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55-year-old man with wrist instability and pain.

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There are a multitude of findings, but the

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most important are the loss of the intrinsics,

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which we often evaluate in the coronal

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projection, namely the scapholunate ligament.

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It's completely gone with a widened

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appearance of these two structures.

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On x-ray, this is known as the

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Terry Thomas sign, because poor Mr.

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Terry Thomas had a big space between

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his teeth, and there is a big space

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between the scaphoid and the lunate.

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That space is obvious on the T1-weighted image.

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It's not a space; it's a gully.

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It's not a gully; it's a gorge.

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In other words, it's a big one.

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So the next thing I might do, if I was reading

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this case in my office by myself, is to see

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what the scaphoid and lunate are doing in the

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sagittal projection before I proceed any further.

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Let's do that, shall we?

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Here's the sagittal projection.

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Let's scroll the sagittal.

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Typically, when you lose the scapholunate

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ligament, the lunate will be dorsal-facing.

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So, this is ventral, palmar; this is dorsal.

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Here's our lunate.

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Our lunate is not dorsal-facing.

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Our lunate is ventral-facing or palmar-facing.

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It's the opposite of what you would

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expect in a scapholunate ligament tear.

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Why is that?

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We've got a counterintuitive

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finding in the sagittal projection.

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That finding tells you there must be something

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wrong not just with the scapholunate ligament.

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There's got to be something also wrong with

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the lunotriquetral ligament, and there is.

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It's torn.

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But by using the sagittal projection findings that

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are incongruent, you're going to come to the correct

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conclusion that both intrinsic ligaments are lost.

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But we're not done yet with the sagittal projection.

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Let's see what our scaphoid is doing.

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Our scaphoid should normally stand up

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about 60 degrees relative to the radius.

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In other words, we said this

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is the long axis of the radius.

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Our scaphoid should look something

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like this, in terms of its angle.

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But instead, our scaphoid is laying down.

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It's laying down because the

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scaphoid stabilizers are torn.

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One of which is the scapholunate ligament.

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So, so far from this complex case, scapholunate

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ligament failure, the presence of a ventral-facing

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lunate, here it is, so-called volar intercalary

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segmental instability, which leads us back

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to the coronal to diagnose lunotriquetral

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ligament tear, then back to the sagittal, which

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shows that the scaphoid is laying down, and

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there is rotatory instability of the scaphoid.

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This wrist is in big trouble.

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It's headed for a fusion.