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This is an 18-year-old football player who sustained an injury

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on the field, and he was referred to us to assess

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for rotator cuff tear.

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When we look at these patient's axial images from top to bottom,

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we can see the acromioclavicular joint and

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the distal clavicle end comes into view.

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It's outlined by fluid.

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There is fluid surrounding the distal clavicle,

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and then we don't see the opposing acromion until two or three

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cuts lower than where we see the distal clavicle end.

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So, this is concerning for acromioclavicular

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separation, and in the classification,

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this would be a grade three where this distal clavicle end

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is superiorly placed with respect to the opposing acromion.

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The relationship can be better assessed in the oblique coronal plane.

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Again, distal clavicle end acromion,

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complete disruption of the acromioclavicular ligaments,

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superior and inferior acromioclavicular ligaments.

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And then, we have fluid that is coming from the joint space

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through the torn capsule, outlining the distal clavicle,

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the superiorly translated distal clavicle.

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Now for these two happen,

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not only the acromioclavicular ligaments have to be disrupted,

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there needs to be a disruption of the ligaments holding together

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the coracoid process and the clavicle.

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So, we call this the coracoclavicular ligaments.

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There are two groups of fibers in this location.

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The conoid and trapezoid are components of the coracoclavicular

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ligaments, and on fluid-sensitive sequences,

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that should be low signal intensity.

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We can see how the ligaments here on the sagittal plane are

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completely disrupted.

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There is this plane of fluid signal intensity,

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traverse in the fibers, also noted here in the coronal plane,

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in keeping with a full-thickness tear

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of the coracoclavicular ligaments.

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Now, just to put this into perspective,

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we can see the distal clavicle end in this

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oblique coronal image here,

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and if we go to the next cut,

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we can see the acromion lower down.

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So, that difference in distance is what makes

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this a grade 3 acromioclavicular separation,

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because there is no alignment between the distal clavicle

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and the acromion.

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In the axial plane, we can see the

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widening of the acromioclavicular interval.

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So, we can draw here.

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That's the acromion. This is the clavicle,

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and we see that there is widening

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of the acromioclavicular distance.

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That should not be greater than 7 mm.

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The distance between the coracoid and the clavicle

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can also be assessed on MR images.

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So, we would be measuring the distance between

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the coracoid here and the clavicle.

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And this distance should be no more than 11 mm.

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If it is, it means that the ligaments are disrupted

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and are allowing the clavicle to migrate superiorly,

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with respect to the acromion.