Assessing Musculoskeletal Disorder Risks in an Automobile Part Manufacturing Factory: A Comparison Study of Biomechanical and Ergonomic Tools

Background: Various tools and methods are available to assess the risk of musculoskeletal injuries in occupational settings, each considering different assessment criteria. While these methods have been previously studied, further comparative investigations are still needed. Objectives: This study aimed to assess the risk of musculoskeletal disorders (MSDs) in workers performing various tasks using different ergonomic and biomechanical risk assessment tools and to compare the outcomes of these tools. Methods: This analytical and cross-sectional study was conducted in a sector of the SAIPA Automobile Part Manufacturing Factory in Iran. A total of 33 workers engaged in lifting, grinding, pushing, and lowering activities participated. Lifting activities involved handling parts weighing 36, 7.9, and 3.4 kg at three workstations. In total, six tasks were examined, and workers' discomfort levels were evaluated using the Cornell Musculoskeletal Discomfort Questionnaires (CMDQ). Fourteen biomechanical and ergonomic risk assessment tools were utilized and compared. Kendall's tau-b correlation coefficient and Cohen's kappa agreement coefficient were applied to determine relationships between different tools and to match the measurement of risk levels, respectively. Additionally, the mean and standard deviation of the data were calculated. Results: There was a high positive correlation between the outcomes of three biomechanical tools 3D static strength prediction programTM (3DSSPP), hand-calculation back compressive force (HCBCF), and JACK, with 3DSSPP and HCBCF being interchangeable for estimating lumbar spine loads. Ergonomic assessment tools showed a suitable correlation in assessing load-carrying tasks. Manual handling assessment charts (MAC) had perfect agreement with National Institute for Occupational Safety and Health (NIOSH), and SNOOK with Washington Industrial Safety and Health Act (WISHA). Among body posture evaluation methods, rapid upper limb assessment (RULA) and rapid entire body assessment (REBA) had the highest correlation. Lifting fatigue failure tool (LiFFT) correlated well with manual handling methods, and survival chance correlated better with body posture evaluation methods. Lowering activities were identified as the most hazardous. Conclusions: Ease of use and accuracy are key considerations when selecting biomechanical risk assessment tools. Experienced assessors can effectively utilize JACK, 3DSSPP, and HCBCF. The MAC and NIOSH, as well as RULA and REBA tools, are interchangeable. Selecting appropriate tools requires consideration of their limitations and advantages.