GONIOMETER MEASUREMENT AND COMPUTER-ANALYSIS OF WRIST ANGLES AND MOVEMENTS APPLIED TO OCCUPATIONAL REPETITIVE WORK

In epidemiological studies of occupational musculoskeletal disorders t here is a need for quantitative exposure measurements of the physical work load. In studies of neck and upper limb disorders the so-called c umulative trauma disorders (CTDs), in particular the carpal tunnel syn drome, the positions and movements of the wrist are of special interes t. A biaxial flexible electrogoniometer was used to measure continuous ly, with a sampling rate of 20 Hz, wrist flexion/extension and abducti on/adduction angles up to 27 min. Evaluation of the influence of rotat ion on the goniometer showed some inherent crosstalk, which, however, did not invalidate the results. For occupational repetitive work, 99.5 % of the signal power was contained in the 0-5 Hz band. Two-dimensiona l angle distributions and power spectra gave comprehensive information about wrist postures and movements. Measures reflecting both static a nd dynamic properties were derived from time and frequency domains. Th ese measures give quantitative information on different potential risk factors and are therefore useful in epidemiological studies. Mean pow er frequency (MPF) is suggested as a generalized measure of repetitive ness. The method was applied in field studies of fish processing indus try workers with highly repetitive work and risk of CTD.