0:00

There is another structure that has been emphasized in,

0:04

in, uh, recent literature,

0:05

and that is the cable and the cable.

0:08

Along with its, uh, other structure,

0:11

the crescent become very, very important

0:14

to the orthopedic surgeon.

0:16

The cable is a thickened region

0:19

involving distal fibers of the supraspinatus

0:22

and infraspinatus tendon.

0:25

It's not at the footprint, but it's near the footprint

0:28

and it is a curved structure.

0:31

It actually relates to deep capsular fibers

0:34

that are intimate with the deepest tendonous fibers

0:37

of these two tendons.

0:40

In a sagittal Mr.

0:41

Orthographic image, this is what the cable looks like.

0:46

It extends from the anterior portion

0:48

of the supraspinatus tendon to the posterior portion

0:52

of the in infraspinatus tendon,

0:54

and then it also extends into the rotator interval

0:58

as the cortical humeral ligament intimate

1:01

with the traversing biceps penant.

1:04

Now you might ask,

1:06

how often do we see this particular structure

1:10

with conventional radiography?

1:11

I would suggest we do not we, we do not see it that often,

1:15

although I'll show you some examples in this uh,

1:18

lecture, but with Mr.

1:20

Arthrography, we can identify it.

1:22

So I thought I'd show you

1:24

with this Mr Arthrogram where it is.

1:27

Here it is on a transverse image located

1:30

between the supraspinatus tendon anteriorly in the in

1:34

infraspinatus tendon, posteriorly.

1:36

It's in this region located a little bit away

1:40

from the footprint.

1:42

It also extends anteriorly, not shown here

1:45

as the corco humeral ligament.

1:48

Now if we cross reference that structure

1:50

to the coronal images,

1:52

and I put arrows on it, this is the cable.

1:56

You can see it's deep to the tendon itself.

1:59

It is linear, it's of low signal distal

2:03

to it is a thinner area that is known as the crescent.

2:07

Most of the tears that we see involving the tendons

2:10

of the rotator cuff involve portions of the crescent.

2:17

If you're one of the lucky people listening to my lecture

2:21

and you have cables in both of your shoulders

2:24

and they are large, you have a cable dominant shoulder

2:28

with failure occurring within the crescent.

2:31

The degree of retraction typically is to the cable

2:36

and no further.

2:39

If you in fact are the one of the unlucky persons listening

2:43

to this particular lecture where you have little cable

2:46

or in fact no cable.

2:48

With failure occurring within the crescent region,

2:52

the degree of retraction of the torn tendon

2:56

can be greater. All right,

2:58

So please keep this in mind.

3:01

That's why the cable and the crescent become important.

3:06

Now, I wanted to show you examples of a type

3:09

of tear on your left that occurs in a cable

3:14

dominant shoulder.

3:16

And I show you one on your right that occurs

3:21

in a cable non-dominant

3:23

or let's say crescent dominant shoulder.

3:26

And you can see that the degree of retraction that occurs

3:30

with these tears is different, less

3:32

so when you have a prominent cable when than

3:35

when you do not.

3:37

Now, to understand this,

3:39

perhaps the orthopedic surgeons would suggest that we turn

3:42

that image sideways and then we go ahead and draw the cable

3:49

and what do we compare it to?

3:51

We compare it to the top of a suspension bridge.

3:56

So that is why this particular structure consisting

4:00

of collagen fibers attached both anteriorly

4:04

and posterior, provides stability to the tendons

4:08

of the rotator cuff

4:09

and limit the degree of retraction of the torn tend tendon,

4:13

particularly when it occurs

4:15

between these two attachments of the cable.

4:20

Here on your left, a beautiful drawing taken from the

4:23

literature showing you

4:25

as you look down on it here is the cable,

4:28

and this is the crescent.

4:30

This is the posterior border of the cable you can see here,

4:34

and there would also be a border back here that is involved

4:39

with the infraspinatus.

4:41

If you have tears involving the crescent, be they small

4:47

or be they large, the degree of retraction is generally

4:51

to the cable and no further.

4:53

Look at this example here is the cable.

4:57

Here is the tear leading to surface irregularity,

5:01

but it only extends to the area of the cable

5:05

and the cable is not retracted.

5:08

And indeed, when you have these types of tears,

5:11

sometimes the cable even looks more prominent

5:14

because those fibers have retracted to it.

5:19

If we go ahead and look at the bottom image,

5:22

a transverse image, you can see the tear as that kind

5:26

of triangular bright area that's extending

5:29

to the region of the cable.

5:30

You could see that as these curve linear,

5:33

low signal regions.

5:35

That is typical when tears occur in the crescent.

5:40

But if you have tears of the table, be they anteriorly

5:45

or posterior, be they small

5:47

or large, they may propagate rapidly,

5:51

they may become larger in size,

5:53

and the degree of retraction may be more

5:56

Extensive.

5:58

That is why it is very important

6:00

to find these tears particularly anteriorly,

6:05

that you look at the anter

6:06

or leading edge of the supraspinatus tendon

6:11

which align, which lies just lateral

6:17

to the biceps tendon as shown here.

6:19

Let me enlarge that for you.

6:21

So here we see the greater tuberosity gt,

6:25

the lesser tuberosity lt, the biceps tendon,

6:29

and this is the tear

6:31

involving the cable region anteriorly.

6:35

So when I study the rotator cuff in the coronal plane,

6:41

I always start anteriorly.

6:42

I identify the bicipital groove

6:44

and I look for marrow

6:46

as it begins just lateral to the groove.

6:49

That's the greater tuberosity,

6:51

and I double look at that region just

6:55

to be sure there's not a tear right here.

6:57

There should be tendon, not bright signal attaching to

7:02

that facet.

7:06

Now, I wanted to show you examples of three

7:09

of the basic types of tears that are described

7:12

by orthopedic surgeons.

7:14

I'm showing you a crescent shaped tear at the top,

7:18

which is the type of tear that occurs with a prominent cable

7:21

and failure in the crescent, the degree of retraction

7:25

to the cable and no further.

7:28

I'm showing you in the middle a U-shaped tear,

7:30

which is the kind of tear that occurs in the absence

7:35

of a prominent cable.

7:38

And you can see it's more U-shaped rather

7:40

than crescent shape.

7:42

And then there are L-shaped

7:43

and even reverse L-shaped tears

7:45

where there is an elongated degree

7:47

of retraction in certain regions.

7:50

Let me show you one example.

7:53

Here is a U-shaped tear.

7:57

Now this is very similar

7:58

to the GA picture I showed at the very

8:01

beginning of this lecture.

8:02

This is a delaminated tear. It is full thickness.

8:07

It's involving both the bursal sided

8:09

and the articular sided fibers,

8:12

the sal sided fibers shown by the yellow triangle

8:17

or arrowhead,

8:18

and the small blue arrow showing you the retracted

8:21

articular sided fibers.

8:23

The fact that they are retracted

8:25

to different degrees means the tear is delaminated,

8:29

and almost without exception,

8:32

it is the articular sided fibers that typically

8:36

are retracted more immediately than the bursal sided fibers.

8:40

Here's what it would look like if you were looking down at

8:43

it, the time of arthroscopy.

8:45

And here in an axial image we are looking at the retracted

8:50

articular cited fibers shown here.

8:53

This is a U-shaped tear.