Get a Group Membership for your Organization. Free Trial
Pricing
Free TrialLogin

The Magnified Labrum: Components, Variations and Injuries Part III

HIDE
PrevNext

0:00

Welcome back to our discussion on

0:02

the hip labrum, which supports a

0:04

lot of weight in most human beings.

0:06

Let's talk about some variations.

0:08

We'll start out with the shape of the

0:10

labrum, which is most often triangular,

0:13

probably about 70% of the time.

0:15

The second most common appearance is the

0:17

labrum being round, somewhat meniscoid looking.

0:21

And as long as it's smooth, that's okay.

0:24

The labrum may sometimes be

0:26

flat or truncated looking.

0:27

Now that produces kind of a problem.

0:29

Because that can simulate a radial tear.

0:33

The tip-off should be, you don't have an

0:35

effusion, you do not have a fragment,

0:39

and you don't have other signs of instability,

0:42

or other signs of impingement syndrome.

0:45

So it's there all by itself.

0:47

And then there is the rare situation

0:49

where as part of a dysplasia, whether it's

0:52

developmental dysplasia or congenital absence

0:54

of ligamentum teres, you don't have a labrum,

0:57

which is reported in 3% of specimens,

1:00

but I think this is an overestimation.

1:03

Then you've got variations in signal intensity.

1:06

Most hips, with labra, which is the majority

1:11

of them, are going to have some signal inside.

1:14

In fact, it is rare not to have some

1:16

intralabral signal, analogous to what

1:19

you have in the meniscus of the knee.

1:21

It has an amorphous, somewhat central location.

1:25

It can be seen on the T1,

1:27

or the proton density fat

1:29

suppression, less commonly on the T2.

1:33

If it's on the T2, and it is specifically

1:35

not just grey, but more bright, then you have

1:40

to be worried about an intrameniscal cyst,

1:42

which fortunately, isn't that common in the hip.

1:45

It is more common in the knee,

1:47

although both are uncommon.

1:49

It is reported that high T2 signal

1:53

occurs 15% of the time.

1:54

That has not been my experience.

1:57

A bigger problem is the sulcus.

2:02

The labral sulcus is usually found just lateral

2:05

to the interface between the hyaline cartilage

2:08

and the labrum, the so-called transition zone.

2:10

You'll usually see it over here.

2:12

It'll be shallow,

2:14

less than 25% to 30%

2:16

of the depth of the labrum.

2:18

It usually has a smooth top.

2:20

It has smooth edges.

2:22

In other words, it's not a

2:23

serrated appearing structure.

2:25

It usually isn't very needle-like

2:27

or straight up and down.

2:30

Like we see here with a very

2:31

thin margin or edge to it.

2:34

As stated, it isn't very deep, it's not

2:36

associated with swelling, or an effusion,

2:39

or a change in labral shape, or other signs

2:42

of impingement syndrome most of the time.

2:45

Now it's said that the most common

2:47

location for the sulcus is posterosuperior

2:50

about 48% of the time,

2:52

anterosuperior, 44% of the time,

2:55

anteroinferior, 4% of the time.

2:57

My experience in looking at surgeries

3:00

and labral specimens is not the same.

3:03

In fact, there is a sulcus anterosuperior,

3:06

but as you come down and around into the

3:08

anteroinferior quadrant, it actually deepens.

3:12

So you should be able to follow it.

3:13

So if you go from low to high, and that

3:16

defect in the labrum is getting deeper

3:18

and deeper as you go up, that's a problem.

3:22

And most of the time, in the anterosuperior

3:25

quadrant, and directly

3:27

superior, I am not reading a sulcus.

3:30

I am reading either a chronic labral tear,

3:33

age-related, from overuse, or from chronic

3:36

impingement, or from developmental dysplasia,

3:39

or a labral tear from other etiology.

3:42

I will read a sulcus when I see something

3:44

smooth and shallow that progressively deepens

3:47

as I'm able to follow the labrum around into

3:50

the anteromid and anteroinferior quadrant.

3:55

And finally, we have another potential

3:58

pitfall, and that is the paralabral

4:01

plica, which I'll make here in yellow.

4:03

It is a thin structure, oft attached to the

4:06

ligament, that parallels the edge of the labrum.

4:10

Now if we look at the labrum as a

4:11

triangular structure, we have this

4:13

little sliver-like structure next to it.

4:15

You can see someone might confuse this as

4:18

a piece of labrum that has been shaved off.

4:21

Not unlike what occurs in the shoulder

4:25

when you have low-grade subluxations and

4:28

dislocations, and you have functional labral

4:30

tears that are not through and through.

4:33

And then one other comment.

4:35

Don't confuse this area of hyaline

4:38

transition between the labrum, which is

4:41

here, and the hyaline cartilage, as a defect.

4:45

There's going to be a slight transition in

4:47

signal intensity between the two, but do pay attention to

4:51

this area, because it is an area that is

4:54

very prone to injury when you have large

4:56

labral tears, or you have big traumas,

4:59

where the labrum is detaching from the

5:01

hyaline cartilage and the acetabulum,

5:03

and this is oft the site of detachment.

5:06

And then the labrum, as we've stated

5:08

previously, will start to flip up.

5:11

This area will get wider, and this area the

5:14

area between the ligament and the underlying

5:17

acetabulum will also widen and strip all the way

5:20

up with fluid and effusion filling the space.

5:24

Let's move on and look at some

5:26

magnified images of the labrum on

5:28

MRI if you've got the gumption today.

5:31

Thanks.

Report

Description

Faculty

Stephen J Pomeranz, MD

Chief Medical Officer, ProScan Imaging. Founder, MRI Online

ProScan Imaging

Tags

Musculoskeletal (MSK)

MRI

Hip & Thigh

Congenital

Bone & Soft Tissues

Acquired/Developmental

© 2024 MRI Online. All Rights Reserved.

Contact UsTerms of UsePrivacy Policy