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Dynamic Instability



- See: Kinematics
        Carpal Instability

- Discussion:
    - pts w/ dynamic instability can actively subluxate wrist w/ forearm pronated & wrist in or out of ulnar deviation;
    - dynamic forms of dorsal or volar intercalated-segment instability are secondary to loss of support across ulnar half of mid-carpal joint

- Radiographs:
    - static radiographs are considered normal, although alignment of radiocarpal link may have palmar or dorsiflexion bias;
    - x-rays should be made w/ pt's forearm & hand pronated, elevated on bolster, & placed against x-ray plate, which is held vertically;
         - x-ray is directed horizontally across wrist; (lateral view);
         - will accentuate either volar or dorsal intercalated-segment instability, w/ loss of alignment between capitate & radius