Development and evaluation of challenge and recovery models of upper-extremity cumulative trauma disorders based on job attributes analysis.

Abstract

This dissertation presents investigations of upper-extremity stress and its association with job attributes. The objective is to relate cumulative trauma disorder (CTD) risk factors to job attributes. Particular concerns are: (1) to develop theoretical models that describe exposure to CTD risk factors as a sequential process of challenge and recovery; (2) to conduct an in-plant survey of jobs and tools, and to relate it to the challenge and recovery models; and (3) to examine associations between health outcome and the challenge-recovery model. In the first of three studies, the morbidity patterns of CTDs and the traditional systems of work measurement are reviewed. Based on this background knowledge, a model is proposed to describe CTD risk as a function of the sequential process of challenge and recovery. This model is applicable to worker health, in that the failure of the recovery process to keep up with challenge can result in both short-term and long-term effects. The second study is a survey of 132 jobs and tools used in the chassis and trim departments of an automotive assembly plant. The study examines the cycle time and the percent of cycle time devoted to assembly, material h and ling, holding the tool, using the tool, and recovery. It was found that a significantly greater percent of cycle time was devoted to assembly on jobs affected by shoulder CTD compared to the unaffected jobs (74% and 61% respectively.) The percent of cycle time spent on material h and ling was significantly lower in the affected jobs compared to unaffected ones (16% and 27% respectively). The weight of tools was significantly heavier in the affected jobs (1.8 kg to 1.4 kg respectively). The third study examines the association between in-house medical visits for shoulder CTD and shoulder postures in 89 jobs in an industrial setting. The odds ratio of developing shoulder CTD while performing any overhead operations was found to be 9.6 compared to jobs with no overhead work. The rate of shoulder CTD was also significantly higher (OR = 6.4) on jobs that required the use of non-neutral shoulder posture for more than half of the work cycle.