Pub Date : 2025-11-12DOI: 10.1016/j.jmbbm.2025.107257
Will J. Clayton , Davis R. Ballard , Amelia J. Strozier , Maryam F. Afzali , Kelly S. Santangelo , John L. Williams
The infrapatellar fat pad (IFP), an adipose tissue located in the anterior knee joint, is hypothesized to absorb shocks and aid in joint lubrication. We investigated the consequences of IFP removal on joint friction and damping in an in vitro animal model. The hindlimbs of female New Zealand white rabbits were dissected to retain the knee ligaments, joint capsule, and patellar retinaculum. Knees were mounted in a pendulum with the knee joint serving as the fulcrum while keeping the quadriceps tendon unloaded to assess joint friction and damping in each knee for three conditions: Control, Sham, and no IFP (IFP-R). Friction and damping were assessed under a 15N tibio-femoral joint load (40 % of body weight) at three flexion angles (50°, 100°, and 130°), and gyroscopic data were recorded to obtain the time decay of amplitude. Two models, a linear friction and an exponential decay friction model, were fit to the amplitude decay over time. The linear model provided Stanton's joint boundary friction coefficient (μL); the exponential decay model provided an exponential decay friction (μE) and a viscous damping (c) coefficient. When compared across all angles of testing, IFP removal decreased μL by 6 % (p = 0.0057) vs Controls (μL = 0.0217 vs 0.0230); IFP removal decreased c by 9 % (p < 0.001) vs Controls (c = 0.00262 vs 0.00239 kgm2/s) and by 6 % vs Sham (p = 0.017, c = 0.00255 vs 0.00239 kgm2/s). IFP removal did not affect μE (p = 0.12).
髌下脂肪垫（IFP）是一种位于膝关节前部的脂肪组织，被认为可以吸收冲击并帮助关节润滑。我们在体外动物模型中研究了IFP去除对关节摩擦和阻尼的影响。解剖雌性新西兰大白兔后肢，保留膝关节韧带、关节囊和髌骨支持带。在三种情况下：对照组、假手术和无IFP (IFP- r)，双膝以膝关节为支点，保持股四头肌肌腱卸载，以评估每个膝关节的关节摩擦和阻尼。在三个屈曲角度（50°，100°和130°）下，在15N的胫骨-股骨关节载荷（体重的40% %）下评估摩擦和阻尼，并记录陀螺仪数据以获得振幅的时间衰减。两个模型，线性摩擦和指数衰减摩擦模型，适合振幅衰减随时间的变化。线性模型给出了斯坦顿节理边界摩擦系数（μL）；指数衰减模型给出了指数衰减摩擦系数μE和粘性阻尼系数c。在所有测试角度进行比较时，与对照组（μL = 0.0217 vs 0.0230）相比，IFP去除率降低了6 μL % (p = 0.0057)；奖学金项目删除c降低了9 % (p & lt; 0.001)和控制(c = 0.00262 vs 0.00239 kgm2 / s)和6 % vs骗局(p = 0.017 c = 0.00255 vs 0.00239 kgm2 / s)。去除IFP对μE无影响（p = 0.12）。
{"title":"The influence of infrapatellar fat pad resection on knee joint friction and damping: An in vitro study in New Zealand white rabbits","authors":"Will J. Clayton , Davis R. Ballard , Amelia J. Strozier , Maryam F. Afzali , Kelly S. Santangelo , John L. Williams","doi":"10.1016/j.jmbbm.2025.107257","DOIUrl":"10.1016/j.jmbbm.2025.107257","url":null,"abstract":"<div><div>The infrapatellar fat pad (IFP), an adipose tissue located in the anterior knee joint, is hypothesized to absorb shocks and aid in joint lubrication. We investigated the consequences of IFP removal on joint friction and damping in an in vitro animal model. The hindlimbs of female New Zealand white rabbits were dissected to retain the knee ligaments, joint capsule, and patellar retinaculum. Knees were mounted in a pendulum with the knee joint serving as the fulcrum while keeping the quadriceps tendon unloaded to assess joint friction and damping in each knee for three conditions: Control, Sham, and no IFP (IFP-R). Friction and damping were assessed under a 15N tibio-femoral joint load (40 % of body weight) at three flexion angles (50°, 100°, and 130°), and gyroscopic data were recorded to obtain the time decay of amplitude. Two models, a linear friction and an exponential decay friction model, were fit to the amplitude decay over time. The linear model provided Stanton's joint boundary friction coefficient (μ<sub>L</sub>); the exponential decay model provided an exponential decay friction (μ<sub>E</sub>) and a viscous damping (c) coefficient. When compared across all angles of testing, IFP removal decreased μ<sub>L</sub> by 6 % (p = 0.0057) vs Controls (μ<sub>L</sub> = 0.0217 vs 0.0230); IFP removal decreased c by 9 % (p < 0.001) vs Controls (c = 0.00262 vs 0.00239 kgm<sup>2</sup>/s) and by 6 % vs Sham (p = 0.017, c = 0.00255 vs 0.00239 kgm<sup>2</sup>/s). IFP removal did not affect μ<sub>E</sub> (p = 0.12).</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107257"},"PeriodicalIF":3.5,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145569483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-12DOI: 10.1016/j.jmbbm.2025.107268
C.S. Moreira , F.S. Araújo , L.C.S. Nunes
Shear load transfer is crucial for the redistribution of internal tendon loads and to prevent excessive local stress that can lead to severe damage and injury. To better understand this transfer mechanism, it is important to know the stress state. The aim of the present study is to investigate the normal and shear stresses in tendons sheared with the shear force applied parallel to the fascicles and collagen fibers. A key novelty of the paper is the simultaneous measurement of normal and shear forces, as well as the amount of shear of tendon samples under simple shear. For the sake of simplicity, a more straightforward model is employed to describe the normal and shear behavior of tendons. Expressions were simultaneously fitted to the measured normal and shear stresses. The results reveal that the shear behavior did not exhibit any evidence of strain-stiffening, because the shear stress was approximately proportional to the amount of shear. However, compressive and tensile normal stresses, or positive and negative Poynting effects, respectively, were observed in different samples. Each tendon specimen was sheared along the orientation of the longitudinal fascicles and collagen fibers, which were maintained by random fiber networks associated with connective tissue and cross-link structures. Compressive normal stress indicates that random fiber networks did not influence the behavior or were not significant in a certain range, whereas random fiber networks contribution was more pronounced in the case of tensile normal stress. These findings suggest that the effects of random fiber networks, which can manifest over different length scales, play an important role in the state of normal stress in tendons under simple shear. Understanding how random fiber networks influence tendon mechanics could lead to better treatments for tendon injuries and help design biomimetic materials.
{"title":"Negative and positive Poynting effects in tendon under simple shear","authors":"C.S. Moreira , F.S. Araújo , L.C.S. Nunes","doi":"10.1016/j.jmbbm.2025.107268","DOIUrl":"10.1016/j.jmbbm.2025.107268","url":null,"abstract":"<div><div>Shear load transfer is crucial for the redistribution of internal tendon loads and to prevent excessive local stress that can lead to severe damage and injury. To better understand this transfer mechanism, it is important to know the stress state. The aim of the present study is to investigate the normal and shear stresses in tendons sheared with the shear force applied parallel to the fascicles and collagen fibers. A key novelty of the paper is the simultaneous measurement of normal and shear forces, as well as the amount of shear of tendon samples under simple shear. For the sake of simplicity, a more straightforward model is employed to describe the normal and shear behavior of tendons. Expressions were simultaneously fitted to the measured normal and shear stresses. The results reveal that the shear behavior did not exhibit any evidence of strain-stiffening, because the shear stress was approximately proportional to the amount of shear. However, compressive and tensile normal stresses, or positive and negative Poynting effects, respectively, were observed in different samples. Each tendon specimen was sheared along the orientation of the longitudinal fascicles and collagen fibers, which were maintained by random fiber networks associated with connective tissue and cross-link structures. Compressive normal stress indicates that random fiber networks did not influence the behavior or were not significant in a certain range, whereas random fiber networks contribution was more pronounced in the case of tensile normal stress. These findings suggest that the effects of random fiber networks, which can manifest over different length scales, play an important role in the state of normal stress in tendons under simple shear. Understanding how random fiber networks influence tendon mechanics could lead to better treatments for tendon injuries and help design biomimetic materials.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107268"},"PeriodicalIF":3.5,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145552451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-11DOI: 10.1016/j.jmbbm.2025.107267
James Wu , Xuan Hu , David Benoit , Franck Le Navéaux , Julien Clin , Shaofan Li , Reno Genest , Ram Gopisetti , Bo Ren
Although the finite element method (FEM) is a valuable computational tool for analyzing factors that influence bone–screw fixation strength in osteosynthesis, it faces challenges in capturing the effects of screw insertion prior to pullout simulation due to mesh distortion and element erosion. To address these limitations, this study introduces an orthopedic computational model based on the Smoothed Particle Galerkin (SPG) method, offering an enhanced approach for simulating bone–screw interactions.
The Smoothed Particle Galerkin (SPG) method is an advanced mesh-free numerical technique capable of simulating large deformations and material removal while avoiding common mesh-related issues in FEM. In this study, the SPG method is used to model the Sawbones material during screw insertion and pullout. A bond-failure model is incorporated into the SPG framework to represent material removal, employing two failure criteria: the critical effective shear strain and the critical effective plastic strain. This modeling approach allows for accurate reproduction of thread formation in the bone during screw insertion, capturing the appropriate contact geometry and residual stress conditions for subsequent pullout simulations.
To validate the accuracy of the proposed simulation model, experimental tests were performed using Sawbones specimens composed of grade 15 PCF polyurethane foam, serving as an analog for human cancellous bone. The nonlinear material properties of the Sawbones were characterized following ASTM D1621 for compression and ASTM D1623 for tension. Parameters of the bond-failure model were calibrated through a combined screw insertion and pullout simulation using a non-fluted screw with a pilot hole. For the predictive analysis, three test cases were modeled, each combining different pilot-hole sizes and screw types, with and without cutting flutes.
The proposed simulation model successfully reproduces thread formation, a feature that is difficult to capture using conventional FEM approaches. The results demonstrate that screw insertion induces residual stress, which strongly affects the pullout force. In addition, both pilot-hole size and screw design are shown to significantly influence residual stress and pullout performance. Comparison of pullout forces between experiments and simulations across three prediction cases, showing average errors of +4.0 %, −11.8 %, and −6.0 %, indicates that the proposed model is a promising tool for analyzing bone–screw fixation strength while accounting for the screw insertion effect, a capability not available in existing simulation frameworks.
{"title":"A virtual model for the osteosynthesis fixation strength analysis of cancellous screws considering the insertion effect in sawbones with experimental validation","authors":"James Wu , Xuan Hu , David Benoit , Franck Le Navéaux , Julien Clin , Shaofan Li , Reno Genest , Ram Gopisetti , Bo Ren","doi":"10.1016/j.jmbbm.2025.107267","DOIUrl":"10.1016/j.jmbbm.2025.107267","url":null,"abstract":"<div><div>Although the finite element method (FEM) is a valuable computational tool for analyzing factors that influence bone–screw fixation strength in osteosynthesis, it faces challenges in capturing the effects of screw insertion prior to pullout simulation due to mesh distortion and element erosion. To address these limitations, this study introduces an orthopedic computational model based on the Smoothed Particle Galerkin (SPG) method, offering an enhanced approach for simulating bone–screw interactions.</div><div>The Smoothed Particle Galerkin (SPG) method is an advanced mesh-free numerical technique capable of simulating large deformations and material removal while avoiding common mesh-related issues in FEM. In this study, the SPG method is used to model the Sawbones material during screw insertion and pullout. A bond-failure model is incorporated into the SPG framework to represent material removal, employing two failure criteria: the critical effective shear strain and the critical effective plastic strain. This modeling approach allows for accurate reproduction of thread formation in the bone during screw insertion, capturing the appropriate contact geometry and residual stress conditions for subsequent pullout simulations.</div><div>To validate the accuracy of the proposed simulation model, experimental tests were performed using Sawbones specimens composed of grade 15 PCF polyurethane foam, serving as an analog for human cancellous bone. The nonlinear material properties of the Sawbones were characterized following ASTM <span><span>D1621</span><svg><path></path></svg></span> for compression and ASTM <span><span>D1623</span><svg><path></path></svg></span> for tension. Parameters of the bond-failure model were calibrated through a combined screw insertion and pullout simulation using a non-fluted screw with a pilot hole. For the predictive analysis, three test cases were modeled, each combining different pilot-hole sizes and screw types, with and without cutting flutes.</div><div>The proposed simulation model successfully reproduces thread formation, a feature that is difficult to capture using conventional FEM approaches. The results demonstrate that screw insertion induces residual stress, which strongly affects the pullout force. In addition, both pilot-hole size and screw design are shown to significantly influence residual stress and pullout performance. Comparison of pullout forces between experiments and simulations across three prediction cases, showing average errors of +4.0 %, −11.8 %, and −6.0 %, indicates that the proposed model is a promising tool for analyzing bone–screw fixation strength while accounting for the screw insertion effect, a capability not available in existing simulation frameworks.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107267"},"PeriodicalIF":3.5,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145515359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The aortic elasticity plays a vital role in buffering pulsatile blood flow, propelling blood to distal organs and the heart, and reducing cardiac workload. Aortic repair with a stent-graft can reduce this elasticity and hinder the aorta's ability to effectively perform its function. Conventional stent-grafts are associated with increased arterial stiffness, elevated pulse wave velocity (PWV), and adverse hemodynamic changes. This is largely driven by stiffness mismatch between the stent-graft and the native aortic wall, which alters mechanical compliance and hemodynamic response. This study evaluates a novel compliant nanofiber stent-graft (NF-SG) developed to closely mimic native aortic mechanics. Using a bench-top physiological flow circuit, we assessed the hemodynamic impacts of stent-graft stiffness and length on arterial parameters, including PWV, pulse pressure (PP), and distensibility in vitro, and compared these effects with conventional stent-grafts. Stent-graft stiffness significantly affected PWV, PP, and distensibility. Conventional stent-grafts showed 14 %–52 % increase in PWV depending on stent-graft length (p < 0.001), 5 %–32 % increase in PP, and 82 % reduction in mid-graft distensibility. In contrast, NF-SGs maintained PWV and PP near baseline levels with marginal effect of the stent-graft length. Distensibility in the mid-graft was reduced by 13 %–20 %, depending on the stent-graft length. The NF-SG's superior compliance and reduced hemodynamic perturbation were attributed to its mechanically optimized fabric and skeleton design. These findings underscore the clinical potential of the compliant stent-grafts to significantly mitigate long-term cardiovascular complications and preserve aortic functionality post-intervention.
{"title":"Effect of stent-graft length and compliance on aortic hemodynamics in a bench-top physiological flow circuit","authors":"Ramin Shahbad, Elizabeth Zermeno, Sayed Ahmadreza Razian, Kaspars Maleckis, Majid Jadidi, Anastasia Desyatova","doi":"10.1016/j.jmbbm.2025.107269","DOIUrl":"10.1016/j.jmbbm.2025.107269","url":null,"abstract":"<div><div>The aortic elasticity plays a vital role in buffering pulsatile blood flow, propelling blood to distal organs and the heart, and reducing cardiac workload. Aortic repair with a stent-graft can reduce this elasticity and hinder the aorta's ability to effectively perform its function. Conventional stent-grafts are associated with increased arterial stiffness, elevated pulse wave velocity (PWV), and adverse hemodynamic changes. This is largely driven by stiffness mismatch between the stent-graft and the native aortic wall, which alters mechanical compliance and hemodynamic response. This study evaluates a novel compliant nanofiber stent-graft (NF-SG) developed to closely mimic native aortic mechanics. Using a bench-top physiological flow circuit, we assessed the hemodynamic impacts of stent-graft stiffness and length on arterial parameters, including PWV, pulse pressure (PP), and distensibility in vitro, and compared these effects with conventional stent-grafts. Stent-graft stiffness significantly affected PWV, PP, and distensibility. Conventional stent-grafts showed 14 %–52 % increase in PWV depending on stent-graft length (p < 0.001), 5 %–32 % increase in PP, and 82 % reduction in mid-graft distensibility. In contrast, NF-SGs maintained PWV and PP near baseline levels with marginal effect of the stent-graft length. Distensibility in the mid-graft was reduced by 13 %–20 %, depending on the stent-graft length. The NF-SG's superior compliance and reduced hemodynamic perturbation were attributed to its mechanically optimized fabric and skeleton design. These findings underscore the clinical potential of the compliant stent-grafts to significantly mitigate long-term cardiovascular complications and preserve aortic functionality post-intervention.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107269"},"PeriodicalIF":3.5,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145569484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-10DOI: 10.1016/j.jmbbm.2025.107254
Zhouyu Shen, Yaoke Wen, Weixiao Nie, Huicheng Wang, Haoran Xu
Traditional helmet foam pads have limited energy absorption for blunt impacts, unable to meet protective needs in complex ballistic scenarios such as fragments and bullets. Auxetic (negative Poisson's ratio) materials have been tested for helmet pads, but existing studies focus mainly on low-velocity impact protection. Thus, optimizing auxetic pad structures for high-velocity impacts is essential.
In this study, lightweight expanded thermoplastic polyurethane (TPU-LW) was used as the base material, with 3D printing to fabricate pad samples. First, TPU-LW's material constitutive model was established via uniaxial tensile tests. Simulations later revealed a key issue: a single auxetic pad caused excessive skull peak stress. To solve this, an innovative “auxetic + foam” composite pad was designed, verified by 9 mm pistol bullet and 1.1 g fragment tests.
The composite pad outperformed single auxetic and foam pads in key head blunt impact indicators. Simulations showed that under high-velocity fragment impact, the helmet's maximum backface deformation (BFD) dropped to 14.50 mm, and skull peak stress was 22.7 % lower than the foam pad. Experiments indicated that under 714 m/s fragment impact, peak head pressure was only 25 kPa - far below the foam pad's 165 kPa.
This study fills the biomechanical data gap of auxetic TPU-LW in ballistic protection. The proposed composite structure provides a theoretical basis and technical solution for upgrading helmet pads from “single-material” to “composite energy-absorbing structure,” applicable to various protective helmet research and development.
{"title":"Protective performance of auxetic TPU pad for helmet: An investigation into design improvements for blunt impact protection","authors":"Zhouyu Shen, Yaoke Wen, Weixiao Nie, Huicheng Wang, Haoran Xu","doi":"10.1016/j.jmbbm.2025.107254","DOIUrl":"10.1016/j.jmbbm.2025.107254","url":null,"abstract":"<div><div>Traditional helmet foam pads have limited energy absorption for blunt impacts, unable to meet protective needs in complex ballistic scenarios such as fragments and bullets. Auxetic (negative Poisson's ratio) materials have been tested for helmet pads, but existing studies focus mainly on low-velocity impact protection. Thus, optimizing auxetic pad structures for high-velocity impacts is essential.</div><div>In this study, lightweight expanded thermoplastic polyurethane (TPU-LW) was used as the base material, with 3D printing to fabricate pad samples. First, TPU-LW's material constitutive model was established via uniaxial tensile tests. Simulations later revealed a key issue: a single auxetic pad caused excessive skull peak stress. To solve this, an innovative “auxetic + foam” composite pad was designed, verified by 9 mm pistol bullet and 1.1 g fragment tests.</div><div>The composite pad outperformed single auxetic and foam pads in key head blunt impact indicators. Simulations showed that under high-velocity fragment impact, the helmet's maximum backface deformation (BFD) dropped to 14.50 mm, and skull peak stress was 22.7 % lower than the foam pad. Experiments indicated that under 714 m/s fragment impact, peak head pressure was only 25 kPa - far below the foam pad's 165 kPa.</div><div>This study fills the biomechanical data gap of auxetic TPU-LW in ballistic protection. The proposed composite structure provides a theoretical basis and technical solution for upgrading helmet pads from “single-material” to “composite energy-absorbing structure,” applicable to various protective helmet research and development.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107254"},"PeriodicalIF":3.5,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145515309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-07DOI: 10.1016/j.jmbbm.2025.107255
Jan-Oliver Sass , Iman Soodmand , Ann-Kristin Becker , Christopher Jabs , Michael Dau , Rainer Bader , Maeruan Kebbach
This computational study aimed to evaluate the bone-implant interaction of dental implants made from materials with varying Young's moduli under various conditions of bone quality. A subject-specific numerical workflow was developed by integrating boundary conditions obtained from a musculoskeletal multibody simulation (MMBS) into a finite element (FE) analysis of the mandible bone. Implants made from commercially pure titanium (cp-Ti), zirconia ceramic (ZrO2), low-stiffness β-titanium alloy (β-Ti), and poly-ether-ether-ketone (PEEK) were evaluated during a clenching scenario. A systematic analysis was performed using statistical modeling to examine ten variations in bone quality, including cortical thickness and homogeneous bone stiffness. Additionally, two CT-based subject-specific comparisons were carried out using mandibles with distinctly different bone qualities. Implants made from materials with lower stiffness resulted in increased peri-implant strain and stress levels. In the statistical analysis, these effects were not significant when accounting for inter-individual variability of the bone qualities (p > 0.05). Cortical bone stiffness strongly correlated with peri-implant bone stress (r = 0.96 ± 0.01), while trabecular bone stiffness correlated with maximum (r = 0.71 ± 0.01) and minimum (r = −0.83 ± 0.02) principal strain in the bone. In the subject-specific analysis, stress and strain in the peri-implant bone increased for the low-quality bone and were significant for a PEEK-based implant (p < 0.001). Within the restrictions of the simplified numerical models and limited generalizability of the present findings, materials with lower stiffness may reduce peri-implant stress shielding but simultaneously increase stress at the bone-implant interface. However, their overall effect was not statistically significant when inter-individual variation in bone quality were considered.
{"title":"Systematic biomechanical evaluation of different dental implant materials at various bone stock conditions using a statistical and subject-specific computer-based workflow","authors":"Jan-Oliver Sass , Iman Soodmand , Ann-Kristin Becker , Christopher Jabs , Michael Dau , Rainer Bader , Maeruan Kebbach","doi":"10.1016/j.jmbbm.2025.107255","DOIUrl":"10.1016/j.jmbbm.2025.107255","url":null,"abstract":"<div><div>This computational study aimed to evaluate the bone-implant interaction of dental implants made from materials with varying Young's moduli under various conditions of bone quality. A subject-specific numerical workflow was developed by integrating boundary conditions obtained from a musculoskeletal multibody simulation (MMBS) into a finite element (FE) analysis of the mandible bone. Implants made from commercially pure titanium (cp-Ti), zirconia ceramic (ZrO<sub>2</sub>), low-stiffness β-titanium alloy (β-Ti), and poly-ether-ether-ketone (PEEK) were evaluated during a clenching scenario. A systematic analysis was performed using statistical modeling to examine ten variations in bone quality, including cortical thickness and homogeneous bone stiffness. Additionally, two CT-based subject-specific comparisons were carried out using mandibles with distinctly different bone qualities. Implants made from materials with lower stiffness resulted in increased peri-implant strain and stress levels. In the statistical analysis, these effects were not significant when accounting for inter-individual variability of the bone qualities (p > 0.05). Cortical bone stiffness strongly correlated with peri-implant bone stress (r = 0.96 ± 0.01), while trabecular bone stiffness correlated with maximum (r = 0.71 ± 0.01) and minimum (r = −0.83 ± 0.02) principal strain in the bone. In the subject-specific analysis, stress and strain in the peri-implant bone increased for the low-quality bone and were significant for a PEEK-based implant (p < 0.001). Within the restrictions of the simplified numerical models and limited generalizability of the present findings, materials with lower stiffness may reduce peri-implant stress shielding but simultaneously increase stress at the bone-implant interface. However, their overall effect was not statistically significant when inter-individual variation in bone quality were considered.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107255"},"PeriodicalIF":3.5,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145508569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-07DOI: 10.1016/j.jmbbm.2025.107256
Xiao Li , Warwick Duncan , Joanne Choi , Dawn Coates
{"title":"Channel-pillars scaffold for bone regeneration: structure design, manufacturing, and physicochemical properties","authors":"Xiao Li , Warwick Duncan , Joanne Choi , Dawn Coates","doi":"10.1016/j.jmbbm.2025.107256","DOIUrl":"10.1016/j.jmbbm.2025.107256","url":null,"abstract":"","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107256"},"PeriodicalIF":3.5,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145464841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-30DOI: 10.1016/j.jmbbm.2025.107253
Heinrich Leon Souza Viera, Fábio Juner Lanferdini
Although the growing studies investigating muscle echo intensity (EI) and shear modulus, little is known about the effects of adipose tissue thickness (ATT) on these measures. We investigated whether ATT influences the EI and shear modulus measurements of the human tibialis anterior superficial (TAsuperficial) and deep (TAdeep) compartments. Ultrasound measurements were taken from the TA at rest, near the highest cross-sectional area, in ten physically active adults in the following conditions: without fat layers and with one and two fat layers. The EI and shear modulus of both TAsuperficial and TAdeep were determined, and the best-fit regression model was calculated to assess the influence of ATT on EI and shear modulus. A repeated measures ANOVA were adopted to investigate the differences in EI and shear modulus in the different fat layers. The ATT was seen to affect the EI of both TAsuperficial (R2 = 0.58; p < 0.001) and TAdeep (R2 = 0.44; p < 0.001). When the thickness of TAsuperficial was summed with ATT, the EI of TAdeep was also affected but to a less extent (R2 = 0.25; p = 0.004). No significant influence of ATT on shear modulus was seen for both TA compartments (p ≥ 0.061). While EI decreased in both TA compartments (p < 0.05), the repeated measures ANOVA revealed that only TAdeep shear modulus decreased with the addition of two fat layers (p = 0.005). Corrective formula for EI measurements was determined. Thus, while skeletal muscle EI measurements should be corrected for the thickness of subcutaneous adipose tissue as well as the depth of region of interest, shear modulus does not.
{"title":"Effect of adipose and muscle tissue thickness on skeletal muscle echo intensity and passive shear modulus: An ultrasound elastography approach","authors":"Heinrich Leon Souza Viera, Fábio Juner Lanferdini","doi":"10.1016/j.jmbbm.2025.107253","DOIUrl":"10.1016/j.jmbbm.2025.107253","url":null,"abstract":"<div><div>Although the growing studies investigating muscle echo intensity (EI) and shear modulus, little is known about the effects of adipose tissue thickness (ATT) on these measures. We investigated whether ATT influences the EI and shear modulus measurements of the human tibialis anterior superficial (TA<sub>superficial</sub>) and deep (TA<sub>deep</sub>) compartments. Ultrasound measurements were taken from the TA at rest, near the highest cross-sectional area, in ten physically active adults in the following conditions: without fat layers and with one and two fat layers. The EI and shear modulus of both TA<sub>superficial</sub> and TA<sub>deep</sub> were determined, and the best-fit regression model was calculated to assess the influence of ATT on EI and shear modulus. A repeated measures ANOVA were adopted to investigate the differences in EI and shear modulus in the different fat layers. The ATT was seen to affect the EI of both TA<sub>superficial</sub> (R<sup>2</sup> = 0.58; p < 0.001) and TA<sub>deep</sub> (R<sup>2</sup> = 0.44; p < 0.001). When the thickness of TA<sub>superficial</sub> was summed with ATT, the EI of TA<sub>deep</sub> was also affected but to a less extent (R<sup>2</sup> = 0.25; p = 0.004). No significant influence of ATT on shear modulus was seen for both TA compartments (p ≥ 0.061). While EI decreased in both TA compartments (p < 0.05), the repeated measures ANOVA revealed that only TA<sub>deep</sub> shear modulus decreased with the addition of two fat layers (p = 0.005). Corrective formula for EI measurements was determined. Thus, while skeletal muscle EI measurements should be corrected for the thickness of subcutaneous adipose tissue as well as the depth of region of interest, shear modulus does not.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107253"},"PeriodicalIF":3.5,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145440284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-27DOI: 10.1016/j.jmbbm.2025.107248
Ricardo D. Parga Montemayor , Enrique Lopez Cuellar , Karol Marek Golasiński , Luis Lopez-Pavon , Luis A. Reyes Osorio , Hee Young Kim
This work studies the thermomechanical behavior of Ti–25Nb, Ti–25Nb–0.3O and Ti–25Nb–0.7O shape memory alloys (SMAs), for potential biomedical applications. A constitutive model derived from Brinson's model was developed to simulate the superelastic response. A numerical model of biomedical implant support was also developed using Abaqus and compared with experimental data. Results indicate that oxygen addition enhances phase stability, superelastic recovery, and stress distribution uniformity, with Ti–25Nb–0.3O exhibiting lower peak stresses and more homogeneous deformation. The support implant is composed of a lattice (X-type, honeycomb-type) structure with varying ligament thicknesses evaluated, demonstrating that ligament size strongly affects mechanical response and porosity, with thinner ligaments maintaining desirable superelastic characteristics. The combination of Ti–25Nb–0.3O alloy and optimized lattice geometry is a promising alternative to conventional Ti–6Al–4V alloy for implantable support structures, providing improved mechanical compatibility and elastic behavior. Future work should focus on fatigue resistance, manufacturability, and biocompatibility under physiological conditions to advance clinical relevance.
{"title":"Modeling of superelastic implant structures made of biomedical oxygen-added Ti–25Nb based shape memory alloys","authors":"Ricardo D. Parga Montemayor , Enrique Lopez Cuellar , Karol Marek Golasiński , Luis Lopez-Pavon , Luis A. Reyes Osorio , Hee Young Kim","doi":"10.1016/j.jmbbm.2025.107248","DOIUrl":"10.1016/j.jmbbm.2025.107248","url":null,"abstract":"<div><div>This work studies the thermomechanical behavior of Ti–25Nb, Ti–25Nb–0.3O and Ti–25Nb–0.7O shape memory alloys (SMAs), for potential biomedical applications. A constitutive model derived from Brinson's model was developed to simulate the superelastic response. A numerical model of biomedical implant support was also developed using Abaqus and compared with experimental data. Results indicate that oxygen addition enhances phase stability, superelastic recovery, and stress distribution uniformity, with Ti–25Nb–0.3O exhibiting lower peak stresses and more homogeneous deformation. The support implant is composed of a lattice (X-type, honeycomb-type) structure with varying ligament thicknesses evaluated, demonstrating that ligament size strongly affects mechanical response and porosity, with thinner ligaments maintaining desirable superelastic characteristics. The combination of Ti–25Nb–0.3O alloy and optimized lattice geometry is a promising alternative to conventional Ti–6Al–4V alloy for implantable support structures, providing improved mechanical compatibility and elastic behavior. Future work should focus on fatigue resistance, manufacturability, and biocompatibility under physiological conditions to advance clinical relevance.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107248"},"PeriodicalIF":3.5,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145412827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-27DOI: 10.1016/j.jmbbm.2025.107252
Marius Burman Ingeberg , Elijah Van Houten , Martijn Froeling , Jaco J.M. Zwanenburg
Introduction
Strain tensor imaging allows for the construction of the full 3D strain tensor in the human brain from precise measurements of systolic cardiac-induced tissue deformation. Such tensors can be decomposed into principal strains, where the first principal strain (FPS) describes the direction of maximum stretch while the third principal strain (TPS) describes the direction of maximum shortening. This technique offers an opportunity to study the mechanical properties of brain tissue in vivo. It allows us to explore how strain directions are influenced by global boundary conditions and local microstructure. Additionally, it helps to determine whether human brain tissue exhibits mechanical anisotropy.
Method
We obtained strain tensor and diffusion tensor imaging (DTI) data across 8 healthy subjects from a previous 7T MRI study. The strain tensor was constructed from the DENSE displacement measurements. We compared the measured strain directions with two conceptual models to assess the impact of global boundary conditions and local brain microstructure on the measured strain.
Results
The boundary condition-based model effectively explained the measured FPS directions across all subjects (mean ; ), indicating that global boundary conditions largely dictate the direction of the stretching that occurs during cerebral arterial pulsations. The TPS demonstrated a tendency to align perpendicularly to the DTI.
Conclusion
These results highlight a potential indicator of mechanical anisotropy along white matter tracks using a novel approach, adding a new perspective to the ongoing discussion of the brain's structural characteristics.
{"title":"Alignment of cardiac-induced brain tissue strain with global boundary conditions and local microstructure: potential effects of anisotropy","authors":"Marius Burman Ingeberg , Elijah Van Houten , Martijn Froeling , Jaco J.M. Zwanenburg","doi":"10.1016/j.jmbbm.2025.107252","DOIUrl":"10.1016/j.jmbbm.2025.107252","url":null,"abstract":"<div><h3>Introduction</h3><div>Strain tensor imaging allows for the construction of the full 3D strain tensor in the human brain from precise measurements of systolic cardiac-induced tissue deformation. Such tensors can be decomposed into principal strains, where the first principal strain (FPS) describes the direction of maximum stretch while the third principal strain (TPS) describes the direction of maximum shortening. This technique offers an opportunity to study the mechanical properties of brain tissue <em>in vivo</em>. It allows us to explore how strain directions are influenced by global boundary conditions and local microstructure. Additionally, it helps to determine whether human brain tissue exhibits mechanical anisotropy.</div></div><div><h3>Method</h3><div>We obtained strain tensor and diffusion tensor imaging (DTI) data across 8 healthy subjects from a previous 7T MRI study. The strain tensor was constructed from the DENSE displacement measurements. We compared the measured strain directions with two conceptual models to assess the impact of global boundary conditions and local brain microstructure on the measured strain.</div></div><div><h3>Results</h3><div>The boundary condition-based model effectively explained the measured FPS directions across all subjects (mean <span><math><mrow><msup><mi>R</mi><mn>2</mn></msup></mrow></math></span>; <span><math><mrow><mn>0.61</mn><mo>±</mo><mn>0.03</mn></mrow></math></span>), indicating that global boundary conditions largely dictate the direction of the stretching that occurs during cerebral arterial pulsations. The TPS demonstrated a tendency to align perpendicularly to the DTI.</div></div><div><h3>Conclusion</h3><div>These results highlight a potential indicator of mechanical anisotropy along white matter tracks using a novel approach, adding a new perspective to the ongoing discussion of the brain's structural characteristics.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107252"},"PeriodicalIF":3.5,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145412922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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