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This vignette,

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which in correlation with other vignettes,

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has been focusing on the six components of the cuff:

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supraspinatus, infraspinatus, Teres minor,

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subscapularis, coracohumeral ligament, and capsule

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is now going to address the arches about the shoulder.

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Arches, you say? Well, quite well, you may.

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I'll explain them now, there are three of them.

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Let's begin with the one everybody knows,

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the medial arch, the arch below the AC joint.

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First, everybody has an abnormal AC joint.

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So you have to decide when you want to put the hammer down

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on the joint, and the answer should be not very often.

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But as far as impingement goes...

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Impingement is a clinical syndrome of inflammation

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and cuff disease, and labral disease.

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So if you have encroachment on the medial aspect of the arch,

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call it just that, stenosis or encroachment.

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But don't use the word impingement,

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because the myotendinous unit is so strong and so powerful,

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it almost never gets interrupted at this medial arch.

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It may get compressed a little bit,

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but it's usually asymptomatic.

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The most important arch is the subacromial

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arch underneath the acromion,

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where the acromion may appear like a shelf or a keel,

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or a telephone receiver, and contributes to

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impingement syndrome anatomically.

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And then we have the third arch, the forgotten arch,

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the coracoid arch that contributes to coracoid abutment

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syndrome and a condition known as anterosuperior

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impingement syndrome, also known as ASI.

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There is a coracoid index.

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There's a distance that some have proposed between

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the coracoid and the humeral head.

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None of those things work very well. I'm not a measurer.

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I almost never measure.

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What do I do?

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I look at the degree of compression or encroachment

1:58

of the tissues underneath it. Are they inflamed?

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Are they damaged?

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And are there secondary signs that there is abutment

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between the coracoid and the humeral head,

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like small, irritative pseudocysts and pitting,

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which there is.

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You might say, well, there's a pretty good distance here.

2:18

You're right.

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But what about when they're lying down?

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What about when they're throwing?

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What about when their arm is cocked?

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There's probably abutment at some

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chain in that chain of events.

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And the same thing is true for the other types of

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pseudocysts and erosions that you see in the humeral head.

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We're in the back of the shoulder,

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there's usually contact with the acromion with the arm cocked.

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If they're in the front of the shoulder,

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there's usually contact with the acromion with the arm

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in front of the mid-coronal plane.

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The three arches,

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the medial arch at the level of the AC joint,

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contributing sometimes to stenosis,

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but rarely contributing to actual inflammatory

2:59

impingement or cuff tears.

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The lateral arch,

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the major contributor and the oft-forgotten,

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subcoracoid arch, deep to the coracoid

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in front of the humeral head.