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

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A single spot sagittal view

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of the hip perhaps helps us highlight

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our search pattern a little bit.

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I'm not going to scroll through all the images

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right now since this is more introductory,

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but I'll tell you the most important

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thing to look for in this projection.

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Sometimes, and I mean 20% of the time

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or more, the only projection that

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you see a labral tear in is the sagittal.

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So you have to look very carefully and

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make sure there is not a line; there

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should be no line going either halfway

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through or all the way through the labrum.

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In fact, there shouldn't be any line at all.

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Now, if you have a tear like this,

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and you attempt to do a coronal

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projection, what are you going to see?

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A little tiny pinhead coming at you,

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which makes visualization of this type of tear

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that is running back to front very challenging.

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So you will miss this tear in the

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coronal projection but only see

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it in the sagittal projection.

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But don't be dismayed, because the sagittal

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is extremely reliable in showing you a

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contiguous labral structure without a line

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through it, without a sulcus through it.

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So this line has very important implications.

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Now occasionally you'll also see involvement of

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hyaline cartilage transitioning longitudinally.

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I think I may have to make

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my line a little smaller.

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I'm going to do that.

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transitioning into the labrum

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somewhat longitudinally.

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Now this will be detectable or detected

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on the sagittal and in other projections.

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But this horizontal type of tear

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that goes from back to front in the

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labrum is the most important critical

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finding in the sagittal projection.

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The second most important critical finding

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in the sagittal projection is identification

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of an abrasion or an erosion in the labrum.

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and the hyaline cartilage.

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Let me make that green if I can.

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So you're looking for hyaline involvement or

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penetration in the bone anteriorly, which is

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usually seen directly adjacent to labral tears

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in patients with type 1 CAM type impingement.

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On the other hand, if you have pincer-type

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impingement, a lot of the hyaline disease

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is going to be in the back, and then it'll

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propagate to the front all the way around.

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And that's going to be pretty

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obvious and very easy once you

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make the connection of pincer-type.

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Or type 2 impingement.

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And then you go back and look at the

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posterior aspect of the labrum where

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the cup is too deep and everything is

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sort of forced backwards and then the

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hyaline disease propagates to the front.

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A couple of other, uh, salient points and

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areas to look at in the sagittal projection.

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We have the iliofemoral ligament

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and the iliopsoas tendon.

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Frequently, we'll have hip flexor disease,

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so on the PD spur, I often look in this area

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to see if there's high signal intensity

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as a manifestation of a hip flexor

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strain, which you can see in any

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projection with a PD spur, but I do like

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to view it in the sagittal projection.

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I also like to view the iliopsoas

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tendon insertion on the lesser

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trochanter, which is not shown here.

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And don't forget the greater trochanter is

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the site where the piriformis is located.

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The superior gemellus, the inferior gemellus,

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the obturator internus and externus are all

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going to insert on this area, and you can

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follow these tendons serially from medial

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to lateral in straight orthogonal sections.

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You'll learn a little bit later on that

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there are specialized piriformis views

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for patients with piriformis syndrome.

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The other thing you'll want to do is

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you'll want to look at the sciatic nerve,

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which is not in this plane just yet,

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and follow it from proximal to distal.

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And, and we're not, we're just

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spot viewing this right now.

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One other identified structure here,

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which I will highlight in purple, is

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the transverse ligament, which some

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have, uh, uh, said looks like a St.

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Andrew's cross.

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It forms the inferior aspect of the hip support.

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There is no bone or labrum along the

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direct inferior aspect of the hip.

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The hip is supported by a little

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trampoline here, the transverse ligament.

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So that concludes our real quick diagrammatic

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approach, uh, to the hip with special

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attention to this area of the labrum whose

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tear may only be seen about 20 percent

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of the time and in no other projection.

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Let's move on, shall we?

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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