International Journal for Numerical Methods in Biomedical Engineering最新文献

Atherosclerotic plaque formation alters local vascular geometry, leading to disturbed blood flow patterns. These geometric irregularities produce spatial heterogeneity in wall shear stress (WSS), which plays a critical role in endothelial dysfunction and early immune cell recruitment during atherogenesis. However, the dynamic effect of spatial heterogeneity of wall shear stress on endothelial-immune interactions remains unclear. A multiscale computational model that integrates hemodynamics, endothelial cell phenotype transitions, and immune responses was developed. The model is used to investigate endothelial cell (EC) phenotype transitions and immune cell dynamics under varying damage threshold (D_NO) conditions. Low-shear stress regions were found to expand with increasing D_NO. Nitric oxide (NO) production was decreased, leading to accelerated EC activation and death. Monocyte Chemoattractant Protein-1 (MCP-1) expression was elevated, and monocyte recruitment and differentiation were enhanced, resulting in a higher proportion of pro-inflammatory M1 macrophages. The model reproduced experimental observations and provided robust predictions under different D_NO scenarios. These results indicate that dynamic WSS drives EC state transitions and regulates immune cell recruitment and differentiation, providing a framework for studying vascular inflammation. Spatially heterogeneous WSS induces local NO depletion, which accelerates EC activation and death in low-shear stress regions, explaining focal endothelial dysfunction. EC injury further increases MCP-1 production, enhances monocyte recruitment, and promotes macrophage polarization toward a pro-inflammatory phenotype, demonstrating the ability of the model to capture flow-dependent vascular immune dynamics and inflammatory lesion development. This work provides mechanistic insight into the interplay between mechanical forces and vascular immune responses and may guide strategies for preventing endothelial injury and promoting anti-inflammatory therapy.

We present a comprehensive computational model to simulate the coupled dynamics of aqueous humor flow and heat transfer in the human eye. To manage the complexity of the model, we make significant efforts in meshing and efficient solution of the discrete problem using high-performance resources. The model accurately describes the dynamics of the aqueous humor in the anterior and posterior chambers and accounts for convective effects due to temperature variations. Results for fluid velocity, pressure, and temperature distribution are in good agreement with existing numerical results in the literature. Furthermore, the effects of postural changes and wall shear stress behavior are analyzed, providing new insights into the mechanical forces acting on ocular tissues. Overall, the present contribution provides a detailed three-dimensional simulation that enhances the understanding of ocular physiology and may contribute to further progress in clinical research and treatment optimization in ophthalmology.

Sacroiliac joints (SIJ) injury has been recognised as a crucial cause of low back pain (LBP), but investigations on SIJ are insufficient. The aim of this study was to reveal the mechanism of SIJ injury induced by different vibration conditions and body inclinations and thus to analyse the relationship between vibration and LBP. Based on whole-body finite element models, eight load cases were analysed, where the multi-axis vibration loading cases were closer to the typical vehicle environment. In addition, three different body inclinations were involved to analyse the effect of body inclinations on vibration transmission of SIJ. The results showed that the vertical vibration would induce larger loads on SIJ than the fore-and-aft vibration. Single-axis vibrations tended to cause large fore-and-aft loads of SIJ, and multi-axis vibrations tended to cause large vertical loads. For the three body inclinations, static loads on SIJ were minimal at 100° and dynamic loads were minimal at 110°, which indicated that the 100° inclination was a recommended sitting posture for occupational drivers to reduce their incidence of LBP. These findings might be helpful for understanding the association between different vibration conditions and LBP, and provide reasonable ergonomics recommendations for occupational drivers to reduce the incidence of LBP.

Bone remodeling refers to the physiological behavior of bone tissue changes with changes in the biomechanical environment. Researches of bone remodeling process are significant for bone tissue engineering. The use of numerical simulation technology is an important means to analyze the bone remodeling process. The research of computational methods can deeply reveal the growth law of bone tissue under external load and environmental effects. This work aims to develop the computational model using a meshless method, and simulate an evolution of the porous structure of trabecular bone. The main research objectives include: (1) proposing a novel bone remodeling model based on the radial point interpolation method (RPIM), which integrates the mechanical and biological aspects of bone remodeling; (2) analyzing the theoretical foundations of the meshless method, including the mechanical model driven by strain energy stimulation and the biological model regulated by cell growth, death, and proliferation. This work and the presented cases are limited to two-dimensional areas. The results demonstrate that the proposed bone remodeling model can reflect the bone remodeling process and reflect the dynamic changes inside the bone throughout its life cycle. The developed computational algorithm is highly efficient, and can form the porous structure of trabecular bone through image fitting.

Poor long-term implant–bone fixation remains a significant clinical problem for Total Ankle Replacement (TAR). Recent advancements in metal additive manufacturing technology facilitate the development of porous lattice-structured implants. However, the optimal porous structure parameter, especially porosity, for the designing of porous implants for TAR remains ambiguous. The objective of the present study is to design porous diamond-structured tibial implant for TAR using macro–micro FE and Machine Learning (ML) based approach to enhance biomechanical and osseointegration performance. Four porous diamond architectures were designed with porosity varying from 50% to 80%. The study entails the macro-microscale FE modelling of four different porous diamond structured tibial implants (PDSTI) to assess the biomechanical performance and to perform bone ingrowth simulations using a physics based progressive mechanoregulatory tissue differentiation algorithm. ML models were used to predict the value of site-specific bone ingrowth, and the average value was compared between these PDSTI. ML models were accurately able to predict the site-specific bone ingrowth for each PDSTI. Bone ingrowth results revealed that the PDSTI at 70% porosity is more conducive to bone formation as well as better load transfer (less stress shielding) to the bone in comparison to a traditional solid implant. The lowest value of bone ingrowth was noted for the PDSTI at 80% porosity, indicating that large porosity is not suitable for bone ingrowth. The findings ultimately contribute to improving the clinical outcomes for TAR by reducing the risk of aseptic loosening.

The mechanical properties of spongy bone are a function of the tissue's microstructure including the strength and microarchitecture of the trabeculae. The thickness and number of trabeculae (morphological data) are the most important parameters that can indicate the porosity of tissue. Osteoporosis is known as a decrease in the thickness or loss of trabeculae that causes a reduction in the density and strength of bone. This research aims to model osteoporosis using cellular (lattice) structures and also presents mechanical relationships to predict tissue behavior during osteoporosis using morphological data for spongy tissue. Experimental trendlines (Young's modulus and relative density) are developed and equivalent lattice structures for osteoporotic spongy bone are presented using eight different types of unit cells such as cubic, hexagonal, tesseract, diamond, BCC, truncated cube, octahedral, and rhombic dodecahedron. Also, structural damage modes including trabeculae thinning, trabeculae elimination, and hybrid mode are implemented for determining the optimum geometrical characteristics of lattice structures for modeling osteoporosis. Comparison between normalized elastic moduli for unit cell structures indicates that the diamond unit cell exhibits less than 5% difference with experimental values. Also, for a reduction of relative density from 0.3 to 0.1 as a result of the hybrid damage mode, the normalized elastic moduli of the diamond numerical model and experimental result were reduced by about 0.013 and 0.0186, respectively. Finally, results show that among all the unit cell types, the diamond unit cell when used alongside the hybrid damage mode can predict the osteoporosis behavior of bone with the best accuracy.

In idiopathic pulmonary fibrosis (IPF), the juxtaposition of preserved regions and fibrotic areas creates heterogeneous lung mechanics and abnormal stress environments, which are hypothesized to activate mechanotransduction pathways and drive fibrosis progression. This study uses the “squishy ball lung” concept to quantify the potentially injurious mechanical stimuli arising from this heterogeneity. We developed a mechanical model that simulates the static inflation of an alveolus. This is described as a hyperelastic membrane with surface tension that is partially confined by springs representing fibrotic tissue. Finite element analysis (FEA) was used to assess the mechanical state under various confinement conditions. FEA revealed bulging deformation and significant meridian stress/strain peaks at transitions between confined and unconfined zones, which could potentially exceed safe physiological limits. To rigorously evaluate the predicted stress and strain environment, as well as its sensitivity to parameter uncertainty, such as material properties and the extent of confinement, we performed comprehensive uncertainty quantification (UQ) and quantitative sensitivity analysis (QSA). UQ confirmed the robustness of these localized stress peaks across parameter variations, while QSA identified the angle of confinement and spring stiffness as the primary determinants of peak stress magnitude. By quantifying these potentially injurious stress peaks, this study provides insights into the mechanical environment hypothesized to initiate mechanotransduction pathways in idiopathic pulmonary fibrosis (IPF), laying the groundwork for future studies that incorporate biological responses such as growth and remodeling.