File:Negative ulnar variance.png

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Revision as of 19:24, 3 April 2022 by Jeremy (talk | contribs) (Negative ulnar variance. This patient has negative ulnar variance, that is, the ulnar does not reach as far distally as the radius. Here, the entire articulation is given by the red lines. The blue lines represent the articular area not used because the ulna is too proximal. In this anatomic configuration the carpus articulates with the radius alone, thereby creating a smaller contact area for the lunate, with resultant greater pressure on it. (Pressure, is of course, force/area; and a smalle...)
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Negative_ulnar_variance.png(396 ร— 272 pixels, file size: 101 KB, MIME type: image/png)

Summary

Negative ulnar variance. This patient has negative ulnar variance, that is, the ulnar does not reach as far distally as the radius. Here, the entire articulation is given by the red lines. The blue lines represent the articular area not used because the ulna is too proximal. In this anatomic configuration the carpus articulates with the radius alone, thereby creating a smaller contact area for the lunate, with resultant greater pressure on it. (Pressure, is of course, force/area; and a smaller area for a given force leads to increased pressure.) In turn, the bone is more apt to fail mechanically.

From https://orthopaedia.com/page/Kienbocks-disease

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current19:24, 3 April 2022Thumbnail for version as of 19:24, 3 April 2022396 ร— 272 (101 KB)Jeremy (talk | contribs)Negative ulnar variance. This patient has negative ulnar variance, that is, the ulnar does not reach as far distally as the radius. Here, the entire articulation is given by the red lines. The blue lines represent the articular area not used because the ulna is too proximal. In this anatomic configuration the carpus articulates with the radius alone, thereby creating a smaller contact area for the lunate, with resultant greater pressure on it. (Pressure, is of course, force/area; and a smalle...

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