0:00

<v ->We move on to those bursa

0:02

that are located on the volar aspect of the wrist.

0:05

And I don't know how many of you

0:06

who were listening and spent time

0:09

trying to understand these bursa.

0:11

But let me just tell you a little bit about them.

0:14

It is an infection within these bursa

0:16

that produces a characteristic finding

0:18

known as the horseshoe abscess.

0:21

I'll show you another example of this in a moment.

0:24

In order for you to understand these bursa,

0:26

let's just look at a little bit of anatomy.

0:29

This is the volar aspect of the wrist,

0:31

we're gonna add some structures to it.

0:34

The first thing I'm gonna add are two soft tissue spaces

0:38

deep to the flexor tendons.

0:40

The thenar space, radially, the midpalmar space,

0:44

located more ownly.

0:46

These can be infected.

0:48

Superficial to them,

0:50

we see the digital flexor tendon sheaths

0:52

in the second third and fourth fingers.

0:55

Classically, they end approximately just approximal

0:59

to the metacarpal heads.

1:01

If we look at the tendon sheath

1:03

about the flexor pollicis longus tendon,

1:06

we can see that it communicates in almost a 100% of persons

1:11

with a bursa located within the wrist.

1:13

That is the radial bursa.

1:16

If we look at the tendon sheath

1:17

involving the flexor pollicis longus tendon

1:21

in the fifth finger, we can see that in most cases,

1:25

it communicates with a larger bursal sack,

1:29

here shown in blue, this is the ulnar bursa,

1:32

which has small digital extensions.

1:35

Hence there's an area here

1:37

in which there is no tendon sheath,

1:39

and that's gonna become important in a moment.

1:43

The radial and ulnar bursa are often connected

1:46

by intermediate bursa.

1:48

Sitting at top this, we have the transverse carpal ligament.

1:52

And one other space, a deep, soft tissue space

1:55

beneath the distal radius, is the Space of Parona.

1:59

That too can be infected.

2:02

Here, examples shown first by diagram of the location

2:06

of the thenar and midpalmar spaces.

2:08

Here's what they would look like

2:10

if they were involved in an abscess.

2:13

Here, you can see a thenar space was a gas

2:16

containing abscess, deep to the flexor tendons.

2:20

So, there's a lot of interest in hand infections

2:23

and particularly, infections that involve these deep spaces

2:28

on the volar aspect of the hand.

2:32

Now, Dr. Aguiar did a very nice study

2:35

when he was with us in San Diego,

2:37

and he looked at the connections

2:40

between the flexor tendon sheaths,

2:42

and these ulnar and radial bursa.

2:45

As well as the connections between the bursa themselves.

2:48

And this just kinda goes along with what I just said

2:51

with regard to the last slide.

2:54

Common connection between the radial and ulnar bursa,

2:57

almost a 100% connection between the radial bursa

3:00

and the flexor pollicus longus.

3:03

50 to 80% in the fifth finger, and then elsewhere,

3:07

the frequency of connection of these tendon sheaths

3:10

to the bursa is very low.

3:13

Here's an example of fluid in a cadaveric wrist

3:17

that you can see is in the radial bursa

3:20

and in the ulnar bursa.

3:21

And I'll call your attention to how narrow it is here,

3:25

we'll get back to that finding in a moment.

3:29

So, this will be an example of the shape

3:32

that you would expect when there is bursitis involving both,

3:36

the radial and ulnar bursa.

3:39

And exactly what happens within horseshoe abscess.

3:43

An infection perhaps begins out here in the thumb,

3:46

it spreads via the tendon sheath, gets to the radial bursa,

3:50

connects to the ulnar bursa,

3:52

ends up extending out into the fifth finger,

3:55

and you end up with a horseshoe abscess.

4:00

And that is what it would look like, the shape on the left.

4:03

Here's another example.

4:04

This one is not a bacterial horseshoe abscess.

4:09

It relates to atypical mycobacteria,

4:12

and you can see the rice bodies.

4:14

More about those in a few minutes.

4:17

And another example, this one in rheumatoid arthritis,

4:20

where there's a lot of bursal fluid,

4:22

both in the radial and ulnar bursa.

4:25

Now, in some instances,

4:26

perhaps in those in which there's not a connection

4:29

between the ulnar bursa and the radial bursa,

4:33

the pattern of fluid is a little bit different.

4:36

It's confined to the ulnar bursa.

4:38

And when you look at this shape

4:40

of the distended ulnar bursa, it looks like an hourglass.

4:44

So, here you can see it's distended distally,

4:47

it constricts within the carpal tunnel,

4:49

and then it's distended in the region of the wrist.

4:54

That is very characteristic of ulnar bursitis.

4:59

To show you a couple of examples,

5:00

this is related to rheumatoid arthritis,

5:04

note the abnormal signal related to fluid,

5:07

and you can see synovial proliferation

5:09

as well as areas of intermediate signal.

5:13

This one, a little rare, is pigmented villonodular bursitis,

5:17

involving mainly the ulanr bursa.

5:20

You can see the hemosiderin deposition

5:22

shown by the black arrows.

5:24

We can see fluid, and we can see synovial proliferation.