Objective:To investigate the occurrence of work-related musculoskeletal disorders (WMSDs) in bus drivers in Zhuhai City, analyze the ergonomic factors, and explore the prevention and control measures of WMSDs.Methods:From March to May 2023, 1675 active bus drivers from 5 branches of a bus group in Zhuhai were selected by stratified sampling method. The incidence of WMSDs among bus drivers in the past 12 months was investigated by using the modified Chinese Version of Musculoskeletal Disorders Questionnaire. The influencing factors of WMSDs were analyzed by χ2 test and generalized linear model. Results:The total incidence of WMSDs in bus drivers in the past 12 months was 47.2% (790/1675) , and the incidence of WMSDs in neck and shoulder and lower back was 36.9% (618/1675) and 31.7% (531/1675) , respectively. The χ2 test showed that there were statistically significant differences in the incidence of WMSDs among bus drivers with different individual factors such as body mass index (BMI) , physical exercise and looking down at mobile phones ( P<0.05) . There were significant differences in the incidence of WMSDs in the neck and shoulder of bus drivers with different years of service and number of stops on their routes ( P<0.05) . There were statistically significant differences in the incidence of WMSDs in the lower back of bus drivers with different one-way driving time, shift patterns, and rest breaks during work ( P<0.05) . Abnormal BMI, professional working years >12 years, uncomfortable working posture, frequent turning, slightly forward neck posture, large forward neck posture and long shoulder posture were the risk factors for WMSDs of bus drivers ( P<0.05) , and comfortable seat was the protective factor ( P<0.05) . One-way driving time >70 min, shift work schedules, uncomfortable working posture, slightly forward back posture, and frequent turning were the risk factors leading to lower back WMSDs ( P<0.05) , and physical exercise, comfortable driving cabin space, and seat comfort were the protective factors ( P<0.05) . Conclusion:The total incidence of WMSDs in bus drivers is higher, and ergonomic factors are related to the occurrence of WMSDs. In the implementation of bus driving space comfort, human-computer interaction interface friendliness and seat comfort, employers should be reasonable allocation of fitness facilities, regular training, reasonable shift organization and other measures to prevent and control the occurrence of bus drivers WMSDs.

Objective To identify potential ergonomic risk factors of works and quickly assess their risks of developing work-related musculoskeletal disorders (WMSDs) in the medical staff. Methods A total of 188 medical staff were selected as the research objects using a two-stage random sampling method. The method for the identification of musculoskeletal stress factors (PLIBEL) was used to analyze the adverse ergonomic factors in the work process, and the rapid entire body assessment (REBA) was used to quickly assess the whole-body posture load. Results The PLIBEL assessment results showed that various adverse ergonomic factors affected different parts of the body during the work process of medical staff. Specifically, 18 adverse ergonomic factors were identified in the neck, shoulders, and upper back, while 10 adverse ergonomic factors were identified in the elbow, forearm, hand, and lower back. Rehabilitation therapists and nurses engaged in patient handling in general wards and medication preparation and blood collection were exposed to ≥35 adverse ergonomic factors. The REBA assessment showed that the REBA score was 3-12 points for medical staff during their work process. Rehabilitation therapists were classified as having an extremely high ergonomic risk. High-risk occupations included ward housekeeping nurses, surgery assistant nurses, operating-room instrument nurses, and surgeons. Medium-risk occupations included general ward nurses (medication preparation and blood collection, venipuncture/infusion, and patient handling), intensive care unit (ICU) nurses, internal medicine residents, and dentists. Low-risk occupations included administrative front-desk nurses, outpatient internal medicine physicians, and technicians/physicians in ultrasonography, laboratory medicine, physical examination, and occupational health departments. Conclusion Adverse ergonomic factors of medical staff predominantly affect the neck, shoulders, upper back, elbows, forearms, hands, and the lower back during the work process. Rehabilitation therapists, ward housekeeping nurses, ICU nurses, operating-room instrument nurses, and surgeons are high-risk groups for WMSDs. Attention should be paid to the management and control of adverse ergonomic factors for medical staff to prevent the occurrence of WMSDs.

Ergonomic Principle for the Prevention of Work-Related Musculoskeletal Disorders Part 1: General Principles (T/WSJD 14.1-2020) is the first guideline standard for the prevention of work-related musculoskeletal disorders provided to employers and occupational health technical service institutions in China, which covers ergonomic risk factors and their hazard definition, ergonomic prevention principles, risk assessment process, risk control process and risk evaluation principles. The standard specifically clarify the specific types of adverse ergonomic risk factors and control strategies and the standard process of systematic ergonomic risk assessment, providing implementation paths and practical guidance for eliminating/reducing adverse ergonomic risks and enhance workplace environments to prevent work-related musculoskeletal disorders. This paper interprets and analyzes the background of standard establishment, formulation process, fundamental basis, and main content, etc., to provide scientific and accurate technical support for enterprise managers, labours and technical personnel of occupational health institutions to optimize the use of this standard.

Objective:To investigate the incidence of shoulder work-related musculoskeletal disorders (WMSDs) among occupational population in China, and to explore their intrinsic association with personal and work-related factors.Methods:In April 2024, 73497 valid questionnaires of the Chinese version of the Musculoskeletal Disorders Electronic Questionnaire were retrospectively analyzed from June 2018 to December 2023 in 22 provinces and 29 key industries in China, and the general information, occurrence of WMSDs and related risk factors of key occupational populations in different regions in China were collected. By using Chi-square test and confirmatory factor analysis, the relationship between shoulder fatigue and pain in key occupational groups and individual factors, work type, work posture and work organization was discussed, and the internal relationship was analyzed based on structural equation model.Results:Higher incidence of shoulder fatigue and pain were associated with female, lack of physical exercise, uncomfortable working posture and neck leaning forward ( P<0.05). Structural equation model analysis showed that work type, work posture and work organization were strongly correlated ( r=0.58, 0.55). Work organization and work type were strongly correlated with shoulder fatigue ( r=0.65) and moderately correlated with shoulder fatigue ( r=0.21). Shoulder fatigue was moderately associated with shoulder pain ( r=0.40). Individual factors, work type, work posture and shoulder fatigue could directly affect shoulder pain ( OR=0.07, -0.09, 0.17 and 0.40), and work type and work posture could also indirectly affect shoulder pain through shoulder fatigue ( OR=0.08, 0.03). Work organization only indirectly affected shoulder pain through shoulder fatigue ( OR=0.26) . Conclusion:The main influencing factor of shoulder pain is shoulder fatigue, followed by work posture and individual factors. Structural equation model can better reflect the complex relationship between work type, work posture and work organization and shoulder WMSDs. Improving work posture and work organization may be an effective way to control the influence of shoulder fatigue on shoulder pain.

Objective:To explore the structural equation model to explore the levels of work-related musculoskeletal disorders (WMSDs) and various risk factors in the feet and ankle of China's occupational population, providing scientific basis for for preventing WMSDs in feet and ankles.Methods:Data of 73497 national occupational epidemiological cases were selected from June 2018 to December 2023 used the Chinese version of the Electronic Questionnaire on Musculoskeletal Disorders. The adverse ergonomic factors and their source classification standard and confirmatory factor analysis were used to investigate foot and ankle WMSDs and their related risk factors (including individual factors, work organization, work posture, work type, fatigue, etc.) in key occupational groups in China, and structural equation model hypothesis, fitting, verification, and path and intermediary effect analysis were carried out. The model fit evaluation indexes included Chi-square specific degrees of freedom ( χ2/ df), gauge fit index (NFI), Tucker Lewis index (TLI), goodness of Fit index (GFI), adjusted Goodness of Fit index (AGFI) and approximate root mean square error (RMSEA) . Results:A total of 73497 occupational workers were surveyed, with local muscle fatigue and WMSDs incidence rates in the feet and ankles being 17.17% and 12.06%, respectively. The fitting index of the adjusted structural equation model basically meets the standard (GFI=1, AGFI=1, RMESA=0.042, NFI=0.716, TLI=0.663). The top three factors affecting feet and ankle WMSDs are feet and ankle muscle fatigue, work type, and work organization, with standardized path coefficients of 0.221, 0.105, and 0.095, respectively. The top two factors affecting feet and ankle muscle fatigue are work organization and work type, with standardized path coefficients of 0.548 and 0.383, respectively. Feet and ankle muscle fatigue, work type, work organization, and work posture have a direct effect on feet and ankle WMSDs, with effect values of 0.221, 0.105, 0.095, and 0.077, respectively. The organization and type of work can also have indirect effects through feet and ankle muscle fatigue, with effect values of 0.121 and 0.084, respectively.Conclusion:Feet and ankle muscle fatigue has a direct impact on WMSDs, and plays a mediating role between ankle and ankle WMSDs caused by work organization and work type. Feet and ankle muscle fatigue is an important pathway leading to feet and ankle WMSDs. It is recommended that employers and managers detect job fatigue early and take corresponding prevention and intervention measures, which can play a key role in preventing feet and ankle WMSDs.

The "Guidelines for the Ergonomic Prevention of Work-related Musculoskeletal Disorders Part 3 in Shipbuilding Operations" (T/WSJD 14.3-2024) was published and implemented in March 2024, providing a basis for scientific prevention and control of musculoskeletal disorders in shipbuilding operations. In this paper, the background, formulation process, basis and main content of the standard project are interpreted and analyzed, so as to help relevant practitioners and managers more fully understand and implement the ergonomic program proposed by the standard, and provide scientific and accurate technical support for enterprises.

Objective:To explore the structural relationship between WMSDs in the upper limbs and various risk factors in the occupational population in China, based on a large sample epidemiological survey and structural equation analysis, and to establish a structural equation model, so as to lay a foundation for the prevention and control of such diseases.Methods:The Chinese version of the Musculoskeletal Disorders Electronic Questionnaire was used to conduct a nationwide survey on the prevalence of WMSDs in the upper extremity. Six factors related to WMSDs in the upper extremity were extracted by the classification standard of adverse ergonomic factors and their source and confirmatory factor analysis, including work organization, work type, upper extremity work posture, individual factors, upper extremity fatigue and upper extremity WMSDs. The structural equation analysis was carried out and the structural equation model was established.Results:The incidence of WMSDs and fatigue in the upper limbs was 24.44% and 43.76%, respectively. The adjusted structural equation model fitting indicators were generally up to the standard (GFI=1.000, AGFI=1.000, RMSEA=0.043, NFI=0.808, TLI=0.784) . The four exogenous latent variables of work organization, work type, upper limb work posture and individual factors were correlated. There was a strong positive correlation between job type and upper limb work posture ( r=0.865) , a moderate positive correlation between work organization and job type and upper limb work posture ( r=0.570, 0.490) , and a weak negative correlation between individual factors and the other three exogenous latent variables. Upper limb work posture and individual factors had direct effects on upper limb WMSDs, and the effect coefficients were 0.10 and 0.06, respectively. Upper limb fatigue played a mediating role between work organization, work type, upper limb work posture and upper limb WMSDs. The effect coefficient was 0.46, and the composition ratios of indirect effects were 100.0%, 100.0%, and 38.3%, respectively. The direct path effect of upper limb work posture, individual factors and upper limb WMSDs was weaker than the mediating path through upper limb fatigue. Conclusion:When carrying out the prevention and control of upper limbWMSDs, it is necessary to comprehensively consider the pathogenesis path of upper limb muscle fatigue and upper limb WMSDs caused by work organization, work type, and upper limb work posture, so as to provide theoretical reference for improving the prevention and control level of such diseases.

Objective To study the effect of medial collateral ligament(MCL)release on the squatting motion followling total knee arthroplasty(TKA)and provide reference data for ligament release during knee replacement surgery.Methods Based on CT and MRI images of a volunteer,a three-dimensional(3D)geometric anatomical model of the natural knee joint including bone tissues and major soft tissues was established.A finite element model of the artificial knee joint was established by simulating TKA surgery.The squatting motion after 30％release of the upper end,lower end,and both ends of the MCL was simulated,and motion characteristic data of the knee joint at flexion/extension angles from 0° to 135° were obtained.Results The effects of ligament release at different locations on knee squatting motion varied.After releasing the lower end,the medial translation,posterior translation,superior translation,and adduction of the femur relative to the tibia increased by 13.74％,3.83％,9.74％,and 2.37％,respectively,while the external rotation decreased by 36.8％.After releasing the upper end,the medial translation and posterior translation increased by 10.65％and 10％,respectively,while the superior translation,adduction,and external rotation decreased by 4.52％,33.89％,and 67.1％,respectively.After releasing both ends,the medial translation,posterior translation,and superior translation increased by 14.77％,9.39％,and 22.56％,respectively,while the adduction and external rotation decreased by 15.62％and 47.3％,respectively.Conclusions After MCL released,the medial translation,anterior translation,superior translation,and abduction of the femur relative to the tibia increased,while the external rotation decreased.Releasing the lower end had the least effect on these femoral movements,showing an obvious advantage.

Objective:To investigate the occurrence of work-related musculoskeletal disorders (WMSDs) in bus drivers in Zhuhai City, analyze the ergonomic factors, and explore the prevention and control measures of WMSDs.Methods:From March to May 2023, 1675 active bus drivers from 5 branches of a bus group in Zhuhai were selected by stratified sampling method. The incidence of WMSDs among bus drivers in the past 12 months was investigated by using the modified Chinese Version of Musculoskeletal Disorders Questionnaire. The influencing factors of WMSDs were analyzed by χ2 test and generalized linear model. Results:The total incidence of WMSDs in bus drivers in the past 12 months was 47.2% (790/1675) , and the incidence of WMSDs in neck and shoulder and lower back was 36.9% (618/1675) and 31.7% (531/1675) , respectively. The χ2 test showed that there were statistically significant differences in the incidence of WMSDs among bus drivers with different individual factors such as body mass index (BMI) , physical exercise and looking down at mobile phones ( P<0.05) . There were significant differences in the incidence of WMSDs in the neck and shoulder of bus drivers with different years of service and number of stops on their routes ( P<0.05) . There were statistically significant differences in the incidence of WMSDs in the lower back of bus drivers with different one-way driving time, shift patterns, and rest breaks during work ( P<0.05) . Abnormal BMI, professional working years >12 years, uncomfortable working posture, frequent turning, slightly forward neck posture, large forward neck posture and long shoulder posture were the risk factors for WMSDs of bus drivers ( P<0.05) , and comfortable seat was the protective factor ( P<0.05) . One-way driving time >70 min, shift work schedules, uncomfortable working posture, slightly forward back posture, and frequent turning were the risk factors leading to lower back WMSDs ( P<0.05) , and physical exercise, comfortable driving cabin space, and seat comfort were the protective factors ( P<0.05) . Conclusion:The total incidence of WMSDs in bus drivers is higher, and ergonomic factors are related to the occurrence of WMSDs. In the implementation of bus driving space comfort, human-computer interaction interface friendliness and seat comfort, employers should be reasonable allocation of fitness facilities, regular training, reasonable shift organization and other measures to prevent and control the occurrence of bus drivers WMSDs.

Objective To study the effect of medial collateral ligament(MCL)release on the squatting motion followling total knee arthroplasty(TKA)and provide reference data for ligament release during knee replacement surgery.Methods Based on CT and MRI images of a volunteer,a three-dimensional(3D)geometric anatomical model of the natural knee joint including bone tissues and major soft tissues was established.A finite element model of the artificial knee joint was established by simulating TKA surgery.The squatting motion after 30％release of the upper end,lower end,and both ends of the MCL was simulated,and motion characteristic data of the knee joint at flexion/extension angles from 0° to 135° were obtained.Results The effects of ligament release at different locations on knee squatting motion varied.After releasing the lower end,the medial translation,posterior translation,superior translation,and adduction of the femur relative to the tibia increased by 13.74％,3.83％,9.74％,and 2.37％,respectively,while the external rotation decreased by 36.8％.After releasing the upper end,the medial translation and posterior translation increased by 10.65％and 10％,respectively,while the superior translation,adduction,and external rotation decreased by 4.52％,33.89％,and 67.1％,respectively.After releasing both ends,the medial translation,posterior translation,and superior translation increased by 14.77％,9.39％,and 22.56％,respectively,while the adduction and external rotation decreased by 15.62％and 47.3％,respectively.Conclusions After MCL released,the medial translation,anterior translation,superior translation,and abduction of the femur relative to the tibia increased,while the external rotation decreased.Releasing the lower end had the least effect on these femoral movements,showing an obvious advantage.