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52-year-old man who complains of medial

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wrist pain and a burning sensation while

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shoveling and doing yard work one month ago.

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I don't have that problem because I'm not very good at

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shoveling snow, and I'm terrible at doing yard work.

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Nevertheless, they were concerned about a

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triangular fibrocartilage tear, which he has.

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I always like to start out in my search

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pattern in the coronal projection.

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I look at the relationship of the carpal bones.

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I see how inflamed the joint is.

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It's pretty inflamed.

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I look at the shape of the radial styloid,

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the ulnar styloid, which look normal.

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I look at the overall volume of the carpal

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bones, which are all normal with one exception.

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The lunate is abnormal.

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It's slightly decreased in

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overall height, and it's undulated.

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I look at the scapholunate ligament

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and the lunotriquetral ligament.

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And just as important, perhaps more important, I

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look at the intervals to see if they are arthritic,

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diastatic, inflamed, hyperintense, and/or eroded.

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And really, they're not.

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Perhaps there's a little irregularity at the

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scapholunate interval, but not much else.

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I observe the triangular fibrocartilage

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for its overall volume or height.

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In this case, it's about average volume,

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but it has some complex signal alteration in

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its central and inner third, consistent with

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a complex triangular fibrocartilage tear.

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So they were right.

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There's also a small chondromalacic erosion

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as evident by this very subtle area of

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subchondral edema in the ulnar body.

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There's quite a bit of inflammation along the

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periphery or ulnar aspect of the TFC or TFCC with

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some distention of the peripheral ulnar recess.

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But that, unfortunately, is not

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the main finding in this case.

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By the way, there is a limb of the small, often

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diminutive, lunotriquetral ligament, which is intact.

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The main finding in this case is the lunate.

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The irregular, reed-like, serpiginous signal

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intensity in the lunate, which is remodeled, slightly

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decreased in overall size or height, and therefore

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partially collapsed, is indicative of Kienböck's

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disease, or avascular necrosis of the lunate.

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So let's look at some of the appearances of

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the lunate, and we'll draw a little bit here.

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Let's have a look at the relationship of

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the capitate, which I have up here on the

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right-hand side, with the lunate, which is a

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semilunar, uh, structure, and the capitate.

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The radius, which I've drawn in green.

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So, if we start to get a little bit of sclerosis,

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we'll color it in with green, that may be

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one of the early signs of avascular necrosis.

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In fact, David Lichtman, in 1977, gave

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a grading system, which is most commonly

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used on plain film, to avascular necrosis.

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So, one would be a normal X-ray, two would be

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sclerosis, three would be collapse and fragmentation.

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And on the MRI to your right, we have that.

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We have collapse.

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We've already seen that in the coronal projection, and

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fragmentation with two diastatic lunate fragments.

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We can further divide this stage three Lichtman,

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stage three up into, and by the way, we're

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extrapolating from plain film to MRI, 3A, where

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the radioscaphoid angle is less than 60 degrees.

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Let's try and draw the radioscaphoid angle.

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See if I can do it.

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Here we are.

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There's the scaphoid.

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So we go down the long axis of the scaphoid.

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I'll even do it with my pen.

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Down the long axis of the scaphoid.

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Then the long axis of the radius.

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And this angle should be less than 60 degrees in a 3A.

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But when the scaphoid starts to sag,

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or rotate in a clockwise fashion,

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this angle is going to increase

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to greater than 60 degrees.

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And now we have a Lichtman Stage 3B.

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Stage 4 would be fragmentation with

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intercarpal arthrosis and erosions and

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radiocarpal articulation erosive change.

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Now what else can happen?

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Let's get out of our coloring tool here.

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What else can happen in Kienböck's disease?

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Kienböck's disease.

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Well, because the lunate starts to become misshapen,

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and collapses, and fragments, the intrinsics may

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start to fail, especially the scapholunate ligament.

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When that occurs, the lunate will

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start to drift off to the ulnar side.

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This is known as ulnar translocation of the lunate.

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Now, why, why does this condition occur?

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It most likely occurs because, due to friction,

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in patients that have an abnormal biomechanical

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relationship between the radius and ulna.

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There's more pressure against the radius,

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sorry, more pressure against the lunate.

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This likely occurs because there's more

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pressure between the radius and the lunate.

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This likely occurs in patients more

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frequently who have negative ulnar variance.

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In other words, the ulna is back here.

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Let's draw a little bit again.

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If the ulna is proximal, that means the

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radius is pressing harder against the lunate.

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And therefore, it's interrupting its blood

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supply, which is more robust along the palmar

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versus the dorsal aspect of the lunate.

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And by the way, there's intra- and extra-

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osseous blood supply to the lunate.

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So as this friction occurs, most likely due to

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misshapen, uh, bones or dysplasia, the blood

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supply is interrupted on a repetitive traumatic

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basis, not usually with a single traumatic event.

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And that's what's occurred here.

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Our patient was outside shoveling.

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And they subsequently developed Kienböck's disease.

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There are several different shapes of the lunate, too.

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There is a faceted shape of the lunate, there

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is a shape where the center of the lunate

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has a triangle at the base of it, and so on,

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and that will be a story for another day.

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But perhaps those intrinsic variations in shapes, along

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with the variance or position of the ulna, further

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contribute to the development of Kienböck's disease.

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Now, let's log out of our color.

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Our color program for a moment, and

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take a look at the short axis view.

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When a patient has Kienböck's disease and there

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is fragmentation, there is our fragmentation

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right there, bright signal intensity line,

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between a volar palmar segment and a dorsal

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segment, the lunate may start to sag forward.

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The capitate may also start to sag forward,

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although that hasn't occurred here.

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But the lunate has.

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And as the lunate presses against the

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structures anterior to it, it may

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compromise the carpal tunnel space.

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It may make it more narrow.

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Generally, the carpal tunnel space is a deep carpal

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fat pad, and fat in between the flexor tendons.

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We see virtually no fat in this carpal

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tunnel, and there's a little bit of

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palmar bowing of the flexor retinaculum.

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And one last take-home point.

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On a T2 Spin Echo, or Fast Spin Echo, without

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fat suppression, which this is, the median

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nerve should not be brighter than muscle.

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And it is.

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We take a piece of muscle, that's

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muscle, and that is the median nerve.

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The median nerve should look like this, not this.

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So that, that median nerve, which by

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the way is bifid, is under pressure.

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It's under siege from the volar

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sagging lunate in Kienböck's disease.

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So in summary, this is a patient with stage 3A.

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or Litchman 3A Kienböck's disease.

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The intrinsics are preserved.

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There's no ulnar translocation of the lunate.

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There is some collapse and fragmentation.

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There's volar displacement of the lunate, leading

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to signs of secondary carpal tunnel syndrome.

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And as was suspected clinically, the patient

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does have a triangular fibrocartilage tear,

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but I sincerely doubt that that's the cause of the

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patient's main clinical syndrome of wrist burning

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as a manifestation of chronic

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friction from his shoveling event.