Kinematics of the fingers and hands during computer keyboard use.

BACKGROUND Although there has been extensive research about the kinematics of the neck, arm, and wrist during computer keyboarding, there is almost no information concerning the kinematics of the fingers, thumbs, and hands. The purpose of this descriptive study was to establish normative values of the kinematics of the fingers and hands during computer keyboard use. METHODS This study describes the angles, angular velocities, and angular accelerations of the metacarpophalangeal joints and proximal interphalangeal joints for the right and left hands of 20 computer keyboard users during a word-processing task. A new kinematic variable for computer keyboard use, hand/wrist displacement, is also defined and examined. Hand/wrist displacement refers to the translational movements of the hands in which the entire hand is repositioned to strike the keys. Kinematics of both hands of the keyboard users were captured using a three-dimensional motion capture system. FINDINGS Metacarpophalangeal joint kinematics in flexion/extension and abduction/adduction are reported during typing. Proximal interphalangeal joint kinematics in flexion/extension are also reported. The means and standard deviations for finger postures, velocities and acceleration were generally not significantly different between the right and left hands, with the exception of the 1st digit (thumb). Hand/wrist displacement was significantly different between the right and left hands for side to side movements. Differences in kinematics among the fingers are discussed in view of their potential to be a risk factor for musculoskeletal disorders. INTERPRETATION This study establishes baseline understanding of the kinematics of computer keyboard use. This information will be useful in future studies of potential risk factors associated with keyboard use.