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Anatomy Review: A Look at the Acetabular Anatomy in the Coronal Plane

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Now it's time for me to introduce

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you to our favorite, yes, it's the

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favorite child, the coronal projection.

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Let's use our drawing tool. I think I'll

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go with yellow since it's easy to see.

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Let me draw the acetabular cup,

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which is a little bit undulated, and it has a

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little crease in it called the stellate crease,

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which may sometimes have a band

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coming from it called the stellate lesion.

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Here's the rest of our acetabular bone.

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And it stops right about here.

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And it is supported by the transverse ligament,

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which will make the ligaments now in blue.

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And we'll make the iliofemoral

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ligament also in blue.

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I didn't really make a very round shape

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with my acetabular cup, but I'm human,

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just like you.

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Now, I'll draw my femur.

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My femur's pretty round,

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and it has a little dippity doo in it.

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And that dippity doo is the fovea capitis,

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where the ligamentum teres inserts.

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I made my capsule especially large, or the

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space between the femur and the acetabulum,

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which includes the capsule and fat,

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the pulvinar and the ligamentum teres, so we

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could see the anatomy a little better.

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And we have a ligament that comes up

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from here, two heads, the ligamentum

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teres initio and a pubic head,

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and they insert on the fovea capitis.

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And they'll be surrounded

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by the fatty pulvinar.

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These can be inflamed, or tear,

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or be congenitally absent.

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There is an acetabulum both

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inferiorly and superiorly.

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We'll go with red for acetabulum.

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And its origin is along the calcified border of

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cartilage and the ossified area of acetabulum.

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And then it continues on, blending

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with the hyaline cartilage,

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which we have here, which we have here in orange.

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And then we also have hyaline

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cartilage around the femur too.

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And as we've said previously, the two

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add up to about three millimeters.

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We also have a labrum inferiorly.

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Which forms a labral ligamentous complex.

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Note that the ligamentum teres

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has its origin from a ligament.

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Now, beneath this, we have the capsule,

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and I'm gonna make the capsule green.

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I've drawn these ligaments in

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blue, but the capsule is actually

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below the transverse ligament.

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Whoops.

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There goes my green.

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I need green.

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There's my green, and the capsule comes down

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and inserts on the femoral neck, and it defines.

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The area between the intra- and

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extra-articular portion of the hip.

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This is very important for fractures above

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this area have a grave or graver prognosis.

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So there's a recess between the

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inferior acetabulum and the capsule.

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It is not uncommon to see folds

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or synechiae in this region.

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We'll make them pink, such as the

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pectinophovial or pectinosynovial fold.

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I like pectinophovial better.

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We can have paralabral plica or folds.

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And we can also have folds that

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are located more laterally.

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Sometimes these are referred

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to as folds of Weitbrecht.

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And these can produce some confusion,

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especially when they're near labra,

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and they produce extra planes of hyperintensity

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between themselves and the labra.

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Especially this one up here.

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Another important potential recess, in fact

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a very important one, is the one between

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the red acetabular thorn and the iliofemoral

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ligament, which is part of the capsule.

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These two blend together,

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the green and the blue.

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So in that space, potentially,

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fluid can be found.

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That fluid should not be

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confused with a labral tear.

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On the other hand, you're probably wondering,

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well, how much fluid can you have there?

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In a young person, the answer is, not very much.

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I will allow a little bit of fluid and

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separation between the labrum and this

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ligamentous structure, which is part of

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the capsule, for about two millimeters

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above the labrum, and that's it.

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As you get older, and abduct your hip,

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there is a little bit of stripping that goes on.

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So I'll allow it to be up to 4 millimeters.

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Now you might say, well,

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what if it's 5 millimeters?

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Then you've got to use some common sense.

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Like, is there swelling?

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Is there an effusion?

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Is there a paralabral cyst?

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Is there a labral tear?

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Is there bony acetabular remodeling?

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You've got to use secondary signs to decide if

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you've got a symptomatic capsular separation.

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And it's there with my basic anatomic

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drawing introduction that I'll stop,

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and we'll move on to a live case.

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

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