0:01

Now finally, that sagittal band,

0:03

I've given you a few little looks at it in the previous

0:05

slides here.

0:07

A beautiful dissection from Michelle de Meier.

0:11

Uh, a, a lot of these articles

0:14

that you see in the radiology literature

0:16

that have amazing anatomic pathologic correlations, uh,

0:20

again are what I'll call the disciples

0:22

of Don Resnick Resnick.

0:24

Michelle de also spend time with Don as a scholar, uh,

0:27

in his more junior years as a faculty person.

0:30

So as we look at this diagram, number one

0:34

represents the extensor tendon.

0:35

Two and three represent the superficial

0:37

and deep components of the sagittal band.

0:40

So the superficial

0:42

and deep coalesce one to the other to surround

0:45

that extensor tendon

0:46

and help that tendon to track in a normal fashion.

0:50

As we look at this illustration, it shows us failure

0:53

of the sagittal band close just adjacent

0:57

to the extensor tendon.

0:59

And when we think about this pattern of failure,

1:01

this is a spontaneous sagittal band disruption.

1:05

When you think about these sagittal band injuries

1:07

and you look at your hand and you flex

1:09

and extend people

1:11

with sagittal band injuries often will describe

1:13

or see that tendon snapping across the

1:16

metacarpal phal joint.

1:18

At the dorsal aspect of the articulation here,

1:21

looking at metacarpal phal joints,

1:26

axial two through five imaged here,

1:29

this was an a wrist coil.

1:30

We're looking at a T one weighted image on top

1:32

of fluid sensitive sequence on the bottom.

1:35

And instead of just having to say, wow,

1:37

there's some nonspecific edema, superficial

1:40

to the third metacarpal feal joint,

1:42

we can be much more specific.

1:45

Look at the fluid sensitive sequence,

1:47

the background edema serving as excellent contrast

1:51

to show you the superficial sagittal band

1:54

and the focal discontinuity just at the extensor tendon.

1:59

Deep fibers are intact.

2:01

And so this injury pattern very indicative

2:04

of the spontaneous rupture as we consider failure.

2:09

That sagittal band at a location more distal

2:13

or distant rather from the extensor tendon, this is

2:16

what the traumatic injury to the sagittal band

2:20

often can look like.

2:22

So let's look at this good sensitive sequence.

2:25

And you can see in this case it's not a particularly

2:28

high resolution study.

2:30

This is inversion recovery

2:32

because it was very important for us

2:34

to have good fluid sensitivity in this case.

2:37

And at the same time, resolution was adequate for us

2:41

to make a good diagnosis.

2:43

Here you see the skin surface marker at the level

2:45

of the third metacarpal fall, a**l joint dorsally.

2:49

Here's your extensor tendon.

2:51

Look at the ulnar side as an internal standard, linear,

2:55

delicate, low in signal intensity.

2:56

As you look at the radial side

2:59

Distorted, let's look at the next image discontinuous.

3:03

And when you've got discontinuity

3:05

of the sagittal band on one side,

3:08

what happens The secondary finding of unopposed action

3:11

of the intact side.

3:13

And so that tendon moves towards the intact side

3:16

and sublux is so slight ulnar migration here

3:20

and you've got a tear at the radial band of that

3:26

sagittal band of the third metacarpal fall a**l joint.