BACKGROUND:Medial tibial stress syndrome is a common chronic lower limb injury among runners,potentially linked to the"muscle traction theory."However,this hypothesis has not been fully confirmed.OBJECTIVE:To investigate whether the contraction characteristics of the soleus,posterior tibialis,and flexor digitorum longus muscles during running are correlated with stress levels at the medial tibial border and influence the occurrence and development of medial tibial stress syndrome using musculoskeletal simulation systems and finite element analysis.METHODS:Motion capture data of six subjects running at different speeds were input into the Anybody Modeling System for inverse dynamic simulations during the stance phase at running speeds of 2.5,3.5,and 4.5 m/s.The calculated boundary conditions were combined with finite element models to examine the stress distribution on the medial tibia.Partial least squares regression was used to analyze the correlation between independent variables(muscle force and elastic potential energy)and the dependent variable(tibial stress).RESULTS AND CONCLUSION:(1)There were statistically significant differences in tibial stress levels across different speeds during the stance phase(1％-50％)(P=0.044,F=3.834,ηp2=0.040).(2)Among the three speeds,the average correlation between soleus muscle force and tibial stress was the highest(r=12.999),followed by the correlation between posterior tibialis muscle force and tibial stress(r=-10.735),flexor digitorum longus muscle force(r=-9.751),posterior tibialis elastic potential energy(r=8.012),soleus elastic potential energy(r=9.076),and flexor digitorum longus elastic potential energy(r=-4.782).(3)The results indicate that with increasing running speed,tibial stress levels rise.The contraction of the soleus muscle and the release of absorbed elastic potential energy during running have a significant impact on the development of medial tibial stress syndrome,whereas the roles of the posterior tibialis and flexor digitorum longus muscles have been overestimated.Overall,the study supports the hypothesis that the contraction of the soleus muscle plays a crucial role in the development of medial tibial stress syndrome,consistent with the"muscle traction"hypothesis.

BACKGROUND:Medial tibial stress syndrome is a common chronic lower limb injury among runners,potentially linked to the"muscle traction theory."However,this hypothesis has not been fully confirmed.OBJECTIVE:To investigate whether the contraction characteristics of the soleus,posterior tibialis,and flexor digitorum longus muscles during running are correlated with stress levels at the medial tibial border and influence the occurrence and development of medial tibial stress syndrome using musculoskeletal simulation systems and finite element analysis.METHODS:Motion capture data of six subjects running at different speeds were input into the Anybody Modeling System for inverse dynamic simulations during the stance phase at running speeds of 2.5,3.5,and 4.5 m/s.The calculated boundary conditions were combined with finite element models to examine the stress distribution on the medial tibia.Partial least squares regression was used to analyze the correlation between independent variables(muscle force and elastic potential energy)and the dependent variable(tibial stress).RESULTS AND CONCLUSION:(1)There were statistically significant differences in tibial stress levels across different speeds during the stance phase(1％-50％)(P=0.044,F=3.834,ηp2=0.040).(2)Among the three speeds,the average correlation between soleus muscle force and tibial stress was the highest(r=12.999),followed by the correlation between posterior tibialis muscle force and tibial stress(r=-10.735),flexor digitorum longus muscle force(r=-9.751),posterior tibialis elastic potential energy(r=8.012),soleus elastic potential energy(r=9.076),and flexor digitorum longus elastic potential energy(r=-4.782).(3)The results indicate that with increasing running speed,tibial stress levels rise.The contraction of the soleus muscle and the release of absorbed elastic potential energy during running have a significant impact on the development of medial tibial stress syndrome,whereas the roles of the posterior tibialis and flexor digitorum longus muscles have been overestimated.Overall,the study supports the hypothesis that the contraction of the soleus muscle plays a crucial role in the development of medial tibial stress syndrome,consistent with the"muscle traction"hypothesis.

Objective:To analyze the biomechanical characteristics of the knee joint under different lateral cut angles and ground contact modes using the validated finite element model of the knee joint,which provided a theoretical basis for preventing lateral cut sports injuries in football players and formulating rehabilitation training pro-grams after injury. Method:Fifteen male football players(all of whom are national second-level athletes and above)were recruit-ed to perform cutting movements at the angles of 45°,90° and 135° in front and rear touchdown modes at a speed of 6m/s±10％.The kinematics and dynamics data of the knee joint were calculated by Visual 3D soft-ware,and the peak moment of ground reaction force in the six touchdown actions was numerically simulated based on the verified knee joint model. Result:①The cutting angle is positively correlated with the peak knee flexion angle(P＜0.05),indicating that as the cutting angle increases,while vertical ground reaction force decreases significantly with increase cutting angle(P＜0.05).②Significant differences in kinematics and dynamics exist between forefoot and rearfoot strik-ing(P＜0.05).In the forefoot striking mode,there are larger knee flexion angles,external rotation,and inter-nal rotation peak angles,along with higher upward ground reaction force.③At the moment of side cutting contact,the distribution of Von Mises stress in the meniscus and the contact stress in the femoral cartilage show characteristics related to the cutting angle and the mode of foot contact.In the 90° rearfoot striking mode,there is a noticeable concentration of stress on the external edge of the medial meniscus and the medi-al femoral cartilage,which may indicate an increased risk of knee joint injury under these conditions. Conclusion:Performing a 90° cut with a rearfoot striking pattern may lead to an imbalance in internal knee joint stress,particularly causing significant stress concentration on the external edge of the medial meniscus,indicating a higher risk of injury.

Objective To quantify the lower limb muscle synergy characteristics of athletes during the abdominal take-off phase before and after exercise-induced fatigue(EIF)and reveal the impact of EIF on the lower limb muscle synergy characteristics of athletes during the abdominal take-off phase.Methods The surface electromyographic data of the lower limbs during the abdominal take-off phase of 10 second-level male athletes in track and field special classes before and after EIF intervention were compared.Muscle synergy structures were analyzed before and after EIF.The paired sample t-test was used to compare the differences in synergy parameters before and after EIF.Results Two synergistic elements were extracted before and after EIF,and alternate activation of the muscle synergy structures was observed.After EIF,the degree of activation of synergy element 2 decreased significantly from 53.21±7.90 to 43.44±10.23.However,there was no significant change in synergy element 1.After EIF,the contribution of the rectus femoris muscle of synergy element 1 significantly increased from 0.37±0.04 to 0.44±0.07,and the contribution of the semitendinosus muscle decreased significantly from 0.13±0.05 to 0.08±0.05.Conclusions During abdominal take-off,as fatigue increases,the activation degree of the synergistic elements of each lower limb muscle decreases,and the contribution of the rectus femoris muscle in the synergy element to absorb the ground reaction force increases.This indicates that the rectus femoris muscle is at risk of sprain,and prevention of rectus femoris muscle injury should be strengthened.

Objective To analyze the clinical features of children with EV71 positive hand,foot,and mouth disease(HFMD)and EV71 vaccination,and to explore the relationship between the occurrence of severe disease and the preventive effect of EV71 vaccine.Methods From January 1,2020 to December 31,2022,the clinical data of 131 children with HFMD diagnosed with EV71 infection in Kunming Children's Hospital were retrospectively analyzed.The stool samples of patients with clinically confirmed HFMD were selected for enterovirus nucleic acid detection.The clinical data and EV71 vaccination status of children with universal enterovirus positive and EV71 positive HFMD were analyzed.Results Among the 131 positive cases detected,there were 116 mild cases and 15 severe cases.Among the 80 children who received phone consultations about their EV71 vaccine status,17 were vaccinated,and 63 were not vaccinated.The vaccinated children were all mild cases,while among the unvaccinated children,6 were severe cases.From 2020 to 2022,the period from April to September each year is the peak period for detecting EV71-positive hand,foot,and mouth disease(χ2 = 125.705,P = 0.000).The positive detection rate for children under 1 year old and over 5 years old was higher than that for children aged 1 to 5 years(χ2 = 8.765,P = 0.033),and there was no significant difference in the positive detection rate between boys and girls(χ2 = 1.221,P = 0.269).Conclusion EV71 vaccine is of great significance in reducing the occurrence of severe cases.Combined with the current low vaccination rate in Kunming,Yunnan Province,it is suggested that relevant institutions should continue to increase the publicity of EV71 vaccination.

Objective To propose a human-machine coupling dynamics modeling method based on virtual muscles, so as to quantitatively analyze the characteristics of human-computer interaction force and muscle activation of the musculoskeletal system. Methods First, in the gait experiment of wearing exoskeleton, the human motion capture system and self-developed mechanical monitoring device were used to obtain the wearer’s walking dynamics, electromyography (EMG) signals, exoskeleton drive status and local human-computer interaction information. The human-machine coupling model was established in modeling environment of the bone system, and the gait experiment data and the exoskeleton joint torques were used as driving information of the coupling model to perform inverse mechanical calculations. Finally, by adjusting strength and stiffness parameters of the virtual muscles, the real data of the model was compared with the experimental test result, to quantitatively evaluate effectiveness of the human-machine coupling model of the lower extremity exoskeleton. Results The normal interaction force calculated by inverse dynamics of the coupled model and the activation of lower limb muscles had a good consistency in response curve trend compared with measurement results of the gait experiment, and the interaction force results had a high degree of correlation (r=0.931, P<0.01), the root mean square error was small, and the peak error of lower limb muscle activation was lower than 5%. Conclusions The human-machine coupling model proposed in this study can effectively calculate the interaction force between human and exoskeleton. The establishment of the coupling model provides a theoretical basis for verification and iteration of the exoskeleton structure optimization and control algorithm, as well as performance evaluation on mobility assistance effects of the exoskeleton.

Objective: To examine the effects of obesity and central obesity on hypertension, so as to provide insights into the prevention and control measures of hypertension. Methods: From September to December 2018, residents at ages of 35 to 75 years were sampled using the multi-stage random sampling method in Baiyin District, Baiyin City, Gansu Province, and subjected to questionnaire surveys and physical examinations. The interaction between obesity/central obesity and hypertension was evaluated using logistic regression analysis. The synergy index ( SI ), relative excess risk due to interaction ( RERI ) and attributable proportion due to interaction ( AP ) were calculated using Excel compiled by Andersson et al. Results: A total of 6 246 questionnaires were allocated and 6 169 valid questionnaires were recovered, with an effective recovery rate of 98.77%. The respondents included 3 038 men ( 49.25% ) and 3 131 women (50.75%), with a mean age of ( 52.05±8.78 ) years. There were 832 respondents with obesity ( 13.49% ) and 2 278 with central obesity ( 36.93% ). The crude and standardized prevalence rates of hypertension were 35.89% and 33.05%, respectively. Multivariable logistic regression analysis showed that obesity ( OR=2.020, 95%CI: 1.705-2.393 ) and central obesity ( OR=1.622, 95%CI: 1.433-1.836 ) were statistically associated with hypertension. There was no multiplicative interaction between obesity or central obesity and hypertension ( OR=1.011, 95%CI: 0.655-1.560 ), and no additive interaction was detected between obesity or central obesityand hypertension ( SI=1.405, 95%CI: 0.815-2.424; RERI=0.658, 95%CI: -0.298 to 1.614; AP=0.201, 95%CI: -0.075 to 0.476 ). Conclusions Obesity and central obesity increase the risk of hypertension; however, no interaction is detected between obesity or central obesity and hypertension.

Objective:To analyze the EGFR mutation profile of lung cancer patients in Yunnan, and to provide evidence for clinical personalized treatment.Methods:Demographic and clinical data of 2 967 lung cancer patients undergoing EGFR identification were collected and analyzed from January 2014 to August 2019 in Yunnan Cancer Hospital.Results:The proportion of EGFR mutation in 2 967 patients with lung cancer was 46.2%. Univariate analysis showed that the proportion of EGFR mutation in women was higher than that in men ( P<0.001) and displayed a downward trend with age ( P=0.03). The mutation rate of ethnic minorities was higher than Han ( P=0.012). Mutation rate in patients without smoking history was higher than those with smoking history ( P<0.001), and patients without drinking history was higher than patients with drinking history ( P<0.001). Mutation rate in patients without family history of lung cancer was higher than those with family history ( P=0.008). The mutation rate of adenocarcinoma was higher than other pathological types ( P<0.001). The mutation rate was different among stages, and it was higher in early patients than that in advanced patients ( P<0.001). The mutation rate of tissue specimens was higher than those of cytology and peripheral blood samples ( P<0.001). The mutation rate of Xuanwei area was lower than that in non-Xuanwei area ( P<0.001). Multivariate analysis showed that gender ( P<0.001), age ( P=0.036), smoking history ( P<0.001), pathological type ( P<0.001), specimen type ( P<0.001), and whether or not Xuanwei area ( P<0.001) were the independent factors of EGFR mutation.The EGFR mutation was more common in female, non-smokers, adenocarcinoma, non-Xuanwei area, tissue specimen and young lung cancer patients.The mutation types of EGFR in 1 370 cases mainly included 19-Del and L858R. The predominant mutation of EGFR in Xuanwei area was L858R, while in non-Xuanwei area was 19-Del.The mutation rates of G719X, G719X+ L861Q, G719X+ S768I, and S768I in Xuanwei were higher while the mutation rates of 19-Del, L858R, and 20-ins were lower than non-Xuanwei area ( P<0.05). The 19-Del mutation rate of ethnic minorities is higher than that of Han ( P<0.001). The combined mutation rate of G719X, L861Q in Han was higher than that of ethnic minorities ( P=0.005). Conclusions:The EGFR mutation rate in lung cancer patients in Yunnan is similar to Asian and Chinese, and higher in female, non-smokers, adenocarcinomas, young and non-Xuanwei area patients. The most common types of EGFR mutation in Yunnan are 19-Del and L858R. The predominant mutation of EGFR in Xuanwei area is L858R, while in non-Xuanwei area is 19-Del. The mutation rates of G719X, G719X+ L861Q, G719X+ S768I and S768I are higher in Xuanwei patients than those in non-Xuanwei patients. The combined mutation rate of G719X and L861Q in Han nationality is higher than that of ethnic minorities.

Objective:To analyze the expressions of non-small-cell lung cancer (NSCLC) driver genes and their mutation distribution characteristics in the Yunnan-Kweichow plateau, and to provide evidences for personalized molecular targeted therapy of lung cancer in high-incidence areas.Methods:A retrospective analysis was performed on the medical records of patients with NSCLC who underwent combined lung cancer 8 gene detection, including epidermal growth factor receptor (EGFR), rat sarcoma viral oncogene (RAS), anaplastic lymphoma kinase (ALK), RET proto-oncogene (RET), v-Raf murine sarcoma viral oncogene homolog (BRAF), ROS proto-oncogene 1 (ROS1), human epidermal growth factor receptor-2 (HER-2), and cellular-mesenchymal to epithelial transition factor (MET), from January 2016 to August 2019 in Yunnan Cancer Hospital. Besides, we analyzed the expressions of NSCLC driver genes and their mutation distributions.Results:The positive rate of NSCLC driver genes in Yunnan was 67.05%(1 508/2 249). The mutation rates in Xishuangbanna (76.92%), Yuxi (72.38%), Xuanwei (71.88%), Qujing (71.24%), and Honghe (71.79%) were significantly higher than other areas. The mutation rates of Hui (84.38%), Hani (85.00%), Zhuang (75.00%), Buyi (100%), Manchu (100%), Tujia (100%) and Achang (100%) are significantly higher than the minority national average. Driver gene mutations were related to gender ( P<0.001), smoking history ( P<0.001), age ( P<0.001), pathological type ( P<0.001), and whether the Xuanwei area ( P=0.027), but not related to the nationality ( P=0.748) and family history of lung cancer ( P=0.676). The mutation rates of EGFR, RAS, BRAF, HER-2 and MET genes were 44.46%, 10.98%, 1.24%, 0.89% and 0.76%, and the rearrangement rates of ALK, RET and ROS1 genes were 4.67%, 1.29% and 0.89%, respectively.The mutation rate of EGFR in females was 56.67%, which was higher than 33.19% in males ( P<0.001). The mutation rate of RAS in males was 12.66%, which was higher than 9.17% in females ( P=0.010). The mutation rate of RAS in the Han was 11.49%, which was higher than 7.17% in the minority ( P=0.032). The rate of RAS mutation in Xuanwei patients was 24.74%, significantly higher than 8.15% in non-Xuanwei area ( P<0.001), and the EGFR mutation rate was 40.63%, which was lower than 45.25% in non-Xuanwei area ( P=0.045). The rate of ALK rearrangement in Xuanwei patients was 1.56%, which was significantly lower than 5.31% in the non-Xuanwei area ( P<0.001), and no HER-2 mutation patients were detected in Xuanwei area. The mutation rate of EGFR in patients with non-smoking history was 51.10%, significantly higher than 29.70% of patients with smoking history ( P<0.001). Meanwhile, the rate of ALK rearrangement with non-smoking history patients was 5.35%, which was also higher than 3.16% of patients with smoking history ( P<0.001). The rate of RAS mutation in patients with non-smoking history was 9.34%, lower than 14.63% of patients with smoking history ( P=0.008). Conclusions:The positive rate of driven gene expression in NSCLC patients from the Yunnan-Kweichow Plateau is slightly lower than the national average. The rates of EGFR and RAS mutations are similar to the domestic average. The rates of ROS1, ALK and RET genes rearrangements and the rates of BRAF, HER2 and MET gene mutations are slightly lower than the national average. EGFR, RAS and ALK genes in the NSCLC patients from Yunnan-Kweichow Plateau have high positive rates, and display different demographic and clinical characteristics, which are of great significance in the selection of targeted therapy populations.

Objective:To analyze the EGFR mutation profile of lung cancer patients in Yunnan, and to provide evidence for clinical personalized treatment.Methods:Demographic and clinical data of 2 967 lung cancer patients undergoing EGFR identification were collected and analyzed from January 2014 to August 2019 in Yunnan Cancer Hospital.Results:The proportion of EGFR mutation in 2 967 patients with lung cancer was 46.2%. Univariate analysis showed that the proportion of EGFR mutation in women was higher than that in men ( P<0.001) and displayed a downward trend with age ( P=0.03). The mutation rate of ethnic minorities was higher than Han ( P=0.012). Mutation rate in patients without smoking history was higher than those with smoking history ( P<0.001), and patients without drinking history was higher than patients with drinking history ( P<0.001). Mutation rate in patients without family history of lung cancer was higher than those with family history ( P=0.008). The mutation rate of adenocarcinoma was higher than other pathological types ( P<0.001). The mutation rate was different among stages, and it was higher in early patients than that in advanced patients ( P<0.001). The mutation rate of tissue specimens was higher than those of cytology and peripheral blood samples ( P<0.001). The mutation rate of Xuanwei area was lower than that in non-Xuanwei area ( P<0.001). Multivariate analysis showed that gender ( P<0.001), age ( P=0.036), smoking history ( P<0.001), pathological type ( P<0.001), specimen type ( P<0.001), and whether or not Xuanwei area ( P<0.001) were the independent factors of EGFR mutation.The EGFR mutation was more common in female, non-smokers, adenocarcinoma, non-Xuanwei area, tissue specimen and young lung cancer patients.The mutation types of EGFR in 1 370 cases mainly included 19-Del and L858R. The predominant mutation of EGFR in Xuanwei area was L858R, while in non-Xuanwei area was 19-Del.The mutation rates of G719X, G719X+ L861Q, G719X+ S768I, and S768I in Xuanwei were higher while the mutation rates of 19-Del, L858R, and 20-ins were lower than non-Xuanwei area ( P<0.05). The 19-Del mutation rate of ethnic minorities is higher than that of Han ( P<0.001). The combined mutation rate of G719X, L861Q in Han was higher than that of ethnic minorities ( P=0.005). Conclusions:The EGFR mutation rate in lung cancer patients in Yunnan is similar to Asian and Chinese, and higher in female, non-smokers, adenocarcinomas, young and non-Xuanwei area patients. The most common types of EGFR mutation in Yunnan are 19-Del and L858R. The predominant mutation of EGFR in Xuanwei area is L858R, while in non-Xuanwei area is 19-Del. The mutation rates of G719X, G719X+ L861Q, G719X+ S768I and S768I are higher in Xuanwei patients than those in non-Xuanwei patients. The combined mutation rate of G719X and L861Q in Han nationality is higher than that of ethnic minorities.