Wrist circumduction reduced by finger constraints.

PURPOSE Assessment of wrist motion is important in diagnosing and treating motion impairment after injuries to the wrist. Little is known of how finger posture influences the movement of the wrist. The aim of this study was to investigate the effect of finger constraints on the maximum circumduction movement of the wrist. METHODS Fifteen male right-handed subjects performed maximal circumferential wrist movements under 4 finger conditions: unconstrained fingers, holding a large cylinder (50 mm diameter), holding a small cylinder (25 mm diameter), and closed fist position. The wrist motion was captured by a surface marker-based motion analysis system. To quantify wrist motion capability, we constructed the maximal boundaries of wrist motion (circumduction envelope) from angular plots in flexion-extension (FE) and radial-ulnar deviation (RUD). The ranges of motion in FE and RUD and the envelope area were calculated. RESULTS Finger constraints significantly reduced motion ranges in flexion and ulnar deviation, but not in extension and radial deviation. In comparison to the unconstrained finger condition, the motion ranges in flexion decreased by 13%, 16%, and 27% for the large cylinder, small cylinder, and fist conditions, respectively. The range of ulnar deviation was reduced by 10% for the large and small cylinder conditions and by 11% for the fist condition. The overall mobility in FE and RUD, as quantified by the area of circumduction envelope, decreased by 15%, 15%, and 23% for the large cylinder, small cylinder, and fist conditions, respectively. CONCLUSIONS Wrist mobility is facilitated by the synergistic motion of finger joints. Constraining fingers in static flexion posture reduces wrist flexion and ulnar deviation without decreasing extension and radial deviation. A clinical implication is that wrist motion should be assessed under standardized finger joint configuration.