal ligament

4:49

as its name designates between the basis of the first

4:53

and second metacarpals

4:56

and the ulnar collateral ligament.

4:58

Here we're looking at the coronal imaging plane.

5:01

This is T one fat sat on the left.

5:04

In the middle, we're seeing T one fat sat

5:06

with contrast placed in the articulation

5:09

and on the right, the specimen photograph of the dissection

5:13

of that ulnar collateral ligament.

5:15

When we distend this articulation with contrast,

5:19

you can nicely see the outline of

5:21

that ulnar collateral ligament

5:24

considered an extra capsular ligament originating from the

5:27

distal marginal, the flexor retin aum,

5:30

and then inserting superficial

5:32

and ulnar to the superficial anter oblique ligament.

5:35

When we're thinking about the base of that first metacarpal,

5:40

let's move now to the popular ligaments, perhaps one,

5:44

let's say of the first carpal metacarpal articulation.

5:48

Remember, you're again at the palmar aspect

5:51

of the first CMC,

5:54

so here the white arrow pointing to this

5:56

Superficial structure, the black arrow to that low,

6:00

low signal intensity, linear structure, so deep closest

6:03

to the articulation, superficial, closest to skin surface,

6:07

they're closely applied one to the next.

6:09

We've placed a little contrast in the articulation here

6:12

to help us to delineate those two structures.

6:17

So again, deep and superficial components

6:19

of the anterior oblique ligament

6:22

that deep a OL has been referred to

6:26

as the beak ligament.

6:28

This is intracapsular.

6:29

It inserts at the margin of the trapezium

6:32

and firsthand the, of course, deep

6:34

to the superficial component of this ligamentous structure.

6:38

And that becomes important clinically as it's implicated

6:42

to be attached to the bendit fracture fragment,

6:46

while the superficial component remains intact

6:49

and extends beyond where that fracture fragment

6:53

slightly displaces from the metacarpal base.