Carpal Tunnel Pressure during Typing: Effects of Wrist Posture and Typing Speed

Abstract

With increasing frequency, reports appear in the popular press linking hand and wrist musculoskeletal disorders (MSDs) with keyboard work. Excessive ulnar deviation and self-perceived fast typing speed are two of the many risk factors identified through various epidemiological studies of upper extremity MSD symptoms among those working with keyboards. Yet no study has offered quantitative, biomechanical evidence to explain how these factors might contribute to MSD development. A study was designed to examine carpal tunnel pressure (CTP) during typing, and the effect of radial-ulnar wrist posture and typing speed on CTP. Female subjects typed on a commercially-available keyboard which was oriented in standard and in split configurations. In the split arrangement ulnar deviation was eased in all but one wrist. In the split arrangement, all subjects demonstrated a decrease in CTP concomitant with a decrease in ulnar wrist deviation. However, only one subject exhibited CTP which significantly exceeded pressure thresholds identified in the literature. CTP appeared to be subject-specific in nature. Typing speed was found to affect peak CTP in half of the subjects.