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Abstract:The ear, nose, and throat (ENT) organs are directly in contact with the external environment and help humans perceive information from the outside world. The implementation of the functions of these organs and the development of the related diseases are closely related to mechanical factors. In this review, combined with the latest literature in the field of otolaryngology in 2022, the progress of acoustic conduction in the ear was summarized, including the processes of air conduction and bone conduction, the balance function of the vestibular system, the treatment of obstructive sleep apnea-hypopnea syndrome (OSAHS), the relationship between nasal diseases and structure, and the impact of nasal diseases on adjacent organs. The future research direction in the field of biomechanics of otolaryngology was also discussed.

Abstract:Diseases of hearing loss and deafness have seriously threatened human health and affected people’ s quality of life. The ear is an important sensory organ in human body, and the cochlea is the key sensory structure of human ear. The cochlea is characterized by precision, complex, and hidden location, which causes many insurmountable difficulties in experimental researches, So far, the interpretation of cochlear phonosensitive mechanism is still an important unsolved problem in medicine. There is a growing tendency for many scientists to integrate the interdisciplinary principles of mathematics, mechanics, biology and medicine, develop the real and effective structural biomechanics model, and carry out a thorough investigation on the sensory mechanism of cochlea, so as to provide a theoretical basis for hearing repair and clinical treatment. In this review, the status of researches on the mechanism of sound sensing and clinical application of cochlea was summarized, the existing problems were pointed out, and the future research work was also prospected.

Abstract:Objective To investigate the mechanical regulatory mechanisms, phosphorylation effects and molecular structural basis of β2 / FLNa interactions. Methods The crystal structures of β2 / FLNa-WT and T758P complex were taken from PDB, and performed molecular dynamics simulations. The MM / PBSA method was used to calculate the binding free energy changes of the complex, and data on conformational evolution and residue interactions were analyzed. Results Following phosphorylation modification of β2 integrin THR758, the binding free energy of the complex and the pulling force accumulation were significantly decreased. The dissociation of β2 / FLNa complex showed a biphasic force-dependent property under the stimulation of mechanical signals. A pure slip-bonding mechanism existed in the binding dissociation process of the complex after phosphorylation modification. Conclusions The phosphorylation would down-regulate the binding affinity of β2 / FLNa complex by attenuating the M762-G2269 residue interaction, and tension would bidirectionally regulate the dissociation of the complex. This study contributes to deeper understanding of the inflammatory response process, and provides useful references for the discovery of relevant drug targets and antibody design

Abstract:Objective To investigate the effect of fluid shear stress (FSS) on p21 expression in osteoblasts, and to clarify the role of p21 in osteoblast proliferation induced by FSS. Methods Osteoblasts were treated with 1. 2 Pa FSS for different duration ( 0, 15, 30, 45, 60 min). Osteoblasts were transfected with siRNAp21 or pcDNAp21, and the transfection effect was detected by Western blotting. The proliferation of osteoblasts was assessed by CCK-8 assay or EdU labelling assay. The expression of p21, cyclinD1 and CDK4 was detected by Western blotting. Results 1. 2 Pa FSS significantly down-regulated p21 expression, and the expression level of p21 was the lowest when treated with FSS for 45 min. Both FSS and down-regulation of p21 significantly increased the proliferation of osteoblasts and the expression of cyclin D1 and CDK4. However, after up-regulating p21 expression, FSS couldn’ t increase the proliferation of osteoblasts and the expression of cyclin D1 and CDK4. Conclusions 1. 2 Pa FSS can down-regulate p21 expression in osteoblasts, and the expression level of p21 was the lowest when treated with FSS for 45 min. Down-regulation of p21 can promote osteoblast proliferation, and FSS promotes osteoblast proliferation through down-regulating p21.

Abstract:Objective To investigate the effects of ambient temperature on airflow and particle deposition patterns in human respiratory tract. Methods The gas-solid two-phase flows in human respiratory tract with mucus layer were simulated using computational fluid dynamics (CFD) method. Particles with 8 different sizes (1-8 μm) in human respiratory tract under six different ambient temperatures (-25,-15,0,15,26. 7,45 ℃) were considered.Results The difference between the flow velocity and the average flow velocity under six temperatures could reach 39. 42% . The difference between the air flow turbulent kinetic energy and the average turbulent kinetic energy under six temperatures could reach 11. 59% . The difference between the change of airflow temperature and the average change of air flow temperature under six temperatures could reach 82. 4% . The difference between the particle total deposition rate and the average value of the total deposition rate under six temperatures was 14. 72% . The difference between the particle local deposition rate and the average value of the local deposition rate under six temperatures could reach 37. 08% . Conclusions The ambient temperature will have an impact on the properties of the airflow field, and further affect the properties of particle deposition in human respiratory tract. Therefore, it is necessary to consider the influence of ambient temperature when accurately predicting patterns of particle transport and deposition in human respiratory tract is required.

Abstract:Objective To investigate characteristics of the airflow in lower respiratory tract for patient with chronic obstructive pulmonary disease (COPD) under different motion states using computational fluid dynamics (CFD) method. Methods The CT scanning data and pulmonary function data of COPD patients were collected to reconstruct the three-dimensional (3D) model of lower respiratory tract. The numerical simulation was performed by applying individualized boundary conditions, so as to analyze parameters such as wall pressure, wall shear stress ( WSS), flow rate and pressure drop in lower respiratory tract of the patient. Results With exercise intensity increasing, the wall pressure, WSS, flow velocity and pressure drop of lower respiratory tract in COPD patients gradually increased. The differences in parameters between the resting state and low-intensity exercisestate were small, while such parameters under high-intensity exercise state increased significantly. Among the parameters, WSS was a sensitive mechanical parameter, and the area occupied by WSS>1. 0 Pa was 272. 35, 438. 24, 4 369. 48 mm2 under three motion states, respectively. Conclusions The airway wall pressure, WSS, flow velocity and pressure drop of COPD patients under motion states are significantly increased, which increases the possibility of mucosal injury and inflammation in lower respiratory tract. The results explain the mechanism of bronchial inflammation in COPD patients and the reasons why patients cannot exercise for a long time from the mechanical perspective.

Abstract:Objective Currently, the mainstream intraocular pressure( IOP) measurement devices in the market are contact and irritant, which can easily bring discomfort to patients and even lead to corneal infection during use. To solve this problem, a non-contact measurement method of IOP based on ultrasound imaging was proposed. Methods The method was verified by finite element analysis and experiment, and the simulation results of corneal deformation were obtained. A simulated eye was made and an experimental system for measuring IOP was built. A mathematical model of IOP, corneal deformation and pressure was established and its accuracy and repeatability were verified. Results The flattened diameter and vertex displacement of the cornea had a power and linear relationship with pressure under a certain IOP. Both the flattened diameter and the vertex displacement had a power relationship with IOP under constant pressure, which could be used as the index of IOP measurement. The average relative error of IOP measured by this method was smaller than 8% , the relative average deviation was smaller than 9% , and the retest reliability was greater than 0. 9. Conclusions The measurement results of the method are accurate and have a good repeatability. The results of this study provide an effective way for non-contact measurement of IOP, which has a good application prospect.

Abstract:Objective To study the effects of different hole sizes on implantable collamer lens ( ICL) deformation and flow field in anterior chamber. Methods From the perspective of the combination of medicine and engineering, the fluid-structure coupling numerical simulation method was adopted to study the influence of different hole sizes of ICL on its deformation and intraocular aqueous humor flow field ( mass flow, velocity, pressure and temperature). Results In terms of fluid dynamics, the hole sizes for aqueous humor flowing through the central hole of ICL from large to small was 0. 36, 0. 40, 0. 30, 0. 20, 0. 10 mm, respectively, and such flow showed a nonlinear relationship with hole sizes. The pressure of posterior chamber was slightly higher than that of anterior chamber, and the pressure difference between anterior and posterior chambers graduallydecreased with the increase of hole sizes. The temperature distribution in the eye was not sensitive to the effect of hole sizes. In terms of solid statics, the ICL with the diameter of 0. 36 mm had the smallest deformation, and its deformation was dominated by the flow of aqueous humor through the central hole. The larger the flow rate, the smaller the ICL deformation. Conclusions Through comprehensive analysis of fluid dynamics and solid statics, this study verified the rationality of the existing 0. 36 mm hole size, and proposed that an ideal hole size range should be d≥0. 36 mm. The results are helpful to explore the failure mechanism of ICL, improve the success rate of clinical surgery, and provide experience for ICL localization in the future.

Abstract:Objective To analyze the effects of excitation source location, detection area length and detection depth on human corneal optical coherence elastography (OCE). Methods The finite element model of human eye with non-uniform distributions of corneal elastic modulus was constructed based on actual distributions of corneal elastic modulus. By simulating the process of shear wave OCE experiment, the finite element simulation results and theoretical results were compared and analyzed. Results When the excitation source locations were different, the shear wave velocity errors of the anterior and posterior corneal stroma were different. The shear wave velocities of the anterior and posterior corneal stroma changed nonlinearly when the detection area lengths were different. For the model with hyperelastic materials, the shear wave velocity changed obviously when the detection depths were different. Conclusions Due to the non-uniform distributions of corneal elastic modulus, the finite element simulation results of shear wave OCE are different at different excitation source locations, different detection area lengths and different detection depths in the anterior and posterior corneal stroma. In OCE experiments, the accuracy of OCE results will be affected if biological tissues with non-uniformity are regarded as homogeneity for measurement.

Abstract:Objective To study the effect of seat back angle (SBA) on neck injury of pilots. Methods Based on head-neck multi-body dynamic model, dynamic simulations were conducted on 17°and 22° SBA under two typical flight conditions ( sharp turning and stable hovering). The maximum forces of neck muscle and time-varying curves of axial force, bending moment were obtained. Neck injury was evaluated and predicted based on neck injury criterion (NIC), Nij criterion and abbreviated injury scale (AIS). Results Under the same flight condition, the neck was under flexion at 17° SBA, and the trapezius and splenius capitis were stretched. While the neck was under extension at 22° SBA, and the lingualis was stretched. The muscle force of the trapezius at 17° SBA was the maximum. For the same segment, the axial force at 17° SBA was higher than that at 22° SBA, while the extension moment at 22° SBA was larger than the flexion moment at 17° SBA. The axial force and moment under all flight conditions did not exceed the defined injury assessment reference values, and no damage to the cervical spinal cord would occur. The Nij of C7-T1 segment at 22° SBA under sharp turning condition was the maximum under all simulated conditions, reaching the critical value in aviation field, and the probability of moderated injury and serious injury for the neck was 3. 93% and 2. 63% , respectively. Conclusions The results in this study will provide support for evaluating the effect of SBA on neck injury of pilots.

Abstract:Objective Aiming at the low accuracy problem of the traditional finite element method ( FEM) in analyzing the piezoelectric femur remodeling after total hip arthroplasty (THA), the edge-based smoothed finite element method ( ES-FEM ) was applied to simulate remodeling process of the piezoelectric femur after prosthesis implantation. Methods According to the adaptive bone remodeling theory, the prosthesis-piezoelectric femur model was established. Based on background mesh of the model, the edge-based smoothing domains were constructed. Then, the smoothed remodeling stimuli were calculated by introducing the gradient smoothing technology. The distribution of apparent density in proximal femur could be obtained. Results After prosthesis implantation, the stress points were transferred from the femoral head to the prosthesis. Hence, the stress shielding phenomenon occurred. The apparent density distributions changed obviously. Compared with the FEM the ES-FEM could soften the numerical model and improve the simulation accuracy. Based on the same mesh, the computation accuracy of the potential and density was improved by about 27% and 30% , respectively. Conclusions The ES-FEM in this study possesses better accuracy in analyzing the bone remodeling after THA, which provides an effective theoretical basis for clinical study of artificial joint replacement.

Abstract:Objective To explore a suitable judging criterion of the strain under compressive fracture condition. Methods Fracture simulation of cortical bone structure under compression loads was performed based on the continuum damage mechanics theory. The principal strain and the equivalent strain were used to judge the damage and failure state in the element, and the fracture simulation was performed. Then, the simulation results were compared with the corresponding experimental data to determine the prediction accuracy by using two kinds of strains. Results The fracture time in the simulation using the equivalent strain was remarkably later than that using the principal strain. Compared with the equivalent strain, the simulation results obtained by applying the principal strain were closer to the animal experimental results. Conclusions Under compression loads, it is more accurate to use the principal strain to determine the mechanical state of cortical bone element for fracture simulation. Through comparative method, a feasible numerical simulation method can be found to accurately simulate the fracture of cortical bone under compression loads, which can provide theoretical basis for improving the fracture prediction accuracy in clinic.

Abstract:Objective To make finite element analysis on a novel trapezoid sleeve combined with prosthesis stem by different length (90, 105, 20, 135 mm) and shapes (straight and curved stem), and study the differences in their primary stability. Methods The finite element model of femur-sleeve-prosthesis was established, the contact mode was set as face-to-face contact, and the micromotion of femur-sleeve-prosthesis stem was studied by simulating the loading conditions of standing on one foot and fast walking in physiological activities. Results The micromotion of trapezoid sleeve combined with straight stem was larger than that of curved stem during standing on one foot and fast walking. The maximum and average micromotion reached the peak when the length of prosthesis stem was 120 mm. During standing on one foot and fast walking, the average micromotion of trapezoid sleeve combined with straight stem was ( 67. 7± 43. 5) μm and ( 64. 1± 59. 2) μm, and the maximum micromotion was 121 μm and 146 μm. The micromotion around the trapezoidal sleeve remained constant as the length and shapes of prosthetic stem changed. Conclusions The trapezoidal sleeve combined with curved stem is superior to that with the straight stem. When the length of prosthetic stem is 90 mm, the optimal primary stability can be maintained.

Abstract:Objective To compare the biomechanical characteristics of proximal tibia after unicompartmental knee arthroplasty (UKA) between conventional osteotomy, radial-corner shape reserved osteotomy and radial-corner shape extended osteotomy. Methods On the basis of CT data from the Sawbones tibia, the complete tibia model and the UKA model under different osteotomy methods were constructed. The finite element analysis was performed on these models under axial compression condition to compare the strain situation of proximal tibia and the difference of bone cement stress. Results Under axial compression conditions, the peak von Mises strain on the resected area of cortical bone was calculated. The strain of the radial-corner shape extended group was increased compared with that in regular osteotomy group and the radial-corner shape reserved group, while the peak von Mises strain of cancellous bone was decreased by 24. 3% -42. 9% and 26. 0% -48. 7% , respectively. Comparing the peak von Mises strain difference between cancellous bone and cortical bone in the resected area, it was found that the difference of the radial-corner shape extended group was much smaller than the other two groups. There were no significant differences in the minimum principal strain on the anteromedial tibial cortex between different models after UKA, but they increased by 23. 3% -34. 5% compared with the intact tibial model. The average von Mises stress in the cement unit of the radial-corner shape extended group tended to decrease as the fillet radius of the corner increased, which was smaller than that of the regular osteotomy group and the radialcorner shape reserved group. Conclusions The new radial-corner shape extended osteotomy method results in more uniform stress transfer to the proximal tibia under healthy bone conditions, lower peak von Mises strain, and less compression at the prosthesis-bone interface, which is more advantageous than regular osteotomy method and radial-corner shape reserved osteotomy method.

Abstract:Objective To investigate the effect of thickness and elastic modulus of anterior talofibular ligament (ATFL) on ankle stability, and provide references for ankle instability diagnosis. Methods The threedimensional (3D) model of ankle joint was established. By changing the thickness and elastic modulus of ATFL, the ankle anteroposterior stiffness (AAS) was calculated and used as a quantitative indicator to assess ankle stability. Results AAS changed significantly when the thickness of ATFL was in the range of 0. 78 mm to 2. 31 mm, and such relationship was in an S-shaped curve. AAS significantly increased with the elastic modulus of ligament increasing, when the elastic modulus of ATFL was in the range of 60 MPa to 400 MPa. Conclusions Both the thickness and elastic modulus of ATFL will influence the stability of ankle joint.

Abstract:Objective To explore the protective mechanism of ankle braces in patients with functional ankle instability (FAI), so as to provide references for the selection of ankle braces. Methods Fifteen FAI patients randomly wore semi-rigid and elastic ankle braces or wore without braces for walking and running at the selfselected speed. The lower extremity biomechanical parameters were collected by infrared motion capture and three-dimensional (3D) force plate. The 3 × 2 repeated two-way ANOVA was used to test the effects of ankle brace and movement patterns on biomechanical parameters of the lower extremity. Results There was no interaction between ankle braces and movement patterns on all indexes in the study (P>0. 05). Regardless of movement patterns, compared with no ankle brace support, the elastic ankle brace significantly reduced peak ankle inversion angle, inversion angular velocity and energy absorption (P<0. 05) for ankle joint, and increased ankle eversion moment ( P < 0. 001). The semi-rigid ankle brace increased peak ankle inversion angle and inversion angular velocity ( P < 0. 05). In addition, the elastic ankle brace reduced the knee internal rotation moment at the landing moment and the peak knee external rotation moment (P<0. 05). Conclusions Compared with no ankle brace support, the elastic ankle brace reduced the ankle inversion angle, inversion angular velocity and energy absorption, increased the ankle eversion moment and played a role in preventing ankle sprain. For FAI patients wearing semi-rigid ankle brace, regular attention should be paid to the risk of chronic ankle injury. Overall, the protective effect of elastic ankle brace may be more prominent and does not cause knee joint function compensation, which can be used as an effective measure to prevent ankle sprain in FAI patients.

Abstract:Objective To compare the biomechanical behavior of knee joints with mild and severe knee osteoarthritis (KOA), and to elaborate the biomechanical mechanism of KOA progression. Methods The finite element models of the left mild KOA knee (KL grade I) and the right severe KOA knee joint (KL grade IV) for the same patient were constructed respectively. Under the same setting of material properties, boundary conditions and loads, the change characteristics of knee meniscus, femoral cartilage and tibial cartilage between mild and severe KOA, including contact area, contact pressure and von Mises stress were compared by using finite element analysis. Results The total contact area and lateral compartment of knee joint with severe KOA was larger than that of knee joint with mild KOA, but the contact area of medial compartment was smaller than that of knee joint with mild KOA. The peak contact pressure, von Mises stress on meniscus, femoral cartilage and tibial cartilage of knee joint with severe KOA were higher than those of knee joint with mild KOA. The contact pressure and peak von Mises stress on the lateral meniscus of both knees were greater than those on the medial meniscus, and the contact pressure and peak von Mises stress of the medial compartment between femoral cartilage and tibial cartilage of both knees were greater than those of the lateral compartment. Conclusions The stress distribution of knee joint with severe KOA is different from that of knee joint with mild KOA. The changes of contact area, contact pressure and peak von Mises stress are related to factors such as meniscus dislocation and cartilage defect. The changes of biomechanical behavior and anatomical structure promote the progress of KOA.

Abstract:Objective To explore the effects of different sitting postures on compensatory characteristics of the spine and pelvis, and provide the theoretical basis for finding an ideal sitting posture, reduce posture compensation caused by inappropriate sitting posture. Methods The parameters of surface morphology and hip pressure from 20 healthy young adults in upright sitting, cocke-legged sitting and cross-legged sitting were measured using Diers formetric and Pedscan modules. Results Compared with upright sitting, cocke-legged sitting led to pelvic posterior tilt, lateral tilt and relative torsion (P<0. 05). The pressure area of the cocke-legged hip decreased (P<0. 05), the maximum pressure and average pressure significantly increased (P< 0. 05). The maximum pressure ratio, average pressure ratio of both hips (P<0. 05) as well as symmetry of pressure areas (P<0. 05) for both hips were reduced. Compared with upright sitting, the sagittal plane deviation angle in crosslegged sitting increased ( P < 0. 05), with the trunk flexion, the lumbar kyphosis ( P < 0. 05), accompanied by pelvic posterior tilt (P<0. 05), and pressure areas of both hips decreased (P<0. 05). Conclusions Among three kinds of sitting postures, the upright sitting can be considered as an ideal sitting posture with the uniform force on both hips, the optimal surface morphological parameters of the back, and the least compensation in the lumbar and pelvis.

Abstract:Objective To evaluate the feasibility of virtual box block test ( VBBT) designed by force feedback device combined with virtual reality technology for remote evaluation of upper limb moter function. Methods A VBBT system for upper limb motor function assessment was designed. This system could be used to calculate the VBBT score, mean velocity, spectral arc length, energy consumption and mean grasping force of the subjects. In total 20 healthy subjects and 16 post-stroke patients were recruited to perform the VBBT. Results Significant differences were found in all VBBT parameters (P< 0. 05) between post-stroke patients and healthy subjects. Receiver operating characteristic ( ROC) curve analysis showed that the VBBT parameters werepossible to distinguish the two groups ( P< 0. 05). The correlations between VBBT parameters and traditional clinical assessments indicated the concurrent validity of the VBBT. Multiple regression analysis showed that the kinematic and kinetic parameters of the VBBT could partially explain the variance of the traditional clinical assessments. Conclusions The VBBT can be used as a remote assessment of upper limb motor function in post-stroke patients.

Abstract:Objective To study the sensory system characteristics of posture control in stroke patients, and to analyze the contribution rate and utilization rate of each receptor to postural control ability of stroke patients. Methods Sensory organization tests (SOT) were conducted on 30 elderly stroke patients (patient group) and 30 healthy elderly patients (control group) with computer dynamic posture tracing system. The balance scores and balance comprehensive score were recorded under 6 conditions, and the contribution rate and overall utilization rate of vision, proprioception, and vestibular sense under different standing conditions were calculated and analyzed. Results The balance score of patient group was significantly lower than that of control group under the conditions of closed eyes / stable support surface ( Z = - 3. 248, P = 0. 001), visual disturbance/ stable support surface (Z = - 2. 829, P = 0. 005), closed eyes / unstable support surface ( Z = - 4. 283, P = 0), and visual disturbance/ unstable support surface (Z = - 4. 074, P = 0). The balance comprehensive score was significantly lower than that of the control group ( Z = - 4. 133, P = 0). In eyes-open/ stable-support and eyes-closed/ stablesupport tests, the proportion of proprioception in patient group was 16. 351% and 34. 942% , and 14. 307% and 18. 390% in control group. The proportion of proprioception in patient group was always greater than that in control group, indicating that proprioception had a greater effect in patient group than that in control group. Similarly, the effect of vision on patient group was greater than that on control group. The lowest contribution rate of vestibular sense under different standing conditions was 64. 648% , indicating that the main factor to maintain balance of human body is vestibular sense. The utilization rates of proprioception, vision and vestibular sense in patient group were 95. 092% , 72. 382% , and 32. 879% , respectively. The utilization rate of proprioception ( Z = -1. 984, P= 0. 047) and vestibular sense ( Z = - 4. 283, P = 0) was significantly lower than that of the control group. Conclusions The decline in contribution and utilization of sensory system in stroke patients is one of the important factors for stroke patients with postural control disorders. Posture control contributes the most to vestibular sense, followed by proprioception and vision. The largest utilization rate of posture control is proprioception, followed by vision and vestibular sense. One of the reasons that affect the decline in posture control ability of stroke patients is the decline in the efficiency of proprioception and visual sensory information input of stroke patients, as well as the partial decrease in proprioception and vestibular sense participating in motor output. It is suggested that stroke patients should pay attention to the training of proprioception and vestibular sense to improve their posture control ability.

Abstract:Objective To investigate the acute effect of changing foot strike patterns on in vivo kinematics of the medial longitudinal arch during shod running. Methods The high-speed dual fluoroscopic imaging system(DFIS) was used to acquire fluoroscopic images of the right foot during stance phase before and after changing foot strike patterns [running speed: (3±0. 15) m / s] in 15 healthy male runners. The three-dimensional (3D) model of the first metatarsal bone and calcaneus and the local coordinate system were reconstructed from CT images, and the six degrees of freedom (6 DOF) data of the medial longitudinal arch (simplified as motion of the first metatarsal bone relative to the calcaneus) during stance phase were obtained by 3D-2D registration. Statistical parametric mapping (SPM) was used to compare the 6 DOF data of the medial longitudinal arch before and after changing foot strike patterns, and paired sample t-tests were used to compare the specific values. Results Compared with rearfoot strike, the lateral translation during 15% -21% of stance phase, anterior translation during 17% -45% of stance phase and dorsiflexion during 18% -39% of stance phase for motion of the first metatarsal bone relative to the calcaneus were significantly increased during forefoot strike running ( P < 0. 05). The maximum anterior translation, the maximum dorsiflexion, the anterior-posterior translation, and the compression of the medial longitudinal arch for motion of the first metatarsal bone relative to the calcaneus were significantly increased during forefoot strike running (P<0. 05). Conclusions Transitioning from habitual rearfoot strike to immediate forefoot strike resulted in greater deformation of the medial longitudinal arch in sagittal plane, especially the variation of arch compression increased by approximately 10% , which might contribute to the storage and release of elastic energy in the medial longitudinal arch.

Abstract:Objective To study the effects of exergame and aerobic dance on improvement of physical fitness and balance ability in older adults. Methods A total of 40 older adults were randomly assigned to the exergame group or aerobic dance group. Both groups received moderate to high intensity exercise training for 12 weeks. Physical fitness and balance ability were measured in both groups before and after the exercise intervention. Results Compared with aerobic dance group, lung capacity (P<0. 05, d= 0. 85), and diastolic blood pressure (P<0. 05, d= -0. 24) in exergame group were significantly improved. The exergame group had better performance in sway area during static balance test (d = -0. 57), as well as in the rear (d = -0. 70), right front upward ( d = -0. 67) motor control ability during dynamic balance test. Compared with exergame group, aerobic dance group had more improvement in performance of standing on one foot with eyes closed ( d = - 0. 61) and left-sided upward motor control ability during dynamic balance test ( d = 1. 14). Conclusions Compared with aerobic dance, exergame has more advantages in enhancing physical fitness and maintaining balance ability in older adults, which can be used as an important way of physical exercises in older adults, so as to further improve their health and prevent the occurrence of fall injuries

Abstract:Objective By comparing the differences of surface electromyography ( sEMG) signals and dynamic stability of lower limbs during cognitive dual-task walking and motor dual-task walking under different loads, the effects of dual tasks with different types and loads on dynamic postural control in healthy adults were investigated. Methods The average electromyography (AEMG) and dynamic stability indexes of 28 subjects during cognitive dual-task walking and motor dual-task walking under different loads were collected by wireless sEMG tester and three-dimensional (3D) motion capture system. The effects of task type ( cognitive task and motor task) and task load ( simple task and difficult task ) on sEMG and dynamic stability of human lower limbs and their interactions were analyzed by two-factor repeated measures of variance. Results The AEMG of left and right biceps femoris muscles and right tibialis anterior muscle during walking with simple load were lower than those during walking with difficult load (P<0. 05), and the AEMG of left tibialis anterior muscle during simple motor dualtask walking was lower than that during difficult motor dual-task walking (P<0. 05). The AEMG of right gastrocnemius muscle during difficult cognitive dual-task walking was lower than that during difficult motor dualtask walking (P<0. 05), the AEMG during simple cognitive dual-task walking was higher than that during difficult cognitive dual-task walking (P<0. 05), and the AEMG during simple motor dual-task walking was lower than that during difficult motor dual-task walking (P< 0. 05). The margin of stability ( MoS) of simple cognitive dual-task walking was larger than that of simple motor dual-task walking (P<0. 05), the MoS of difficult cognitive dual-task walking was smaller than that of difficult motor dual-task walking (P<0. 05), and the MoS of simple motor dualtask walking was smaller than that of difficult motor dual-task walking (P<0. 05). Conclusions Dual tasks with different types and loads have interaction effects on dynamic posture control. The neuromuscular control around the ankle muscle and dynamic stability during difficult motor dual-task walking are better than those during difficult cognitive dual-task walking, and the neuromuscular control around the ankle muscle and dynamic stability during difficult motor dual-task walking are better than those during simple motor dual-task walking.

Abstract:Objective To study the joint angle and contact force of the thumb during one-handed operation on mobile phones, analyze the biomechanical characteristics and influencing factors of the thumb joint angle and contact force, and provide the biomechanical basis for prevention, rehabilitation and treatment of thumb stenosing tenosynovitis. Methods Vicon optical motion capture system and resistive thin film force sensor were used to collect the thumb joint angle and fingertip contact force of college volunteers when they operated mobile phones with one hand, and statistical multi-factor correlation analysis on human body parameters, joint angle and contact force was conducted. Results The joint angle and contact force of one-handed mobile phone operation, such as sliding up, turning clockwise, right pointing, left pointing and sliding left, were obtained through the instrument measurement. Statistical analysis showed that hand length and thumb length had a significant influence on the average angle and the maximum contact force of each joint (P<0. 05), and hand length was basically negatively correlated with the average angle and the maximum contact force of metacarpophalangeal joints. Conclusions Reducing the amplitude of thumb movement to avoid thumb hyperextension or flexion, or reducing the frequency of using mobile phones, or reducing the force of operating mobile phones, can reduce the friction between flexor tendon and tendon sheath of thumb and bone fiber duct, as well as the mutual squeezing force to some extent, thus reducing the formation of thumb stenosing tenosynovitis.

Abstract:Objective To evaluate the test-retest reliability of electromyography (EMG) normalization in patients with knee osteoarthritis by the standard isometric contraction (SIC) and maximum voluntary isometric contraction (MVIC ) tests. Methods For patients with knee osteoarthritis, the EMG data in gluteus maximus, semitendinosus, rectus femoris, lateralis femoris, tibialis anterior, lateral gastrocnemius and soleus of their affected legs during jogging, SIC tests and MVIC tests were collected using the wireless EMG system. Intra-class correlation coefficients (ICC) with 95% confidence intervals were used to assess the test-retest reliability. Results For patients with knee osteoarthritis, the test-retest reliability of all 7 muscles was good during SIC tests, but the test-retest reliability was high for 2 muscles and moderate for 5 muscles during MVIC tests. The test-retest reliability of all 7 muscles normalized by SIC was higher than that normalized by MVIC, and the test-retest reliability of rectus femoris normalized by SIC was significantly higher than that normalized by MVIC. Conclusions For patients with knee osteoarthritis, SIC is a more reliable EMG normalization method than MVIC, and it has good promotion potential in clinic.

Abstract:Objective To study the effect of channel bend number and length on foam stability of varicose vein foam sclerotherapy. Methods Three groups of experiments were set up: experimental group 1 with different channel turns (channel turn of subgroup A, B, C was 1, 2, 3, respectively), experimental group 2 ( control group) with different channel total lengths ( total length of subgroup A, B, C was 2, 6, 10, respectively), experimental group 3 with different channel length ratios (ratio of long and short sides for subgroup A, B, C was 1 ∶1, 5 ∶1, 9 ∶1, respectively). A 5 mL syringe was used, the liquid-gas ratio was 1 ∶4, and the Tessari method of CO2 and air was used to prepare foam experiments at room temperature. The whole process of experiments on each group was photographed, and the experiment was repeated 5 times. Data such as water separation time, half-life, and water separation rate curve were obtained by video playback. Results In experimental group 2, the water removal rate of CO2 foam was 40% and 80% , and there were significant differences between subgroup A, subgroup B and subgroup C. In air foam, there is a significant difference between subgroup B and subgroup A with a water separation rate of 20% and 50% ; for all water separation rates, subgroup C and subgroup A had a significant difference. The total length of the channel had a more significant impact on the CO2 foam. The longer the total length of the channel, the more stable the foam would be. Compared with control group, the CO2 foam in experimental group 1 had a significantly higher water separation rate curve than that in the control group, while the air foam overlapped and crossed, and the difference was not obvious. Compared with the control group, the curve of the CO2 foam in experimental group 3 was significantly higher than that in control group, while the air foam was only significantly higher than that in control group when the water separation reached 100% . The influence of the channel length ratio was more obvious in CO2 foam. The half-life had a greater impact in CO2 foam. Conclusions The number of channel turns used to prepare the foam enhances stability of the foam. The increase in total length of the channel has a positive effect on stability of the foam, and the ratio of the channel length has a greater influence on stability of the foam. The results have certain significance for clinical preparation of foams and the stability research of other foams.

Abstract:Objective To study the effect of geometric parameters of micro-texture on the surface of staples in gastrointestinal microenvironment on extracellular fluid velocity and wall shear force, so as to provide theoretical references for promotion of the textured surface of staples on cell adhesion. Methods The micro-texture structure on the surface of staples was introduced into the bottom surface of flat plate flow chamber. The twodimensional ( 2D ) model of flat plate flow chamber was established by ANSYS fluent and meshed. In gastrointestinal microenvironment, the extracellular velocity and wall shear force of flat plate flow chamber with different height, side length and spacing parameters were simulated, and the data were processed and analyzed. Results The introduction of micro-texture on the surface of staples enhanced the flow velocity in plate flow chamber, and the appropriate geometric parameters of micro-texture could increase wall shear force at the microridge of micro-texture. The extracellular fluid velocity in micro-pits was low and vortices would be formed. The increase in micro-texture height, spacing and the decrease in side length could enhance the intensity of vortices in micro-pits. Conclusions The extracellular fluid velocity and wall shear force can be changed by controlling parameters of micro-texture, thus promote the adhesion of cells.

Abstract:Objective To analyze the stress distribution and deformation of vaginas, broad ligament (BL), round ligament (RL) under different uterine loads (abdominal pressure and uterine weight) after radical trachelectomy (RT) by finite element method, and obtain the sensitivity of BL, RL and vaginas to changes in uterine loads. Methods The three-dimensional ( 3D) geometric models of the posterior uterus, BL, RL and vagina were established and imported into ABAQUS software. After the constraints were set and the loads were applied, the stress and deformation of each part were calculated. Results The stress and displacement of BL and RL increased in different degrees after the RT operation. The stress and deformation of BL, RL and vagina increased with the increase of uterine load. The deformation and stress of BL were mainly distributed in the middle and lower part (with abdominal pressure changing) or the middle and upper part (with uterine weight changing). The stress and deformation of RL were mainly distributed in the middle and lower part, and the stress and deformation of vagina were mainly distributed in the middle and upper part. When abdominal pressure and uterine weight changed alone or together, the vaginal stress and its sensitivity to load changes were the greatest, and the displacement of BL and its sensitivity to load change were the greatest. The order of the total stress and deformation was slightly different due to different load conditions, and the influence of uterine weight on ligaments and vagina was more significant than that of abdominal pressure. Conclusions The results are consistent with clinical data, and can provide guidance for clinical surgical plan optimization and pathogenesis exploration.

Abstract:Type 2 diabetic osteoporosis ( T2DOP) is a musculoskeletal system complication caused by type 2 diabetes (T2D), which is characterized by bone mass reduction, bone microstructure damage, bone strength reduction and increased fracture risk. T2DOP is asymptomatic in the early stage with complex pathogenesis and limited diagnostic method. Patients have high disability and mortality rates. At present, T2DOP is mainly treated with anti-diabetic and anti-osteoporosis medications. In this review, the characteristics, pathogenesis, diagnosis and treatment of T2DOP were summarized, and the future direction of T2DOP treatment was discussed to reduce the bone fracture risk.

Abstract:The changes in spinal cord injury are very complex. It is difficult for animal models to accurately simulate the injury environment and measure the biomechanical properties of local tissues, while the finite element model can analyze the stress and strain distributions of spinal cord tissues, thereby providing a more efficient and ethical approach to pathological research and treatment of spinal cord injury from the biomechanical perspective. At present, the finite element model has been widely used and complemented with animal experimental models. In this study, the research progress of finite element analysis in spinal cord injury was reviewed, and the research status of finite element analysis in spinal cord ontology modeling, biomechanical behavior of spinal cord injury and its clinical application was classified and summarized, so as to provide more comprehensive theoretical references for spinal cord injury in clinic.

Abstract:The maintenance of bone structure integrity and bone mass requires a certain amount of mechanical stimulation. Studies have shown that mechanical stimulation can participate in bone remodeling processes by regulating various regulatory factors such as hormones, transcription factors, and signaling molecules. Mechanical stimulation plays a crucial role in bone remodeling by regulating the expression of microRNAs (miRNAs). However, the role and mechanism of miRNAs regulated by mechanical stimuli in bone remodeling are not fully understood. This review summarized the role and mechanism of miRNAs regulated by mechanical stimuli in bone remodeling, and their potential applications in the treatment of osteoporosis were emphasized as well.