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Talking instability in this vignette, we're turning

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our attention to the most favorite nation projection,

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the coronal projection, the one everybody loves.

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It's the easiest to look at because you're all

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used to looking at AP radiographs of the shoulder.

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So I prefer to have a pair of coronal projections.

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And if you're a novice or a beginner, it might not

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be a bad idea to have three coronal projections.

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The coronal projection should parallel the long

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axis of the scapular spine and scapular body.

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So it shouldn't be a straight orthogonal.

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In other words, your coronal shouldn't go this way.

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That would be a big mistake.

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I like to have the arm at the side with

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the thumb up in the neutral projection.

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Occasionally, it'll be necessary for you to stretch

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out the anterior glenohumeral ligaments, which are

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right here, and also to stretch out the labrum,

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which would normally be right here, although it's

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absent because the patient has an ALPS lesion,

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or an anterior labral periosteal sleeve avulsion.

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But the reason we want to stretch it out is sometimes

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there are partial rim tears or partial rents

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That we can't see, and the best way to stretch it

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out is to do a special view called an ABER view.

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An abduction external rotation view, also known

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as the Dion Sanders view in the United States.

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So you put your hand behind your head, your elbows back,

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and this stretches out the anterior band of the IGHL, and

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also the capsule is taut on the labrum, so it pulls or

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tugs a little bit on the labrum and lays it out for you.

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I don't do that in every case.

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Only in certain difficult instability cases

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where I don't get the answer straight away.

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So it is actually not part of my routine exam, although

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I will bring it back, or sometimes I'll prescribe that it

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be used if somebody has a specialized form of instability.

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And what do I mean by that?

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Well, they might have relative instability, functional

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instability, partial instability, micro-instability.

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These all mean the same thing.

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And what do they mean?

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They mean that the patient has not

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dislocated, and they haven't locked.

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Who gets this?

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People with arthrosis, people

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with repetitive low-grade trauma.

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Who gets the acute type of unidirectional instability?

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It's usually the collision athlete.

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And then there's one other subgroup that you should dial

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into, and that's the family of patients who have dysplasia.

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Where the glenoid is malformed or the humerus is malformed.

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Glenoid more common than humerus.

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So now let's return to the coronal projection.

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I like to have a T1-weighted image and right next

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to it, my favorite, my favorite sequence is a

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very heavily fat-suppressed PD or proton density.

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What type of fat suppression?

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Well, that's up to you and your scanner.

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You've got spare, you've got special.

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You've got even, you've got spur, and you can even

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use STIR, short-time inversion recovery at low field.

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But what I don't want you to do is I

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don't want you to lengthen out the TE.

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In other words, I want you to keep the TE in the

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middle, where you get the most robust signal,

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and therefore the most robust water intensity.

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And what's that?

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About 40, 45, no more than 50 milliseconds.

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Start going above that, now you're into T2 territory.

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If you're gonna add another coronal, okay, you can

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add a T2 if you're a novice or a beginner, but I

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prefer to be practical, and I will use my T2 fat

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suppression imaging in the sagittal projection.

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So that, for the most part, in 95 plus percent

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of cases, I can get away with four sequences.

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An axial GRE, high-quality GRE, a coronal proton density

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fat suppression, a coronal T1, again, they're angled along

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the axis of the scapula, and then a sagittal that's going to

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be orthogonalized this way, and that can be your T2 image.

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So your T2 fat suppression image will have to be

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cross-referenced with these other images to get a

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good feel for the status of the cuff, the nature

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of rotator cuff tears, the depth of tears, etc.

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Now since we're talking instability, the coronal

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projection is invaluable in instabilities

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that affect the superior and inferior labra.

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That makes perfect sense, right?

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You're perpendicular to these structures.

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So anything going up this way, easy to see.

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Anything going down this way, easy to see.

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So for axillary injuries, like Hegel lesions, humeral

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avulsions of the glenohumeral ligament, in other words,

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this avulses from the neck of the humerus, or bony Hegels.

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Or in this case, we have an axillary IGHL tear.

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And in this case, we also have an Alps lesion, an anterior

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labral periosteal sleeve avulsion, where the labrum is slid

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underneath the periosteum as a macerated structure.

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Pay no attention to this globular thing, which

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is coagulated blood, which might easily confuse you.

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So it's obvious.

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You know, coronal projection,

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when we go high, then we go low.

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We go high, we go low.

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On the T1-weighted image, we have

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our best view of any bone pathology.

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For instance, we've got a hatchet

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job on the supralateral humeral head.

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We've got a pretty deep Hill Sachs.

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Now, I might not use this projection to assess

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the percent of involvement of my humeral

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head, I'll use the axial projection for that.

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We'll talk more about that in individual cases.

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But I will use it to see how far

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medial or lateral my Hill-Sachs is.

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The more medial the Hill-Sachs lesion is, the more

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problematic recurrent dislocation may become.

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And we'll see why that is in other vignettes.

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Obviously, the bigger the Hill-Sachs, the more

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problematic recurrent dislocation is as well.

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But this is your Hill-Sachs projection.

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Now let's turn our attention to Hill-Sachs for a minute.

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Remember that Hill-Sachs fractures were

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called fractures because you know what?

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That is all you could see with conventional radiographs.

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Until MRI came along.

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And then you could see microtrabecular injuries.

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So this one's easy, right?

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It's a depressed fracture.

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But what if you had an intramedullary and

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chondral bone, medullary bone abnormality?

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You'd see nothing on X-ray.

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But you would see it very clearly as an

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area of low intramedullary signal on MRI,

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and high intramedullary signal on X-ray.

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PD Spur, spare, or special.

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Again, this one's easy.

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We got a depressed fracture of

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the sup, lateral humeral head.

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So this is your Hill-Sachs view.

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This is your axillary labral injury view.

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This is your inferior glenohumeral ligament view.

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This is your view to see the labrum axis medial

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to lateral as opposed to anterior to posterior.

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And the T1-weighted image is gonna help you

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cover your bone pathology.

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So, that concludes our discussion of the coronal projection.

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You know, there'll be other things that you're looking at

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as a general search for a general shoulder examination.

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You're going to be looking at the subacromial

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arch, the coracoacromial ligament and

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its size, which comes off right here.

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You'll be looking at the AC joint, the size of the

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muscles, fatty infiltration, the configuration of

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the glenoid cup, the shape of the humeral head.

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Whether the growth plate is open or closed,

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whether there's any masses in the spinal glenoid

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notch or rim, but that's a story for another day.

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But a quick review.

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Let's have a look at the companion

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vignette, the sagittal projection.