0:01

We're now gonna move on to the second pattern

0:04

by the Mayo classification system.

0:06

Carpal instability, non dissociative, abbreviated sin.

0:11

So this is derangement between rows but not in rows.

0:16

So derangement between the radius and proximal carpal row.

0:20

And I'll show you one example.

0:22

We'll talk about NAR translocation

0:25

and also between carpal rows

0:28

and I'll show you a couple of examples of that.

0:31

Nar translocation means that indeed what is happening,

0:35

the proximal carpal row is migrating in an ulnar direction

0:40

along the slanted surface of the distal radius,

0:44

often related to problems involving the

0:48

ulnar side of the wrist.

0:50

It may be rheumatoid arthritis with erosion of the bone,

0:53

Madeline type form deformity

0:56

where the distal ulnar has been excised

0:58

or with certain traumatic conditions.

1:01

In order for these bones

1:04

to slide in an ulnar direction this way

1:08

produce translocation, you may ha you must have problems

1:13

with the obliquely oriented extrinsic

1:17

radiocarpal li uh ligaments.

1:18

So we may see problems of the radio scaphoid,

1:22

the radio sca fo capitate and the radio luno triquetral or,

1:27

and also called the long radio lunate ligament.

1:30

And that will allow the proximal carpal road a slide in

1:34

an ulnar direction.

1:36

So this is what it would look like.

1:37

This is called type one nar translocation.

1:42

The entire carpus has slid in an ulnar direction.

1:47

The my drawing shows you disruption of the radio OID

1:50

and radio scap o capitate ligaments.

1:54

But this picture over here also shows you disruption

1:57

of the radial no triquetral ligament.

2:00

So those are the types of ligaments

2:02

that will fail when you see this.

2:05

This is an interesting pattern I've seen spontaneously in

2:09

rheumatoid arthritis.

2:11

This is a cadaver with rheumatoid arthritis.

2:13

We sectioned it, the wrist coronally,

2:16

and you can see the ulnar translocation type one

2:21

with the lunate now locked in its position

2:24

as it overlaps the distal radi.

2:27

The type two

2:29

is a problem in the scapholunate interosseous space.

2:34

It leads to massive widening

2:37

between the scaphoid and lunate.

2:40

The prognosis for this particular type

2:43

of problem is worse than a simple scapholunate dissociation.

2:47

The scapholunate interosseous ligament is torn

2:51

and some ligaments also including the radio lunar

2:54

triquetral, may be torn as the lunate migrates, uh,

2:59

in an ulnar direction.

3:00

So here's an example.

3:02

Uh, this was an interesting example

3:04

because the patient did have a lunar triquetral,

3:07

non osseous fusion as well.

3:09

But you can see massive disruption.

3:12

I'm showing you the scap lunate ligament failure at its

3:16

lunate site of attachment.

3:17

The scaphoid remains in place.

3:20

So this would be a type two pattern of ulnar translocation.

3:26

And then the other, and this is the part

3:28

that's gonna be a little bit confusing, particularly

3:30

for those of you who are beginning at this,

3:32

is an entity known as mid carpal spin where the problem lies

3:37

between the, the proximal and distal carpal row.

3:42

And in general, to get problems between these two rows

3:45

of carpal bones, you have to have problems with ligaments

3:50

that cross the mid carpal joint, the arcuate

3:53

and the deltoid ligament.

3:55

There are four subcategories of this. I'm listing them here.

3:59

I'm gonna show you only two of them.

4:02

But here are diagrams indicating what is happening.

4:06

And you can see here

4:07

that the major abnormalities are at the level

4:10

of the mid carpal compartment.

4:12

Okay? So it's, it's not a problem within a compartment.

4:17

It's a problem between two compartments.

4:20

We to see this, you should have abnormalities of the arcuate

4:24

and or deltoid ligaments.

4:26

Let me show you two examples.

4:28

The first one would be labeled dorsal mid carpal

4:31

instability, dorsal subluxation of the capitate

4:35

and dorsal tilting of the scaphoid and lunate.

4:38

And typically there may be additional tearing

4:41

of the radio scap capitate ligament.

4:44

So here's the normal alignment.

4:45

This is what happens with this pattern.

4:49

The scaphoid and lunate move together

4:52

because the ligaments between them are normal.

4:55

The problem is in the position of the capitate

4:59

with respect to the lunate.

5:01

So here is what it looks like.

5:04

You can see this, uh, in beautiful uh, diagram here

5:08

and I'll show you what it looks like.

5:10

So note that there is dorsi flexion of the scaphoid,

5:14

but there is dorsiflexion of the lunate.

5:16

So there's no dissociation.

5:19

It's the capitate in its position,

5:21

which is dorsally translated.

5:24

Okay, that makes this a mid carpal instability,

5:29

specifically dorsal mid carpal instability.

5:33

And then there is the other type I wanted

5:37

to show you extrinsic.

5:39

This is a similar problem that occurs typically related

5:42

to Amal united fracture of the distal radius.

5:46

So let me show you here is normal alignment.

5:49

Here is a malted fracture of the distal radius.

5:53

As you know, there's often dorsal tilting

5:56

Of the articular surface

5:58

and you can see the MA alignment that may accompany that

6:03

with abnormalities centered in the mid carpal joint.

6:06

Here is what it looks like.

6:08

This is a remote ma united fracture of the radius.

6:12

The scaphoid is dorsally tilted as is the lunate.

6:15

They're moving together. The capitate is translated in

6:19

a dorsal direction.

6:20

This is known as extrinsic, mid carpal instability.