[Structural equation analysis and modeling of wrist WMSDs and its adverse ergonomic factors]

Objective: To investigate the relationships and impacts between various occupational ergonomic hazards and hand and wrist fatigue, as well as work-related musculoskeletal disorders (WMSDs) of the hand and wrist, and to propose targeted preventive and intervention measures for adverse occupational ergonomic factors causing WMSDs of the hand and wrist. Methods: From 2018 to December 2023, a nationwide epidemiologic survey study of wrist WMSDs was conducted using the Chinese version of the electronic questionnaire system for musculoskeletal disorders.A total of 88, 609 valid questionnaires were collected. The exclusion criteria were as follows: patients with congenital spinal deformities, as well as those with wrist WMSDs caused by external injuries, infectious diseases, and malignant tumors. A total of 73, 497 questionnaires were finally included in the study analysis, with an effective questionnaire return rate of 82.5%. Exploratory factor analysis was used to analyze and summarize the factors affecting wrist WMSDs from the questionnaires, including individual factors, work organization, work type, wrist work posture, wrist fatigue, and wrist WMSDs as latent variables, and to hypothesize, fit, and validate the structural aspect model, as well as to conduct mediation effect analysis. Results: The incidence of WMSDs and fatigue in wrist was 12.19% and 16.30% respectively. The fitting indexes of the modified structural equation model were basically up to the standard (GFI was 0.981, AGFI was 0.973, RMSEA was 0.031, NFI was 0.863, IFI and CFI were 0.865). There is a correlation between individual factors, work organization, wrist working posture and work type. There was a low negative correlation between individual factors and other factors, and there was a positive correlation between work organization, work type and wrist WMSDs (r=0.346, 0.295), and these two factors were positively correlated with wrist fatigue height (r=0.862, 0.599), and were positively correlated with wrist working posture (r=0.443, 0.620). There was moderate positive correlation between wrist working posture and wrist fatigue (r=0.469). The three most influential factors on wrist WMSDs were work organization, individual factor and work type, and the path coefficients were 0.247, 0.210 and 0.136, respectively. The first two factors that have the greatest influence on wrist fatigue are work organization and work type, and the path coefficients are 0.758 and 0.188, respectively. Individual factors, work type, wrist working posture and work organization had direct effects on wrist WMSDs, and the effect values were 0.093, 0.253, 0.718 and 0.583, respectively. Wrist fatigue played a partial mediating role between individual factors, work type, wrist working posture and work organization and wrist WMSDs, with the indirect effect ratio of 25.6%, 45.8%, 3.2% and 65.5%. Conclusion: Wrist fatigue plays an important mediating role in the path of various factors affecting wrist WMSDs, especially in the path of work organization, work type, individual factors and wrist WMSDs. Poor wrist working posture is an important risk factor that directly affects the occurrence of wrist WMSDs.