Biomechanical and epidemiological investigation of carpal tunnel syndrome at workplaces with high risk factors.

This paper deals with the problem of carpal tunnel syndrome (CTS) through investigations of both biomechanical and epidemiological data on seventeen high risk jobs. Biomechanical data were collected from continuous recording of prehension muscular efforts and wrist angular flexion-extension positions for each hand. In order to characterize both static and dynamic behaviours of signals, nine angle and four force indices were built for each hand. The epidemiological data evaluated the probability to contract the CTS (prevalence) on the dominant hand, the non-dominant hand, and both hands simultaneously. Biomechanical and epidemiological data were evaluated using multiple correspondence factor analysis which may consider heterogeneous variables to clarify non-linear relations in a very large data set. The CTS occurred twice more frequently on the two hands together (average 20%) than on the dominant hand alone. Such a result confirmed the outcome of other studies that non-occupational factors could be more important than occupational factors. The prevalence for both hands was highly correlated with the frequency of flexion and use of high forces. High or low flexions appeared to be a greater risk factor than high or low extensions.