Journal of biomechanics最新文献_第8页

Intervertebral disc deformation in the lower lumbar spine during object lifting measured in vivo using indwelling bone pins 使用留置骨针活体测量下腰椎间盘在提举物体过程中的变形。

IF 2.4 3区医学 Q3 BIOPHYSICS

Journal of biomechanics

Pub Date : 2024-09-27 DOI: 10.1016/j.jbiomech.2024.112352

Stefan Schmid , Inès Kramers-de Quervain , Walter Baumgartner

Object lifting is often categorized into squat and stoop techniques, with the former believed to protect the back by maintaining a neutral spine, and the latter considered harmful due to spinal flexion. Despite the widespread promotion of these beliefs, there is no evidence to support such dichotomy, as spinal flexion is not conclusively linked to low back pain. This study aimed to investigate intervertebral disc deformation in the lower lumbar spine during squat and stoop lifting using indwelling bone pins. Five healthy males underwent insertion of Kirschner wires into the L3, L4, and L5 spinous processes, followed by biomechanical data collection using magnetic and optical tracking systems during upright standing, isolated flexion/extension, and object lifting with both squat and stoop techniques. Except for one subject, stoop lifting resulted in up to 90 % greater disc wedging compared to squat lifting, with a significant difference at L4/L5 (p = 0.042). The anterior annulus fibrosus experienced 10 % to 40 % more compression during stoop lifting, but no significant differences were found in posterior annulus fibrosus expansion between techniques. Lever arms were about 35 % longer during stoop compared to squat lifting. These results indicate that even though stoop lifting generally led to greater disc deformation, significant deformation was also observed during squat lifting, challenging the notion of maintaining a neutral spine with this technique. Moreover, the considerable variability observed among participants raises concerns about the suitability of current one-size-fits-all lifting guidelines.

物体提举通常分为下蹲和弯腰两种技术，前者被认为可以通过保持脊柱中立来保护背部，而后者则被认为由于脊柱弯曲而有害。尽管这些观点得到了广泛的宣传，但并没有证据支持这种二分法，因为脊柱弯曲与腰痛并没有确凿的联系。本研究旨在利用留置骨针调查下蹲和弯腰举重时下腰脊柱椎间盘的变形情况。五名健康男性分别在 L3、L4 和 L5 棘突中插入了 Kirschner 线，然后使用磁性和光学跟踪系统收集了直立、孤立屈伸以及采用下蹲和弯腰技术抬举物体时的生物力学数据。除一名受试者外，弯腰抬举与下蹲抬举相比，椎间盘楔入程度最多可增加 90%，在 L4/L5 处差异显著（p = 0.042）。在弯举过程中，椎间盘前纤维环受到的挤压增加了10%到40%，但在椎间盘后纤维环膨胀方面，不同技术之间没有发现显著差异。与蹲举相比，弯举时的杠杆臂长约 35%。这些结果表明，尽管弯举通常会导致椎间盘更大的变形，但在蹲举过程中也观察到了明显的变形，这对使用这种技术保持脊柱中立的观点提出了挑战。此外，在参与者之间观察到的巨大差异也让人们对目前 "一刀切 "的举重指南是否适用产生了担忧。

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引用次数: 0

Energetic scaling behavior of patterned epithelium 模式化上皮细胞的能量缩放行为

IF 2.4 3区医学 Q3 BIOPHYSICS

Journal of biomechanics

Pub Date : 2024-09-26 DOI: 10.1016/j.jbiomech.2024.112342

Frank D. Peters , Tasnif Rahman , Haokang Zhang , Leo Q. Wan

Cellular monolayers display various degrees of coordinated motion ranging from the small scale of just a few cells to large multi-cellular scales. This collective migration carries important physical cues for creating proper tissue morphology. Previous studies have demonstrated that the energetics of the epithelial monolayer show a linear variation with time in conjunction with an arrest in monolayer motion after confluency. However, little is known about how the energetics of monolayer development are affected by confined geometries. Here, we demonstrate that micropatterned epithelial monolayers display a non-linear change in energetic variables, which coincides with the large-scale coordination of migration. This non-linear scaling behavior was further seen to be associated with the biased alignment of cells and cell–cell adhesion. These findings provide a new understanding of how developing epithelia may be impacted by different conditions in vivo.

细胞单层显示出不同程度的协调运动，小到几个细胞，大到多细胞。这种集体迁移为形成正确的组织形态提供了重要的物理线索。以前的研究表明，上皮单层的能量随时间呈线性变化，同时在汇合后单层运动会停止。然而，人们对单层发育的能量如何受到封闭几何结构的影响知之甚少。在这里，我们证明了微图案上皮单层显示出能量变量的非线性变化，这与迁移的大规模协调相吻合。这种非线性缩放行为还与细胞的偏向排列和细胞间的粘附有关。这些发现为了解发育中的上皮如何受到体内不同条件的影响提供了新的认识。

引用次数: 0

Strategies for unplanned gait termination at comfortable and fast walking speeds in children with cerebral palsy 脑瘫儿童在舒适和快速行走速度下的计划外步态终止策略。

IF 2.4 3区医学 Q3 BIOPHYSICS

Journal of biomechanics

Pub Date : 2024-09-26 DOI: 10.1016/j.jbiomech.2024.112349

Minoru Kimoto , Kyoji Okada , Kazutaka Mitobe , Masachika Saito , Hitoshi Sakamoto

Collision avoidance while walking is necessary for safe living, and faster walking speeds tend to increase collision risk. However, gait termination strategies for patients with cerebral palsy (CP), from comfortable to faster speed, remain unexplored. This study aimed to analyze these strategies in children with CP compared to typically developing (TD) children at two different speeds. Study participants included 10 children with CP (mean age, 12.5; five females; mean height, 147.8 cm; mean weight, 41.7 kg) and 10 TD children (mean age, 11.4; nine females; mean height, 142.0 cm; mean weight, 38.1 kg). Effects of walking speed on spatial, force, and temporal parameters were assessed at 100 % (WS1) and 125 % (WS2) speeds of comfortable walking. The TD group exerted a more pronounced braking force at the first step after the stop line appeared on the floor until the contralateral step at both WS1 (P = 0.006) and WS2 (P = 0.019); however, the CP group exerted a more potent force after the second step (WS1: P = 0.026, WS2: P = 0.023) in the anterior-posterior (AP) direction. Additionally, an increase in the center of mass (COM)-center of pressure (COP) divergence in the AP direction (P = 0.032), which decreased in the mediolateral (ML) direction (P = 0.036) at faster walking speeds, influenced the kinetic characteristics of the CP group from WS1 to WS2. The complex adaptations, such as unique braking forces and changes in the COM-COP divergence, suggest that gait interventions should consider the distinctive forces and adopt dynamic balancing strategies to avoid collisions during walking.

行走时避免碰撞是安全生活的必要条件，而较快的行走速度往往会增加碰撞风险。然而，脑瘫（CP）患者的步态终止策略（从舒适到较快的速度）仍未得到研究。本研究旨在分析脑瘫儿童与典型发育（TD）儿童在两种不同速度下的步态终止策略。参加研究的人员包括 10 名患有 CP 的儿童（平均年龄 12.5 岁；女性 5 名；平均身高 147.8 厘米；平均体重 41.7 千克）和 10 名患有 TD 的儿童（平均年龄 11.4 岁；女性 9 名；平均身高 142.0 厘米；平均体重 38.1 千克）。在 100 %（WS1）和 125 %（WS2）的舒适行走速度下，评估了行走速度对空间、力量和时间参数的影响。在 WS1（P = 0.006）和 WS2（P = 0.019）时，TD 组在地板上出现停止线后的第一步至对侧步前施加了更明显的制动力；然而，CP 组在第二步后（WS1：P = 0.026，WS2：P = 0.023）在前后（AP）方向施加了更强的制动力。此外，质心（COM）-压力中心（COP）在 AP 方向上的发散增加（P = 0.032），而在行走速度较快时，在内侧外侧（ML）方向上的发散减少（P = 0.036），这影响了 CP 组从 WS1 到 WS2 的运动特征。这种复杂的适应性，如独特的制动力和COM-COP发散的变化，表明步态干预应考虑独特的力，并采取动态平衡策略，以避免行走过程中的碰撞。

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引用次数: 0

A clinical investigation of force plate drift error on predicted joint kinetics during gait 步态过程中受力板漂移误差对预测关节动力学的临床研究。

IF 2.4 3区医学 Q3 BIOPHYSICS

Journal of biomechanics

Pub Date : 2024-09-26 DOI: 10.1016/j.jbiomech.2024.112351

J. Milnes, D. Kiernan

Inverse dynamic analysis is a technique used during gait analysis to estimate intersegmental forces and net joint moments. Inverse dynamic calculations are susceptible to various forms of error. One such error is force plate drift, often produced by humidity condensing within the input connectors and electronics, causing an undesired change in output over time. This can be particularly concerning for movement laboratories where inverse dynamics are considered in clinical decision-making processes. Manufacturers will provide tolerance levels for drift. However, levels of acceptable drift are rarely considered from a clinical perspective. Therefore, this study aims to establish clinically acceptable limits of force plate drift error, induced by applying systematic errors to force plate channels, on predicted lower limb joint moments during gait. Gait data of 10 children with typical development were analysed and induced errors of 0.5 N, 1 N, 1.5 N, 3 N, 6 N and 12 N were incrementally applied to the horizontal and vertical force channels. Data were recalculated for each increment and mean profiles compared to an error free mean (±1SD) band. Error was deemed clinically significant when moments fell outside the mean (±1SD) band. Induced error at 6 N and above was sufficient to cause a clinically significant change. Sagittal and coronal plane moments at the hip were most affected, followed by the knee and then the ankle. While manufacturer guidelines for acceptable drift are usually well below 6 N, care is needed when using force plates over several minutes or more as drift may eventually exceed clinically acceptable limits.

反动态分析是步态分析中用于估算节间力和净关节力矩的一种技术。逆动态计算容易出现各种形式的误差。其中一种误差是力板漂移，通常是由于输入连接器和电子元件内的湿气凝结造成的，从而导致输出随时间发生不希望的变化。对于在临床决策过程中需要考虑反向动力学的运动实验室来说，这一点尤为重要。制造商会提供漂移的容差水平。然而，临床上很少考虑可接受的漂移水平。因此，本研究旨在确定临床上可接受的力板漂移误差限值，该限值是通过将系统误差应用于力板通道，对步态过程中的下肢关节力矩进行预测而引起的。研究分析了 10 名发育典型儿童的步态数据，并在水平和垂直力通道上分别施加了 0.5 N、1 N、1.5 N、3 N、6 N 和 12 N 的诱导误差。对每个增量重新计算数据，并将平均曲线与无误差平均值（±1SD）带进行比较。当力矩超出平均值（±1SD）范围时，误差被认为具有临床意义。6 N 及以上的诱导误差足以导致临床显著变化。髋关节矢状面和冠状面力矩受影响最大，其次是膝关节，然后是踝关节。虽然制造商给出的可接受漂移值通常远低于 6 N，但在数分钟或更长时间内使用测力板时仍需谨慎，因为漂移值最终可能会超过临床可接受的范围。

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引用次数: 0

Effects of foot orthoses application during walking on lower limb joint angles and moments in adults with flat Feet: A systematic review with Meta-Analysis 行走时使用足部矫形器对成人扁平足患者下肢关节角度和力矩的影响：系统综述与 Meta 分析

IF 2.4 3区医学 Q3 BIOPHYSICS

Journal of biomechanics

Pub Date : 2024-09-25 DOI: 10.1016/j.jbiomech.2024.112345

AmirAli Jafarnezhadgero , Ali Esmaeili , Seyed Hamed Mousavi , Urs Granacher

This systematic review with meta-analysis aimed to investigate the effects of foot orthoses (FO) application on lower limb joint angles and moments in adults with flexible flat-feet during walking. The following five databases were systematically searched from inception until March 2024: Scopus, PubMed, EMBASE, PEDro, and Cochrane Central Register of Controlled Trials (CENTRAL). Between-group standardized mean differences (SMDs) with 95% confidence intervals were computed using a random-effects model. Study heterogeneity was assessed using the I²-index. Twenty-four studies were identified and meta-analyzed. Studies were then categorized according to the applied flat-feet assessment method: (1) foot posture index (FPI-6) or clinical observation; (2) foot print arch index or radiography; (3) arch height index (including navicular drop, the arch height index, navicular height normalized to foot length [NNHT]); (4) forefoot varus method; (5) rearfoot eversion or resting calcaneal stance position (RCSP). The meta-analysis showed significant effects of FO application during walking on peak rearfoot eversion (ten studies: moderate SMDs), peak ankle dorsiflexion (five studies: small SMDs), and eversion (seven studies: moderate SMDs). This meta-analysis indicated significant effects of FO application on peak ankle eversion moment (five studies: small SMDs) and peak knee adduction moment (six studies: small SMDs). We observed greater effects of FO application on walking mechanics in the studies that used the FPI-6 method for the assessment of foot posture. Since previous research showed particularly high test–retest reliability measures for the FPI-6 method, we recommend to uniformly use this type of foot posture measure in future studies.

本系统性综述和荟萃分析旨在研究应用足部矫形器（FO）对患有灵活扁平足的成年人在行走过程中下肢关节角度和力矩的影响。从开始到 2024 年 3 月，系统检索了以下五个数据库：Scopus、PubMed、EMBASE、PEDro 和 Cochrane 对照试验中央注册中心 (CENTRAL)。采用随机效应模型计算组间标准化均值差异（SMD）及 95% 置信区间。研究异质性采用 I2 指数进行评估。共确定了 24 项研究并进行了元分析。然后根据应用的扁平足评估方法对研究进行了分类：（1）足姿指数（FPI-6）或临床观察；（2）足印足弓指数或放射学检查；（3）足弓高度指数（包括舟状突下降、足弓高度指数、舟状突高度与足长归一化[NNHT]）；（4）前足外翻法；（5）后足外翻或静止小腿站立位（RCSP）。荟萃分析表明，行走时应用 FO 对后足外翻峰值（10 项研究：中等 SMD）、踝关节外翻峰值（5 项研究：小 SMD）和外翻（7 项研究：中等 SMD）有显著影响。这项荟萃分析表明，应用 FO 对踝关节外翻峰值力矩（5 项研究：小 SMD）和膝关节内收峰值力矩（6 项研究：小 SMD）有显著效果。在使用 FPI-6 方法评估足部姿势的研究中，我们观察到应用 FO 对步行力学的影响更大。由于之前的研究表明，FPI-6 方法的测试-再测试可靠性特别高，因此我们建议在未来的研究中统一使用这种脚部姿势测量方法。

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引用次数: 0

Using dynamic ultrasound to assess Achilles tendon mechanics during running: The effect on running pattern and muscle–tendon junction tracking 使用动态超声波评估跑步过程中的跟腱力学：对跑步模式和肌肉肌腱连接跟踪的影响。

IF 2.4 3区医学 Q3 BIOPHYSICS

Journal of biomechanics

Pub Date : 2024-09-25 DOI: 10.1016/j.jbiomech.2024.112344

Wouter Schallig , Ytjanda Sloot , Milou M. van der Schaaf , Sicco A. Bus

Achilles tendon strain can be quantified using dynamic ultrasound, but its use in running is limited. Minimal effects on running pattern and acceptable test–retest reliability of muscle–tendon junction (MTJ) tracking are prerequisites for ultrasound use during running. We aimed to assess (i) the effect of wearing an ultrasound transducer on running pattern and (ii) the test–retest reliability of MTJ tracking during running. Sixteen long-distance runners (nine injury-free, seven with Achilles tendinopathy) ran at different speeds on an instrumented treadmill with a 10-camera system tracking skin-mounted retroreflective markers, first without and then with an ultrasound transducer attached to the lower leg to track the MTJ of the gastrocnemius medialis. Spatiotemporal parameters, joint kinematics and kinetics were compared between conditions using mixed ANOVAs and paired t-tests. MTJ tracking was performed manually twice by three raters in ten participants. Variability and standard error of measurement (SEM) quantified the inter- and intra-tester test–retest reliability. The running pattern was not affected by wearing the ultrasound transducer, except for significantly less knee flexion during midstance (1.6°) and midswing (2.9°) found when wearing the transducer. Inter-rater and intra-rater SEMs for MTJ tracking to assess the tendon strain (0.43%, and 0.56%, respectively) were about four times as low as between-group differences presented in literature. The minimal effects found on the running pattern and acceptable test–retest reliability indicates that dynamic ultrasound during running can be appropriately used to study Achilles tendon mechanics and thereby help improve our understanding of Achilles tendon behavior during running, injury development and recovery.

跟腱应变可通过动态超声波进行量化，但其在跑步中的应用有限。在跑步过程中使用超声波的先决条件是对跑步模式的影响最小以及肌肉-肌腱交界处（MTJ）跟踪的测试-复测可靠性可接受。我们的目的是评估：(i) 佩戴超声波传感器对跑步模式的影响；(ii) 跑步时追踪 MTJ 的重测可靠性。16 名长跑运动员（9 人未受伤，7 人患有跟腱病）在装有仪器的跑步机上以不同的速度跑步，跑步机上装有 10 个摄像头系统，跟踪安装在皮肤上的反向反射标记。使用混合方差分析和配对 t 检验比较了不同条件下的时空参数、关节运动学和动力学。MTJ 跟踪由三名评定者对 10 名参与者进行两次人工跟踪。变异性和标准测量误差（SEM）量化了测试者之间和测试者内部测试-再测试的可靠性。跑步模式不受佩戴超声波传感器的影响，只是在佩戴传感器时，膝关节中段屈曲（1.6°）和中段屈曲（2.9°）明显减少。MTJ 跟踪评估肌腱应变的评分者间和评分者内 SEM 值（分别为 0.43% 和 0.56%）比文献中的组间差异低约四倍。对跑步模式的影响极小，测试-重复可靠性也可接受，这表明跑步过程中的动态超声波可适当用于研究跟腱力学，从而帮助我们更好地了解跟腱在跑步、损伤发展和恢复过程中的行为。

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引用次数: 0

The effects of soft vs. rigid back-support exoskeletons on trunk dynamic stability and trunk-pelvis coordination in young and old adults during repetitive lifting 软质与硬质背部支撑外骨骼对年轻人和老年人在重复性提举过程中躯干动态稳定性和躯干-骨盆协调性的影响。

IF 2.4 3区医学 Q3 BIOPHYSICS

Journal of biomechanics

Pub Date : 2024-09-24 DOI: 10.1016/j.jbiomech.2024.112348

Rahul Narasimhan Raghuraman, Divya Srinivasan

While back-support exoskeletons are increasing in popularity as an ergonomic intervention for manual material handling, they may cause alterations to neuromuscular control required for maintaining spinal stability. This study evaluated the effects of soft and rigid passive exoskeletons on trunk local dynamic stability and trunk-pelvis coordination. Thiry-two young (18–30 years) and old (45–60 years) men and women completed repetitive lifting and lowering tasks using two different exoskeletons and in a control condition. Both exoskeletons significantly reduced the short-term maximum Lyapunov exponent (LyE) of the trunk (p < 0.01), suggesting improved local dynamic stability. There was also a significant main effect of age (p = 0.05): older adults exhibited lower short-term LyE that young adults. Use of the soft exoskeleton significantly increased, while the rigid exoskeleton significantly decreased, long-term LyE, and these changes were more pronounced in the young group compared to the old group. Additionally, exoskeleton use resulted in significant increase (p < 0.001) of mean absolute relative phase (MARP) and deviation phase (DP) by ∼30–60 %, with greater increases due to the rigid than the soft device. Thus, trunk-pelvic coordination and coordination variability were negatively impacted by exoskeleton use. Potential reasons for these findings may include exoskeleton-induced changes in lifting strategy, reduced peak trunk flexion velocity, and cycle-to-cycle variability of trunk velocity. Furthermore, although the soft and rigid devices caused comparable changes in trunk-extensor muscle activity, they exhibited differential effects on long-term maximum Lyapunov exponents as well as trunk-pelvic coordination, indicating that exoskeleton design features can have complex effects on trunk neuromuscular control.

虽然背部支撑外骨骼作为人工材料搬运的一种人体工学干预措施越来越受欢迎，但它们可能会改变维持脊柱稳定性所需的神经肌肉控制。本研究评估了软质和硬质被动外骨骼对躯干局部动态稳定性和躯干-骨盆协调性的影响。132 名年轻（18-30 岁）和年长（45-60 岁）的男性和女性在使用两种不同的外骨骼和对照组的情况下完成了重复性的抬起和放下任务。两种外骨骼都明显降低了躯干的短期最大莱普诺夫指数（LyE）（p

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引用次数: 0

Does proprioceptive reweighting contribute to reactive balance strategies during slip-like perturbations? a proof-of-concept in healthy adults 本体感觉再加权是否有助于在类似滑倒的扰动过程中采取反应平衡策略？

IF 2.4 3区医学 Q3 BIOPHYSICS

Journal of biomechanics

Pub Date : 2024-09-24 DOI: 10.1016/j.jbiomech.2024.112341

Tamaya Van Criekinge , Upasana Sahu , Kurt Claeys , Tanvi Bhatt

Falls commonly occur during walking, particularly when struggling to respond to unexpected perturbations. Proprioception plays a significant role in detecting body destabilization even before reactions to perturbations are required. This study investigates the contribution of proprioceptive reweighting strategies to reactive balance during walking. This cross-sectional, proof-of-concept study included fifteen healthy adults (18–40 years). Ankle and back muscle vibrators disrupted proprioceptive input in stance, allowing calculation of the proprioceptive reweighting index. Walk-slip perturbations were then administered on an ActiveStep treadmill. A linear regression model assessed the significance of proprioceptive reweighting in predicting post-slip stability (margin of stability). Participants shifted from an ankle-steered to a central-steered proprioceptive strategy on a foam surface with closed eyes (Difference = 15.70 % (SD=37.87), 95 %CI [0.41, 30.99], p = 0.045). The regression model explained 22.7 % of the variance in pre-touchdown margin of stability, with proprioceptive reweighting on foam significantly contributing to post-perturbation postural control (p < 0.001). Proprioceptive reweighting provides a moderate explanation for the mechanisms of reactive balance, highlighting that the key to effective balance recovery strategies may lie in the person’s ability to both detect and respond to imbalances. Further research should explore if these proprioceptive strategies are a matter of directional control and if responses differ in older adults.

跌倒通常发生在行走过程中，尤其是在对意外干扰做出反应时。本体感觉在检测身体失稳方面发挥着重要作用，甚至在需要对扰动做出反应之前。本研究调查了本体感觉再权重策略对步行过程中反应性平衡的贡献。这项横断面概念验证研究包括 15 名健康成年人（18-40 岁）。踝部和背部肌肉振动器扰乱了站立时的本体感觉输入，从而可以计算本体感觉再加权指数。然后在 ActiveStep 跑步机上进行行走滑动扰动。线性回归模型评估了本体感觉再加权在预测滑步后稳定性（稳定幅度）方面的意义。参与者在闭眼的情况下，在泡沫表面上从以脚踝为中心的本体感觉策略转向以中心为中心的本体感觉策略（差异 = 15.70 % (SD=37.87), 95 %CI [0.41, 30.99], p = 0.045）。回归模型解释了触地前稳定幅度变异的 22.7%，泡沫上的本体感觉再加权显著促进了扰动后姿势控制（p

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引用次数: 0

Synovial fluid does not retard fluid exudation during stress-relaxation of immature bovine cartilage 在未成熟牛软骨的应力松弛过程中，滑液不会延缓液体渗出

IF 2.4 3区医学 Q3 BIOPHYSICS

Journal of biomechanics

Pub Date : 2024-09-24 DOI: 10.1016/j.jbiomech.2024.112340

C.V. Sise , C.A. Petersen , J. Yun , S. Vukelic , C.T. Hung , G.A. Ateshian

Interstitial fluid load support (FLS) is a dominant mechanism of lubrication in cartilage, producing a low friction coefficient while enhancing the tissue’s load bearing capabilities. Due to its viscosity, synovial fluid (SF) may retard loss of FLS by slowing the exudation of interstitial fluid from the cartilage. This study tested this hypothesis by comparing the stress-relaxation (SRL) response of immature bovine articular cartilage immersed either in phosphate buffered saline (PBS) or in healthy mature bovine SF, under unconfined compression (fluid exudation across cut lateral tissue boundary) and indentation testing (fluid exudation across articular surface). To investigate the influence of diffusion of SF molecular constituents into cartilage, the effect of incubation time in SF on SRL was also investigated. The SRL response in unconfined compression was not significantly different in PBS versus SF when compared directly (p = 0.98) and had a slope of

m

= 1.00 ± 0.04 (

R^{2}

= 0.989 ± 0.007). Samples tested in PBS exhibited characteristic relaxation times,

τ^{PBS}

=42.6 ± 5.3 s and

τ^{SF}

= 40.8 ± 4.7 s, that were not significantly different (p = 0.40). Incubation time of 24 h in SF resulted in no significant difference in the SRL response (p = 0.39,

m

=1.03 ± 0.12;

R^{2}

=0.983 ± 0.011, and

τ^{PBS}

= 43.4 ± 10.7 s versus

τ^{SF}

= 41.5 ± 4.8 s, p = 0.59). Indentation testing showed some statistically significant, but functionally insignificant, difference in SRL responses in PBS versus SF with a slope of

m

= 0.958 ± 0.060 (

R^{2}

= 0.957 ± 0.020, p = 0.029, and

τ^{PBS}

= 16.9 ± 2.6 s versus

τ^{SF}

= 19.4 ± 3.3 s, p = 0.073). Based on these results, we reject the hypothesis that healthy SF can retard the loss of FLS in cartilage due to its viscosity.

间质流体负载支撑（FLS）是软骨润滑的主要机制，可产生低摩擦系数，同时增强组织的承载能力。滑液（SF）因其粘度，可通过减缓软骨间质的渗出来延缓FLS的损失。本研究通过比较浸泡在磷酸盐缓冲盐水（PBS）或健康成熟的牛滑液中的未成熟牛关节软骨在无约束压缩（液体渗出横切侧组织边界）和压痕测试（液体渗出关节表面）下的应力-松弛（SRL）反应来验证这一假设。为了研究 SF 分子成分扩散到软骨中的影响，还研究了 SF 中培养时间对 SRL 的影响。直接比较在 PBS 和 SF 中的 SRL 反应，在无约束压缩中的 SRL 反应没有明显差异（p = 0.98），斜率为 m = 1.00 ± 0.04（R2 = 0.989 ± 0.007）。在 PBS 中测试的样品表现出特有的弛豫时间，τPBS=42.6 ± 5.3 秒，τSF=40.8 ± 4.7 秒，两者差异不大（p = 0.40）。在 SF 中孵育 24 小时后，SRL 反应无显著差异（p = 0.39，m=1.03 ± 0.12；R2=0.983 ± 0.011，τPBS = 43.4 ± 10.7 秒与τSF = 41.5 ± 4.8 秒相比，p = 0.59）。压痕测试表明，PBS 与 SF 的 SRL 反应在统计学上存在显著差异，但在功能上并不显著，斜率为 m = 0.958 ± 0.060（R2 = 0.957 ± 0.020，p = 0.029；τPBS = 16.9 ± 2.6 s，τSF = 19.4 ± 3.3 s，p = 0.073）。基于这些结果，我们否定了健康 SF 因其粘度而能延缓软骨中 FLS 损失的假设。

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引用次数: 0

A multiscale discrete fiber model of failure in heterogeneous tissues: Applications to remodeled cerebral aneurysms. 异质组织失效的多尺度离散纤维模型：重塑脑动脉瘤的应用。

IF 2.4 3区医学 Q3 BIOPHYSICS

Journal of biomechanics

Pub Date : 2024-09-24 DOI: 10.1016/j.jbiomech.2024.112343

Ryan R Mahutga, Ruturaj M Badal, Victor H Barocas, Patrick W Alford

Damage-accumulation failure models are broadly used to examine tissue property changes caused by mechanical loading. However, damage accumulation models are purely phenomenological. The underlying justification in using this type of model is often that damage occurs to the extracellular fibers and/or cells which changes the fundamental mechanical behavior of the system. In this work, we seek to align damage accumulation models with microstructural models to predict alterations in the mechanical behavior of biological materials that arise from structural heterogeneity associated with nonuniform remodeling of tissues. Further, we seek to extend this multiscale model toward assessing catastrophic failure events such as cerebral aneurysm rupture. First, we demonstrate that a model made up of linear elastin and actin and nonlinear collagen fibers can replicate bot the pre-failure and failure tissue-scale mechanics of uniaxially-stretched cerebral aneurysms. Next, we investigate how mechanical heterogeneities, like those observed in cerebral aneurysms, influence fiber and tissue failure. Notably, we find that failure occurs and the interface between regions of high and low material stiffness, suggesting that spatial mechanical heterogeneity influences aneurysm failure behavior. This model system is a step toward linking structural changes in growth and remodeling to failure properties.

损伤累积失效模型被广泛用于研究机械负载引起的组织特性变化。然而，损伤累积模型纯粹是一种现象学模型。使用这类模型的基本理由通常是细胞外纤维和/或细胞发生了损伤，从而改变了系统的基本机械行为。在这项研究中，我们试图将损伤累积模型与微观结构模型结合起来，以预测生物材料力学行为的改变，这种改变源于与组织非均匀重塑相关的结构异质性。此外，我们还试图将这种多尺度模型扩展到评估灾难性失效事件（如脑动脉瘤破裂）。首先，我们证明了由线性弹性蛋白和肌动蛋白以及非线性胶原纤维组成的模型可以复制单轴拉伸脑动脉瘤的失效前和失效组织尺度力学。接下来，我们将研究机械异质性（如在脑动脉瘤中观察到的异质性）如何影响纤维和组织的失效。值得注意的是，我们发现失效发生在高材料刚度和低材料刚度区域之间的界面，这表明空间机械异质性会影响动脉瘤的失效行为。该模型系统朝着将生长和重塑过程中的结构变化与失效特性联系起来迈出了一步。

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