Journal of the Mechanical Behavior of Biomedical Materials最新文献_第4页

Combined experimental and micro finite element analysis of CF/PEEK pedicle screw pullout CF/PEEK椎弓根螺钉拔出的实验与微有限元结合分析

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-12-10 DOI: 10.1016/j.jmbbm.2025.107307

Dominic Mischler , Matteo Frigelli , Ivan Zderic , Michael Indermaur , Patrik Wili , Amin Dolati , Philippe Zysset , Peter Varga

Purpose

Pedicle screw pull-out remains a challenge in thoracolumbar spine fixation, contributing to fixation failure. Computational simulations offer a pathway to optimize screw designs across diverse materials and bone qualities towards reducing failure rates. Non-linear explicit micro-finite element (μFE) simulation was hypothesized to accurately predict pullout forces of CF/PEEK screws, with bone volume fraction (BV/TV) influencing performance. This study aimed to validate the μFE model and assess BV/TV effects on the basis of experimental testing.

Methods

Thirteen cadaveric vertebrae were instrumented with 4.5 mm (n = 13) and 5.5 mm (n = 9) CF/PEEK screws using sample-specific 3D-printed guides. Quasi-static pullout tests were conducted and simulated using non-linear explicit μFE models based on high-resolution peripheral quantitative computed tomography (HR-pQCT). Regression analysis evaluated the relationship between BV/TV and pullout force. Correlation coefficient (R²), concordance correlation coefficient (CCC), standard error of estimate (SEE), and relative standard error (RSE) were used to assess the agreement between experimental and μFE-predicted pullout forces.

Results

The linear regression relationship between BV/TV and pullout force was significantly different for the 4.5 mm and 5.5 mm screws (p = 0.001). Ordinary least squares (OLS) regression showed significant BV/TV influence on pullout strength (p = 0.001 experimental, p < 0.001 μFE). Linear regression in log10-log10 space for experimental versus μFE forces showed strong correlation (R² = 0.931, p < 0.001), despite μFE overprediction (slope = 0.752 vs. 1:1, p < 0.001; CCC = 0.745, SEE = 428.7 N, RSE = 85.2 %).

Conclusions

The validated μFE model accurately predicted pullout strength of pedicle screw of different designs, supported by strong correlation with experimental data, despite light overprediction, potentially due to the lack of insertion damage modeling. The robust in silico framework can be used to enhance orthopedic screw designs, supporting improved fixation stability across diverse bone qualities.

目的椎弓根螺钉拔出是胸腰椎固定的难点，容易导致固定失败。计算模拟为优化不同材料和骨质量的螺钉设计提供了途径，从而降低故障率。采用非线性显式微有限元（μFE）模拟方法准确预测CF/PEEK螺钉的拔出力，骨体积分数（BV/TV）对拔出力有影响。本研究旨在验证μFE模型，并在实验测试的基础上评估BV/TV效应。方法采用样品特异性3d打印导轨，分别用4.5 mm （n = 13）和5.5 mm (n = 9) CF/PEEK螺钉固定13具尸体椎骨。采用基于高分辨率外周定量计算机断层扫描（HR-pQCT）的非线性显式μFE模型进行准静态拉拔试验并进行模拟。回归分析BV/TV与拔牙力的关系。采用相关系数（R2）、一致性相关系数（CCC）、估计标准误差（SEE）和相对标准误差（RSE）评价实验结果与μ fe预测结果的一致性。结果4.5 mm和5.5 mm螺钉的BV/TV与拔牙力的线性回归关系有显著性差异（p = 0.001）。普通最小二乘（OLS）回归显示，BV/TV对拉拔强度有显著影响（实验p = 0.001, p < 0.001 μFE）。尽管μFE预测过高（斜率= 0.752 vs. 1:1, p < 0.001; CCC = 0.745, SEE = 428.7 N, RSE = 85.2%），但实验力与μFE力在log10-log10空间的线性回归显示出很强的相关性（R2 = 0.931, p < 0.001）。结论验证的μFE模型准确预测了不同设计的椎弓根螺钉的拔出强度，与实验数据具有较强的相关性，尽管存在轻微的高估，但可能是由于缺乏插入损伤建模。坚固的硅框架可用于增强骨科螺钉设计，支持改善不同骨质量的固定稳定性。

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引用次数: 0

Mechanics of bone graft and implant choices for spino-pelvic reconstruction following combined hemipelvectomy, sacrectomy and L5 vertebrectomy 联合半骨盆切除术、骶骨切除术和L5椎体切除术后脊柱-骨盆重建的骨移植物和植入物选择力学。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-12-09 DOI: 10.1016/j.jmbbm.2025.107310

Ritika Raj Menghani , Karthik Tappa , Peiyan Li , Katelyn Kevorkian , Alexander F. Mericli , Valerae O. Lewis , Justin E. Bird , Raudel Avila

Spino-pelvic reconstruction following extended hemipelvectomy is a highly complex surgical procedure with significant variability in biomechanics between patients due to differences in surgical techniques. Despite its clinical significance, experimentally identifying the key biomechanical factors that govern the integrity of the reconstructed pelvis remains challenging. To address this, we developed a multiscale computational modeling framework, ranging from 1D beam theory and 2D composite trusses to anatomically accurate 3D reconstructions, to systematically evaluate the biomechanical trade-offs of bone graft selection in spino-pelvic reconstructions. Anatomically accurate, three-dimensional finite element models, reconstructed from postoperative CT imaging, were developed to simulate stress distributions in both bone and implant components of the reconstructed pelvis under quasi-static sitting conditions, representing the postoperative recovery phase. Two key choices were systematically evaluated: bone graft selection and implant material properties. Comparative analysis of tibial, femoral, and fibular grafts demonstrates that the femoral graft provides superior mechanical performance due to its larger cross-sectional area. The tibial graft exhibits approximately twice the stress level of the femur, while the fibular graft experiences stresses nearly three times higher, indicating limited suitability for structural reconstruction. Implant material analysis reveals that titanium and stainless steel minimize stress accumulation and reduce the risk of mechanical failure, making them preferable under high-load conditions. In contrast, polymer-based implants mitigate stress shielding and may be advantageous when bone remodeling is a priority. Together, these findings offer new insight into spino-pelvic reconstruction strategies and support simulation-driven design optimization to improve future outcomes for patients undergoing these complex procedures.

延长半骨盆切除术后的脊柱-骨盆重建是一项高度复杂的手术，由于手术技术的差异，患者之间的生物力学存在显著差异。尽管具有临床意义，但通过实验确定控制重建骨盆完整性的关键生物力学因素仍然具有挑战性。为了解决这个问题，我们开发了一个多尺度计算建模框架，从1D梁理论和2D复合桁架到解剖学精确的3D重建，系统地评估骨移植选择在脊柱-骨盆重建中的生物力学权衡。基于术后CT图像重建的三维有限元模型在解剖学上精确，模拟了准静态坐姿条件下重建骨盆骨和种植体组件的应力分布，代表了术后恢复阶段。系统评估两个关键选择：骨移植选择和种植材料性能。胫骨、股骨和腓骨移植物的对比分析表明，股骨移植物由于其更大的横截面积而具有更好的机械性能。胫骨移植物的应力水平大约是股骨的两倍，而腓骨移植物的应力水平几乎是股骨的三倍，这表明结构重建的适用性有限。植入物材料分析表明，钛和不锈钢最大限度地减少了应力积累，降低了机械故障的风险，使它们更适合在高负荷条件下使用。相反，聚合物为基础的植入物减轻了应力屏蔽，当骨重塑是优先考虑时可能是有利的。总之，这些发现为脊柱-骨盆重建策略提供了新的见解，并支持模拟驱动的设计优化，以改善接受这些复杂手术的患者的未来预后。

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引用次数: 0

Hydrolytic degradation behaviour of electrospun poly(ɛ-caprolactone) filaments for biological tissue repair 电纺丝聚己内酯丝在生物组织修复中的水解降解行为。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-12-08 DOI: 10.1016/j.jmbbm.2025.107308

Thales Zanetti Ferreira , Huanming Chen , Kaili Chen , Pierre-Alexis Mouthuy , Laurence Brassart

Electrospun polymeric fibres are promising materials for biomedical applications, owing to their biocompatibility, biodegradability, and ability to be assembled into a non-woven fibrous mesh. In particular, continuous filaments can be produced and subsequently assembled into multi-filament braided structures for ligament and tendon tissue repair. In these applications, characterising the evolution of the mechanical properties of the filament as it degrades is of primary importance. The role of applied mechanical loads during the degradation process also needs to be understood. In this study, we characterised the hydrolytic degradation behaviour of pre-stretched electrospun filaments made of poly(

ɛ

- caprolactone) (PCL) in buffer saline solution at 45 °C for up to 5 weeks, considering both non-loaded and loaded conditions. We show that PCL filaments degrade significantly over this relatively short time period, with non-loaded specimens showing a 21 % reduction in molecular weight after 5 weeks of exposure. Tensile loads applied during degradation further accelerate the degradation rate, with filaments subjected to a 25 g load showing a 33 % reduction in molecular weight over the same time period. Applied loads also impact the mechanical properties of the degraded specimens, causing an increase in elastic modulus and strength but a sharp decrease in elongation at break with exposure time. Our findings have implications for the design of PCL electrospun constructs in load bearing biomedical applications.

电纺丝聚合物纤维由于其生物相容性、生物可降解性和组装成无纺布纤维网的能力，在生物医学应用方面是很有前途的材料。特别是，连续细丝可以产生并随后组装成多细丝编织结构，用于韧带和肌腱组织修复。在这些应用中，表征长丝在降解过程中机械性能的演变是至关重要的。在降解过程中施加的机械载荷的作用也需要了解。在这项研究中，我们在45°C的缓冲盐水溶液中表征了预拉伸的聚（β -己内酯）（PCL）制成的静电纺丝的水解降解行为，并考虑了负载和非负载条件。我们发现PCL细丝在相对较短的时间内显著降解，未加载的样品在暴露5周后分子量减少21%。在降解过程中施加的拉伸载荷进一步加速了降解速度，在相同的时间内，受到25克载荷的长丝的分子量减少了33%。外加载荷也会影响退化试样的力学性能，导致弹性模量和强度增加，但断裂伸长率随着暴露时间的增加而急剧下降。我们的研究结果对PCL静电纺丝结构体在承载生物医学应用中的设计具有启示意义。

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引用次数: 0

Reproducibility in the morphological and mechanical properties of a natural polymer for guided bone regeneration applications 用于引导骨再生应用的天然聚合物的形态和机械性能的再现性。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-12-08 DOI: 10.1016/j.jmbbm.2025.107306

Benedetta Isella , Aleksander Drinic , Alissa Heim , Hans Leemhuis , Nadja Kröger , Rene Tolba , Alexander Kopp

Dental barrier membranes play a key role in guided bone regeneration (GBR) to separate soft tissue from regenerating bone. Bioabsorbable collagen membranes, the gold standard in GBR procedures, are appealing due to elimination of the need for secondary surgeries and mechanical properties mimicking native tissue. However, challenges include rapid degradation, inconsistent reproducibility in mechanical and morphological properties, and use of animal-derived tissues. This study explored silk fibroin, a biocompatible and slowly bioabsorbable biomaterial as an alternative for GBR membranes. Silk fibroin showed comparable mechanical performance and demonstrated improved reproducibility. Two silk fibroin-based multilayered membranes (SF1 and SF2) were developed showing homogeneous appearance, density, and thickness, with lower variability than the other tested commercial options. These membranes exhibited elasto-plastic mechanical behaviour in both dry and hydrated states, supporting improved surgical handling and dimensional stability. Furthermore, elastic modulus in hydrated state (23.8 ± 3.2 MPa for SF1, 27.6 ± 3.9 MPa for SF2), burst pressure (17.5 ± 5.0 mmHg for SF1, 290.0 ± 32.6 mmHg for SF2), and force at first deformation in the suture retention strength test in hydrated state (0.10 ± 0.03 N for SF1, 0.26 ± 0.11 N for SF2) were comparable to commercial collagen membranes, suggesting the suitability for GBR applications. These findings provide a basis for further biological and preclinical characterization as well as clinical application of silk fibroin-based GBR membranes.

牙屏障膜在引导骨再生（GBR）中将软组织与再生骨分离的过程中起着关键作用。生物可吸收的胶原膜是GBR手术的金标准，由于消除了二次手术的需要和模仿天然组织的机械性能，它很有吸引力。然而，挑战包括快速降解，机械和形态特性的不一致可重复性，以及动物来源组织的使用。本研究探索了一种具有生物相容性和缓慢生物吸收性的生物材料——丝素蛋白作为GBR膜的替代材料。丝素表现出类似的机械性能，并表现出更好的再现性。两种基于丝素蛋白的多层膜（SF1和SF2）显示出均匀的外观、密度和厚度，比其他测试的商业选择具有更低的可变性。这些膜在干燥和水合状态下都表现出弹塑性力学行为，支持改进手术操作和尺寸稳定性。此外，水合状态下的弹性模量（SF1为23.8±3.2 MPa， SF2为27.6±3.9 MPa），破裂压力（SF1为17.5±5.0 mmHg， SF2为290.0±32.6 mmHg），以及水合状态下缝合保持强度测试中的首次变形力（SF1为0.10±0.03 N， SF2为0.26±0.11 N）与商用胶原膜相当，表明其适用于GBR应用。这些发现为丝素基GBR膜的进一步生物学和临床前表征以及临床应用提供了基础。

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引用次数: 0

Bioinspired auxetic metamaterial liners and sockets for transtibial prostheses: Energy absorption and stress redistribution 仿生仿生超材料衬垫和骨槽：能量吸收和应力再分配。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-12-06 DOI: 10.1016/j.jmbbm.2025.107305

Mahdi Bodaghi , Saman Jolaiy , Kaveh Rahmani , Sheng Li , Fei Gao , Ali Zolfagharian

Prosthetic comfort depends on how the residual limb, liner, and socket share load. A crab-inspired auxetic metamaterial is introduced and applied to transtibial liners and sockets, with region-specific and fully auxetic variants benchmarked against conventional interfaces. Patient CT/3D scans guided anatomically targeted components. Auxetic lattices were additively manufactured in TPU (liners) and PA-12 (sockets). Cyclic compression experiments calibrated material models, and finite-element analyses quantified interface stresses and energy metrics. Across four sensitive liner regions, a four-zone auxetic TPU liner cut peak von Mises stresses by up to 60 %, and a fully auxetic liner by up to 65 %, relative to silicone/EL50 baselines. In sockets, a PA-12 design with two auxetic zones reduced peak stresses by ∼40–45 % versus ABS, while a fully auxetic socket achieved ∼80 % reductions with higher specific energy absorption. These findings indicate that bioinspired auxetics, integrated where anatomy needs compliance, improve pressure redistribution and mass-efficient energy management. The workflow from imaging to lattice design, printing, testing, and simulation was validated and is compatible with multi-jet fusion, enabling patient-specific prosthetic interfaces suitable for clinical translation.

假肢的舒适性取决于残肢、衬垫和关节窝如何分担负荷。一种受螃蟹启发的补足超材料被引入并应用于跨骨衬垫和插座，具有特定区域和完全补足的变体，对传统接口进行基准测试。患者CT/3D扫描引导解剖目标部件。在TPU（衬垫）和PA-12（插座）中增材制造辅助晶格。循环压缩实验校准了材料模型，有限元分析量化了界面应力和能量指标。相对于硅胶/EL50基线，在四个敏感衬管区域，四区auxetic TPU衬管可将峰值von Mises应力降低60%，而完全auxetic衬管可将峰值von Mises应力降低65%。在插座中，与ABS相比，具有两个辅助区的PA-12设计可将峰值应力降低约40- 45%，而完全辅助的插座具有更高的比能吸收，可将峰值应力降低约80%。这些发现表明，在解剖学需要顺应性的地方，结合生物启发的辅助疗法可以改善压力再分配和质量效率的能量管理。从成像到格子设计、打印、测试和模拟的工作流程经过验证，并与多射流融合兼容，使患者特定的假肢接口适合临床翻译。

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引用次数: 0

Biomechanical evaluation of load transfer in Talus focal resurfacing implant: experimental and finite element models 距骨局部表面植入物载荷转移的生物力学评估：实验和有限元模型。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-12-04 DOI: 10.1016/j.jmbbm.2025.107300

A. Ramos, M. Vieira

Introduction

Osteochondral lesions (OTLs) are common injuries in ankle sprains, occurring in up to 70 % of patients. Recovery options are limited due to the talus bone's poor vascularization. This study aimed to develop a computational model of an ankle joint to evaluate cartilage stress in the presence of an OTL and assess the biomechanical effectiveness of a focal resurfacing prosthesis in reducing joint stress.

Materials and methods

Both in silico and physical model models were developed based on a previous case study involving a patient with a medial OTL in the right ankle. A 10 mm diameter focal resurfacing prosthesis was tested in two positions: proud (+0.5 mm) and recessed (−0.5 mm), as recommended in clinical guidelines. Cartilage stress and trabecular bone strain in the talus were evaluated. The in vitro model, produced via additive manufacturing and instrumented with strain gauges, was used to validate the finite element (FE) model by comparing measured and simulated strains.

Results

The FE model showed strong agreement with experimental data, with a correlation coefficient of 0.88. Both the lesion and prosthesis placement influenced talar cartilage stress. The OTL increased stress by approximately 23 % near the lesion site and 8 % in more distal regions. The highest cartilage stress (7.20 MPa) occurred with the prosthesis in the recessed position. Prosthesis positioning significantly affected cartilage stress distribution (p < 0.001).

Conclusions

While fixation of the focal prosthesis remains challenging, placing it slightly proud can help reduce stress on talar cartilage. However, excessive proud positioning increases stress on tibial cartilage and should be avoided. Proper prosthesis placement is critical for optimal stress reduction. Furthermore, fixation in the talus reduces trabecular bone strain, potentially mitigating bone loss and enhancing implant stability.

骨软骨病变（OTLs）是踝关节扭伤中常见的损伤，发生率高达70%。由于距骨血管化不良，恢复选择有限。本研究旨在建立一个踝关节的计算模型，以评估踝关节外翻时的软骨应力，并评估局部表面置换假体在减轻关节应力方面的生物力学有效性。材料和方法：计算机模型和物理模型都是基于先前的案例研究开发的，该案例研究涉及一名右脚踝内侧外伤性损伤的患者。按照临床指南的建议，在两个位置测试直径为10mm的局部表面修复体：骄傲（+0.5 mm）和凹陷（-0.5 mm）。评估距骨软骨应力和骨小梁应变。通过增材制造和应变仪制作的体外模型，通过比较实测应变和模拟应变来验证有限元（FE）模型。结果：有限元模型与实验数据吻合较好，相关系数为0.88。损伤和假体放置对距骨软骨应力均有影响。OTL使损伤部位附近的应力增加约23%，远端区域的应力增加约8%。假体处于凹位时，软骨应力最大（7.20 MPa）。假体定位显著影响软骨应力分布(p)结论：虽然局灶性假体的固定仍然具有挑战性，但将假体略微抬高有助于减少距骨软骨的应力。然而，过度骄傲的定位会增加胫骨软骨的压力，应该避免。适当的假体放置是最佳的应力减少的关键。此外，距骨内固定可减少骨小梁应变，潜在地减轻骨丢失并增强植入物的稳定性。

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引用次数: 0

Collagen fibril organization and its association with glycosaminoglycans in human, pig, and mouse cornea 人、猪和小鼠角膜中胶原原纤维组织及其与糖胺聚糖的关系。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-12-03 DOI: 10.1016/j.jmbbm.2025.107303

Hamed Hatami-Marbini, Md Esharuzzaman Emu

The primary objective of the present study was to characterize the species-specific effects of GAGs on the microstructure of corneal extracellular matrix (ECM). To this end, the keratanase enzyme was used to remove GAGs from human, pig, and mouse corneal ECM. Then, transmission electron microscopy (TEM) was done to determine the microstructure of samples before and after GAG depletion. In particular, TEM images were analyzed using ImageJ software to determine the diameter of collagen fibrils and interfibrillar spacing (IFS). An insignificant change in the average collagen fibril diameter of human (28.7 nm–>28.8 nm), porcine (34.7 nm–>35.2 nm), and murine (33.0 nm–>33.4 nm) was observed because of GAG depletion. The enzyme treatment significantly increased the average IFS from 45.8 nm, 53.0 nm, and 54.6 nm to 48.9 nm, 57.3 nm and 61.5 nm in human, porcine, and murine corneal samples, respectively (α < 0.05). The effects of GAGs on microstructural properties of corneal ECM were discussed in terms of their ability to form tiny bridges between collagen fibrils and their net negative charge density. It was concluded that, despite existing differences among collagen fibril diameter and IFS of human, porcine, and mouse cornea, GAG depletion showed relatively similar effects on the microstructure of their ECM. The findings of the present study may help explain the pathological effects associated with changes in GAG content and offer a basis for better understanding of interspecies variations in biomechanical response of cornea.

本研究的主要目的是表征gag对角膜细胞外基质（ECM）微观结构的物种特异性影响。为此，使用角化酶去除人、猪和小鼠角膜ECM中的gag。然后用透射电镜（TEM）测定了GAG耗尽前后样品的微观结构。特别使用ImageJ软件分析TEM图像，确定胶原原纤维直径和纤维间间距（IFS）。由于GAG耗损，人（28.7 nm->28.8 nm）、猪（34.7 nm->35.2 nm）和鼠（33.0 nm->33.4 nm）的胶原纤维平均直径变化不显著。酶处理显著提高了人、猪和小鼠角膜样品的平均IFS，分别从45.8 nm、53.0 nm和54.6 nm提高到48.9 nm、57.3 nm和61.5 nm (α

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引用次数: 0

Mechanical and microstructural characterization of the human tunica albuginea 人白膜的力学和微观结构表征。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-12-02 DOI: 10.1016/j.jmbbm.2025.107280

Pierre-Hugo Minster , Clément Parat , Paul Neuville , Damien Carnicelli , Nicolas Morel-Journel , Karine Bruyère-Garnier

The tunica albuginea (TA) is a fibrous connective membrane surrounding the corpora cavernosa (CC), which plays a crucial role in the erection. In case of erectile dysfunction, inflatable penile prothesis (IPP) may be a treatment of choice and mechanical interactions occur between prostheses and these penile tissues. There is still much to be learned about their mechanical behavior to help to improve IPP and penile surgical techniques. This paper presents the characterization of the TA mechanical behavior combined with the observation of its microstructural organization, as well as the mechanical behavior of the cavernous tissue. Uniaxial tensile tests were performed on 40 TA samples and 17 CC samples collected from 5 post mortem human subjects. TA samples were cut along both longitudinal and circumferential directions, and in both proximal and distal regions. Histological slices were produced from biopsies contiguous to the samples to observe the collagen fiber organization in the TA. We observed that this fiber organization usually schematized by 2 layers of perpendicular fibers is more complex, with some dispersion in the fiber orientations and interlacing of the 2 layers. The mechanical characterization of the TA samples revealed no clear anisotropy but different properties for the proximal and distal locations, whereas the CC showed a very low elastic modulus. These data complement those already published and further analysis of the microstructure of the TA will be needed to explain the variability of the mechanical behavior of the TA in view of selecting and identifying nonlinear behavior models.

白膜（TA）是一种围绕海绵体（CC）的纤维结缔组织膜，在勃起中起着至关重要的作用。在勃起功能障碍的情况下，充气阴茎假体（IPP）可能是一种治疗选择，假体与这些阴茎组织之间发生机械相互作用。为了提高IPP和阴茎手术技术，仍有很多需要了解的机械行为。本文结合对其显微组织的观察，对TA的力学行为进行表征，并对海绵组织的力学行为进行研究。对从5名死后人类受试者身上采集的40个TA样本和17个CC样本进行了单轴拉伸试验。TA样品沿纵向和圆周方向切割，并在近端和远端区域。通过与样品相邻的活组织切片，观察TA中胶原纤维的组织。我们观察到，通常由两层垂直纤维表示的这种纤维组织结构更为复杂，在纤维方向上有一定的分散，并且两层纤维相互交错。TA样品的力学特性没有明确的各向异性，但在近端和远端位置有不同的性质，而CC显示出非常低的弹性模量。这些数据补充了已经发表的数据，并且需要对TA的微观结构进行进一步分析，以解释TA的力学行为的可变性，从而选择和识别非线性行为模型。

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引用次数: 0

Characterization of mechanical tissue properties in post-mortem human brain using magnetic resonance elastography 用磁共振弹性成像表征死后人脑的机械组织特性。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-12-02 DOI: 10.1016/j.jmbbm.2025.107292

Joy Mojumder , Yuan-Chiao Lu , Alexa M. Diano , Ahmed A. Alshareef , Matthew McGarry , Philip V. Bayly , Curtis L. Johnson , John A. Butman , Dzung L. Pham

Traumatic brain injury (TBI) is a serious health condition that can cause neurological dysfunction to varying degrees depending on the nature of the mechanical insult. In biomechanical studies of TBI under high loading conditions, post-mortem human subjects (PMHS), although difficult to acquire, are often used since ethical concerns prohibit such experiments in living human subjects. Because PMHS brains undergo significant changes following death, it is important to understand the relationship between the mechanical properties of PMHS and living brain tissue. In this study, we performed magnetic resonance elastography (MRE) on three PMHS specimens to estimate the material properties of the cadaveric brain, namely the storage modulus and the loss modulus, as well as the resulting shear stiffness and damping ratio. We also performed longitudinal MRE scans on one of the PMHS brain over the span of two months to investigate the evolution of tissue properties with post-mortem degradation. In comparison to in vivo subjects of age range 70–75 years, a substantially higher stiffness (mean: 5.96 kPa) and lower damping ratio (mean: 0.09) were found in PMHS models. This study also revealed an initial increase in shear stiffness up to the seventh day post-mortem, followed by a steady decrease by the fifty-eighth day. However, the damping ratio displayed an opposite trend to that of shear stiffness. These changes were heterogeneous across brain regions. The collected measurements and analysis elucidate the changes in mechanical properties in post-mortem subjects, and can be used to build and validate computational models of TBI.

创伤性脑损伤（TBI）是一种严重的健康状况，可引起不同程度的神经功能障碍，这取决于机械损伤的性质。在高负荷条件下脑外伤的生物力学研究中，虽然很难获得死后人体受试者（PMHS），但由于伦理问题禁止在活体受试者中进行此类实验，因此经常使用死后人体受试者。由于PMHS的大脑在死亡后会发生显著变化，因此了解PMHS与活体脑组织的力学特性之间的关系非常重要。在这项研究中，我们对三个PMHS样本进行了磁共振弹性成像（MRE），以估计尸体大脑的材料特性，即存储模量和损失模量，以及由此产生的剪切刚度和阻尼比。我们还对其中一个PMHS大脑进行了为期两个月的纵向核磁共振扫描，以研究组织特性在死后降解中的演变。与70-75岁的体内受试者相比，PMHS模型具有更高的刚度（平均5.96 kPa）和更低的阻尼比（平均0.09）。该研究还显示，在死后第7天，剪切刚度开始增加，随后在第58天稳步下降。阻尼比与剪切刚度的变化趋势相反。这些变化在不同的大脑区域是不同的。收集的测量和分析阐明了死后受试者力学性能的变化，可用于建立和验证TBI的计算模型。

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引用次数: 0

Assessing age and cold ischemia effects on liver tissue viscoelastic properties: Implications for graft quality assessment with MRE during machine perfusion 评估年龄和冷缺血对肝组织粘弹性的影响：机器灌注时用MRE评估移植物质量的意义。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-12-01 DOI: 10.1016/j.jmbbm.2025.107291

Lisa-Marie Skrip , Leonard Boerger , Kilian A. Walter , Alexander Arnold , Lene A. Böhne , Eriselda Keshi , Anna S. Pietsch , Nathanael Raschzok , Timo A. Auer , Uli Fehrenbach , Felix Krenzien , Johann Pratschke , Igor M. Sauer , Jing Guo , Jürgen Braun , Heiko Tzschätzsch , Ingolf Sack , Karl H. Hillebrandt , Simon Moosburner

Objective

Liver transplantation remains the primary treatment for end-stage liver disease, however, a shortage of suitable grafts persists. Factors contributing to this imbalance include insufficient organ quality, which exhibit higher complication rates, exacerbated by static cold storage. Normothermic Machine Perfusion (NMP) is proposed as an alternative, offering dynamic preservation, and quality assessment. This study introduces magnetic resonance elastography (MRE), to evaluate changes of viscoelastic properties of the liver after NMP for quality assessment.

Materials and methods

In this study, using a rat liver NMP model, we investigated whether older age and extended cold ischemia time (CIT) affect liver tissue properties after NMP. Ex vivo MRE measurements were conducted using a multifrequency tabletop 0.5-T MRE with excitation frequencies ranging from 500 Hz to 5300 Hz and viscoelastic model fitting with power-law exponent α.

Results

Samples of 24 Sprague Dawley rat livers were analyzed after 6- or 12-h of cold ischemia time and consequent 6-h NMP. All samples had predominantly viscous-fluid properties (ɑ>0.5). The powerlaw exponent ɑ was the highest in livers from 3-month-old rats and short cold ischemia (0.61, IQR 0.61–0.75) and lowest in long cold ischemia and older liver grafts (0.56, IQR 0.55–0.62; p < 0.001). Furthermore, shear modulus μ was significantly lower in 3-month-old rats and short cold ischemia than all other groups (p < 0.001).

Conclusion

Despite NMP, viscoelastic properties of liver tissues were still slightly impaired after extended CIT. MRE could serve as a diagnostic imaging tool, complementing MRI and pathological evaluation, for assessing the quality of liver grafts after NMP.

目的：肝移植仍然是终末期肝病的主要治疗方法，然而，仍然缺乏合适的移植物。造成这种不平衡的因素包括器官质量不足，这表现出较高的并发症发生率，并因静态冷藏而加剧。常温机器灌注（NMP）被建议作为一种替代方法，提供动态保存和质量评估。本研究引入磁共振弹性成像（MRE）技术，评价NMP后肝脏粘弹性的变化，用于质量评估。材料和方法：本研究采用大鼠肝脏NMP模型，研究年龄和延长冷缺血时间（CIT）对NMP后肝组织特性的影响。体外MRE测量采用多频台式0.5 t MRE，激励频率为500 Hz至5300 Hz，粘弹性模型拟合幂律指数α。结果：24只大鼠肝脏在冷缺血6、12小时后及随后的6小时NMP后进行分析。所有样品都具有主要的粘流体性质（[]> .5]）。3月龄短冷缺血大鼠肝脏的幂律指数最高（0.61，IQR为0.61 ~ 0.75），长冷缺血大鼠肝脏的幂律指数最低（0.56，IQR为0.55 ~ 0.62）；p结论：尽管NMP，延长CIT后肝组织的粘弹性仍有轻微损伤，MRE可作为一种诊断成像工具，补充MRI和病理评价，用于评价NMP后肝移植质量。

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