What is the pathomechanics of radial and ulna deviation relevant to ulnar-sided wrist pain?

Updated: Apr 26, 2021
  • Author: David M Lichtman, MD; Chief Editor: Harris Gellman, MD  more...
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Radial deviation of the hand and distal carpus is associated with palmar flexion of the entire proximal row, and ulnar deviation of the hand and distal row is associated with proximal row extension. This reciprocal motion is caused by the resulting joint reactive forces around the proximal row when the wrist is deviated radially and ulnarly. Radial deviation compresses the scaphotrapeziotrapezoid (STT) joint, forcing the scaphoid into flexion. With intact interosseous ligaments, the entire proximal row follows the scaphoid into flexion.

Ulnar deviation guides the triquetrum into its extended position against the hamate. With intact ligaments, the entire proximal row now follows the triquetrum into extension. In neutral deviation, these opposing forces are dissipated if the wrist is relaxed, and they are neutralized by intact bone and ligamentous supports if the wrist is stressed, as by a clenched fist. Consideration of this transverse ring model of carpal kinematics enables a clearer understanding of the pathomechanics of various carpal instabilities.

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