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Welcome to our discussion and

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vignettes on shoulder instability.

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This is our first introductory vignette.

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And there, there are two major causes of shoulder

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instability, and they both lie at the end of a continuum.

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At one end of the spectrum are major traumatic, so

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called collision, first-time dislocation events.

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And then these are followed by often repeat dislocations

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that require lesser degrees of force and provocation.

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Because of the anatomic abnormalities that preceded.

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Uh, these are usually, initially, unidirectional events,

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as opposed to the more chronic scenario where the

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abnormalities, uh, and biomechanics are multidirectional.

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At the other end of the spectrum,

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there's no antecedent, uh, trauma.

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The patients have glenohumeral hypermobility,

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which leads to destabilization.

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It can be developmental, and it's usually in

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multiple directions, and it worsens over time.

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In, in the latter scenario, instability causes

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symptoms due to recurrent glenohumeral subluxation

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and often not necessarily full dislocation,

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because the degree of subluxation may be minimal.

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And this condition has been described clinically as relative

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instability or functional instability or micro instability.

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So a question you might ask is, who gets this?

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And the answer is, overuse athletes, overhead athletes.

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Collision athletes, people with various types of dysplasia

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and individuals with arthrosis with bony remodeling.

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What are the patient's symptoms?

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Well, you'd be surprised.

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You're not surprised by pain.

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But pain is the only symptom?

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Yeah, that can be the only symptom.

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At least the only apparent symptom.

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But here's a surprise.

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Decreased range of motion and instability.

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Now that decreased range of motion may

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be due to bony remodeling or simply due

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to guarding on the part of the patient.

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So don't be surprised if you get an unstable

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shoulder with a history that says decreased ROM.

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More commonly and typically is increased range of motion.

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And that can be flat-out history of dislocation or it

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can be a history of clicking or subluxation or locking.

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And patients that have usually macro

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instability with dislocation, they know

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they've dislocated and sometimes report.

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Dislocation or locking as their only symptom.

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Now why use MRI?

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MRI shows you the bone, the ligaments, the

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associated rotator cuff if it is injured

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concomitantly, and the character of the glenoid

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cup with the adjacent hyaline cartilage.

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It gives you the direction of instability, whether it's

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single directional, unidirectional, or multidirectional,

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or whether one specific geography predominates.

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A Hill-Sachs lesion, what's the nature of it?

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Is it more medial?

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Or more lateral, the more

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medial ones are more contentious.

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Is it depressed or non-depressed?

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Is it microtrabecular?

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Is it one that is going to engage or not engage?

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And we'll talk about this separately.

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It also looks at the character of the bone stock

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and bony abnormalities of the anterior glenoid.

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And tells you whether you have a fracture or simply

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wearing down, loss of the bone stock of the glenoid,

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which greatly affects what the patient's going to have.

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It looks at the capsule.

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Is there capsular deformation,

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plasticity, dilatation, rupture?

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Is there avulsion of one of the major

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ligaments, especially the inferior glenohumeral

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ligament and one of its three bands?

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It also helps you decide, once you assess

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all these findings, whether the patient can

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have an open versus a closed or mini-open

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type procedure to repair the abnormality.

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Does the patient need capsulorrhaphy or remplissage?

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Or do they need some type of bone regeneration

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or rejuvenation like a latarjet procedure?

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You immediately, when you look at an MRI, get a feel for the

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overall status of the shoulder by simply looking at the fit.

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And I have a picture right here, the fit of the

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humeral head as it relates to the glenoid cup.

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And you can see that the humeral head looks

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pretty darn big compared to the, The way the cup

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tries to wrap itself around the humeral head.

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It's actually pretty deficient in the normal individual,

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and that's why the shoulder is one of the most common,

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if not the most common joint, to dislocate in the body.

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You can see the labrum on either side,

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and the hyaline cartilage in the middle.

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So, not only are you going to get a look at all the

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things that we've discussed, you're going to see the

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articular surface, you'll see later on that there's

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hyaline cartilage on the humeral side, as well as on

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the glenoid side, but most importantly, your first gaze.

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It's going to be at the relationship and position of the

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humeral head relative to glenoid and what type of fit, what

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type of concavity, and the smoothness that we have therein.

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That concludes our introduction.

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Let's get moving on to other subjects.