The Prevalence of Upper Extremity Cumulative Trauma Disorders in Industry (Ergonomies, Occupational Epidemiology).

Upper extremity cumulative trauma disorders (CTDs) largely affect the musculoskeletal system or the peripheral nervous system. It has been suggested that the major occupational risk factors include repetitiveness, force, awkward postures, vibrating and non-vibrating h and tools. The main objective of this investigation was to determine if forceful and repetitive job attributes were positively associated with CTDs of the h and and wrist. Posture and vibration were not considered in this investigation. 574 active workers from 6 different industrial sites were categorized into four exposure groups: low force-low repetitive, high force-low repetitive, low force-high repetitive and high force high repetitive. Workers in low force-low repetitive jobs served as an internal comparison population for the three other groups. At least one job in each exposure category was selected per plant and 3 workers per job were videotaped performing the job. Surface electromyographic (EMG) recordings from the forearm flexor muscles were used to estimate force requirements of the job. Cycle time and percent of the cycle time performing repeating sequences of elements were used to estimate repetitiveness. The presence of CTDs was determined by structured interview and physical examination. Only workers who had been working on the study jobs for at least one year at the time of evaluation were eligible for selection. Identification of CTDs and categorization of jobs were carried out independently by investigators who were appropriately blinded to exposure and outcome. Analysis of associations between CTDs and exposure categories were performed using Mantel-Haenszel plant adjusted odds ratios and unconditional multiple logistic regression. Significant findings included an 8 fold increased risk of shoulder CTDs with high force-low repetitive jobs and 16 to 30 fold increased risks of various h and wrist CTDs with high force-high repetitive jobs. Increased risk of h and wrist CTDs were also identified with high force or high repetitive jobs, although the magnitude of association was not as great as when these two factors were combined. These associations were independent of age, sex, years on the specific job and plant.Ph.D.Public healthUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/160595/1/8512507.pd