0:00

So we move on to our second type of tear, which goes

0:04

by a variety of names.

0:06

Longitudinal, horizontal, circumferential, horizontal

0:10

or horizontal tear.

0:12

It's often known as a cleavage tear.

0:16

We see this often in older people related

0:19

or associated with meniscal degeneration,

0:22

and it may relate to sheer force.

0:25

Typically, this tear begins at the inner margin

0:28

or near the inner margin of the meniscus,

0:31

and it takes the path

0:33

of least resistance extending toward the periphery

0:37

or a certain distance.

0:39

As it gets to the periphery, it may branch

0:42

because we have many longitudinal circumferential collagen

0:47

fibers present in that particular region.

0:51

So here's what it looks like in my drawing.

0:53

That is a longitudinal horizontal or cleavage tear.

0:57

And if that extends all the way from the tip way out

1:02

to the periphery, you may see widening kind

1:05

of like a fish mouth appearance of the inner margin.

1:09

You may get this gap particularly involving the tip

1:13

of the meniscus.

1:14

The length of a longitudinal horizontal tear relates

1:18

to its circumferential or antral posterior dimension.

1:22

The width is the central peripheral dimension.

1:26

Now it's these particular tears

1:28

that are associated most commonly

1:30

with para meniscal ganglion cysts, right?

1:33

Other tears can be,

1:35

but this is the pattern that we see typically

1:38

with a para meniscal cyst.

1:40

Now, we all know to look for these, we tend to think of them

1:43

as being bright on our fluid sensitive sequences like

1:47

this, right?

1:48

And generally the feeling is what we're dealing

1:51

with is joint fluid, which is then extending

1:54

through the this tear,

1:56

which has violated the meniscal surface,

1:59

and then the fluid extending into the cyst.

2:03

The cyst is strong,

2:04

but not certain evidence that there is a meniscal tear.

2:09

Now, I wanna remind you,

2:10

sometimes you will get para meniscal cysts without

2:14

surfacing tariffs.

2:16

If you have extensive ness or OID change within the meniscus

2:21

and even intra meniscal tearing, you can end up

2:24

with a bright para meniscal cysts.

2:27

All right. Here we can see this. These are Mr.

2:30

Orthographic images.

2:32

And on this one, no gadolinium is filling

2:35

that particular cyst,

2:37

but on the fluid sensitive sequence,

2:39

we can see there is fluid like signal within it.

2:43

So although most of these do communicate

2:45

with the joint lumen, some do not.

2:48

Now, a few words about these para meniscal gang,

2:52

they insists they're more frequent on the medial side.

2:55

They're larger, they're kind of more aggressive on

2:58

The medial side.

3:00

Generally, yes, they're associated with meniscal tears,

3:03

particularly on the medial side.

3:05

I'm gonna show you an exception on the lateral side.

3:08

And when they get large,

3:10

and they may, they may erode bone, either the femur

3:13

or tibia or both?

3:15

Both. All right. Showing you here, in fact,

3:18

an extensive large para meniscal cyst to point out

3:21

that these may extend from the posterior horn

3:25

of the medial meniscus

3:27

behind the posterior cruciate ligament

3:30

and may simulate a para cruciate ganglion cyst.

3:34

They can look aggressive, they can extend around

3:37

or even through the medial supporting structures.

3:40

So here we're dealing

3:41

with large para meniscal ganglion cyst.

3:45

Now, the one exception I want to comment on

3:47

because it's been emphasized in the literature,

3:50

is the presence of a para meniscal cyst often leaking

3:55

with edema in Hoffa's pap pad adjacent to the anterior horn

4:00

of the lateral meniscus shown here,

4:02

occurring in the immature skeleton in particular,

4:06

because this has been pointed out as a finding

4:09

that may not be accompanied by an adjacent meniscal tear.

4:15

When you deal with a tall meniscus,

4:17

and I don't have a precise height to tell you,

4:20

but if there is a tall meniscus,

4:23

there is a pattern of failure.

4:25

We'll call central cavitation.

4:28

It's like a very broad longitudinal horizontal tear,

4:31

but it does not have to communicate

4:35

with the surface of the meniscus.

4:37

And this is a pattern of failure that we see

4:40

with discoid meniscus.

4:42

Now I'm gonna be talking about other patterns of failure

4:44

with such meniscus a little bit later.

4:47

So grade two signal,

4:49

particularly if it is really bright,

4:52

even if you cannot follow it to the surface

4:55

of a meniscus in a discoid meniscus, is consistent

5:00

with a meniscal tear.

5:01

And here's an example with a para meniscal cyst.