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In this section, we're going

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to classify carpal instability.

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Let's have a quick scroll.

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You are all noticing extensive arthrosis,

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especially in the radial styloid, but erosions

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throughout the carpal bone, seen on the PD fat set.

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Yes, there is a radial fracture.

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There is deformity of the radial styloid.

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And in the introductory section, I reminded you that

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there are three arcs of Gallula, one arc along the

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proximal aspect of the proximal carpal row, another arc

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along the distal aspect of the proximal carpal row, and

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finally the third arc around the capitate and hamate.

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These three arcs will help you decide

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what type of carpal instability you have.

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For if there is dissociation in one row, in

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other words the relationship of this bone to

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this bone, or this bone to the bone next to it

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is altered, we call that Dissociative Carpal

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Instability or Carpal Instability Dissociative (CID).

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We do have dissociation between the scaphoid

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and the lunate, scapholunate dissociation

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due to failure of the scapholunate ligament.

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But there's oh so much more to be discussed.

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What is non-dissociative carpal instability

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or carpal instability non-dissociative (CIND)?

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That is when you have a derangement between

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the radius and the bones next to it, and we do.

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We've got this deformed, overgrown styloid

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with irregularity of the scaphoid fossa.

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Or you have derangement between one

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carpal row and the other carpal row.

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We have that too.

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We have the capitate pistoning

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proximally into this opening space.

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So the capitate is settling between

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the scaphoid and the lunate.

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So in the purest sense, we do have carpal

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instability, non-dissociative, between two carpal

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rows, but also between the radius and the scaphoid.

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So what happens when you have both of them?

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Both disruption of the same row

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and disruption between rows.

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The radiocarpal row or the intercarpal

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rows from this row to the next row.

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Then we will call that complex instability

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or complex carpal instability (complex).

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What is adaptive carpal instability?

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That is when the origins of instability

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are proximal or distal to the wrist.

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So those are the four basic

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types of carpal instability.

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Let's do them one more time.

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Carpal instability, dissociative (CID),

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same row, either this row or that row.

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Carpal instability, non-dissociative, between rows.

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Carpal instability, complex, both of them are going

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on at the same time, in the same row and between rows.

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And finally, adaptive, where the

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abnormality is not in the wrist, but it's

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either distal or proximal to the wrist.