Résumé
OBJECTIVE: To evaluate the effect of height and tilt adjustable keyboard tray on work-related musculoskeletal pain in visual display terminal (VDT) workers. METHOD: Twenty-one VDT workers, who had myofascial pain in upper trapezius (UTZ) and extensor carpi radialis longus (ECRL) or brevis (ECRB) during VDT work, were randomly assigned to a control (n=10) that used conventional keyboard or experimental group (n=11) that used height and tilt adjustable keyboard tray. A pretest assessed the visual analog scale (VAS), pain threshold of UTZ and ECRL or ECRB, and grip and tip pinch strength as well as upper extremity function index (UEFI). Post-test was conducted 1 month later. Additionally, differences in working posture between the two groups were evaluated. RESULTS: For the UTZ, the decrease of VAS (p<0.05) and increase of pain threshold (p<0.01) in experimental group were significantly greater than control group after 1 month. Increase of right grip strength (p<0.01) and UEFI (p<0.05) in the experimental group were significantly larger than control group. Experimental group showed lower keyboard height (p<0.01) and smaller elbow angle (p<0.01) as well as more anterior tilted keyboard angle (p<0.01) than the control group. CONCLUSION: Application of height and tilt adjustable keyboard tray seems to affect the working posture, thus reduce the work-related musculoskeletal pain of UTZ as well as enhance the strength of right grip strength and upper extremity function in VDT workers. Additionally, anterior keyboard tilting may help to reduce wrist extension in low keyboard height which contributes to decreasing UTZ muscle tension.