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Okay, so we have a 20-year-old man who has

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history of recurring shoulder dislocations.

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This is his fourth time dislocating the shoulder

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and we're going to start with the axial images

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Typically give us the best overview of what's going

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on in the setting of glenohumeral instability.

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So starting at the top, we are at the level of

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the coracoid process here, and we see that the

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humeral head had a focal area of impaction injury.

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This is a Hill-Sachs lesion with flattening

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of the cortex and reactive marrow edema.

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As we go south along the anterior glenoid margin, we

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see that there is a detachment of the anterior labrum.

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So this is a Bankart injury where the periosteum,

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you can see the periosteum is disrupted and the

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anterior labrum is detached from the glenoid rim.

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I'm going further down and we can see in the

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anterior inferior glenoid margin that there

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is no labral, normal labral tissue there.

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The labrum appears markedly edematous and irregular.

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So this is a Bankart.

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Now, in terms of osseous lesion on the glenoid side, you

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can see the margin of the glenoid, the cortical margin

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of the glenoid, posterior inferiorly here, and then

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anterior inferiorly there is also bone marrow edema.

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And there is indistinctness of the cortex.

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So this patient not only has a soft Bankart injury, but there is

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also an associated, um, osseous Bankart injury with flattening.

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of the anterior inferior glenoid rim.

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When we notice that, we go immediately to the, uh, T1 weighted

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sequence, the sagittal sequence, and we're going to use the best

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fit circle method to calculate the amount of glenoid bone loss.

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So what we do, we find the supraglenoid

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tubercle and the infraglenoid tubercle to

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have the longitudinal axis of the scapula.

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Then we draw a best fit circle using the posterior inferior

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margin of the glenoid to fit the circle, and then we measure the

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antiposterior dimension of the circle, the width of the circle.

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And the next step is to calculate how much glenoid bone has been

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lost in the process of recurring, uh, shoulder dislocations.

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So if we follow the cortical margin, you can see that

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the anterior inferior glenoid margin is flattened.

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It doesn't have the normal avocado shape or pear shape.

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that it should have, it should have a nice belly

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anterior inferiorly and that belly is flattened.

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So I'm measuring the distance between that

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flattened belly and the circle at the level

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of the equator and I'm getting 37 centimeters.

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When I calculate the percentage of glenoid

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bone loss is 14 percent, uh, which is.

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Under 20%, 20 percent is considered the threshold

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for orthopedic surgeons to decide to do an

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augmentation bone procedure in a given person.

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So this patient has 14 percent calculated

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glenoid bone loss using the best circle method.

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We're going to get rid of the, um.

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markings here so that we can continue assessing

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the findings on this patient with anterior

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shoulder dislocation and glenohumeral instability.

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Let's move on to the oblique coronal sequence.

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So, we have, um, here a rendition of that

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Hill-Sachs defect, flattening of the pelvis.

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posterior, superior and lateral humeral head, and then the

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reciprocating impaction injury, the anterior inferior glenoid.

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You can see the discontinuity of the cortical line,

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that's the osseous Bankart, and we already know

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that it's a very extensive anterior Bankart lesion.