Bone Surface Variation With vs. Without GWMD (CORO view)

Carpal bone instability occurs when the ligaments holding the scaphoid, lunate, and triquetrum together (the scapholunate (SL) and lunotriquetral (LT) ligaments) are torn, allowing these bones to shift out of alignment during wrist motion. When the wrist drifts out of the imaging plane during motion, the same bone can appear to change shape or size across frames, an artifact of out-of-plane displacement rather than true anatomical change, which can bias carpal motion measurements.

This video compares the cross-sectional area of the scaphoid, lunate, and triquetrum across the motion cycle, acquired with and without the guidance wrist movement device (GWMD). A bone that stays within the imaging plane should maintain a relatively stable cross-sectional area throughout motion; larger fluctuations in area indicate greater out-of-plane displacement. The reduced amplitude of area variation seen with the GWMD, compared to without it, reflects its effect in constraining the wrist to the imaging plane and standardizing acquisition conditions.