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We've got a 55-year-old man with

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wrist instability and carpal pain.

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It's obvious in the coronal projection there

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is massive loss or failure of the scapholunate

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ligament, intrinsic or SL instability.

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It is obvious that there is arthritis with failure

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of the lunotriquetral ligament, which you

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can see rather nicely on the T1-weighted image.

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Through loss of the joint space, and the complete

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absence of visualization of that ligament.

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But now, what does the hand surgeon

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need to know from a case of this ilk?

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Because everything is really wrong.

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The hand surgeon wants to know, can I fix this?

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Does the patient need a fusion?

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If so, what type of fusion?

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What's stable?

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What's unstable?

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And what is the nature of the instabilities?

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Which can be difficult to get from a static study.

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In other words, a non-dynamic study.

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Let's go through the checklist in this

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scenario of proximal row intrinsic ligament

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failure that the surgeon wants to know.

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First, let's go simple.

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Arthritis.

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How much of it is there?

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Moderate to severe.

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Where is it?

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Most of it is in the midcarpal space.

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Between the scaphoid and the carpi, the

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lunate and the carpi, and the capitate.

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and the adjacent carpi.

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Look at those capitate erosions.

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The arthritis is not very severe in the SL

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interval, but very severe in the LT interval.

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There's styloidal arthritis and

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foveal arthritis of the ulna.

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Finally, in searching for scapholunate advanced

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collapse, which is a sequela of intrinsic proximal

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carpal ligamentous instability, we look at the

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scaphoid fossa of the radius to see if there

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are erosions, or deformity, or hypertrophy of

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the radial styloid, none of which are present.

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So, we don't have the cardinal or typical features

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of SLAC wrist (scapholunate advanced collapse),

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which consists of scaphoid fossa erosions and

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radial styloid hypertrophy, even though we do have

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pretty severe carpal arthritis concentrated in

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the middle of the wrist in the midcarpal space.

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What types of instability do we have

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besides the failure of the intrinsics?

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That's easy.

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We go to the sagittal projection.

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We see a ventral-facing lunate.

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The patient has volar intercalary

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segmental instability, or VISI.

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Surgeon wants to know that.

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What about the scaphoid?

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Is the scaphoid in its normal position?

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Which is standing up at about 60

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degrees relative to the radius.

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No, it's sagging downwards.

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So we have some component of

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rotatory subluxation of the scaphoid.

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Or in this projection, the

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scaphoid is rotating clockwise.

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Now with this failure, the mid

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carpal space is very arthritic.

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The proximal carpal row is coming apart.

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The capitate is migrating proximally.

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But this patient also has symptoms

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of carpal tunnel syndrome.

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And why?

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In the short-axis projection, is there a mass

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encroaching on the carpal tunnel space, like a

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capsular cyst or a giant bursa or a huge effusion,

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or a ruptured tendon or an anomalous structure?

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None of the above.

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It is the capitate, which is not only migrating

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proximally, but also sagging towards the

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palmar aspect of the wrist, compressing

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all of the volar structures and anatomy.

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Including, contributing to compromise of the visualized

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ulnar nerve that has led to carpal tunnel syndrome.

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So this patient has a complex instability syndrome,

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with a complex arthritis that is centered in the mid

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carpal space, with VISI, with rotatory instability

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of the scaphoid, and the midcarpal instability has

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contributed to compromise of the carpal tunnel canal.