Carpal Tunnel Syndrome Effects on Grip Force Coordination

Abstract

This study investigated the effects of carpal tunnel syndrome (CTS) on the coordination between grip force on and the force applied with a hand tool. A simulated tool device was developed to measure pinch grip force exerted on the tool and the force applied with the tool to a workpiece. Two measures of grip force coordination efficiency were calculated for seven subjects with diagnoses of carpal tunnel syndrome and seven controls. The dependent measures reflected subjects' abilities to (1) modulate grip force in parallel with the tool application force and (2) minimize the ratio of grip force to application force when dynamically applying forces with the tool. The parallel modulation of grip force with application force was 12% lower (p < 0.05) and the ratio of grip force to application force was 54% higher (p < 0.05) for the CTS group than for the controls. These results suggest that individuals with carpal tunnel syndrome lose some ability to efficiently coordinate grip force with tool application force.