| Distal upper extremity (DUE) musculoskeletal disorders (MSDs) are rapidly spreading throughout the industrialized world. These disorders are work-related and have enormous economic and social consequences if they are not addressed properly. This study establishes the relationship between job, individual and psychosocial risk factors and DUE MSDs, that will help health and safety professionals to modify work tasks and thereby reduce distal upper extremity musculoskeletal disorders due to work.; This cross-sectional study took a sub population of 525 workers out of 900 workers from manufacturing, assembly and packaging industries, who are part of a large prospective cohort study conducted by the University of Wisconsin-Milwaukee (UWM), Medical College of Wisconsin (MCW), and University of Utah. Teams of engineering graduate students and occupation therapists collected job physical exposure data using structured questionnaires and videotapes. The videotapes were further analyzed to extract out the job variables, which included intensity of exertion, percentage duration of exertion, efforts per min, hand/wrist posture, speed of work, Hand Activity Level (HAL) and type of grip and pinch exertions involved. Teams of board certified hand therapists, occupational therapists and board approved occupational medicine physicians collected health exposure data using laptop administered structured interviews and physical examinations. The job exposure teams were kept blinded to health outcomes during the study period.; This research assessed job variables at two levels: the typical exposure and peak exposure. Four health variables were used in statistical analysis: (i) a specific disorders that includes: Carpal Tunnel Syndrome (CTS), Lateral and Medial Epicondylitis, de Quervain's disease, Flexor and Extensor Tendinitis, Trigger Finger/Thumb; (ii) nonspecific pain of rating 0; (iii) all specific disorders grouped together, including and excluding CTS; (iv) all specific disorders and non-specific pain of rating ≥3 grouped together, including and excluding CTS. Primary analysis was done using the Independent Sample t-test, Pearson Chi-square test or Fisher's exact test depending on the type of variable studied. Later the findings were confirmed using binomial logistic regression analysis.; Study findings indicate that among the job variables percentage duration of exertion, efforts per minute, and Hand Activity Level (HAL) were significantly higher for all four health variables at both typical and peak exposures. Individual variables: age, Body Mass Index (BMI), gender and diabetes were significant for all the four health variables. Among the psychosocial variables family problems, physical and metal exhaustion, depression, job satisfaction, to take job again and employer care were found to be associated with all the health outcomes.; Based upon the current study population work characteristics, this study also sets a safe work exposure levels for repetition, which is a combination of percentage duration of exertion and efforts per minute, i.e., working with ≤55% of cycle time and efforts per minute ≤12 is considered safe. If for the jobs with task intensity ≤0.5 on Borg CR-10 scale are ignored, the safe exposure for percentage duration of exertion and efforts per minute changes to ≤45% and 8 efforts per minute.; The Strain Index could predict jobs as safe or hazardous for "medial epicondylitis", "all specific disorders grouped together" only at typical exposure, however for peak exposure, the Strain Index method could correctly predict safe and hazardous jobs for "non-specific pain (≥3)", "all specific disorders grouped together" and "all specific disorders and non-specific pain grouped together, including and excluding CTS". However, TLV for HAL predicted safe and hazardous jobs correctly for CTS, "all specific disorders grouped together, including and excluding CTS" for typical exposure. For peak exposure, TLV for HAL cou... |
