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Okay, here's a 53-year-old woman with

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an injury while playing softball.

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We have an axial fat-suppressed water-weighted image

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on the left, T1 fat-weighted image in the middle, and

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another sagittal water-weighted image on the far right.

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So this patient has a dark, hypointense area

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of linear signal on the water-weighted image

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that looks for all the world like bone marrow.

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in the axial projection.

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So is that a spur, or something else?

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Now remember we've talked about the concepts of

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antiversion and retroversion in, in other vignettes.

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And in this case, what's most likely happened, and this

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is one of the most favored theories for this lesion,

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which is known as the Bennett lesion, is that the patient

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starts out with a pulp sa, and bleeds into the periosteum.

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That bleeding then ossifies in an arc

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like curvilinear fashion, like this, and

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creates what's known as the Bennett lesion.

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The pulp sa lesion arises not so much from a dislocation,

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but from a tug phenomenon on the capsuloperiosteal sleeve.

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So if this is true, our CT should show some ossification.

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in this region.

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Now, in talking about antiversion and retroversion,

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this patient has developed compensatory antiversion.

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In other words, the posterior rim juts

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out more than the anterior rim and forces

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the humeral head a little bit forward.

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The more common scenario is retroversion.

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And sometimes we'll see that in actual glenoid hypoplasia,

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where the patient is actually missing the anterior rim.

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This portion, I better get another

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color, that's better, like yellow.

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The patient is actually missing this portion of the

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labrum, and so the angle looks something like this.

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And the humeral head is forced back.

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This is one of the more common developmental abnormalities

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of the shoulder, and it results in multidirectional

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microinstability, but mostly in the posterior geography.

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years of age, especially when participating in sport.

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And the name given to this is glenoid hypoplasia.

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They also get abnormalities of the scapular neck.

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And, uh, there are various, there are various

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names that are given to these anomalies like

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the J anomaly, or the delta anomaly, and they have

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various subtypes that we won't get into today.

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So let's take a look at our Bennett lesion.

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Let's focus on it.

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It has an ossified appearance

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on the axial T1-weighted image.

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It has a curvilinear appearance in the sagittal projection.

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It is a sign of posterior micro-instability.

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It is considered a tug lesion.

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It most likely occurs as a manifestation of a chronic pulps

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or a large, a large Perthes lesion with blood that ossifies.

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And let's corroborate it by looking at our

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CT and seeing if there's ossification there.

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So here's our CT.

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We did a CT arthrogram.

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And let's follow the back rim of the glenoid.

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So this is anterior.

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We have the patient prone.

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So here's our needle.

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And there it is.

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Let's blow it up for you.

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There is this rim-like area of ossification.

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And sometimes, although not in this case, let me see if

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I can get another, another picture of it right there.

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Sometimes you'll actually be able to see a cleft.

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You won't actually see merger of the

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ossification with the underlying bony glenoid.

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You'll see a thin line or cleft between the two.

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But you see how long it runs from bottom to top.

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It's arc-shaped as demonstrated on the sagittal, the

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Bennett lesion, a tug lesion, a sequela of bleeding into

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the posterior aspect of the shoulder, an important lesion

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seen as a manifestation of micro-instability and overuse.