Predictive models of carpal tunnel syndrome (CTS) causation among VDT operators
Abstract
Carpal tunnel syndrome (CTS), a cumulative trauma disorder of the hand and wrist, is one of the most common disabling injuries experienced by video-display terminal (VDT) operators. The purpose of this study was to develop a theoretically based operational quantitative predictive model of the risk of acquiring work-related CTS among VDT operators. A total of 100 female VDT operators, who performed a variety of office functions, were studied at a major midwestern university. Data were collected on job exposure, anthropometry and posture factors. Job exposure factors included: typing speed, work duration, percent of workday devoted to VDT use and years of VDT work. Posture factors included static wrist and upper body postures such as wrist extension and ulnar deviation, trunk incline, upper arm and forearm extension, and elbow height relative to the keyboard. Anthropometric measurements included eleven measures of upper extremities and other personal factors such as age, height and weight. Job satisfaction was also measured. The results of the study indicated the following: (1) Percentage of workday working with a VDT was the most significant factor and accounted for 60% of the variance explaining the causation of musculoskeletal discomforts associated with CTS. Discriminant function with six variables (i.e. work duration, trunk incline, wrist extension, wrist ulnar deviation, overall anthropometric measure, weighted anthropometric measure) correctly classified 73% of the CTS group and 72% of the Non-CTS group. (2) Using the logistic regression model, the probabilities associated with changes in the predictive variables as effecting CTS risk are presented such that, for example, increasing the daily work duration from 1 hour to 4 hours increases the probability of CTS risk from 0.45 to 0.92. The results of the study suggest that the main causation of CTS is job design, the secondary (and lesser cause) is posture associated with the workplace design and the least contributing factor to CTS causation is the individual's anthropometric make-up.
Degree
Ph.D.
Advisors
Salvendy, Purdue University.
Subject Area
Industrial engineering|Occupational safety
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