THE RELATIVE CONTRIBUTION OF SELECTED CARPAL BONES TO GLOBAL WRIST MOTION DURING SIMULATED PLANAR AND OUT-OF-PLANE WRIST MOTION

The relative contribution of the scaphoid, lunate, triquetrum, and cap itate to wrist motion was examined in 6 fresh cadaver forearms. A wris t-joint motion simulator was used to dynamically move each wrist throu gh planar and nonplanar motions. During wrist flexion-extension, the m otion of the capitate closely followed the motion of the third metacar pal, while the lunate motion was approximately 50% of the total motion ; the triquetrum, 65%, and the scaphoid, 90%. Similar differences in m otion for these carpal hones occurred during radioulnar deviation and circumduction and dart-throw motions. This suggests that the scaphoid, lunate, and triquetrum do not normally function as a single unit, but that each bane has an unique are of motion during global wrist motion .