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I'd like to talk about some unique situations

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and some kind of a unique, quirky kind of guy.

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The first unique situation, with regard to

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parameters, is the relationship of the radius and

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ulna and how congruent they are to each other.

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Pretend my two fingers on each hand represent

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each hand, and one represents the radius,

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the middle finger, and the shorter finger,

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my index finger, represents the ulna.

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Now, when you pronate or supinate, there should be

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a congruent rotational relationship between the two.

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Sometimes what can happen is the

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ulna can start to float dorsally.

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Now fortunately, it only does it usually on one side.

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So the optimal thing is to scan a patient with either

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CT or MRI in a steep pronated and supinated view.

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And compare how dorsal the ulna is to the

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radius in the short axis axial projection.

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This is an extremely important maneuver because

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it's a common cause of wrist pain, namely radial

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ulnar instability, usually only in one wrist.

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So you're looking for something as simple as symmetry.

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Then I've got another maneuver for you.

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I hardly ever put intra

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articular contrast in the wrist.

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There is no need.

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As we'll see later on, the direct and the

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indirect signs of scapholunate and lunato

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triquetral insufficiency are more than enough.

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Sometimes, you can augment your diagnosis

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without an arthrographic injection by simply

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looking at the wrist in the neutral position.

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And then imaging it coronally in the steep radial,

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sorry, steep ulnar deviation position and steep radial

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deviation position to see if the intrinsic proximal row

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ligaments separate in either radial or ulnar deviation.

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You'll have to call for these views in unique

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situations or train your technologist to

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do so When the situation is appropriate.

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Now let me do a little bit of drawing.

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I want to talk about a controversial

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subject that hand surgeons and radiologists

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go back and forth on quite a bit.

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And that is the concept of variance.

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So I'm going to do my best to draw you an

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ulnar with an ulnar styloid and a radius.

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And here's our radial ulnar articulation.

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There's our scaphoid fossa just to get oriented.

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Now surgeons like to talk about variance on x ray.

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The relationship proximal to

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distal of the ulna to the radius.

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In certain positions, like a clenched fist view

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or steep pronation, the ulna may jut distally.

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and may abut and encroach on the lunate.

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Now we're not using x ray, we're using

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MRI, often in a neutral position, sometimes

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pronated, sometimes supinated, so there's

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a tremendous amount of variability in

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how the technologist positions the wrist.

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In general, I use about 8 millimeters of

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disparity between the marginal edge of the

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ulna and the marginal edge of the radius.

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So if it's short by 8 millimeters, or if

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it's too long by 8 millimeters, I suggest

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that there's ulnar variance posture.

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I put that posture word in there so

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the hand surgeons won't yell at me.

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In other words, I don't want to use their

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term, ulnar variance, which is an x ray term.

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I use the posture adjective to get out of jail free

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and make sure they know that there's a tendency for

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the ulna to be a little too long or a little too short.

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Sometimes, I'll even do a clenched fist view.

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The most valuable aspect of determining

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whether variance posture contributes

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to disease are the secondary signs.

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When the ulna is too short, you'll frequent.

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You'll frequently see swelling over here

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at the peripheral attachments of the TFCC.

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If the ulna is too long, positive variance

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posture, it'll abut against the lunate.

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And it'll produce erosions in the lunate,

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and you'll also see some adjacent areas of

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chondromalacia around the lunate and around the ulna.

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So you'll see some chondromalacia right there,

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and you'll see some chondromalacia right there.

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You may have a little bit of fluid, a little bit of

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swelling, and it's these indirect signs that tell

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you when posture is really relevant to the diagnosis.

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My final, unique, quirky point.

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Contrast.

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I rarely, to uncommonly, use contrast in the wrist.

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If I have some weird looking mass that I can't

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characterize, in other words, looks like a

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ganglion, smells like a ganglion, feels like

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a ganglion, but it's in a funny spot with

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some features of atypicality, it's funny.

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I'm going to inject it, but if it's in

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the typical position along the scapho

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lunate capsule with the proper signal and

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smooth and round, I'm not injecting it.

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Finally, arthrographic injection.

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I use arthrographic injection almost every day.

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0 percent of the time to diagnose

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scapho lunate ligament injuries.

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I'll use it about 10 20 percent of the time to diagnose

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lunato triquetral ligament injuries since this ligament

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is smaller and sometimes more difficult to identify.

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But that is really an exception.

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So I don't commonly give injections, IV

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for masses, and I don't commonly inject.

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Intra articulately, with an arthrogram,

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for the wrist, unless I'm forced to.

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My next point gets its own discussion.

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Proper angles for assessment of the scaphoid bone.

Report

Faculty

Stephen J Pomeranz, MD

Chief Medical Officer, ProScan Imaging. Founder, MRI Online

ProScan Imaging

Tags

Musculoskeletal (MSK)

MRI

Idiopathic

Hand & Wrist

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