BACKGROUND:At present,there are few reports on the postoperative efficacy of arthroscopic coracoid tunnel-free suspension fixation and coracoid single tunnel fixation in the treatment of acromioclavicular joint dislocation at home and abroad.The specific clinical efficacy of the two procedures and whether there are other risks need to be explored. OBJECTIVE:To compare the short-term postoperative clinical efficacy of arthroscopic TightRope band plate fixation with single tunnel fixation of the coracoid process and tunnel-free suspension fixation of the coracoid process in the treatment of acute type Ⅲ-Ⅴ acromioclavicular joint dislocation. METHODS:A retrospective analysis was performed in 45 patients with acromioclavicular joint dislocation who met the inclusion criteria admitted to the Sixth Affiliated Hospital of Xinjiang Medical University from June 2019 to September 2022,and were divided into coracoid single tunnel fixation group(20 cases)and coracoid tunnel-free suspension fixation group(25 cases)according to the surgical treatment plan.Operation time,incision length,blood loss,Constant-Murley score,visual analogue scale score,the American Shoulder and Elbow Surgeons(ASES)score and intraoperative and postoperative complications of the shoulder joint before operation,3 months after surgery and the last follow-up were compared between the two groups. RESULTS AND CONCLUSION:All patients successfully completed the operation,and there was no important nerve or blood vessel damage during the operation.The operation time of the coracoid tunnel-free suspension fixation group was significantly shorter than that of the coracoid tunnel-free suspension fixation group(P<0.05).There was no significant difference in intraoperative blood loss and incision length between the two groups(P>0.05).All patients were followed up for 12 to 24 months,with an average of(15.29±2.73)months.In the coracoid single tunnel fixation group,at 3 months after operation and the final follow-up,the visual analogue scale score was significantly lower than the preoperative score(P<0.05);Constant-Murley score and ASES score were significantly increased compared with the preoperative values(P<0.05).In the coracoid tunnel-free suspension fixation group,at 3 months after operation and the final follow-up,the visual analogue scale score was significantly lower than the preoperative score(P<0.05);the Constant-Murley score and the ASES score were both significantly higher than the preoperative scores(P<0.05).At 3 months after operation,the Constant-Murley score of the coracoid tunnel-free suspension fixation group was higher than that of the coracoid single tunnel fixation group(P<0.05),while there was no significant difference in visual analogue scale and ASES scores between the two groups(P>0.05).There was also no significant difference in the visual analogue scale,Constant-Murley,and ASES scores between the two groups at the corresponding time points before surgery and at the final follow-up(P>0.05).Intraoperative and postoperative complications:In the coracoid single tunnel fixation group,there was one case of coracoid cortical rupture and fracture during the tunnel drilling during the operation,and one case of a loss of reduction at 3 months after operation,which was repositioned and fixed with hook plate transposition of the coracoacromial ligament.All patients had good acromioclavicular joint function recovery and no re-dislocation at the final follow-up.All patients in the coracoid tunnel-free suspension fixation group did not suffer from coracoid fractures,loss of reduction and other complications during surgery,postoperatively and at the last follow-up.To conclude,these two arthroscopic treatments for acute type Ⅲ-Ⅴ acromioclavicular joint dislocation have the advantages of less trauma,reliable reduction and fixation,and good recovery of shoulder joint function after operation.However,compared with the coracoid single tunnel technique,the coracoid tunnel-free suspension fixation requires shorter time,faster recovery of shoulder joint function in the short term,and avoids the establishment of bone tunnels on the coracoid process,which reduces the probability of iatrogenic fracture of the coracoid process during operation and provides a higher degree of safety.

BACKGROUND:Stroboscopic visual training can force sensory reweighting to restore the original weights by increasing sensitivity to proprioceptive information,which may be an effective method to improve proprioception. OBJECTIVE:To determine the effects of balance training in three conditions,low frequency,high frequency and normal vision,on ankle proprioception in patients with chronic ankle instability. METHODS:Thirty-six patients with chronic ankle instability recruited from the students of Southwest Medical University were randomly assigned to a low-frequency vision training group,a high-frequency vision training group,and a normal vision training group,with 12 subjects in each group.Subjects in the three groups underwent progressive hop stabilization and balance training,in which the low-frequency vision training group and the high-frequency vision training group wore stroboscopic spectacles during the training,with a stroboscopic frequency of 1.75 and 5 Hz,respectively.The training in each group was performed three times a week for 4 consecutive weeks.Assessments,including ankle proprioception,ankle stability self-assessment and dynamic postural stability,were performed before training and within 1 week after the completion of training. RESULTS AND CONCLUSION:There was a significant main effect of time factor in ankle proprioception(P<0.05).Compared with the pre-training period,subjects in the low-frequency vision training group and the high-frequency vision training group showed significant improvement in ankle proprioception after 4 weeks of training(P<0.05);and subjects in the low-frequency vision training group showed a significant improvement in ankle proprioception compared with that of the normal vision training group after 4 weeks of training(P<0.05).There were significant main effects of time factor and group×time interaction in ankle proprioception(P<0.05).Compared with the pre-training period,the ankle stability self-assessment in all three groups was improved after 4 weeks of training(P<0.05).And the ankle stability self-assessment in high-frequency visual training group was higher than that in normal vision training group after 4 weeks of training(P<0.05).Compared with the pre-training period,subjects in the low-frequency vision training group and the high-frequency vision training group showed significant improvements in forward dynamic postural stability,posteromedial dynamic postural stability,and posterolateral dynamic postural stability after 4 weeks of training(P<0.05),while in the normal vision training group,forward dynamic postural stability and posterolateral dynamic postural stability were significantly improved after 4 weeks of training(P≤0.05).To conclude,balance training under stroboscopic visual conditioning improves proprioception,ankle stability self-assessment,and dynamic postural stability in patients with chronic ankle instability regardless of frequency.

BACKGROUND:Acute exercise tends to cause skeletal muscle tissue damage and lipid metabolism disorders in vivo,but the mechanism by which acute exercise combined with electroacupuncture modulates metabolic and autophagic pathways in vivo is unclear. OBJECTIVE:To observe the changes in metabolic enzymes and autophagy levels in skeletal muscle of rats subjected to acute exercise by electroacupuncture at the acupoints of"Zusanli"and"Huantiao." METHODS:Fifty male Sprague-Dawley rats were randomly divided into three groups:quiet control group(n=10),model group(n=20),and reverse electroacupuncture group(n=20).The latter two groups were set up with two time points,i.e.immediate and 3 hours after exercise groups(n=10 per time point).The model group and the reverse electroacupuncture group underwent acute exercise training after adaptive treadmill training.The rats in the reverse electroacupuncture group underwent electroacupuncture treatment(parameters:electroacupuncture on both sides of the rats at the acupoints of"Zusanli"and"Huantiao,"continuous wave,frequency of 2 Hz,intensity of 2 mA,leaving the needle in the body for 30 minutes,once a day for 7 consecutive days)before treadmill training.Bilateral gastrocnemius muscle tissues were taken under anesthesia immediately after exercise and 3 hours after exercise,and hematoxylin-eosin staining was used to observe the histopathological changes of rat skeletal muscle.ELISA kit was used to detect the activities of hepatic lipase,fatty acid synthase,hormone-sensitive lipase,and carnitine palmitoyltransferase 1 in rat skeletal muscle tissues.Immunohistochemistry and western blot were used to detect the changes in the expression of autophagy genes. RESULTS AND CONCLUSION:After hematoxylin-eosin staining,the arrangement of gastrocnemius muscle fibers in the model group was disturbed,swollen and ruptured immediately after exercise and 3 hours after exercise.In the reverse electroacupuncture group,gastrocnemius muscle fibers were tightly arranged and the number of swollen and ruptured cells was greatly reduced immediately after exercise and 3 hours after exercise,and there was no significant difference when compared with the quiet control group.Compared with the quiet control group,the activities of hepatic lipase and fatty acid synthase were lower while the activities of lipoprotein lipase,hormone-sensitive lipase,and carnitine palmitoyltransferase 1 were higher in the model group and the reverse electroacupuncture group 3 hours after exercise(P＜0.05 or P＜0.01).Compared with the model group,the activities of lipoprotein lipase and carnitine palmitoyltransferase 1 were higher in the reverse electroacupuncture group immediately after exercise(P＜0.05),while the activity of lipoprotein lipase was higher and the activity of hormone-sensitive lipase was lower in the reverse electroacupuncture group 3 hours after exercise(P＜0.01).Immunohistochemical results showed that compared with the quiet control group,the expression of P62,autophagy-related gene 5 and autophagy-related gene 7 was higher in the model group immediately and 3 hours after exercise,as well as in the reverse electroacupuncture group immediately after exercise(P＜0.05 or P＜0.01);compared with the model group,the expression of P62 and autophagy-related gene 7 was lower in the reverse electroacupuncture group immediately and 3 hours after exercise(P＜0.05).Western blot results showed that the protein expression of P62 and autophagy-related gene 7 in the reverse electroacupuncture group was lower than that in the model group immediately after exercise(P＜0.05);the protein expression of Parkin in the model group was higher than that in the quiet control group immediately and 3 hours after exercise(P＜0.05);and the protein expression of Parkin in the reverse electroacupuncture group was lower than that in the model group immediately and 3 hours after exercise(P＜0.05).To conclude,acute exercise induces disorders,swelling and rupture of gastrocnemius muscle fibers in rats and electroacupuncture on both sides of the acupoints of"Zusanli"and"Huantiao"can improve the level of lipid metabolism and regulate autophagy cells in rat skeletal muscle,preventing the disorders of lipid metabolism and damage of gastrocnemius muscle tissues caused by acute exercise.The mechanism may be closely related to the regulation of autophagy-related factor P62,autophagy-related gene 5,autophagy-related gene 7,and Parkin protein expression to promote the occurrence of autophagy or regulate the autophagy pathway in rat skeletal muscle cells.

BACKGROUND:Flap transplantation technique is a commonly used surgical procedure for the treatment of severe tissue defects,but postoperative flap necrosis is easily triggered by ischemia-reperfusion injury.Therefore,it is still an important research topic to improve the survival rate of transplanted flaps. OBJECTIVE:To review the pathogenesis and latest treatment progress of flap ischemia-reperfusion injury. METHODS:CNKI,WanFang Database and PubMed database were searched for relevant literature published from 2014 to 2024.The search terms used were"flap,ischemia-reperfusion injury,inflammatory response,oxidative stress,Ca2+overload,apoptosis,mesenchymal stem cells,platelet-rich plasma,signaling pathways,shock wave,pretreatment"in Chinese and English.After elimination of irrelevant literature,poor quality and obsolete literature,77 documents were finally included for review. RESULTS AND CONCLUSION:Flap ischemia/reperfusion injury may be related to pathological factors such as inflammatory response,oxidative stress response,Ca2+overload,and apoptosis,which can cause apoptosis of vascular endothelial cells,vascular damage and microcirculation disorders in the flap,and eventually lead to flap necrosis.Studies have found that mesenchymal stem cell transplantation,platelet-rich plasma,signaling pathway modulators,shock waves,and pretreatment can alleviate flap ischemia/reperfusion injuries from different aspects and to varying degrees,and reduce the necrosis rate and necrosis area of the grafted flap.Although there are many therapeutic methods for skin flap ischemia/reperfusion injury,a unified and effective therapeutic method has not yet been developed in the clinic,and the advantages and disadvantages of various therapeutic methods have not yet been compared.Most of the studies remain in the stage of animal experiments,rarely involving clinical observations.Therefore,a lot of research is required in the future to gradually move from animal experiments to the clinic in order to better serve the clinic.

BACKGROUND:Osteoporotic fracture is the most serious complication of osteoporosis.Previous studies have demonstrated that gut microbiota has a regulatory effect on skeletal tissue and that gut microbiota has an important relationship with osteoporotic fracture,but the causal relationship between the two is unclear. OBJECTIVE:To explore the causal relationship between gut microbiota and osteoporotic fractures using Mendelian randomization method. METHODS:The genome-wide association study(GWAS)datasets of gut microbiota and osteoporotic fracture were obtained from the IEU Open GWAS database and the Finnish database R9,respectively.Using gut microbiota as the exposure factor and osteoporotic fracture as the outcome variable,Mendelian randomization analyses with random-effects inverse variance weighted,MR-Egger regression,weighted median,simple model,and weighted model methods were performed to assess whether there is a causal relationship between gut microbiota and osteoporotic fracture.Sensitivity analyses were performed to test the reliability and robustness of the results.Reverse Mendelian randomization analyses were performed to further validate the causal relationship identified in the forward Mendelian randomization analyses. RESULTS AND CONCLUSION:The results of this Mendelian randomization analysis indicated a causal relationship between gut microbiota and osteoporotic fracture.Elevated abundance of Actinomycetales[odds ratio(OR)=1.562,95%confidence interval(CI):1.027-2.375,P=0.037),Actinomycetaceae(OR=1.561,95%CI:1.027-2.374,P=0.037),Actinomyces(OR=1.544,95%CI:1.130-2.110,P=0.006),Butyricicoccus(OR=1.781,95%CI:1.194-2.657,P=0.005),Coprococcus 2(OR=1.550,95%CI:1.068-2.251,P=0.021),Family ⅩⅢ UCG-001(OR=1.473,95%CI:1.001-2.168,P=0.049),Methanobrevibacter(OR=1.274,95%CI:1.001-1.621,P=0.049),and Roseburia(OR=1.429,95%CI:1.015-2.013,P=0.041)would increase the risk of osteoporotic fractures in patients.Elevated abundance of Bacteroidia(OR=0.660,95%CI:0.455-0.959,P=0.029),Bacteroidales(OR=0.660,95%CI:0.455-0.959,P=0.029),Christensenellacea(OR=0.725,95%CI:0.529-0.995,P=0.047),Ruminococcaceae(OR=0.643,95%CI:0.443-0.933,P=0.020),Enterorhabdus(OR=0.558,95%CI:0.395-0.788,P=0.001),Eubacterium rectale group(OR=0.631,95%CI:0.435-0.916,P=0.016),Lachnospiraceae UCG008(OR=0.738,95%CI:0.546-0.998,P=0.048),and Ruminiclostridium 9(OR=0.492,95%CI:0.324-0.746,P=0.001)would reduce the risk of osteoporotic fractures in patients.We identified 16 gut microbiota associated with osteoporotic fracture by the Mendelian randomization method.That is,using gut microbiota as the exposure factor and osteoporotic fracture as the outcome variable,eight gut microbiota showed positive causal associations with osteoporotic fracture and another eight gut microbiota showed negative causal associations with osteoporotic fracture.The results of this study not only identify new biomarkers for the early prediction of osteoporotic fracture and potential therapeutic targets in clinical practice,but also provide an experimental basis and theoretical basis for the study of improving the occurrence and prognosis of osteoporotic fracture through gut microbiota in bone tissue engineering.

BACKGROUND:Osteosarcoma has a complex pathogenesis and a poor prognosis.While advancements in medical technology have led to some improvements in the 5-year survival rate,substantial progress in its treatment has not yet been achieved. OBJECTIVE:To screen key molecular markers in osteosarcoma,analyze their relationship with osteosarcoma treatment drugs,and explore the potential disease mechanisms of osteosarcoma at the molecular level. METHODS:GSE99671 and GSE284259(miRNA)datasets were obtained from the Gene Expression Omnibus database.Differential gene expression analysis and Weighted Gene Co-expression Network Analysis(WGCNA)on GSE99671 were performed.Functional enrichment analysis was conducted using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes separately for the differentially expressed genes and the module genes with the highest positive correlation to the disease.The intersection of these module genes and differentially expressed genes was taken as key genes.A Protein-Protein Interaction network was constructed,and correlation analysis on the key genes was performed using CytoScape software,and hub genes were identified.Hub genes were externally validated using the GSE28425 dataset and text validation was conducted.The drug sensitivity of hub genes was analyzed using the CellMiner database,with a threshold of absolute value of correlation coefficient|R|>0.3 and P<0.05. RESULTS AND CONCLUSION:(1)Differential gene expression analysis identified 529 differentially expressed genes,comprising 177 upregulated and 352 downregulated genes.WGCNA analysis yielded a total of 592 genes with the highest correlation to osteosarcoma.(2)Gene Ontology enrichment results indicated that the development of osteosarcoma may be associated with extracellular matrix,bone cell differentiation and development,human immune regulation,and collagen synthesis and degradation.Kyoto Encyclopedia of Genes and Genomes enrichment results showed the involvement of pathways such as PI3K-Akt signaling pathway,focal adhesion signaling pathway,and immune response in the onset of osteosarcoma.(3)The intersection analysis revealed a total of 59 key genes.Through Protein-Protein Interaction network analysis,8 hub genes were selected,which were LUM,PLOD1,PLOD2,MMP14,COL11A1,THBS2,LEPRE1,and TGFB1,all of which were upregulated.(4)External validation revealed significantly downregulated miRNAs that regulate the hub genes,with hsa-miR-144-3p and hsa-miR-150-5p showing the most significant downregulation.Text validation results demonstrated that the expression of hub genes was consistent with previous research.(5)Drug sensitivity analysis indicated a negative correlation between the activity of methotrexate,6-mercaptopurine,and pazopanib with the mRNA expression of PLOD1,PLOD2,and MMP14.Moreover,zoledronic acid and lapatinib showed a positive correlation with the mRNA expression of PLOD1,LUM,MMP14,PLOD2,and TGFB1.This suggests that zoledronic acid and lapatinib may be potential therapeutic drugs for osteosarcoma,but further validation is required through additional basic experiments and clinical studies.

BACKGROUND:Many recent studies have shown a close relationship between inflammatory cytokines and osteoporosis and bone mineral density(BMD).However,the causal relationship between inflammatory cytokines and BMD has not been fully revealed. OBJECTIVE:To explore the potential causal relationship between inflammatory cytokines and BMD using a two-sample Mendelian randomization analysis. METHODS:The single nucleotide polymorphisms associated with 41 circulating inflammatory cytokines were selected from the open database of genome-wide association studies(GWAS)as instrumental variables.The GWAS data about BMD were from the Genetic Factors for Osteoporosis Consortium,involving a total of 32 735 individuals of European ancestry.Inverse variance weighting was used as the primary analysis to evaluate the causal effect.Weighted median,MR Egger regression,simple mode,and weighted mode methods were used to supplement the explanation.We used the MR-Egger intercept and MR-PRESSO method to conduct a pleiotropy test,the Cochran's Q test was used to determine whether there was heterogeneity in the results,and the leave-one-out method was used to evaluate the stability of the results.In addition,to more accurately assess the causality,the Bonferroni-corrected test was used to identify inflammatory cytokines that have a strong causal relationship with BMD. RESULTS AND CONCLUSION:(1)According to the results of the inverse variance weighting method,we found a positive causal relationship between interleukin-8 and lumbar spine BMD[β=0.075,95%confidence interval(CI):0.033-0.117,P=0.000 5),while a negative causal relationship between interleukin-17 and lumbar spine BMD(β=-0.083,95%CI:-0.152 to-0.014,P=0.018).There might be a negative causal relationship between tumor necrosis factor b and femoral neck BMD(β=-0.053,95%CI:-0.088 to-0.018,P=0.003),while a positive causal relationship between basic fibroblast growth factor and femoral neck BMD(β=0.085,95%CI:0.016-0.154,P=0.015).There might be a negative causal relationship between macrophage inflammatory protein-1a and total body BMD(β=-0.056,95%CI:-0.105 to-0.007,P=0.025).There was a negative causal relationship between interleukin-5(β=-0.019,95%CI:-0.031 to-0.006,P=0.004),stromal cell-derived factor-1a(β=-0.022,95%CI:-0.038 to-0.005,P=0.010),hepatocyte growth factor(β=-0.021,95%CI:-0.041 to-0.002,P=0.030),interleukin-4(β=-0.016,95%CI:-0.032 to-0.001,P=0.034)and heel BMD,while a positive causal relationship between nerve growth factor(β=0.019,95%CI:0.002-0.036,P=0.033),granulocyte colony-stimulating factor(β=0.011,95%CI:0.000-0.022,P=0.050),and heel BMD.Meanwhile,after the Bonferroni-corrected test,there was a strong positive causal effect between interleukin-8 and lumbar spine BMD(P=0.000 5).And consistent directional effects for all analyses were observed in MR Egger,weighted median,simple mode,and weighted mode methods.(2)Sensitivity analyses revealed no heterogeneity,pleiotropy,or outliers for the causal effect of circulating inflammatory cytokines on BMD.

BACKGROUND:Intertrochanteric fracture of femur has various fracture types and fixation methods,and the mechanical stability of each fixation system is quite different.It is of scientific clinical significance to use finite element analysis method to carry out biomechanical research on various fixation systems. OBJECTIVE:To compare and analyze the mechanical stability of various internal fixations applied to femoral intertrochanteric fracture A031-A2.1 by finite element method. METHODS:Based on the validated finite element model of femur(Intact),the model was cut and made into A031-A2.1 intertrochanteric fracture of femur.Different internal fixation systems were implanted by simulating clinical operation methods,and fixation models of proximal femoral nail antirotation,dynamic hip screw,percutaneous compression plate and proximal femoral locking plate were established respectively.All nodes under the distal femur of the four groups of models were constrained,and compression loads of 700,1 400 and 2 100 N were applied to the femoral head.Von Mises stress distribution and compression stiffness of each group of models were observed through calculation and analysis,and mechanical stability of each group was compared. RESULTS AND CONCLUSION:(1)Through calculation and analysis,after calculating the compression stiffness by comparing the deformation of each model,the compression stiffness of each model under various loads showed the trend:physiological group>proximal femoral nail antirotation group>proximal femoral locking plate group>percutaneous compression plate group>dynamic hip screw group.The compressive stiffness of the complete physiological group model was significantly higher than that of all surgical group models.(2)The stress index was observed.Due to the stress shielding effect,the stress peak value of each fixed group was higher than that of physiological group,and the maximum peak value was concentrated on each internal fixation.Proximal femoral nail antirotation group had the smallest stress peak,while dynamic hip screw group had the highest stress.The stress distribution trend showed physiological group

Background A large number of power supply workers are involved in live working and are exposed to multiple risk factors for long periods of time during outdoor work, which in turn causes occupational health problems. Objective To identify potential ergonomic factors related to work-related musculoskeletal disorders (WMSDs) and estimate the ergonomic risk of electricians. Methods A total of 31 workers were randomly selected from a training base under a power supply enterprise in Guangxi, and their operation processes were recorded by video. Using the Rapid Upper Limb Assessment (RULA) method, the workers were scored by the posture of their arms, neck, and torso during operation, and the final scores were summarized to assess their risk level. Two independent samples t-tests were used to compare the differences in RULA scores. Results A total of 31 videos for mounting/dismounting insulation mask and 29 videos for breaking/connecting contact terminal were collected. The RULA score for mounting/dismounting insulation mask was 6.6 ± 0.7 (left side) and 7.0 ± 0.2 (right side), most of the workers had a score of 7 (71.0% on the left side and 96.8% on the right side), and the upper limb and overall scores on the right side were higher than those on the left side (P < 0.05). The RULA score for breaking/connecting contact terminal was 6.9 ± 0.4 (both right and left sides), most of workers had a score of 7 (89.7% on the left side and 93.1% on the right side), and the difference of the overall scores between the right and left side for this operation were not statistically significant (P > 0.05). The ergonomic risk levels for both operations were level 3 or higher. Conclusion Mounting/dismounting insulation mask and breaking/connecting contact terminal are typical upper limb operations, and have a high level of ergonomics risk, requiring effective preventive and protective measures.

Background When live working line operators engage in upper limb operations, working for a long time with raising arms and the exposure to adverse ergonomic factors tend to increase muscle load, cause fatigue accumulation, and increase the risk of work-related musculoskeletal disorders (WMSDs). Objective To analyze work posture and associated muscle fatigue during executing breaking/connecting contact terminal, and identify adverse ergonomic factors of the work process. Methods This study recruited 10 volunteers to perform breaking/connecting contact terminal simulation. At a distance of 4.5, 3.5, and 2.5 m from the body to the wire, each performed the task 5 times. Visual 3D was used to analyze the kinematic data from motion capture. The surface electromyography (sEMG) signals of the deltoid, biceps, triceps, and brachioradialis were recorded during the simulation and analyzed for muscle fatigue using root mean square (RMS), median frequency (MF), and jointed EMG amplitude and spectrum analysis (JASA). After completion of each task, Borg scale was used to query the volunteers of their subjective fatigue. A 2-min rest was required between each distance. Results The kinematic data from motion capture showed that in the entire process of the task, the right upper limb was higher when lifting, with the right shoulder joint maintaining flexion and fluctuating periodically between abduction and adduction, external and internal rotation, the right elbow joint maintaining flexion and supination. The frequency of task cycle showed a significant effect on the Borg scale scores (P<0.001, partial \begin{document}$ {\eta }^{2} $\end{document}=0.464); the distance showed no significant effect on the Borg scale scores (P>0.05, partial \begin{document}$ {\eta }^{2} $\end{document}=0.002); their interaction effect was not significant (P>0.05, partial \begin{document}$ {\eta }^{2} $\end{document}=0.020). The results of the sEMG signals showed that at a distance of 4.5 m, the volunteers had the highest percentages of maximal voluntary electrical activation (MVE%) in the deltoid and right brachioradialis and the lowest MF values in the deltoid and left brachioradialis after completing 5 task cycles. The results of JASA showed that fatigue was observed in brachioradialis and deltoid after completing 5 task cycles at a distance of 4.5 m, the right deltoid and right brachioradialis at a distance of 3.5 m, in the brachioradialis, deltoid, and left bicep at a distance of 2.5 m. Conclusion The subjective fatigue of workers who engaged in breaking/connecting contact terminal elevates with more repetitive operations. Based on the sEMG and motion capture analysis, it can be found that improper distance between the workers and the target work area can increase the burden from poor posture and improper use of work equipment, and lead to muscle fatigue; the deltoid and brachioradialis are the key muscles of fatigue in this type of operation; changing the angle of the elbow joint and the shoulder joint during the process of the operation can affect the deltoid and brachioradialis exertion and loading.