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    • Changes in lower limb stiffness in older people during the ageing process and progress in research
    李福有 , 郭成根 , 徐浩然 , 李华帅 , 孙璞
    Adopted date: June 02,2023
    [Abstract](4) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Walking down stairs, walking and running are common actions in daily life, but in elderly people with reduced functional capacity, they may lead to falls or injuries. The first motor neuroprotective mechanism that the body activates in order to cope with various situations to avoid falls is the regulation of lower extremity stiffness. Based on this, this study retrieved and collected relevant research results from databases such as China Knowledge, Wanfang, Google scholar and Web of science, with keywords such as elderly and lower extremity stiffness, and summarised the similarities and differences in the changes of lower extremity stiffness in different movement tasks. However, due to the small number of related studies, there is still a need to investigate the effects of movement interventions on the lower limb stiffness of the elderly in order to obtain more reliable regular characteristics and basis.
    Effect of unanticipated factor on lower limb biomechanics during side among athletes with Anterior Cruciate Ligament Reconstruction
    张嘉源 , 马小远 , 鲁林涛 , 周志鹏 , 陈岩 , 宋祺鹏 , 戴国锋 , 王呈 , 孙威
    Adopted date: June 02,2023
    [Abstract](1) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Objective: This study was to quantify the biomechanics of knee during side cutting of athletes after Anterior Cruciate Ligament Reconstruction (ACLR) under unanticipated conditions, and to investigate the potential risk of Anterior Cruciate Ligament (ACL) injury in athletes. Methods: The infrared motion capture system and 3D force platform were used to collect the kinematic and kinetic data of the lower limbs of 30 male athletes after ACLR during side cutting under anticipated and unanticipated conditions. The angle, moment, ground reaction force (GRF) and other test indexes were analyzed statistically by using two-way ANOVA with repeated measures. Results: The knee flexion angle, valgus moment and flexion moment of the affected limb were significantly lower than those of the unaffected limb. The internal rotation moment and tibial anterior shear force of the affected limb were significantly higher than those of the unaffected limb. The knee flexion angle, internal rotation moment and tibial anterior shear force significantly increased under unanticipated conditions compared with the anticipated conditions. The knee external rotation angle, lateral GRF, and anterior and posterior GRF during side cutting had significant interaction effect. The lateral rotation angle of the affected limb was significantly higher than that of the unaffected side under both anticipated and unanticipated conditions. Under unanticipated conditions, the lateral GRF and anterior and posterior GRF of the unaffected limb were significantly lower than the anticipated conditions, and the lateral GRF of the affected limb was significantly higher than the anticipated conditions. Conclusion: (1) Compared with the unaffected side, the affected side of ACLR athletes showed the biomechanical characteristics of smaller knee flexion angle, larger knee internal rotation moment and anterior tibial shear force during side cutting, which may suggest that the affected side have greater potential risk of ACL injury; (2) Under unanticipated conditions, both lower limbs of ACLR athletes showed the biomechanical characteristics of increased knee internal rotation moment, lateral GRF and anterior tibial shear force, which suggest that the potential risk of ACL injury is not limited to the affected side, and ACL injury prevention should also be strengthened in the unaffected lower limb during side cutting.
    Effect of dual-task intervention on gait parameters and symmetry in community stroke patients
    刘鑫玥 , 刘鹏波 , 霍洪峰
    Adopted date: June 02,2023
    [Abstract](3) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Objective To compare the difference of gait parameters and symmetry between single-task walking and double-task walking with different types and different loads in community stroke patients. Methods The gait parameters of 20 community stroke patients in chronic convalescence were collected by Simi Motion three-dimensional motion analysis system during single-task walking, cognitive double-task walking and motor double-task walking with different loads, and the symmetry index was calculated indirectly. The single-factor repeated measure variance analysis was used to compare the gait parameters and symmetry differences between single-task walking and different double-task walking. Results Compared with single-task walking, the walking speed, stride length, stride length of affected side and the proportion of healthy side swing in community stroke patients during intervention of high-low load cognitive tasks were decreased (p<0.05), while the proportion of stride width and support of healthy side and affected side was increased during intervention of difficult cognitive tasks (p<0.05), and the proportion of robust stride length and affected side swing was decreased (p<0.05). The symmetry index of oscillating phase proportion decreased (p<0.05). Conclusions Community stroke patients mainly deal with cognitive task interference by reducing walking speed, reducing stride length and stride length, reducing swing proportion, increasing step width and support proportion, and changing gait pattern. For gait stability, the intervention of high-load cognitive tasks will increase the asymmetry degree of swing proportion of community stroke patients and reduce their gait stability.
    A finite element analysis to assess the stability of pediatric humeral proximal fractures fixed at different levels
    白桓安 , 陆清达 , 刘趁心 , 王欢 , 王家驹 , 梁小菊 , 杨亚婷 , 颉强
    Adopted date: June 02,2023
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    Objective The finite element method was used to compare the impact of various fixation methods on stability in pediatric humeral proximal fractures at different heights. Methods Different pediatric humeral transverse fracture models were created at varying heights and fixed using Elastic Stable Intramedullary Nailing(ESIN) and kirschner wire with different configurations. These models were imported into ANSYS 2019 to simulate the gravity of the upper limbs and the seven working conditions of anterior flexion, posterior extension, adduction, extension, internal rotation, and external rotation. The mean maximum displacement of the distal humerus and the maximum stress of the fixation were analyzed. Results The average maximum displacement of the distal end of the humerus was the smallest when Kocher's needle was fixed below the P1, P2, P3, and P4 fracture surfaces, respectively, for the 4-pin group (1.728mm), 3B group (1.678mm), 4-pin group (1.821mm), and 4-pin group (2.212mm) Conclusion. ESIN are preferable for fixing fractures at a lower position, while four kirschner wire are more effective than ESIN at all heights.
    Finite element analysis of nondestructive testing of tooth defects
    张翠平 , 许小婷
    Adopted date: June 02,2023
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    Objective This paper aims to contribute to the field of ultrasonic non-destructive testing by establishing a model that can effectively detect different types of defects inside teeth. Methods The dG-FEM method is adopted to create an ultrasonic non-destructive testing model in COMSOL. By measuring various types of dental defects and measuring the same defects at different angles, the propagation law of ultrasonic waves in homogeneous media is explained. The results are presented in the form of ultrasound pulse emission and reception diagrams of the defects, as well as the comparison of detection signals and angle signals of different types of defects inside teeth. Results Different types of tooth defects can be detected within 16 microseconds, with the highest detection strength being observed in crack-type defects, at 22%. The detection signal for star-shaped defects is the weakest. Additionally, when the ultrasound source and the defect are aligned in the main direction, the detection strength is the highest, whereas the detection strength is the weakest when they are aligned in the same direction, with a value lower than 3%. Conclusions In conclusion, this study provides a comprehensive investigation of the potential of ultrasonic non-destructive testing in dentistry. With the establishment of an effective model and the demonstration of its potential, this study contributes to the development of new and more accurate diagnostic tools for dental practitioners.
    Effects of different Curve of Scoliosis on Physiological Curvature of Spine and Kinematics Characteristics of Pelvis
    刘杨 , 颜滨
    Adopted date: May 23,2023
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    Abstract:Objective Exploring the spine and pelvic kinematics characteristics of adolescent idiopathic scoliosis (AIS) patients with different curves during standing and walking, and providing reference suggestions for rehabilitation body training. Methods The physiological curvature of spine and pelvic parameters of 45 patients with single curve and 45 patients with double curve and 27 healthy adolescents were measured in standing and walking state using Diers 4D motion module. Results The thoracic angle and lumbar angle in the healthy group in static standing position is the largest, the thoracic enlargement angle in the double curve group is the largest, and the thoracic curve enlargement angle in the healthy group is the smallest; the rotation direction of the pelvis in the scoliosis group is the same as that of the main curve, and the inclination direction of the pelvis in the single curve group is the same as that of the main curve. Conclusion Compared with the standing position, the movement trend of thoracic angle in the three groups during walking is mainly reduced, and affected by the scoliosis curve;The lumbar angle decreased in all groups; The three-dimensional shape of the pelvis in the static standing position of the scoliosis groups is affected by the lumbar compensatory, and the dynamic rotation function of the pelvis during walking is related to the lumbar compensatory and the initial position of the pelvis.
    Optimization Design of Self-positioning Individuation Titanium Mesh Connectome
    张佳园 , 魏凌飞 , 冀敏 , 林海燕 , 于德栋
    Adopted date: May 23,2023
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    Abstract:Objective To optimize the connection between the 3D printing self-positioning titanium mesh main body and the positioning wings at both ends, including thickness, width, and junction configuration of the positioning wings at the connection site. And to analyze and optimize the structural performance of the simulation model before and after the improvement, ultimately obtain the optimal design of a new type self-positioning titanium mesh. Method In the software SolidWorks(Dassault Systemes,America,2020 SP03), build a self-positioning titanium mesh simulation model to optimize and improve dimensional parameters. Then, the simulation software ANSYS Workbench (ANSYS, USA, 2020 R2) is used to conduct multi-objective optimization design for the thickness and width of the connection. And design a discontinuous connection configuration at the connection to obtain an optimized self-positioning titanium mesh. Results When a 40N load was applied to the outer surface of the new self-positioning titanium mesh alveolar crest, the maximum strain at the junction does not exceed the fracture strain of the titanium mesh, and the stress and deformation are within an acceptable range. When a bending force of 10N and 45° was applied to the free end of the positioning wing on one side, the maximum strain at the connection site exceeded the fracture strain of the titanium mesh, and the crack propagation path is concentrated at the connecting line. The experimental results of the virtual model are basically consistent with the mechanical performance verification test. Conclusion By optimizing the size and configuration of the self-positioning individuation titanium mesh connector, it is achieved that when placing and pressing the individuation titanium mesh during surgery, the connector does not break or shift significantly. After surgery, a simple bending of the free end of the positioning wing can achieve a neat fracture and separation of the connector along the connecting line, with a smooth and flat cross-section. This study has achieved ideal clinical results by optimizing the size and configuration of the self-positioning individuation titanium mesh connection.
    Study on Material Adaptability of Coronary Stent Design
    叶锟 , 张弢
    Adopted date: May 23,2023
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    [Objective] To analyze the adaptability of different materials based on a defined coronary stent design and to establish an evaluation method for stent design-material selection. [Methods] Using finite element numerical simulation methods (FEA), the expansion performance of the stent in the blood vessel were analyzed, and the safety and usability of the stent design and materials were investigated for five potential applicable materials. For the permanent materials, the focus was on the fatigue resistance performance after long-term implantation; while for the degradable materials, the changes of support force during degradation were analyzed to clarify the rules of the support force provided by the stent. [Results] For the specific coronary stent design, the results given by the FEA showed that for 316L stainless steel and L605 cobalt-chromium alloy stents, the radial resilience were 25% and 19%, the axial shortening were 0.22% and 0.28%, the maximum equivalent forces were 551.2 MPa and 829.1 MPa, and the fatigue dynamic safety factors were 1.33 and 1.67, respectively. The simulated damage times of the stents based on this design were 30 hours, 6 months and 9 months for the degradable materials such as AZ31 magnesium alloy, iron and poly(L-lactic acid) (PLLA), respectively. [Conclusion] Based on the stent design in this paper, the L605 cobalt-chromium alloy exhibited the best expansion performance and fatigue resistance to match the clinical requirements. Compared with the rapid degradation damage of AZ31, the mechanical properties of iron stent and PLLA stent are close but still need structural optimization. While FEA, especially the expansion performance analysis and fatigue resistance analysis, can be effectively used to simulate the mechanical behavior of the stent and provide basis for the selections of stent materials and the design optimizations.
    Research Progress on the Biomechanical Characteristics of Lumbar Flexion and Extension in Nonspecific Chronic Low Back PainCAO Ben1, ZHOU Xin1, YAO Chongjie2, FANG Min3
    曹奔 , 周鑫 , 姚重界 , 房敏
    Adopted date: May 23,2023
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    Nonspecific chronic low back pain (NSCLBP) is a common condition that has garnered widespread attention, yet its pathogenesis remains unclear. In recent years, the study of the biomechanics underlying the occurrence and progression of this disease, aided by relevant equipment, has become increasingly important. This review focuses on the core function of the lumbar spine - flexion and extension movements - and summarizes the progress made in the research of the biomechanical characteristics of lumbar flexion and extension in NSCLBP both domestically and internationally. Through an in-depth discussion and summary of specific research methods and observation indexes, it was found that patients with NSCLBP exhibit anomalous kinematics, kinetics, surface electromyography records, and other parameters, opening up new avenues for exploring the pathogenesis and scientific prevention and treatment of this condition.
    Prediction and correlation analysis of hemodynamic parameters and volume responsiveness in patients with septic shock
    董倩倩 , 刘德智
    Adopted date: May 18,2023
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    Objective? To explore the changes of hemodynamic parameters in septic shock patients before and after volume stress test and their predictive value and correlation to the volume response of patients.? Methods? 98 cases of septic shock patients admitted to our hospital were selected for clinical research. According to whether the stroke volume change (△SV) of patients before and after rehydration treatment was ≥15%, they were divided into 53 cases of volume load positive group and 45 cases of volume load negative group. For example, compare the pulse wave continuous cardiac output method (PICCO) and echocardiogram related indexes before and after the volume load test of the two groups of patients, and use receiver operating curve (ROC) to analyze the statistically significant indexes for septic shock The value of the patient"s response to the volume load test is analyzed using a logistics regression model to analyze the relationship between various parameters and the volume load test response. Results? Before the volume load test, the CO, CI, SVV, CVP, HR measured values ??of the volume load positive group and the volume load negative group were compared, and the difference was not statistically significant (P>0.05); after the test, the volume load positive group The CO, CI, and CVP values ??were all higher than the volume load negative group (P<0.05), and the HR and SVV values ??were lower than the volume load negative group (P<0.05); before the volume load test, the volume load positive group and the volume load The comparison of LVOT VTI, LVOT peak flow velocity respiratory variability, and VEpeak measurement values ??of patients in the negative group was not statistically significant (P>0.05); after the test, the LVOT VTI measurement value of the positive volume load group was higher than that of the negative volume load group ( P<0.05), LVOT peak flow velocity respiratory variability is lower than volume load negative group (P<0.05); ROC curve results show CO, CI, SVV, CVP, HR, LVOT peak flow velocity respiratory variability, LVOT VTI index prediction The positive AUC values ??of the volume load reaction were 0.515, 0.560, 0.556, 0.499, 0.898, 0.912, 0.922; Logistic regression model results showed: the higher the APACHEⅡ score, the higher the SOFA score, the lower the CO, the lower the CI, and the lower the CVP The higher the SVV, the lower the LVOT VTI, and the greater the respiratory variability of the LVOT peak flow rate were independent risk factors for the negative volume load test in patients with septic shock (P<0.05).? Conclusion Closely monitoring the relevant hemodynamic parameters of patients with septic shock has important clinical value for predicting the patient"s volume load responsiveness, and is of great significance for guiding patients in clinical fluid resuscitation.