One of the growing occupationally-related problems in both the manufacturing and service industries is that of hand and wrist cumulative trauma disorders (CTDs), of which carpal tunnel syndrome (CTS) is the most widely publicized. It is widely accepted that CTDs are related to repetitive and/or forceful exertions of the hand and wrist performed in work environments. The incidence and costs of CTDs are rising every year - - over 50% of the injuries and iilnesses reported to the U.S. Government are due to repeated trauma, with an average cost of $20,000. CTDs have been troublesome in the clerical service sector in the U.S., which has an employment base of over 18,000,000 (Stat. Abstract of the U.S., 1992). Many clerical workers exert 50,000 to 100,000 key strokes per day. Recently, there has been an onslaught of legal cases against manufacturers of computer keyboards by users who have claimed CTD injuries. While the exact cause of occupationally-induced CTDs in keyboard users is not known, it appears that the deviated wrist and forearm posture (ulnar deviation and pronation) dictated by the design of the standard flat keyboard is implicated in the etiology of occupational CTDs. Within the past few years, manufacturers of several new alternative keyboard designs have entered the market, each one claiming their keyboard reduces the musculoskeletal stress on the operator. Typically, these alternative keyboards are split into halves and rotated in the horizontal plane to reduce ulnar deviation and are declined in the vertical plane to lessen forearm pronation. However, little quantitative data are available as to whether the fundamental design of these keyboards actually reduce deviated wrist and forearm posture and lessen musculoskeletal stress.
The specific aim of this research study is to determine whether the fundamental designs of alternative keyboards have a beneficial effect on the kinematic motion patterns in the upper extremity -- i.e. whether operators of alternative keyboards have less injurious motion patterns than those of users of the standard flat keyboard. Another aim of this research is to determine whether the design of the keyboard affects the motion patterns of operators in the early stage of CTS differently than healthy operators. The long term objective of this research is to improve the safety and health of keyboard operators by reducing the incidence, severity, and costs of musculoskeletal disorders in computer work environments. This research could not only enhance the quality of life of keyboard users, but also reduce health care costs, which would benefit employees, employers, and the national economy.
