0:01

Now let's look at pathologic conditions that involve

0:04

the rotator cuff.

0:06

Here I'm showing you a curve of the stress

0:10

and strain o of the uh, tendons of the rotator cuff.

0:13

And as you apply stress to these tendons, they first go

0:18

through physiologic regions, they are relaxed,

0:22

and they will in fact elongate

0:24

and they elongate further through the linear region.

0:28

And then once beyond that, they begin to fail.

0:31

The failure can be partial thickness

0:33

or it can be full thickness.

0:36

I'm showing you the situation in both young and old persons.

0:40

The point of failure of a tendon requires greater stress in

0:44

the young and lesser stress in the elderly, mainly

0:49

because of tendon degeneration.

0:54

So let's look at tendon degeneration.

0:57

The first thing I wanna look at is a normal muscle tendon

1:01

bone unit, and I show you a picture of it.

1:04

If we go ahead and show multiple muscle contractions applied

1:08

to this particular unit.

1:11

The failure can occur at the myo tendonous junction.

1:15

All right? It can occur at the site

1:18

of tendon insertion in the bone,

1:21

or can occur within the bone itself.

1:24

And in the bone itself.

1:25

It may even uls an entire hypothesis.

1:28

As you know, typically

1:30

because the tendon is normal in this young person, failure

1:34

of the tendon is not seen.

1:37

So indeed, in this age group,

1:40

what we may see are muscle strains shown here in the in

1:45

infraspinatus on your left,

1:47

or as I'll talk about tomorrow,

1:49

particularly in the adolescent baseball pitcher,

1:52

failure in the FSIS with widening an abnormal signal

1:57

because that area is weaker than the tendon itself.

2:01

These are the patterns of failure we see in the young.

2:06

So we have a general rule.

2:08

Normal tendons do not tear

2:11

unless they are lacerated

2:13

shown here in a sagittal image occurring in the Achilles

2:17

tendon, or they are crushed.

2:20

Clearly there are exceptions to the rule,

2:23

but typically with failure of a tendon,

2:26

the tendon does have degeneration.

2:31

Now, let's go ahead and add

2:33

to the equation degenerative changes.

2:36

When we have degenerative changes

2:38

and we apply our muscle contractions, the point

2:43

of failure typically is in the tendon.

2:48

Now, it can occur elsewhere or at multiple sites,

2:50

but typically we see that point

2:53

of failure within the tendon

2:56

itself. Now, what

2:58

Do we call that?

3:00

The two terms that are applied

3:02

to this are typically tendinosis or tendinopathy.

3:07

The reason most people do not apply tendonitis

3:11

to this particular process, you mean

3:14

to this particular process, the degree of inflammation

3:19

within the tendon tends to be mild in most cases.

3:24

So it's not an inflammatory process,

3:26

it's a degenerative process.

3:29

Now, whether you prefer tendinosis

3:31

or tendinopathy, I prefer tendonosis.

3:33

And there was a four day conference I saw, I believe,

3:36

in Belgium over the last five years devoted to whether

3:41

tendinosis or tendinopathy was the better term.

3:44

It was a close vote,

3:46

but indeed that particular vote ended up

3:49

tendinosis, was the better term.

3:52

We see that typically as thickening of the tendon

3:56

and graying of the tendon.

3:58

Shall I show you in one example on your left

4:01

with intermediate weighting

4:02

and fluid sensitive, fat suppressed weighting,

4:06

what degeneration of the tendon looks like

4:09

gentle graying is, okay, so gray is okay,

4:14

but typically the signal does not reach that of joint fluid.

4:17

You can see what that looks like here, right?

4:20

Because once it gets that bright, we tend

4:22

to think probably there is a tendon tear that is present.

4:27

I.