0:00

Let's take a case.

0:01

And I'm just going to put one thing

0:03

up on the screen at a time,

0:05

and I'm going to start with a sagittal.

0:09

It's the youngest person, a young gish person,

0:13

and

0:14

usually with younger people,

0:17

we're just talking meniscai today.

0:18

When you're on the meniscal hunt,

0:21

the sagittal is more valuable because the tears

0:25

tend to be in the back and in the front.

0:27

This is just pure common sense.

0:29

If you're dealing with a 65 year

0:31

old woman who has knee pain,

0:33

almost all the tears are going to be

0:34

right in the middle, right here.

0:36

So the coronal projection is going to show the

0:39

overwhelming majority of tears

0:41

in 60 year old men and women.

0:43

So if you want to keep your job and you want

0:46

to be efficient, go to the coronal first.

0:49

In a 60 year old,

0:51

if you're interested in meniscus in a child or

0:54

a young adult, go to the sagittal first,

0:56

just so you can be a little more efficient.

1:00

I'm going to

1:02

make my line a little bit thicker here

1:04

so you can see what I'm doing.

1:06

And let's start out with this

1:08

side view of a meniscus.

1:12

So the meniscus looks a little bit like a

1:15

trapezoid. So I scroll out from the side,

1:18

and I'm dealing with a younger person.

1:20

I don't have the age in front of me,

1:22

but I can tell just from the anatomy,

1:24

even though the growth plates are closed,

1:26

probably someone around 18, 1920 years old.

1:29

So that's young, right? And as we scroll,

1:32

the meniscus should break up into two triangles.

1:35

It doesn't.

1:36

That's not primarily why I'm showing the case,

1:39

but it sort of stays connected right here.

1:42

But I'm showing it more for assessment

1:44

of the signals in the meniscus.

1:46

Let's go over to the medial side for a moment.

1:49

On the medial side, we have our two triangles,

1:51

one in the back, one in the front.

1:53

They are separated.

1:54

They're nice and dark and black,

1:56

unless I make the window a little brighter.

1:58

And now you can see those bundles I was talking

2:01

about before. Let's blow it up.

2:02

Let's make them in this guy really big,

2:04

because that's all we care about today.

2:06

There is some signal,

2:08

and you can see the little tip of the bunny ear.

2:11

There's one tip right there

2:12

under my magnifying glass.

2:13

There's the other tip under my magnifying glass.

2:17

And now let's scroll over to the other side.

2:21

Now, first lesson,

2:23

the meniscai in the overwhelming majority of the

2:29

world's population has more signal

2:30

medial than lateral,

2:32

and the reason is the normal knee walking angle.

2:36

When you walk,

2:38

your legs go down,

2:40

and then they go out to the side a little bit.

2:42

So there's always a little more pressure on the

2:44

inside than the outside because

2:46

there's more pressure,

2:47

there's enhanced transmission of synovial fluid

2:50

through the medial knee compared

2:51

with the lateral knee.

2:53

So it's very unusual to have more signal

2:56

on the outside than the inside.

2:57

So it's okay to have a lot of signal on

2:59

the inside. In fact, in children,

3:01

they have an inordinate amount of signal

3:03

in the outer third on the inside,

3:05

because that's where all the blood supply is.

3:08

So in a child,

3:09

when you see lots of signal and it's not a tear,

3:12

it's invariably normal vascularity.

3:15

But we'll get back to that in a moment.

3:17

So we're in a teenager young adult,

3:20

and we have more signal on the lateral than

3:23

the medial side, so that rule is violated.

3:25

Not only do we have more signal,

3:27

the signal is almost as bright

3:30

as the highland cartilage,

3:31

and it has this little thermometer bulb in the

3:33

front of it, which it's not allowed to have.

3:36

And that little thermometer communicates with

3:39

the rest of the signal.

3:40

In other words,

3:40

it lines right up with it in the center,

3:42

never allowed to happen.

3:44

So if you've got a cyst near

3:45

a meniscus or a pseudocyst,

3:47

and it communicates right in the center,

3:49

it is coming from the meniscus.

3:51

Why is that important?

3:53

Because if you fix the cyst and you don't

3:56

mess with the tear, it comes right back,

3:57

like a month later.

3:58

So you got to deal with it from the inside out,

4:01

not from the outside in.

4:04

So let's go back to our meniscus for a moment.

4:07

We've got a meniscus.

4:10

What are the characteristics of the meniscus that

4:12

I'm interested in. I'm interested in size.

4:16

I'm interested in the fact that the posterior horn

4:21

is a little bit taller than the anterior Horn.

4:23

I'm interested in how smooth it is.

4:26

I'm interested in this internal signal that it's

4:30

faint, that there's no cyst formation,

4:33

that it fades in the inner third.

4:36

I'm interested in the fact that

4:38

there isn't any DJD around it,

4:40

so I'm not going to call anything

4:41

meniscal degeneration.

4:43

I'm interested in the relationship between the

4:46

meniscus and the back free edge of the tibia.

4:48

Which should be about a centimeter or less.

4:50

You shouldn't really have any swelling back there.

4:53

But if you've had an ACL tear,

4:54

everybody has swelling, everybody has a sprain,

4:57

everybody has bleeding back there.

5:01

I'm interested in the fact that it's triangular.

5:04

I'm interested in the fact that it's a little

5:06

bit longer than its anterior counterpart.

5:10

I'm interested in the fact that I know that the

5:13

overwhelming majority of tears in this

5:14

age group are here, not here.

5:17

So I'm going to be much tougher calling a tear

5:20

anterior medial than I will posteromedial.

5:24

You're saying, well, you're playing the ods.

5:27

Of course I'm playing the ods.

5:29

That's what radiologists do.

5:30

That's what good doctors do.

5:32

They figure out the likelihood of something being

5:34

present. And if you go against the grain,

5:37

you better not be stupid.

5:39

You better be sure that you're right.

5:42

If you're going against the grain,

5:45

what else do we want to know?

5:47

We want to know if the meniscus is twisted.

5:49

We want to know if it's atrophic.

5:51

We want to know if it's been chopped.

5:54

How do we know if it's been chopped?

5:56

Well, here's what a surgeon does.

5:57

They go in there,

5:59

and they start to trim and trim and trim.

6:01

Let's say we had a tear right here.

6:03

Let's say we had a complex tear that

6:05

they were going in to deal with,

6:07

and then maybe a little sort of

6:10

horizontal component. Well,

6:11

they would trim and trim and trim.

6:13

Maybe let's make another color just

6:15

so our trimming is really clear,

6:17

and it's a little more fun for me.

6:19

So let's go pink. We're trimming, we're trimming,

6:22

we're trimming. And the surgeon says, oh, okay,

6:25

it looks a little better now.

6:26

I better stop. So halfway into the meniscus,

6:30

they cease knowing full well that they have left

6:34

behind something inside this meniscus

6:36

in the middle of the outer third.

6:37

But they can't take that out.

6:40

They can't sew that back together.

6:42

Or perhaps they can sew it,

6:44

but they can't resect it.

6:46

So they always leave behind the middle and

6:48

outer third with some signal in it.

6:51

And when you chop back to this level, now,

6:55

this thing, which wasn't at the free edge,

6:57

is now at the new free edge.

7:00

That's called conversion signal.

7:03

So when you're dealing with

7:04

a postoperative meniscus,

7:06

you are bound to see signal here forever.

7:09

After an ACL tear,

7:11

you're going to see vertical signal here forever.

7:14

How do you word it?

7:16

Small,

7:18

stable appearing meniscal remnant with conversion

7:21

signal. No signs of acute traumatic tear.

7:25

How do you know it's not acute?

7:27

It's not swollen, it's not displaced,

7:30

it's not gapped.

7:31

There's no contusion above or below it.

7:34

There's no other signs of a new pivot shift.

7:36

Common sense stuff.

7:38

Here's another common sense thing.

7:40

Let's say they chopped it back to here.

7:42

Do you know how many times I've been in the

7:45

situation where somebody has had some signal over

7:48

here and they call it a tear in this tiny little

7:51

remnant that is of no consequence whatsoever to

7:56

the patient unless it gets ripped off and

7:59

stuck in the knee and causes locking.

8:01

That's absurd.

8:03

That's like making the cashier

8:05

take your extra penny.

8:07

When you're paying $100 for a product and

8:09

she doesn't want to take your penny,

8:11

you force the penny down her throat.

8:14

Don't force the penny down their throat.

8:17

Now, this structure is irrelevant.

8:20

What's relevant is all the chondromalacia that's

8:23

going to develop here 98% of the time.

8:26

That's why the patient comes in and has pain.

8:28

Your job is to see if it's that 1% where that

8:32

remnant is really doing something bad.

8:35

Twisting, turning, splitting, gapping, locking.

8:39

Otherwise, don't do an Mr.

8:41

Arthrogram, I don't care what the literature says.

8:44

That is waste of time and money and of little

8:49

productivity to you or to the patient.