Bone Surface Variation With vs. Without GWMD (SL)

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. Tracking each bone's cross-sectional area across the motion cycle provides a way to assess whether the imaging plane is capturing this motion, since larger fluctuations can reflect out-of-plane displacement.

This video compares the lunate and scaphoid surface area over time in the oblique axial plane aligned to the SL axis, acquired with and without the guidance wrist movement device (GWMD). Here, both bones show a larger, coordinated cyclical variation with the device, rather than a reduced one, the opposite of the coronal-plane trend. This individual case illustrates the inter-subject variability behind the SL comparison, where the effect of the GWMD did not reach statistical significance at the group level.