This review summarizes the knowledge regarding ergonomics and musculoskeletal disorders and the association with computer work. A model of musculoskeletal disorders and computer work is proposed and the evidence and implications of the model together with issues for future research is discussed. The model emphasizes the associations between work organization, psychosocial factors and mental stress on the one hand and physical demands and physical load on the other. It is hypothesized that perceived muscular tension is an early sign of musculoskeletal disorder, which arises as a result of work organizational and psychosocial factors as well as from physical load and individual factors. It is further hypothesized that perceptions of exertion and comfort are other possible early signs of musculoskeletal disorders in computer work. Interventions aimed at reducing musculoskeletal disorders due to computer work should be directed at both physical/ergonomic factors and work organizational and psychosocial factors. Interventions should be carried out with management support and active involvement of the individual workers.

Background. Our objectives were to estimate prevalence of musculoskeletal disorders among office workers at a newspaper in Mexico City, analyze the relationship between musculoskeletal disorders and use of the personal computer (PC) and associated ergonomic factors in the aforementioned population, and to analyze the modifying effect that psychosocial factors have on the relationship between ergonomic factors and musculoskeletal disorders and extant jobs at the newspaper.

Methods. A total of 73% (218 of 298) of office workers at a newspaper were studied. Information was collected by a questionnaire completed by participants. Cases for work-related musculoskeletal disorder in hands (WMSD-H), upper extremity (WMSD-UE), and back (WMSD-B) were established. Working conditions, computer use, and ergonomic and psychosocial factors were studied as independent variables. To study the relationship between musculoskeletal disorders and independent variables, prevalence ratios adjusted for potential confounders (sex, age, educational level, and marital status) were estimated.

Results. Risk of musculoskeletal disorders was greater among workers at the newspaper who used computers, those involved in editing work, and those who adopted uncomfortable positions. The modifying effect of psychosocial factors was observed only in the relationship between ergonomic factors and WMSD-B because among workers with control over work, WMSD-B risk was reduced by the greater number of work breaks. Among workers without social support, increase in number of postures and rotation/inclination of the neck was associated with substantial risk increase, while amid workers under psychological demand number of PC tasks and number of rest pauses were associated with increase in WMSD-B risk.

Conclusions. The findings of our study showed that PC use increased risk of developing musculoskeletal disorders (WMSD-H and WMSD-UE). Such an increase is mediated by ergonomic factors such as mouse use, remaining seated for prolonged periods, adoption of inadequate or uncomfortable postures, performing certain PC tasks, and psychosocial factors.