| BackgroundMusculoskeletal disorders (MSDs) are injuries or dysfunctions affecting muscles, bones, nerves, tendons, ligaments, joints, cartilages, and spinal discs. MSDs cases with mild symptoms often feel uncomfortable or slightly painful, while severe cases are often unable to work and need to be treated with medication or special tools training, usually with unexpected poor prognosis. MSDs are prevalent and are a serious problem among working population around the world. MSDs were listed as one of the ten occupational problems needing intensive research in2002by National Institute for Occupational Safety and Health, NIOSH, and the ten years of2000to2010was identified as "Bone and Joint Decade2000-2010" by world health organization, WHO. Agricultural workers are mostly affected by MSDs, especially in labor-intensive practices such as fruit and vegetable planting. China being a vast agricultural country, MSDs among farmers, however, have been paid scarce attention. Therefore, it is of vital significance to study farmers’ MSDs and the risk factors.Greenhouse vegetables have been widely planted in Shouguang, Shandong Province, and are increasingly being cultured in mainland China due to high economic profits. But due to the fact that greenhouse vegetable-planting is an arduous practice, and its peculiar greenhouse microenvironment (high temperature, high humidity, high carbon dioxide, etc.), greenhouse vegetable-planting farmers may be much more likely to be affected by MSDs such as osteoarthritis, low back pain, neck and shoulder pain.Many factors could influence the occurrence and development of MSDs, such as occupational factors, individual factors, psychosocial factors, etc, which are difficult to determine and measure in surveys. What’s more, the causal relationship between possible risk factors and diseases is usually difficult to demonstrate in cross-sectional studies. Structural equation model (SEM), one of the three achievements in statistics in the twentieth century, is a statistical technique for testing and estimating causal relations using a combination of statistical data and qualitative causal assumptions, allowing both confirmatory and exploratory modeling, meaning they are suited to both theory testing and theory development. SEM has been widely used in the field of medicine such as chronic diseases but there have been few studies reported in the application of analysis of MSDs’risk factors. The application of SEM to analyze risk factors of MSDs among greenhouse vegetable-planting farmers and to determine the relative levels, which would benefit the understanding of MSDs’risk factors, is of vital significance to guide future studies.ObjectiveTo study the prevalence of MSDs among both greenhouse vegetable-planting farmers and non-greenhouse vegetable-planting farmers, and to explore the risk factors influencing greenhouse vegetable-planting farmers’MSDs, and to seek measures preventing greenhouse vegetable-planting farmers’MSDs.MethodsA self-administered questionnaire based on the Modified Nordic Questionnaire and the Dutch Musculoskeletal Questionnaire was conducted to both greenhouse vegetable-planting farmers in a greenhouse vegetable-planting area and non-greenhouse vegetable-planting farmers in the near villages by stratified cluster sampling. Then one-year prevalence rate of MSDs was calculated and compared between greenhouse vegetable-planting farmers and non-greenhouse vegetable-planting farmers (control group). Structural equation model was used to analyze the risk factors of greenhouse vegetable-planting farmners’ MSDs and to determine the risk levels.Results1. Study of Prevalence639greenhouse vegetable-planting farmers and318non-greenhouse vegetable-planting farmers completed the self-administered questionnaire. The1-year prevalence rate of MSDs was61.2%among greenhouse vegetable-planting farmers and43.4%among non-greenhouse farmers. The first four MSDs of greenhouse vegetable-planting farmers were low back disorders, shoulder(s) disorders, knee(s) disorders and neck disorders. The1-year prevalence rate of low back disorders, shoulder(s) disorders, knee(s) disorders and neck disorders among greenhouse vegetable-planting farmers was49.6%,29.0%,24.6%and12.8%respectively, statistically higher than that of non-greenhouse vegetable-planting farmers with the corresponding rate of28.0%,11.6%,10.7%and4.4%respectively (P<0.05).2. Analysis of risk factorsThe coefficient of determination of latent variables on low back disorders was0.847in the structural equation model. The structural coefficient of force exertion, static loads, dynamic loads, ergonomic environmental factors, repetitive loads and psychosocial factors on low back disorders was0.385,0.342,0.122,0.064,0.040and0.098respectively (P<0.05). The total effects of force exertion, static loads, ergonomic environmental factors, dynamic loads, psychosocial factors, repetitive loads and age on low back disorders were0.385,0.342,0.285,0.122,0.098,0.040and0.034respectively. The direct effect of ergonomic environmental factors on static loads was0.646.The coefficient of determination of latent variables on shoulder(s) disorders in the structural equation model was0.654. The structural coefficients of greenhouse factors, repetitive factors, force exertion, age, postures of shoulder(s), gender and uncomfortable postures on shoulder(s) disorders were0.448,0.283,0.106,0.079,0.069,0.065and0.033respectively (P<0.05). The total effects of greenhouse factors, repetitive factors, force exertion, age, postures of shoulder(s), gender and uncomfortable postures on shoulder(s) disorders were0.660,0.283,0.106,0.079,0.069,0.065and0.033respectively. The direct effects of greenhouse factors on force exertion and repetitive loads were0.553and0.544respectively.The coefficient of determination of latent variables on knee(s) disorders in the structural equation model was0.674. The structural coefficients of uncomfortable postures, individual factors (mainly height and bodyweight), psychosocial factors and health status on knee(s) disorders were0.632,0.259,0.089and0.039respectively (P<0.05). The total effects of uncomfortable postures, individual factors (mainly height and bodyweight), psychosocial factors and health status on knee(s) disorders were0.632,0.259,0.089and0.039respectively.The coefficient of determination of latent variables on neck disorders was0.736in the structural equation model. The structural coefficients of repetitive loads, postures of neck, individual factors (age), uncomfortable postures and psychosocial factors on neck disorders were0.559,0.344,0.037,0.030and0.001respectively (P<0.05). The total effects of repetitive loads, postures of neck, individual factors (age), uncomfortable postures and psychosocial factors on neck disorders were0.559,0.344,0.037,0.030and0.001respectively.Conclusions1. The prevalence of MSDs among greenhouse vegetable-planting farmers was quite high, and the first four MSDs were low back disorders, shoulder(s) disorders, knee(s) disorders and neck disorders. What’s more, the everyday work of greenhouse vegetable-planting farmers was affected due to MSDs.2. The main risk factors of low back disorders among greenhouse vegetable-planting farmers were force exertion, static loads, ergonomic environmental factors and dynamic loads. The main risk factors of shoulder(s) disorders among greenhouse vegetable-planting farmers were greenhouse factors, repetitive loads and force exertion. The main risk factors of knee(s) disorders among greenhouse vegetable-planting farmers were uncomfortable postures and obesity. The main risk factors of neck disorders among greenhouse vegetable-planting farmers were repetitive loads and neck postures.3. Suggestions:to improve greenhouse configuration; to optimize work organization; to meliorate operating styles. |
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