0:00

We're gonna now move on away from the meniscus,

0:03

and I'm gonna spend the next, uh, 45 minutes

0:07

or so discussing, uh, injuries of the knee, mechanisms

0:12

of injury and the footprints that they, uh, leave behind.

0:18

I have two general objectives here

0:20

that I would like to, uh, note.

0:22

I'm gonna review the normal structure of human ligaments

0:26

and emphasize again, the collagen framework

0:29

of the ligaments of the knee.

0:31

And then in a longer segment,

0:33

I'm gonna describe in detail the footprints,

0:36

mainly in the form of bone contusions

0:38

and fractures that are left behind

0:41

on the MR images following the injury

0:45

that allow you the observe to predict the mechanism

0:48

of injury, and then knowing that predict the probable sites

0:52

of ligament injuries.

0:55

When we deal with a collagen structures of tendons

0:58

and ligaments, they are very, very similar.

1:01

The major collagen bundles in tendon

1:04

or ligament are oriented along the long axis

1:08

of the ligament or tendon.

1:10

Now, this is ideal

1:11

because as you think about it,

1:13

tensile force is generally applied to a tendon or ligament.

1:17

The collagen fibers in large part are oriented along

1:22

the force of the tensile, uh, stress, and

1:25

therefore they can resist it.

1:27

There are reports

1:28

that indicate minor differences in the collagen bundles

1:32

in a tendon and ligament.

1:33

The ligaments perhaps there are slightly less

1:37

oriented in a linear fashion,

1:39

so perhaps they look more like string beans,

1:41

and that's why I added string beans

1:43

to this particular, uh, slide.

1:48

When I deal with ligament injuries,

1:49

there are three basic patterns that I, uh, see.

1:53

Uh, the, the first of these are complete tears,

1:57

typically transverse

1:59

or obliquely oriented, uh, defects within the, uh,

2:04

uh, ligament that disrupt all of the collagen bundles.

2:08

The second would be something I call a partial tear.

2:11

Were obliquely

2:13

or transversely oriented defects disrupt some,

2:16

but not all of the collagen bundles,

2:19

and I show you here with some ACL pictures complete

2:23

and partial tears.

2:25

The third pattern is our friend delamination, indicating

2:29

that the point of failure is between

2:32

or among the collagen bundles and not through them.

2:35

So I illustrate that with diagrams to indicate

2:39

what that might look like.

2:40

Whether it is complete

2:42

or incomplete, this is what a delaminated type

2:45

of pattern would look like.

2:47

And perhaps this would be what we might see

2:50

on an MR examination with fluid sensitive sequence.

2:54

We can appreciate here the, uh, altered linear

2:59

Signal oriented along the long axis

3:01

of the collagen bundles.

3:03

Now, when we talk about delamination of ligaments,

3:06

we particularly stress the anterior cruciate ligament

3:11

and what we expect to see in many older persons,

3:14

particularly middle aged

3:15

and elderly persons, as a pattern of mus

3:19

and oid change that involves the cellular tissue

3:23

between the collagen bundles.

3:26

This is something that on clinical examination generally is

3:30

associated with a stable ligament

3:31

and not ligament instability.

3:34

It is suggested in the anterior cruciate ligament.

3:37

It is the posterolateral bundle that is typically involved.

3:41

It may lead to pain typically in terminal extension,

3:45

but in some persons it the, uh,

3:48

there are no symptoms or signs.

3:51

One of the interesting aspects of cystic

3:54

or mucinous degeneration

3:56

of the anterior cruciate ligament is

3:59

that it may also extend into the anterior root ligament

4:02

and even the anterior horn of the lateral meniscus.

4:06

That's not hard to, uh, understand.

4:08

As we look at the footprint

4:11

of the anterior cruciate ligament here,

4:13

and then we see the adjacent root ligament footprint,

4:17

it's not surprising that dramatic changes in this location

4:21

could pass into the footprint of the root ligament

4:25

of the lateral meniscus.

4:26

And here's an example. Okay, showing you in fact

4:29

that the cystic degeneration in the anterior cruciate

4:33

ligament is extending into the root ligament

4:36

and anterior horn of the lateral meniscus.

4:40

Now, as you look at the previously, um,

4:43

reported descriptions of severe cystic degeneration

4:46

of the anterior cruciate ligament,

4:48

some have suggested it looks like celery stalk,

4:51

as in this particular example.

4:54

Others suggest it looks like a bag of worms.

4:58

One of the interesting associated

5:00

abnormalities that we can see.

5:03

Intraosseous cyst formation as fluid passes

5:06

from the abnormal ligament into the sub bone.

5:10

More commonly than not,

5:12

it is the tibia rather than the femur.

5:14

But you may see similar changes, uh, in the, uh, femur

5:18

or in both bones.

5:21

In addition, in some of these cases,

5:22

you will have para cruciate ganglion cyst as well,

5:26

most commonly located posteriorly rather than anteriorly.

5:32

Now, what happens if you see a similar appearance in a young

5:36

person, perhaps even an adolescent?

5:39

The case I'm showing you is not an adolescent,

5:41

it's a 26-year-old soccer player,

5:43

but if you see something like this in an adolescent

5:47

with linear areas of altered signal,

5:50

although they are subtle,

5:51

but with a ligament that looks a little bit broad

5:54

with intermediate or high signal intensity,

5:57

What do you call it?

5:59

Well, if you're dealing with an adolescent or even a child

6:02

and you call it cystic degeneration, the mother or a father

6:06

or both of them will say,

6:07

why is my child having degeneration of the ligaments?

6:12

We have seen this sort of appearance in adolescence

6:16

and in young adults, those who are involved in a lot

6:20

of physical activities, particularly in sports,

6:24

and many of the early cases that I saw

6:27

of this were soccer players.

6:28

These were cases sent to me from some

6:31

of our previous scholars from Brazil.

6:34

Now, this sort of appearance, I think is delamination, okay?

6:39

The failure is really in the connective tissue between

6:43

and among the collagen bundles.

6:45

So typically you will see a stable ligament when the,

6:49

when the the knee is examined on clinical examination

6:53

and usually perhaps with a little bit of rest

6:56

before the person resumes these sports activities,

7:01

the changes will, will go away.

7:04

There may be minor clinical findings,

7:07

but in general, a lot of times this particular appearance is

7:10

associated with no symptoms or signs.