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    • Evaluation of microstructure mechanical behavior of proximal femur based on MRI biomechanical modeling
    晨晨 无 霍 , 海胜 杨
    Adopted date: May 07,2024
    [Abstract](3) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Objective Establish and validate a biomechanical modeling method based on micro-magnetic resonance imaging (μMRI) and microstructure segmentation to noninvasively assess microstructural behavior of the proximal femur. Methods Firstly, μMRI images were obtained for the femoral samples, and bone microstructures were segmented through regionized image processing to create the μMRI finite element model (μMRI-FEM). Finite element analysis was performed utilizing a lateral fall posture simulation, and stress and strain results were calculated. Secondly, the accuracy of μMRI image segmentation of bone microstructure was verified using micro-computed tomography (μCT), and the accuracy of μMRI FEM calculation results was verified using a finite element model constructed based on μCT (μCT-FEM). Finally, simulated lateral fall posture, the accuracy of bone surface strain calculated by μMRI-FEM was verified through strain gauge measurements in vitro mechanical loading experiments. Results The bone microstructure parameters BV/TV calculated by μMRI and μCT were significantly correlated (r=0.89, p<0.05). The maximum/minimum principal stress/principal strain percentile results calculated by μMRI-FEM and μCT-FEM were highly correlated (R2>0.9). Moreover, the strain results calculated by μMRI-FEM were highly correlated with the strain results measured by mechanical experiments (R2=0.82). Conclusions The micro finite element model based on μMRI segmentation of bone microstructure can accurately characterize the micro mechanical behavior of the proximal femur, which provided an important tool for non-invasive assessment of hip femur microstructure degeneration and osteoporosis fracture risk in vivo.
    Progress in the biomedical of viscoelastic tunable composite hydrogel based on dynamic covalent bonds
    ZHANG Siqi , ZHOU Yvru , LIU Ran , WU Xiaogang , WANG Yanqin , CHEN Weiyi
    Adopted date: May 06,2024
    [Abstract](4) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Hydrogels possess good biocompatibility and mechanical properties similar to those of natural biological tissuessimilar mechanical properties to natural biological tissues，and have been widely used in biomedical fields. With the development of biomechanics，more and more researchers have found that the viscoelastic tunable composite hydrogels constructed based on dynamic covalent bonds ，with its superior biomechanical properties and stimulus responsiveness，can better simulate the viscoelastic mechanical properties of biological tissues and natural extracellular matrix (extracellular matrix， ECM) over time due to their superior biomechanical properties and stimulus responsiveness. This paper summarizes in detail the applications of viscoelastic tunable composite hydrogels constructed based on different types of dynamic covalent bonds (such as imide bonds，disulfide bonds，borate ester bonds，etc.) in the fields of regulating cell function，affecting tissue regeneration and repair，as well asand drug delivery，and presents the challenges and opportunities for future research.
    A Biomechanic Study of Different Healing Stages after Elbow Posterior Capsule Injury
    Wang Fang , Tian Botian , Li Mingxin , Hu Jun , Zhou Mingze
    Adopted date: May 06,2024
    [Abstract](13) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Objective To evaluate the mechanical behavior of elbow internal soft tissue at different healing stages of posterior capsular injury. Methods A finite element model of the elbow joint, including muscle activation behavior, was established to simulate the elbow flexion at no injury and 2, 4, 6, and 8 weeks after posterior capsule injury. The von Mises effective stress variation of articular capsule, ulnar cartilage and ligaments were analyzed. Results At no injury and 2, 4, 6 and 8 weeks, the stress of the articular capsule at 60° flexion were 8.23 MPa, 7.87 MPa, 8.27 MPa, 8.99 MPa and 10.5 MPa, respectively. When elbow flexion angle was 30°, ulnar cartilage stress increased by 13.0%, 28.3%, 41.3% and 43.5% at 2, 4, 6 and 8 weeks, respectively, compared with no injury. At 4 weeks, compared with 2 weeks, the stress of the radial collateral ligament at 15°, 30°, 45°, 60° and 75° was reduced by 12.5%, 22.2%, 13.6%, 3.2% and 10.6%, respectively. Conclusion The results provide theoretical basis for the prevention and treatment of capsular contracture and the development of rehabilitation AIDS.
    Astaxanthin repairs pressure injury by alleviating oxidative stress and inflammation
    Chen Yang , Ma Xinrun , Wang Yonghui , Gao Bei , Xu Zhenrong , Gao Yanhong
    Adopted date: May 06,2024
    [Abstract](5) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Objective To explore the effects of astaxanthin on pressure injury wounds. Methods ①In vitro experiment: Fibroblasts were treated with different concentrations of astaxanthin and their proliferation activity was detected by CCK-8 assay. Subsequently, fibroblasts were induced by hypoxia/reoxygenation, and the optimal concentration of astaxanthin was administered. Then the intracellular ROS level was detected by DHE fluorescent probes and the level of TNF-α, IL-1β, IL-6, IL-10, TGF-β was evaluated by RT qPCR. ②In vivo experiment: Two circular magnets (12 mm × 5 mm, 2.4 g, 2000 Gs) were symmetrically adsorbed on both sides of the mice skin for 5 hours. Subsequently, equal amounts of physiological saline, low-dose astaxanthin (10 mg/kg), and high-dose astaxanthin (20 mg/kg) were administered by gavage in groups. Wound images were taken regularly. After 7 days of treatment, wound healing rates were counted and wound tissues were collected for histopathological staining. Results In vitro, the fluorescence intensity of DHE in the astaxanthin groups were reduced dramatically. The relative mRNA expression level of TNF-α, IL-1β, IL-6 in the astaxanthin group declined, and the level of TGF-β and IL-10 mRNA increased significantly. The difference was statistically significant (P<0.05). In vivo, the wound healing rate and the level of TGF-β, IL-10 in high-dose astaxanthin group rose significantly. The ROS content and the level of TNF-α, IL-1β and IL-6 dropped markedly in astaxanthin groups. The difference was statistically significant (P<0.05). Conclusion These results indicate that astaxanthin can alleviate oxidative stress, mitigate inflammation, exerting a protective effect on damaged fibroblasts and pressure injury wounds.
    Mechanical Ventilation-Induced Airway Collapse Due to Abnormal Mechanical Behaviors of Airway Smooth Muscle Cells: A Review
    Luo Mingzhi , Zhang Xiangrong , Sun Changyu , Zhong Jiayuan , Wang Chunhong , Gu Rong , Ni Kai , DENG LINHONG
    Adopted date: April 30,2024
    [Abstract](15) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Mechanical ventilation (MV) provides life support for critically ill respiratory patients, but in the meantime can cause fatal lung injury (VILI), and the latter remains a major challenge in respiratory and critical care medicine because the pathological mechanism has not been fully elucidated. Recently, it has been reported that in the lung with VILI there exists airway collapse at multi-sites of an individual airway, which can not be explained by traditional airway collapse models. It has also been shown that under MV conditions airway smooth muscle cells (ASMC) exhibited abnormal mechanical behaviors, accompanied by regulation of Piezo1 expression and endoplasmic reticulum stress. These reports suggest that MV-induced mechanical abnormality (e.g., hyperresponsiveness or fluidization) ASMC may cause airway collapse and thereby lead to VILI. Therefore, by studying the MV-induced changes of ASMC mechanical behaviors and their relationship with airway collapse in lung injury, as well as the related mechanochemical signal coupling process, it is expected from the cell mechanics perspective to reveal a novel mechanism of MV-associated airway collapse and lung injury. In this review, we first described the phenomenon of airway collapse during MV, then focused on the mechanical behaviors of ASMC under MV and related high stretch, especially the related mechanical-chemical coupling during these processes. Therefore, this article reviewed the recent research progress on airway collapse under MV, changes of ASMC mechanical behavior induced by MV, and related mechanical-chemical coupling mechanisms. These advances may provide novel insights for exploring roles of ASMC mechanical behavior abnormalities in the pathological mechanism of VILI, alternative targets of drug intervention for prevention and/or treatment of VILI as well as for optimizing the ventilation mode in clinical practice.
    Data-driven Inversion Of Hemodynamic Parameters For Combined Stenotic Left Coronary Artery Aneurysms
    Shi Zhengjia , Sun Lifang , Zhao Mingxuan , Ji Mengqiang , Shi Yulong , Sang Jianbing
    Adopted date: April 28,2024
    [Abstract](13) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Objective The aim of this study was to investigate the application of machine learning in the prediction of hemodynamic parameters in combined stenotic left coronary artery aneurysms. Methods This article first conducts parameterized modeling and simulation based on the geometric parameter range of combined stenosis left coronary artery aneurysm in clinical statistics. The obtained simulation data is used as the dataset, and two common machine learning models are constructed and trained for optimization to predict the two key hemodynamic parameters of wall shear stress and pressure. By comparing and analyzing the performance of these models on the training and testing sets, the accuracy of each model was evaluated, and the effectiveness of data-driven prediction of hemodynamic parameters for left coronary artery aneurysm with concomitant stenosis was verified. Results The effectiveness of machine learning methods in inverting hemodynamic parameters of aneurysms has been determined. In predicting wall shear stress, the trained deep learning model and random forest model achieved MSE、MAE and R2 of 0.0528, 0.0322, 0.9883, and 0.0782, 0.0463, and 0.9766, respectively. For pressure prediction, the accuracy of deep learning models and random forest models is comparable, with MSE、MAE and R2 of 4.67×10-6, 3×10-4, 0.9997, and 1.07×10-5, 5×10-4, and 0.9993, respectively. Conclusions Machine learning methods show high accuracy in predicting hemodynamic parameters in combined stenotic coronary artery aneurysm models, and the predictive accuracy of the model, computational efficiency, and the needs of the application scenarios need to be taken into account in machine learning prediction, so that the appropriate model can be selected according to the specific situation. This study has certain clinical significance, which helps doctors to more accurately evaluate the patient's condition and provides new ideas and methods for the diagnosis and treatment of cardiovascular diseases.
    Mechanical behaviors and microscopic mechanisms of the breakage of cell pseudopodia
    ZHANG Yi , YANG Mei , FANG Zhou , WANG Qianchun , LI Dechang , JI Baohua
    Adopted date: April 28,2024
    [Abstract](13) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Objective This study aims to elucidate the mechanisms of interface disruption between the actin filament and the membrane of cell pseudopodium that occurs during the breakage of the pseudopodium. Methods Time-lapse images of the behaviors of actin filament and membrane in the rupture process of cell pseudopodia were captured with confocal microscopy. A theoretical model of fracture of cylindrical interface was developed for analyzing the interface damage between actin filament and membrane in the breakage of cell pseudopodium. Molecular dynamics simulations were employed to simulate the breaking process of the cell pseudopodium, for comparison with the theoretical results. Finally, a finite element model considering the coupling of tensile-torsional deformation of actin filaments was developed to simulate torsional deformation of actin filaments under tension, both in the presence and absence of membrane. Results Our theoretical results indicated that there was an exponential relationship between the critical load for interface broken and the crack length. The critical load increases with the interfacial strength. The effect of the fiber diameter on the critical load depended upon the crack length, exhibiting different impacts for small and large crack lengths. Moreover, the finite element analysis suggested that the membrane substantially constrained the torsional movement when the actin filament was extended. Conclusions This study revealed the breaking process of cell pseudopodia and the mechanical mechanisms of the disruption of the interface between the actin filament and membrane. These results also shed useful light on the studies of cellular behaviors associated with pseudopodium breakage, such as the release of extracellular vesicles.
    Biomechanical Characteristics of INBONE II and INFINITY Artificial Ankle Joints
    WANG Chuang , ZHANG Xiaogang , ZHANG Yanwei , JIN Zhongmin
    Adopted date: April 26,2024
    [Abstract](12) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Objective Assessing the biomechanical differences of the artificial ankle joints of INBONE II and INFINITY after TAA to provide more scientific and individualized treatment options for patients. Methods Based on MSK MBD software AnyBody, a patient individualized TAA lower extremity MSK MBD model was established. Prediction of ankle joint contact force, ankle joint motion and contact characteristics of artificial ankle joint surface. Results The geometric shape of the articular surface of the artificial ankle has no significant effect on the ankle contact force, but it affects the range of motion and the contact characteristics of the articular surface. Compared to INBONE II, the coronal plane articular surface arc height of INFINITY is lower, with increased rotational mobility by 7.91% and 2.61%. The sagittal plane matching is lower, resulting in changes of 21.75%, 21.23%, and 49.26% in the range of motion. INFINITY exhibits lower matching, with corresponding reductions of 18.48%, 30.42%, and 26.36% in articular surface contact area. However, the center of pressure motion trajectory is concentrated on the medial side, avoiding edge contact stress concentration, reducing the risk of joint dislocation, and premature wear of the tibial component. Conclusion The smaller geometric constraints of the INFINITY artificial ankle joint demonstrate better biomechanical performance, promoting improved postoperative ankle joint functional recovery.
    Finite Element Analysis of Mechanical Response of Functional Gradient Material Total Ankle Prosthesis
    MA Jie , LI Yongsheng , CHENG Jing , WU Xiaogang , LING Jiangying , WEN Yunpeng
    Adopted date: April 26,2024
    [Abstract](11) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Objective To study the mechanical response of the distal tibial cancellous bone and the tibial prosthesis after the radial and axial functionally graded materials (FGM) were implanted into the ankle joint. ? Methods Using three functional gradient materials, titanium alloy-bioactive glass composite functional gradient material (FGM-I) , titanium alloy-ideal bone elastic composite functional gradient material (FGM-II) and a titanium alloy-hydroxylapatite composite functional gradient material (FGM-III) . A three-dimensional finite element model of total ankle arthroplasty was established, and a simulation software Abaqus was developed based on Fortran. By changing the volume fraction, the mechanical properties of the functional gradient tibial prosthesis were adjusted both axially and radially. To analyze the stress distribution of tibial component and cancellous bone after FGM axial tibial component and radial tibial component implantation in standing position. Results? Compared with ti-alloy tibial prosthesis, three kinds of FGM can effectively reduce the stress concentration on the tibial prosthesis, and the overall effect of FGM-III tibial prosthesis is better than that of FGM-I and FGM-II tibial prosthesis, the radial distribution of FGM can effectively reduce the maximum Von Mises stress of the prosthesis. For cancellous bone of tibia, three kinds of FGM radial tibial prostheses and FGM-III axial tibial prostheses can effectively increase the distal stress, thus relieving the stress occlusion on cancellous bone, FGM-III radial tibial prosthesis was the most effective in improving the stress level of cancellous bone. Conclusion? FGM ankle prosthesis can reduce the stress shielding effect and prolong the life of the prosthesis, which has a potential application prospect.
    Finite element analysis of the biomechanical effect of lateral wedge insole on foot and ankle
    杜 玮 瑾 , 陈 维毅 , 郭 媛
    Adopted date: April 25,2024
    [Abstract](18) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Lateral wedge insole (LWI) can improve lower limb alignment and relieve pain in patients with early to mid-stage knee osteoarthritis. However, its effect on biomechanics of foot and ankle remains to be elucidated. The aim of this study was to investigate the biomechanical effects of LWI on the internal tissues of the foot and ankle, including foot bones, joints, and ligaments. Methods The study developed and validated a three-dimensional finite element model of the foot-insole-ground and explored plantar pressure distributions, contact pressures on joints, and peak stresses on metatarsals and major ligaments in barefoot and insoles intervention models at three gait instants. Results The 5° LWI model reduced peak plantar pressure by 65.8% compared to the barefoot model. Insole interventions decreased the peak contact pressure at the cuneonavicular joint, but increased the peak contact pressure at the subtalar joint and peak stress at the fourth and fifth metatarsals. Conclusions This study quantitatively assessed the biomechanical effects of LWI on various parts of the foot and ankle, and suggested a design that could appropriately reduce the inclination angle of LWI at the fourth and fifth metatarsals.