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Therapeutic Effect of Targeted Deployment Filling Coils in the Treatment of Intracranial Aneurysms. 靶向部署填充线圈在治疗颅内动脉瘤中的疗效。
IF 2.2 4区 医学 Q3 ENGINEERING, BIOMEDICAL Pub Date : 2024-11-06 DOI: 10.1002/cnm.3880
Xiaoyu Ren, Bin Gao, Wangsheng Lu, Guangming Yang, Yunjie Wang, Yin Yin

Endovascular coil embolization is the primary therapeutic modality for intracranial aneurysms. Substantial reports have been found regarding the coil packing density and inflow jet. However, the hemodynamic effect of increasing the rate of tamponade in the inflow jet area within the aneurysm remains unclear. In this study, individualized geometries of six intracranial aneurysms were recruited: all six aneurysms were located in the internal carotid artery. Two groups were created by changing the position and orientation of the microcatheter for the release of the third segment of the filling coil. The finite element method was used to simulate coil deployment. Computational fluid dynamics was used to characterize hemodynamics in post-deployment aneurysms. The parameters evaluated included velocity reduction, wall shear stress (WSS), low WSS (LWSS), relative residence time (RRT), flow kinetic energy in the neck region of the aneurysms, and residual flow volume (RFV) in the aneurysms. At the peak time (t = 0.17 s), the targeted deployment group has similar proportion of LWSS area to conventional deployment groups: targeted 78.13% ± 34.59% versus normal 74.20% ± 36.94% (mean ± SD, p = 0.583). The targeted deployment group has a higher RRT area (targeted 16.84% ± 5.58% vs. normal 6.42% ± 5.67% [mean ± SD, p = 0.009]), smaller flow kinetic energy (targeted 9.43 ± 4.33 vs. normal 16.23 ± 5.92 [mean ± SD, p = 0.047]), and a larger RFV in the aneurysms (targeted 35.97 ± 24.35 mm3 vs. normal 25.80 ± 18.94 mm3 [mean ± SD, p = 0.44]). Inflow jets play an important role in the treatment of aneurysms, and deploying filling coils in accordance with inflow jets may result in a better hemodynamic environment.

血管内线圈栓塞是治疗颅内动脉瘤的主要方法。有关线圈填塞密度和流入喷射的报道很多。然而,增加动脉瘤内流入射流区域的填塞率对血液动力学的影响仍不清楚。在这项研究中,研究人员采集了六个颅内动脉瘤的个性化几何形状:所有六个动脉瘤都位于颈内动脉。通过改变微导管的位置和方向来释放填充线圈的第三段,创建了两组。使用有限元法模拟线圈的展开。计算流体动力学用于描述部署后动脉瘤的血液动力学特征。评估的参数包括速度降低、壁切应力(WSS)、低WSS(LWSS)、相对停留时间(RRT)、动脉瘤颈部的流动动能以及动脉瘤内的残余血流量(RFV)。在峰值时间(t = 0.17 秒),靶向部署组的 LWSS 面积比例与常规部署组相似:靶向 78.13% ± 34.59% 对常规 74.20% ± 36.94%(平均值 ± SD,P = 0.583)。靶向部署组的 RRT 面积更大(靶向 16.84% ± 5.58% vs. 正常 6.42% ± 5.67% [平均值 ± 标准差,p = 0.009]),流动动能更小(靶向 9.43 ± 4.33 vs. 正常值 16.23 ± 5.92 [平均值±标准差,p = 0.047]),动脉瘤中的 RFV 较大(目标值 35.97 ± 24.35 mm3 vs. 正常值 25.80 ± 18.94 mm3 [平均值±标准差,p = 0.44])。血流喷射在动脉瘤的治疗中起着重要作用,根据血流喷射部署填充线圈可能会带来更好的血液动力学环境。
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引用次数: 0
Modeling Fibrin Accumulation on Flow-Diverting Devices for Intracranial Aneurysms. 颅内动脉瘤分流装置上的纤维蛋白聚集模型。
IF 2.2 4区 医学 Q3 ENGINEERING, BIOMEDICAL Pub Date : 2024-11-05 DOI: 10.1002/cnm.3883
Juan R Cebral, Fernando Mut, Rainald Löhner, Laurel Marsh, Alireza Chitsaz, Cem Bilgin, Esref Bayraktar, David Kallmes, Ramanathan Kadirvel

The mechanisms leading to aneurysm occlusion after treatment with flow-diverting devices are not fully understood. Flow modification induces thrombus formation within the aneurysm cavity, but fibrin can simultaneously accumulate and cover the device scaffold, leading to further flow modification. However, the interplay and relative importance of these processes are not clearly understood. A computational model of fibrin accumulation and flow modification after flow diversion treatment of cerebral aneurysms has been developed under the guidance of in vitro experiments and observations. The model is based on the loose coupling of flow and transport-reaction equations that are solved separately by independent codes. Interaction or reactive terms account for thrombin production from prothrombin stimulated by thrombogenic metallic wires and inhibition by antithrombin as well as fibrin production from fibrinogen stimulated by thrombin and flow shear stress, and fibrin adhesion to device wires and already attached fibrin. The computational model was demonstrated and tested on idealized vessel and aneurysm geometries. The model was able to reproduce the salient features of fibrin accumulation after the deployment of flow-diverting devices in idealized in vitro models of cerebral aneurysms. Namely, fibrin production in regions of high shear stress, initial accumulation at the inflow zone, and progressive occlusion of the device and corresponding flow attenuation. The computational model linking flow dynamics to fibrin production, transport, and adhesion can be used to investigate and better understand the effects that lead to fibrin accumulation and the resulting aneurysm inflow reduction and intra-aneurysmal flow modulation.

使用分流装置治疗后导致动脉瘤闭塞的机制尚未完全明了。血流改变会诱导动脉瘤腔内血栓形成,但纤维蛋白会同时积聚并覆盖装置支架,导致血流进一步改变。然而,人们对这些过程的相互作用和相对重要性并不清楚。在体外实验和观察的指导下,我们建立了脑动脉瘤血流分流治疗后纤维蛋白积聚和血流改变的计算模型。该模型基于流动和传输-反应方程的松散耦合,这些方程由独立的代码分别求解。相互作用或反应项解释了凝血酶原在血栓形成金属丝的刺激下产生凝血酶和抗凝血酶的抑制作用,以及纤维蛋白原在凝血酶和流动剪应力的刺激下产生纤维蛋白,以及纤维蛋白粘附到装置金属丝和已经附着的纤维蛋白上。计算模型在理想化的血管和动脉瘤几何形状上进行了演示和测试。该模型能够再现在理想化的体外脑动脉瘤模型中部署导流装置后纤维蛋白积聚的显著特点。即,在高剪切应力区域产生纤维蛋白、在流入区初始积聚、装置逐渐闭塞以及相应的血流衰减。将流动动力学与纤维蛋白的产生、运输和粘附联系起来的计算模型可用于研究和更好地理解导致纤维蛋白积聚的效应,以及由此引起的动脉瘤流入量减少和动脉瘤内血流调节。
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引用次数: 0
Model order reduction and sensitivity analysis for complex heat transfer simulations inside the human eyeball. 针对人眼球内部复杂传热模拟的模型阶数缩减和敏感性分析。
IF 2.2 4区 医学 Q3 ENGINEERING, BIOMEDICAL Pub Date : 2024-11-01 Epub Date: 2024-09-09 DOI: 10.1002/cnm.3864
Thomas Saigre, Christophe Prud'homme, Marcela Szopos

Heat transfer in the human eyeball, a complex organ, is significantly influenced by various pathophysiological and external parameters. Particularly, heat transfer critically affects fluid behavior within the eye and ocular drug delivery processes. Overcoming the challenges of experimental analysis, this study introduces a comprehensive three-dimensional mathematical and computational model to simulate the heat transfer in a realistic geometry. Our work includes an extensive sensitivity analysis to address uncertainties and delineate the impact of different variables on heat distribution in ocular tissues. To manage the model's complexity, we employed a very fast model reduction technique with certified sharp error bounds, ensuring computational efficiency without compromising accuracy. Our results demonstrate remarkable consistency with experimental observations and align closely with existing numerical findings in the literature. Crucially, our findings underscore the significant role of blood flow and environmental conditions, particularly in the eye's internal tissues. Clinically, this model offers a promising tool for examining the temperature-related effects of various therapeutic interventions on the eye. Such insights are invaluable for optimizing treatment strategies in ophthalmology.

人类眼球是一个复杂的器官,其传热受到各种病理生理和外部参数的显著影响。特别是,热传递对眼球内的流体行为和眼部给药过程有着至关重要的影响。本研究克服了实验分析的挑战,引入了一个全面的三维数学和计算模型,以模拟真实几何形状中的热传递。我们的工作包括广泛的敏感性分析,以解决不确定性问题,并确定不同变量对眼部组织热分布的影响。为了控制模型的复杂性,我们采用了一种非常快速的模型还原技术,该技术具有经过认证的尖锐误差边界,在确保计算效率的同时不影响精度。我们的结果表明与实验观测结果非常一致,并与现有文献中的数值研究结果密切吻合。最重要的是,我们的发现强调了血流和环境条件的重要作用,尤其是在眼球内部组织中。在临床上,该模型为研究各种治疗干预措施对眼部的温度相关影响提供了一种很有前景的工具。这些见解对于优化眼科治疗策略非常宝贵。
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引用次数: 0
Fluid-structure interaction analysis of a healthy aortic valve and its surrounding haemodynamics. 健康主动脉瓣及其周围血流动力学的流体-结构相互作用分析。
IF 2.2 4区 医学 Q3 ENGINEERING, BIOMEDICAL Pub Date : 2024-11-01 Epub Date: 2024-08-29 DOI: 10.1002/cnm.3865
Zhongjie Yin, Chlöe Armour, Harkamaljot Kandail, Declan P O'Regan, Toufan Bahrami, Saeed Mirsadraee, Selene Pirola, Xiao Yun Xu

The opening and closing dynamics of the aortic valve (AV) has a strong influence on haemodynamics in the aortic root, and both play a pivotal role in maintaining normal physiological functions of the valve. The aim of this study was to establish a subject-specific fluid-structure interaction (FSI) workflow capable of simulating the motion of a tricuspid healthy valve and the surrounding haemodynamics under physiologically realistic conditions. A subject-specific aortic root was reconstructed from magnetic resonance (MR) images acquired from a healthy volunteer, whilst the valve leaflets were built using a parametric model fitted to the subject-specific aortic root geometry. The material behaviour of the leaflets was described using the isotropic hyperelastic Ogden model, and subject-specific boundary conditions were derived from 4D-flow MR imaging (4D-MRI). Strongly coupled FSI simulations were performed using a finite volume-based boundary conforming method implemented in FlowVision. Our FSI model was able to simulate the opening and closing of the AV throughout the entire cardiac cycle. Comparisons of simulation results with 4D-MRI showed a good agreement in key haemodynamic parameters, with stroke volume differing by 7.5% and the maximum jet velocity differing by less than 1%. Detailed analysis of wall shear stress (WSS) on the leaflets revealed much higher WSS on the ventricular side than the aortic side and different spatial patterns amongst the three leaflets.

主动脉瓣(AV)的开闭动力学对主动脉根部的血流动力学有很大影响,两者在维持瓣膜正常生理功能方面起着关键作用。本研究的目的是建立一个特定受试者的流体-结构相互作用(FSI)工作流程,该流程能够在生理真实条件下模拟三尖瓣健康瓣膜的运动和周围血流动力学。根据从健康志愿者身上获取的磁共振(MR)图像重建了特定受试者的主动脉根部,同时使用与特定受试者主动脉根部几何形状相匹配的参数模型构建了瓣叶。瓣叶的材料行为使用各向同性超弹性奥格登模型进行描述,特定受试者的边界条件则来自四维流磁共振成像(4D-MRI)。强耦合 FSI 模拟是使用 FlowVision 中实施的基于有限体积的边界符合方法进行的。我们的 FSI 模型能够模拟整个心动周期中房室的开放和关闭。模拟结果与 4D-MRI 的比较显示,两者在关键血流动力学参数上具有良好的一致性,每搏量相差 7.5%,最大射流速度相差不到 1%。对瓣叶壁剪应力(WSS)的详细分析显示,心室一侧的 WSS 远高于主动脉一侧,而且三个瓣叶之间的空间模式不同。
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引用次数: 0
A cluster-based incremental potential approach for reduced order homogenization of bones. 基于集群的增量势能法,用于骨骼的降阶均质化。
IF 2.2 4区 医学 Q3 ENGINEERING, BIOMEDICAL Pub Date : 2024-11-01 Epub Date: 2024-10-07 DOI: 10.1002/cnm.3872
Xiaozhe Ju, Chunli Xu, Yangjian Xu, Lihua Liang, Junbo Liang, Weiming Tao

We develop a cluster-based model order reduction (called C-pRBMOR) approach for efficient homogenization of bones, compatible with a large variety of generalized standard material (GSM) models. To this end, the pRBMOR approach based on a mixed incremental potential formulation is extended to a clustered version for a significantly improved computational efficiency. The microscopic modeling of bones falls into a mixed incremental class of the GSM framework, originating from two potentials. An offline phase of the C-pRBMOR approach includes both a clustering analysis spatially decomposing the micro-domain within an RVE and a space-time decomposition of the microscopic plastic strain fields. A comparative study on two different clustering approaches and two algorithms for mode identification is additionally conducted. For an online analysis, a cluster-enhanced version of evolution equations for the reduced variables is derived from an effective incremental variational formulation, rendering a very small set of nonlinear equations to be numerically solved. Several numerical examples show the effectiveness of the C-pRBMOR approach. A striking acceleration rate beyond 104 against conventional FE computations and that beyond 103 against the original pRBMOR approach are observed.

我们开发了一种基于聚类的模型阶次缩减方法(称为 C-pRBMOR),用于高效地对骨骼进行均质化,该方法与大量通用标准材料(GSM)模型兼容。为此,我们将基于混合增量势公式的 pRBMOR 方法扩展为聚类版本,以显著提高计算效率。骨骼的微观建模属于 GSM 框架的混合增量类,源于两种势能。C-pRBMOR 方法的离线阶段包括在 RVE 中对微域进行空间分解的聚类分析和对微观塑性应变场进行时空分解。此外,还对两种不同的聚类方法和两种模式识别算法进行了比较研究。为了进行在线分析,从有效的增量变分公式中导出了一个群集增强版的减变量演化方程,使得需要数值求解的非线性方程组非常小。几个数值示例显示了 C-pRBMOR 方法的有效性。与传统的 FE 计算相比,C-pRBMOR 方法的加速率超过了 104,与原始的 pRBMOR 方法相比,加速率超过了 103。
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引用次数: 0
A comparison of machine learning methods for recovering noisy and missing 4D flow MRI data. 恢复噪声和缺失四维血流 MRI 数据的机器学习方法比较。
IF 2.2 4区 医学 Q3 ENGINEERING, BIOMEDICAL Pub Date : 2024-11-01 Epub Date: 2024-08-28 DOI: 10.1002/cnm.3858
Hunor Csala, Omid Amili, Roshan M D'Souza, Amirhossein Arzani

Experimental blood flow measurement techniques are invaluable for a better understanding of cardiovascular disease formation, progression, and treatment. One of the emerging methods is time-resolved three-dimensional phase-contrast magnetic resonance imaging (4D flow MRI), which enables noninvasive time-dependent velocity measurements within large vessels. However, several limitations hinder the usability of 4D flow MRI and other experimental methods for quantitative hemodynamics analysis. These mainly include measurement noise, corrupt or missing data, low spatiotemporal resolution, and other artifacts. Traditional filtering is routinely applied for denoising experimental blood flow data without any detailed discussion on why it is preferred over other methods. In this study, filtering is compared to different singular value decomposition (SVD)-based machine learning and autoencoder-type deep learning methods for denoising and filling in missing data (imputation). An artificially corrupted and voxelized computational fluid dynamics (CFD) simulation as well as in vitro 4D flow MRI data are used to test the methods. SVD-based algorithms achieve excellent results for the idealized case but severely struggle when applied to in vitro data. The autoencoders are shown to be versatile and applicable to all investigated cases. For denoising, the in vitro 4D flow MRI data, the denoising autoencoder (DAE), and the Noise2Noise (N2N) autoencoder produced better reconstructions than filtering both qualitatively and quantitatively. Deep learning methods such as N2N can result in noise-free velocity fields even though they did not use clean data during training. This work presents one of the first comprehensive assessments and comparisons of various classical and modern machine-learning methods for enhancing corrupt cardiovascular flow data in diseased arteries for both synthetic and experimental test cases.

实验性血流测量技术对于更好地了解心血管疾病的形成、发展和治疗非常重要。新出现的方法之一是时间分辨三维相位对比磁共振成像(4D 流磁共振成像),它可以对大血管内的速度进行无创的时间依赖性测量。然而,4D 流量磁共振成像和其他实验方法在定量血液动力学分析中的可用性受到一些限制。这些限制主要包括测量噪声、数据损坏或缺失、时空分辨率低以及其他伪影。传统的滤波方法通常用于对实验血流数据进行去噪,但没有详细讨论为什么滤波方法优于其他方法。本研究将滤波与不同的基于奇异值分解(SVD)的机器学习方法和自动编码器型深度学习方法进行比较,以进行去噪和填补缺失数据(估算)。测试方法使用了人为损坏和体素化的计算流体动力学(CFD)模拟以及体外 4D 流磁共振成像数据。基于 SVD 的算法在理想化情况下取得了极佳的结果,但在应用于体外数据时却非常吃力。结果表明,自动编码器用途广泛,适用于所有研究案例。在体外 4D 流磁共振成像数据的去噪方面,去噪自动编码器(DAE)和噪声2噪声(N2N)自动编码器在定性和定量方面都比滤波产生了更好的重建效果。N2N 等深度学习方法即使在训练过程中没有使用干净的数据,也能得到无噪声的速度场。这项研究首次对各种经典和现代机器学习方法进行了全面评估和比较,以增强病变动脉中合成和实验测试案例中损坏的心血管血流数据。
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引用次数: 0
Impacts of post-operation loading and fixation implant on the healing process of fractured tibia. 手术后加载和固定植入物对胫骨骨折愈合过程的影响。
IF 2.2 4区 医学 Q3 ENGINEERING, BIOMEDICAL Pub Date : 2024-11-01 Epub Date: 2024-09-25 DOI: 10.1002/cnm.3870
Shima Doorandish Yazdi, Dorna Hedayat, Amir Asadi, Ali Abouei Mehrizi

Healing of tibia demonstrates a complex mechanobiological process as it is stimulated by the major factor of strains applied by body weight. The effect of screw heads and bodies as well as their pressure distribution is often overlooked. Hence, effective mechanical conditions of the healing process of tibia can be categorized into the material of the plate and screws, post-operation loadings, and screw type and pressure. In this paper, a mathematical biodegradation model was used to simulate the PGF/PLA plate-screw device over 8 weeks. The effect of different post-operation loading patterns was studied for both locking and non-locking screws. The aim was to reach the best configuration for the most achievable healing using FEA by computing the healing pattern, trend, and efficiency with the mechano-regulation theory based on deviatoric strain. The biodegradation process of the plate and screws resulted in 82% molecular weight loss and 1.05 GPa decrease in Young's modulus during 8 weeks. The healing efficiency of the cases ranged from 4.72% to 14.75% in the first week and 18.64% to 63.05% in the eighth week. Finally, an optimal case was achieved by considering the prevention of muscle erosion, bone density reduction, and nonunion, according to the obtained results.

胫骨的愈合是一个复杂的机械生物学过程,因为它受到体重所产生的应变这一主要因素的刺激。螺钉头和螺钉体及其压力分布的影响往往被忽视。因此,胫骨愈合过程的有效机械条件可分为钢板和螺钉的材料、手术后的负荷以及螺钉的类型和压力。本文使用数学生物降解模型模拟了 PGF/PLA 钢板-螺钉装置在 8 周内的情况。研究了锁定螺钉和非锁定螺钉不同操作后加载模式的影响。其目的是利用有限元分析,通过基于偏离应变的机械调节理论计算愈合模式、趋势和效率,以达到最佳愈合配置。在 8 周的时间里,钢板和螺钉的生物降解过程导致了 82% 的分子量损失和 1.05 GPa 的杨氏模量下降。病例的愈合效率在第一周为 4.72% 至 14.75%,第八周为 18.64% 至 63.05%。最后,根据所获得的结果,考虑到防止肌肉侵蚀、骨密度降低和不愈合,达到了最佳病例。
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引用次数: 0
Effect of asymptomatic intervertebral flexion patterns on lumbar disc pressure: A finite element analysis study. 无症状椎间屈曲模式对腰椎间盘压力的影响:有限元分析研究
IF 2.2 4区 医学 Q3 ENGINEERING, BIOMEDICAL Pub Date : 2024-11-01 Epub Date: 2024-10-08 DOI: 10.1002/cnm.3866
Mehdi Nematimoez, Ram Haddas, Alexander Breen

Movement patterns may be a factor for manipulating the lumbar load, although little information is yet available in the literature about the relationship between this variable and intervertebral disc pressure (IDP). A finite element model of the lumbar spine (49-year-old asymptomatic female) was used to simulate intervertebral movements (L2-L5) of 127 asymptomatic participants. The data from participants that at least completed a simulation of lumbar vertebral movement during the first 53% of a movement cycle (flexion phase) were used for further analyses. Then, for each vertebral angular motion curve with constant spatial peaks, different temporal patterns were simulated in two stages: (1) in lumbar pattern exchange (LPE), each vertebral angle was simulated by the corresponding vertebrae of other participants data; (2) in vertebral pattern exchange (VPE), vertebral angles were simulated by each other. The k-mean algorithm was used to cluster two groups of variables; peak and cumulative IDP, in both stages of simulations (i.e., LPE and VPE). In the second stage of the simulation (VPE), Kendall's tau was utilized to consider the relationship between different temporal patterns and IDPs for each individual lumbar level. Cluster analyses showed that the temporal movement pattern did not exhibit any effect on the peak IDP while the cumulative IDP changed significantly for some patterns. Earlier involvement in lumbar motion at any level led to higher IDP in the majority of simulations. There is therefore a possibility of manipulating lumbar IDP by changing the temporal pattern with the same ROM, in which optimal distribution of the loads among lumbar levels may be applied as preventive or treatment interventions. Evaluating load benefits, such as load, on biomechanically relevant lumbar levels, dynamically measured by quantitative fluoroscopy, may help inform interventional exercises.

运动模式可能是操纵腰椎负荷的一个因素,但有关该变量与椎间盘压力(IDP)之间关系的文献资料却很少。我们使用腰椎有限元模型(49 岁无症状女性)来模拟 127 名无症状参与者的椎间运动(L2-L5)。至少在运动周期的前 53%(屈曲阶段)完成腰椎运动模拟的参与者的数据被用于进一步分析。然后,针对每条空间峰值不变的椎体角度运动曲线,分两个阶段模拟不同的时间模式:(1)在腰椎模式交换(LPE)中,每个椎体角度由其他参与者数据中的相应椎体模拟;(2)在椎体模式交换(VPE)中,椎体角度由彼此模拟。在两个阶段的模拟(即 LPE 和 VPE)中,均使用 k-mean 算法对两组变量(峰值和累积 IDP)进行聚类。在模拟的第二阶段(VPE),利用 Kendall's tau 来考虑每个腰椎水平的不同时间模式和 IDP 之间的关系。聚类分析显示,时间运动模式对峰值 IDP 没有任何影响,而某些模式下的累积 IDP 有显著变化。在大多数模拟中,较早参与任何水平的腰部运动都会导致较高的 IDP。因此,有可能通过改变相同 ROM 的时间模式来操纵腰椎 IDP,其中腰椎各层次之间的最佳负荷分布可用作预防或治疗干预措施。通过定量透视动态测量,评估腰椎生物力学相关水平的负荷效益(如负荷),可能有助于为介入性锻炼提供依据。
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引用次数: 0
Biomechanical design of a new proximal humerus fracture plate using alternative materials. 使用替代材料对新型肱骨近端骨折钢板进行生物力学设计。
IF 2.2 4区 医学 Q3 ENGINEERING, BIOMEDICAL Pub Date : 2024-11-01 Epub Date: 2024-09-07 DOI: 10.1002/cnm.3868
Sabrina Islam, Mitchell Dembowski, Emil H Schemitsch, Habiba Bougherara, Z Shaghayegh Bagheri, Radovan Zdero

Comminuted proximal humerus fractures are often repaired by metal plates, but potentially still experience bone refracture, bone "stress shielding," screw perforation, delayed healing, and so forth. This "proof of principle" investigation is the initial step towards the design of a new plate using alternative materials to address some of these problems. Finite element modeling was used to create design graphs for bone stress, plate stress, screw stress, and interfragmentary motion via three different fixations (no, 1, or 2 "kickstand" [KS] screws across the fracture) using a wide range of plate elastic moduli (EP = 5-200 GPa). Well-known design optimization criteria were used that could minimize bone, plate, and screw failure (i.e., peak stress < ultimate tensile strength), reduce bone "stress shielding" (i.e., bone stress under the new plate ≥ bone stress for an intact humerus, titanium plate, and/or steel plate "control"), and encourage callus growth leading to early healing (i.e., 0.2 mm ≤ axial interfragmentary motion ≤ 1 mm; shear/axial interfragmentary motion ratio <1.6). The findings suggest that a potentially optimal configuration involves the new plate being manufactured from a material with an EP of 5-41.5 GPa with 1 KS screw; but, using no KS screws would cause immediate bone fracture and 2 KS screws would almost certainly lead to delayed healing. A prototype plate might be fabricated using alternative materials suggested for orthopedics and other industries, like fiber-metal laminates, fiber-reinforced polymers, metal foams, pure polymers, shape memory alloys, or 3D-printed porous metals.

肱骨近端粉碎性骨折通常使用金属板进行修复,但仍可能出现骨折断、骨 "应力屏蔽"、螺钉穿孔、愈合延迟等问题。这项 "原理验证 "调查是使用替代材料设计新钢板以解决其中一些问题的第一步。通过有限元建模,我们利用广泛的钢板弹性模量(EP = 5-200 GPa),通过三种不同的固定方式(无、1 或 2 个横跨骨折的 "脚架"[KS] 螺钉)创建了骨应力、钢板应力、螺钉应力和节间运动的设计图。我们采用了众所周知的优化设计标准,可以最大限度地减少骨、钢板和螺钉的失效(即使用 1 颗 KS 螺钉时,峰值应力 P 为 5-41.5 GPa;但是,不使用 KS 螺钉会导致立即骨折,而使用 2 颗 KS 螺钉几乎肯定会导致延迟愈合。可以使用骨科和其他行业建议的替代材料,如纤维金属层压板、纤维增强聚合物、金属泡沫、纯聚合物、形状记忆合金或 3D 打印多孔金属,来制造钢板原型。
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引用次数: 0
A semi-automatic method for block-structured hexahedral meshing of aortic dissections. 用于主动脉断裂块状结构六面体网格划分的半自动方法。
IF 2.2 4区 医学 Q3 ENGINEERING, BIOMEDICAL Pub Date : 2024-11-01 Epub Date: 2024-08-29 DOI: 10.1002/cnm.3860
Domagoj Bošnjak, Antonio Pepe, Richard Schussnig, Jan Egger, Thomas-Peter Fries

The article presents a semi-automatic approach to generating structured hexahedral meshes of patient-specific aortas ailed by aortic dissection. The condition manifests itself as a formation of two blood flow channels in the aorta, as a result of a tear in the inner layers of the aortic wall. Subsequently, the morphology of the aorta is greatly impacted, making the task of domain discretization highly challenging. The meshing algorithm presented herein is automatic for the individual lumina, whereas the tears require user interaction. Starting from an input (triangle) surface mesh, we construct an implicit surface representation as well as a topological skeleton, which provides a basis for the generation of a block-structure. Thereafter, the mesh generation is performed via transfinite maps. The meshes are structured and fully hexahedral, exhibit good quality and reliably match the original surface. As they are generated with computational fluid dynamics in mind, a fluid flow simulation is performed to verify their usefulness. Moreover, since the approach is based on valid block-structures, the meshes can be made very coarse (around 1000 elements for an entire aortic dissection domain), and thus promote using solvers based on the geometric multigrid method, which is typically reliant on the presence of a hierarchy of coarser meshes.

文章介绍了一种半自动方法,用于生成主动脉夹层患者主动脉的结构化六面体网格。主动脉夹层是主动脉壁内层撕裂后形成的两个血流通道。因此,主动脉的形态会受到很大影响,使域离散化任务变得极具挑战性。本文介绍的网格划分算法对于单个管腔是自动的,而对于撕裂则需要用户交互。从输入(三角形)曲面网格开始,我们构建了一个隐式曲面表示法和拓扑骨架,这为块状结构的生成提供了基础。之后,通过无限映射生成网格。网格是结构化的全六面体网格,具有良好的质量,并能可靠地与原始表面相匹配。由于生成网格时考虑到了计算流体动力学,因此还进行了流体流动模拟,以验证网格的实用性。此外,由于该方法基于有效的块结构,因此网格可以做得非常粗糙(整个主动脉夹层域约 1000 个元素),从而促进了基于几何多网格法的求解器的使用,该方法通常依赖于更粗糙网格的层次结构。
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International Journal for Numerical Methods in Biomedical Engineering
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