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Let's take a 54-year-old woman who illustrates

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the concept of complex, multidirectional micro

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instability without dislocation and without locking.

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In other words, she has apprehension, she

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has pain, she has alterations in her motion

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dynamics, and in fact, decreased range of motion.

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It's a hard concept to wrap your brain around

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that the hip bone's related to the thigh bone

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and the thigh bone's related to the knee bone.

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Well, the same thing applies here.

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The rotator cuff is involved in the stability of the

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shoulder as is the infraspinatus and anterior glenohumeral

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ligaments, the middle glenohumeral ligament, the

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superior glenohumeral ligament, and even the muscles.

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The muscles are dynamic stabilizers, so if you, if you lose

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muscularity, you are automatically destabilizing the bone.

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That includes everything from the rotator cuff muscles, to

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the pec, to the latissimus, to the periscapular muscles.

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But then you get into structures like the

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coracohumeral ligament, which we often ignore.

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Here we see it right here, coming across.

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And that participates in the stability of the biceps.

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You might say, well, what does

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the biceps have to do with it?

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Well, the biceps courses over the top of the humeral head.

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Here it is.

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You can see it's a little gray right here, so it's inflamed.

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So it helps keep the humeral head depressed.

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For if the humeral head starts to rise up, now

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you have a rotator cuff problem, but you also

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have potential, uh, superior labral problem.

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So you see how these structures are

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all commingled with one another.

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The middle glenohumeral ligament.

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Let's take a look at that for a moment.

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First of all, here's some capsular tissue.

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Look at the linear capsular tissue tight relationship

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to the anterior inferior and anterior labrum.

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We showed you some examples where the

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capsule was destroyed or rolled up in a ball.

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Here's the MGHL right there, nice and linear

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and smooth, inserting on the middle facet

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of the lesser tuberosity.

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It limits anterior translation when

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the shoulder is externally rotated and

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moderately abducted away from the side.

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The only one we haven't really touched

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on is the superior glenohumeral ligament.

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It's up here.

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It's a variable size, and this time it's pretty hard to see.

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In fact, it's hard for me to point out.

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There's a little bit of it right there traveling

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right next to the biceps or in front of it.

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And this functions as a passive

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restraint to inferior translation.

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In other words, downward force.

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Or, or downward displacement of the humeral head and the

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adducted shoulder, when the shoulder is next to the body.

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Let's turn our attention for a moment to the rotator

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cuff, even though this is a macro instability talk.

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Look at how the breakdown of the rotator

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cuff in its mid portion is occurring.

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We're decentering the humeral head.

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It's floating up for a number of

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reasons we'll discuss in a minute.

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Not the least of which is, we have a problem, a

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chronic problem, with our inferoaxillary labrum.

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And that is contributing to upward destabilization.

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And these two things combined, the rotator cuff and the

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inferior labrum, are allowing superoinferior cranial

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caudate instability, which has resulted in a tear.

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The tear is propagated quietly and subtly into the

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adjacent muscular tissues, producing a small cyst

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within the substance of the adjacent

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muscle, and quite a bit of bursitis.

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But that's not why we're here.

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You can continue following it all

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the way medial for quite a distance.

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Now let's go back to why we're here.

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I'm going to blow up my sagittal, and most

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of you will see an obvious tail going to

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the inferior labrum with a large pseudocyst.

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Why is this a pseudocyst?

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Because it's not surrounded by synovium, or capsule.

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It's surrounded by fibrous tissue.

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It's an event where synovial fluid has diffused through

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a small pinhole as a result of microinstability.

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Let's see it in the axial projection.

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There it is, right there.

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Tiny little tail.

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What makes that different from a ganglion?

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It's got a labral tear.

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Whereas a ganglion will arise

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from a small rent in the capsule.

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Or a small rent in the tenosynovial sheath.

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But histologically, under the microscope, they are

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totally identical and contain the same material.

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They're both pseudocysts.

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And they both have tails.

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This one has a tail to the labrum.

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Let's keep following it.

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Oh, there it is.

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And there it is again.

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And again.

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And now we see the cyst propagating into the axillary space.

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It's pretty big.

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It's getting bigger.

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It's getting bigger.

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And it's sitting right next to the neurovascular bundle.

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It's pretty cool.

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Here it is sagittally once again, going into

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the anteroinferior axillary space associated

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with a chronic Fischer-like labral tear.

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It's no surprise there is no Hill-Sachs lesion.

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This is not a single collision event.

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This is somebody with multidirectional micro

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instability, predominantly cranial-caudate.

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If it's cranial-caudate and we know we've got a caudate

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problem, let's check the cranial anatomy to make sure we

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haven't impacted and produced the slap lesion superiorly.

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That's a recess, that's normal.

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That's the takeoff of the biceps and the labrum

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with a small amount of recess fluid in between it.

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Let's go back to where many of the labral tears are found.

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Do we see any?

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No.

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Do we have any paralabral cysts?

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No.

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Do we have a cyst over the spinal glenoid rim?

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No.

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Do we have a cyst in the suprascapular notch?

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No.

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All potential labral tears.

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Checkpoints to look for a complex

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pattern of microinstability.

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But what do we have?

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An upside-down SLAP lesion.

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A SLAP lesion on the bottom.

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Sometimes they refer to these as pale lesions.

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Posterior to anterior, inferior labral tears.

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This one with a paralabral cyst.

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When it has a cyst, I call it a SLAP 12.

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When it has no cyst, I personally call it a SLAP 11.

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This, an example of microinstability.

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with an inferior labral tear, with a large paralabral

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cyst, histologically identical to a ganglion, with

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concomitant failure of the rotator cuff system, producing

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a complex but small rotator cuff tear, allowing a cystic

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structure to propagate into the adjacent musculature.

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Let's take on another one, shall we?