Rockwood Children CH8

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SECTION TWO • Upper Extremity

A

A

B

B

Figure 8-21.  Hafner’s technique to measure ulnar variance. A: The distance from the most proximal point of the ulnar metaphysis to the most proximal point of the radial metaphysis. B: The distance from the most distal point of the ulnar metaphysis to the most distal point of the radial metaphysis. (Adapted by permission from Springer: Hafner R, Poznanski AK, Donovan JM. Ulnar variance in children. Standard mea- surements for evaluation of ulnar shortening in juvenile rheumatoid arthritis, hereditary multiple exostosis and other bone or joint disor- ders in childhood. Skel Radiol. 1989;18(4):513–516. Copyright © 1989 International Skeletal Society.)

Figure 8-22.  Technique for neutral rotation radiograph with wrist neutral, forearm pronated, elbow flexed 90 degrees, and shoulder abducted 90 degrees.

Volar

Dorsal

Dorsal

Volar

Volar

Dorsal

Pronation Midrotation Figure 8-23.  Distal radioulnar joint stability in pronation ( left ) is dependent on tension developed in the volar margin of the triangular fibrocartilage (TFCC, small arrowheads ) and compression between the contact areas of the radius and ulna (volar surface of ulnar articular head and dorsal margin of the sigmoid notch, large arrows ). Disruption of the volar TFCC would therefore allow dorsal displacement of the ulna in pronation. The reverse is true in supination, where disruption of the dorsal margin of the TFCC would allow volar displacement of the ulna relative to the radius as this rotational extreme is reached. The dark area of the TFCC emphasizes the portion of the TFCC that is not supported by the ulnar dome. The dotted circle is the arc of load transmission (lunate to TFCC) in that position. (Redrawn from Bowers WH. Green’s Operative Hand Surgery . New York: Churchill-Livingstone; 1993.) supination