Pub Date : 2026-02-01Epub 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":"2026-02-01","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}
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":"2026-02-01","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}
The Wharton’s jelly, a mucoid connective tissue of the umbilical cord, is promising for regenerative medicine applications. However it is relatively new and poorly documented especially from a mechanical point of view. To help filling the gap in the literature lack of data, this study seeks to address the Wharton’s jelly damage behavior by providing first key results through an efficient analytical approach. The tensile and damage behavior of Wharton’s jelly membranes is studied using tensile tests conducted up to failure under close physiological conditions. The Wharton’s jelly mechanical response has been characterized using an hyperelastic constitutive model based on the Ogden formulation, enhanced with continuum damage mechanics to capture analytically the damage behavior. To support the mechanical analysis, optical coherence tomography was used to assess the stress-free microstructural arrangement of the collagen fibers, revealing a transversely isotropic architecture. This qualitative insight into the internal structure enriched the interpretation of the mechanical behavior. Overall, this analytical study enabled the identification of a comprehensive set of material parameters characterizing both elastic and damage responses. Pearson correlation matrices were used to reveal meaningful relationships between parameters, potential predictive descriptors, and model’s limitations. These findings provide a solid foundation for future modeling developments through numerical simulation and offer new outlooks for surgery and dressing applications.
{"title":"Macro-scale damage characterization of Wharton’s jelly membrane undergoing tension","authors":"Alexis Da Rocha , Anaïs Lavrand , Cristina Cavinato , Cédric Laurent , Cédric Mauprivez , Halima Kerdjoudj , Chrystelle Po , Adrien Baldit","doi":"10.1016/j.jmbbm.2025.107236","DOIUrl":"10.1016/j.jmbbm.2025.107236","url":null,"abstract":"<div><div>The Wharton’s jelly, a mucoid connective tissue of the umbilical cord, is promising for regenerative medicine applications. However it is relatively new and poorly documented especially from a mechanical point of view. To help filling the gap in the literature lack of data, this study seeks to address the Wharton’s jelly damage behavior by providing first key results through an efficient analytical approach. The tensile and damage behavior of Wharton’s jelly membranes is studied using tensile tests conducted up to failure under close physiological conditions. The Wharton’s jelly mechanical response has been characterized using an hyperelastic constitutive model based on the Ogden formulation, enhanced with continuum damage mechanics to capture analytically the damage behavior. To support the mechanical analysis, optical coherence tomography was used to assess the stress-free microstructural arrangement of the collagen fibers, revealing a transversely isotropic architecture. This qualitative insight into the internal structure enriched the interpretation of the mechanical behavior. Overall, this analytical study enabled the identification of a comprehensive set of material parameters characterizing both elastic and damage responses. Pearson correlation matrices were used to reveal meaningful relationships between parameters, potential predictive descriptors, and model’s limitations. These findings provide a solid foundation for future modeling developments through numerical simulation and offer new outlooks for surgery and dressing applications.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107236"},"PeriodicalIF":3.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145442254","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 : 2026-01-01Epub Date: 2025-09-15DOI: 10.1016/j.jmbbm.2025.107201
Yawen Huang, Zhan Wen Chen
Sufficiently high fatigue strength is required for lattices made using electron beam powder bed fusion (EBPBF) for hip implants and understanding the anisotropic fatigue behaviour of EBPBF lattices is necessary for implant design. In this work, the combined effects of loading direction (LD) and cell orientation of EBPBF-Ti6Al4V lattices on the fatigue strength of the structures under cyclic compressive loading have been studied. Simple cubic (SC) ([001]//LD, [011]//LD and [111]//LD) lattices with a relative density of 0.36 were EBPBF made, tested and examined. The fatigue strength of [001]//LD lattices has been determined to be ∼190 MPa at 5 × 106 cycles, ∼8 times higher than that of [011]//LD or [111]//LD lattices. The low fatigue strength of the non-[001]//LD lattices resulted from crack initiation readily occurring in the high tension locations, which are the top and bottom locations of each unit cell. Sideway growth of cracks leading to fracturing along (001) will be shown. This failure mechanism is absent in [001]//LD lattices and thus their fatigue strength is high. Examining the data in the literature has shown that fatigue strength values of all non-SC lattice structures are low, likely due to the same failure mechanism identified for non-[001]//LD SC lattices in this study.
{"title":"Electron beam powder bed fusion additive manufacturing of Ti6Al4V alloy lattice structures: orientation-dependent fatigue strength and crack growth behaviour under compressive cyclic loading","authors":"Yawen Huang, Zhan Wen Chen","doi":"10.1016/j.jmbbm.2025.107201","DOIUrl":"10.1016/j.jmbbm.2025.107201","url":null,"abstract":"<div><div>Sufficiently high fatigue strength is required for lattices made using electron beam powder bed fusion (EBPBF) for hip implants and understanding the anisotropic fatigue behaviour of EBPBF lattices is necessary for implant design. In this work, the combined effects of loading direction (LD) and cell orientation of EBPBF-Ti6Al4V lattices on the fatigue strength of the structures under cyclic compressive loading have been studied. Simple cubic (SC) ([001]//LD, [011]//LD and [111]//LD) lattices with a relative density of 0.36 were EBPBF made, tested and examined. The fatigue strength of [001]//LD lattices has been determined to be ∼190 MPa at 5 × 10<sup>6</sup> cycles, ∼8 times higher than that of [011]//LD or [111]//LD lattices. The low fatigue strength of the non-[001]//LD lattices resulted from crack initiation readily occurring in the high tension locations, which are the top and bottom locations of each unit cell. Sideway growth of cracks leading to fracturing along (001) will be shown. This failure mechanism is absent in [001]//LD lattices and thus their fatigue strength is high. Examining the data in the literature has shown that fatigue strength values of all non-SC lattice structures are low, likely due to the same failure mechanism identified for non-[001]//LD SC lattices in this study.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107201"},"PeriodicalIF":3.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145093181","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 : 2026-01-01Epub Date: 2025-09-13DOI: 10.1016/j.jmbbm.2025.107202
Shimaa Hathan , Dayane Oliveira , Karina G. Amorim , Panagiotis Zoidis , Alex J. Delgado , Jason A. Griggs , Patricia Pereira , Mateus G. Rocha
Objective
The aim of this study was to evaluate the biaxial flexural strength (BFS) and modulus (BFM) of 3D-milled and 3D-printed restorative materials and assess their biomechanical behavior when bonded to dentin analog.
Materials and methods
Five dental material classes were tested: lithium disilicate glass-ceramic (Emax CAD), leucite-reinforced glass-ceramic (Empress CAD), polymer-infiltrated ceramic (Vita Enamic), 3D-milled resin-based composite (Lava Ultimate), and 3D-printed resin-based composite (Crown X). Disk-shaped specimens (n = 20, d = 12 mm, t = 1 mm) were fabricated. BFS and BFM were measured using biaxial flexural testing. Additional specimens were bonded to dentin analog (NEMA G10) and tested for BFS. Finite element analysis (FEA) evaluated stress distribution. Fractographic analysis used digital optical and scanning electron microscopy. Data was analyzed using one-way ANOVA and Weibull distribution (α = 0.05).
Results
Emax CAD exhibited highest mean BFS (312.71 ± 51.89 MPa) and BFM (41.30 ± 0.76 GPa), significantly superior to other materials (P < 0.05). Crown X demonstrated second-highest BFS (156.55 ± 30.88 MPa) but lowest BFM (10.77 ± 0.40 GPa). When bonded to dentin analog, BFS ranking changed: Emax CAD > Empress CAD > Enamic > Lava Ultimate > Crown X. FEA revealed materials with higher moduli retained stress within restoration, while lower modulus materials transferred stress to dentin analog. Weibull analysis showed Vita Enamic had highest Weibull modulus when bonded, indicating lowest variability, while Emax CAD showed lowest despite superior strength.
Conclusions
3D-milled lithium disilicate (Emax CAD) demonstrated superior mechanical properties and stress distribution. While 3D-printed composite (Crown X) showed promising strength when tested alone, performance significantly decreased when bonded to dentin analog.
{"title":"Evaluating the biomechanical properties of 3D-milled and 3D-printed restorative dental materials","authors":"Shimaa Hathan , Dayane Oliveira , Karina G. Amorim , Panagiotis Zoidis , Alex J. Delgado , Jason A. Griggs , Patricia Pereira , Mateus G. Rocha","doi":"10.1016/j.jmbbm.2025.107202","DOIUrl":"10.1016/j.jmbbm.2025.107202","url":null,"abstract":"<div><h3>Objective</h3><div>The aim of this study was to evaluate the biaxial flexural strength (BFS) and modulus (BFM) of 3D-milled and 3D-printed restorative materials and assess their biomechanical behavior when bonded to dentin analog.</div></div><div><h3>Materials and methods</h3><div>Five dental material classes were tested: lithium disilicate glass-ceramic (Emax CAD), leucite-reinforced glass-ceramic (Empress CAD), polymer-infiltrated ceramic (Vita Enamic), 3D-milled resin-based composite (Lava Ultimate), and 3D-printed resin-based composite (Crown X). Disk-shaped specimens (n = 20, d = 12 mm, t = 1 mm) were fabricated. BFS and BFM were measured using biaxial flexural testing. Additional specimens were bonded to dentin analog (NEMA G10) and tested for BFS. Finite element analysis (FEA) evaluated stress distribution. Fractographic analysis used digital optical and scanning electron microscopy. Data was analyzed using one-way ANOVA and Weibull distribution (α = 0.05).</div></div><div><h3>Results</h3><div>Emax CAD exhibited highest mean BFS (312.71 ± 51.89 MPa) and BFM (41.30 ± 0.76 GPa), significantly superior to other materials (P < 0.05). Crown X demonstrated second-highest BFS (156.55 ± 30.88 MPa) but lowest BFM (10.77 ± 0.40 GPa). When bonded to dentin analog, BFS ranking changed: Emax CAD > Empress CAD > Enamic > Lava Ultimate > Crown X. FEA revealed materials with higher moduli retained stress within restoration, while lower modulus materials transferred stress to dentin analog. Weibull analysis showed Vita Enamic had highest Weibull modulus when bonded, indicating lowest variability, while Emax CAD showed lowest despite superior strength.</div></div><div><h3>Conclusions</h3><div>3D-milled lithium disilicate (Emax CAD) demonstrated superior mechanical properties and stress distribution. While 3D-printed composite (Crown X) showed promising strength when tested alone, performance significantly decreased when bonded to dentin analog.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107202"},"PeriodicalIF":3.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145093280","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 : 2026-01-01Epub 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":"2026-01-01","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 : 2026-01-01Epub Date: 2025-10-25DOI: 10.1016/j.jmbbm.2025.107251
Bo E. Seiferheld , Kenneth K. Jensen , Jens B. Frøkjær , Rami K. Korhonen , Petri Tanska , Michael S. Andersen
Cartilage mechanical properties have been suggested to be more effective biomarkers for early-stage osteoarthritis (OA) than conventional clinical pain and image feature detection, when compared with OA grading methods. However, limited research exists evaluating the feasibility of alternative methods, such as magnetic resonance imaging (MRI) techniques, to determine biomechanical properties. Therefore, this study aimed to evaluate the feasibility of clinical MRI for non-invasive evaluation of cartilage creep behaviour and biomechanical properties. Bovine cartilage samples (n = 12, diameter = 6 mm) were loaded at 0.25 MPa/s until reaching 1 MPa, then held under constant stress for 1 h using a counterbalanced study design with two different configurations. The first configuration used a custom-made, hydraulic-based MRI-compatible device to apply the load to the sample. During loading, 2D proton density-weighted fast spin echo MR images with fat suppression (CHESS method) were captured every minute. The second configuration used a universal testing machine as a ground truth (GT) reference. Time-dependent creep deformation was assessed in both configurations, and the instantaneous and equilibrium moduli were calculated at 1 min and at the end of the creep test, respectively. In addition, sample-specific fibril-reinforced poroelastic (FRPE) material parameters were estimated for both configurations using inverse finite element analysis of the measured creep data. The FRPE model successfully simulated experimental data, with mean R2 values of 0.77 [95 % CI: 0.61, 0.92] for MRI and 0.98 [95 % CI: 0.95, 0.99] for GT. Results showed comparable deformation trajectories with no significant differences in the FRPE material properties between the configurations (i.e., ). Only the mean instantaneous modulus at 1 min of creep was higher (p < 0.001) with MRI 4.5 [95 % CI: 2.9, 6.1] MPa compared to GT 2.9 [95 % CI: 2.3, 3.5] MPa. These findings demonstrate that MRI can capture cartilage creep deformation and estimate biomechanical properties with reasonable accuracy in an ex vivo setting. This advocates towards further development of the workflow for creep compression experiments in vivo. Yet, the workflow requires load-controlled relaxation and considerations of 3D contact mechanics of the human knee. While this work does not yet establish clear clinical applicability, it represents important evidence for non-invasive quantification of cartilage biomechanics. It is conceivable that our advancements may contribute to subject-specific estimation of inherent biomechanical tissue properties in the future.
{"title":"Magnetic resonance imaging provides accurate measures of cartilage creep and biomechanical tissue properties: Ex vivo comparison to ground truth mechanical testing","authors":"Bo E. Seiferheld , Kenneth K. Jensen , Jens B. Frøkjær , Rami K. Korhonen , Petri Tanska , Michael S. Andersen","doi":"10.1016/j.jmbbm.2025.107251","DOIUrl":"10.1016/j.jmbbm.2025.107251","url":null,"abstract":"<div><div>Cartilage mechanical properties have been suggested to be more effective biomarkers for early-stage osteoarthritis (OA) than conventional clinical pain and image feature detection, when compared with OA grading methods. However, limited research exists evaluating the feasibility of alternative methods, such as magnetic resonance imaging (MRI) techniques, to determine biomechanical properties. Therefore, this study aimed to evaluate the feasibility of clinical MRI for non-invasive evaluation of cartilage creep behaviour and biomechanical properties. Bovine cartilage samples (<em>n</em> = 12, diameter = 6 mm) were loaded at 0.25 MPa/s until reaching 1 MPa, then held under constant stress for 1 h using a counterbalanced study design with two different configurations. The first configuration used a custom-made, hydraulic-based MRI-compatible device to apply the load to the sample. During loading, 2D proton density-weighted fast spin echo MR images with fat suppression (CHESS method) were captured every minute. The second configuration used a universal testing machine as a ground truth (GT) reference. Time-dependent creep deformation was assessed in both configurations, and the instantaneous and equilibrium moduli were calculated at 1 min and at the end of the creep test, respectively. In addition, sample-specific fibril-reinforced poroelastic (FRPE) material parameters were estimated for both configurations using inverse finite element analysis of the measured creep data. The FRPE model successfully simulated experimental data, with mean R<sup>2</sup> values of 0.77 [95 % CI: 0.61, 0.92] for MRI and 0.98 [95 % CI: 0.95, 0.99] for GT. Results showed comparable deformation trajectories with no significant differences in the FRPE material properties between the configurations (i.e., <span><math><mrow><msubsup><mi>E</mi><mi>f</mi><mn>0</mn></msubsup><mo>,</mo><msubsup><mi>E</mi><mi>f</mi><mi>ε</mi></msubsup><mo>,</mo><msub><mi>E</mi><mtext>nf</mtext></msub><mo>,</mo><msub><mi>k</mi><mn>0</mn></msub><mo>,</mo><mi>M</mi></mrow></math></span>). Only the mean instantaneous modulus at 1 min of creep was higher (<em>p</em> < 0.001) with MRI 4.5 [95 % CI: 2.9, 6.1] MPa compared to GT 2.9 [95 % CI: 2.3, 3.5] MPa. These findings demonstrate that MRI can capture cartilage creep deformation and estimate biomechanical properties with reasonable accuracy in an <em>ex vivo</em> setting. This advocates towards further development of the workflow for creep compression experiments <em>in vivo</em>. Yet, the workflow requires load-controlled relaxation and considerations of 3D contact mechanics of the human knee. While this work does not yet establish clear clinical applicability, it represents important evidence for non-invasive quantification of cartilage biomechanics. It is conceivable that our advancements may contribute to subject-specific estimation of inherent biomechanical tissue properties in the future.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107251"},"PeriodicalIF":3.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145412923","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 : 2026-01-01Epub Date: 2025-10-22DOI: 10.1016/j.jmbbm.2025.107244
Satya Pal , Thomas E. Angelini , Abir Bhattacharyya
Regulating elastic modulus of basic synthetic hydrogels, such as polyacrylamide, is crucial for their application in various fields of biotechnology. However, the measurement of elastic modulus and stress-strain response under different deformation modes is challenging in soft and fragile hydrogels. In this study, a non-contact, 2-dimensional digital image correlation (2D-DIC) technique is used to measure tensile and simple shear stress-strain responses of fully swelled polyacrylamide hydrogels at semi-dilute concentrations, over strain rates ranging between 10−3-10−1/s. The measured strain fields exhibit uniformity across all the deformation modes up to threshold strain levels. The elastic moduli were found to be strain-rate insensitive, except at small strains for 10−1/s due to strain acceleration and inertia of the specimen. The E and G determined from the initial slopes of stress-strain responses of lower strain-rate experiments followed De Genne's c9/4 power law scaling with equilibrium gel concentrations. The Poisson's ratio determined from the measured axial and lateral strains at small strains was found to closely match with the Poisson's ratio determined from E/G, indicating that the gels follow linear elasticity for nearly incompressible solids at small strains, but deviate from linear elasticity and becoming compressible at higher tensile strains leading to nonlinearity in tensile stress-strain response marked by reduction in instantaneous tensile modulus. The simple shear stress-strain response remains linear throughout. Finally, a polymer physics-based explanation connecting hydrogel concentration, mesh size and elastic moduli is proposed to explain strain-dependent evolution of stresses in semi-dilute polyacrylamide hydrogels for different deformation modes. Therefore, design of technologies using hydrogels must consider active deformation mode.
{"title":"Elastic moduli and strain-dependent lateral strain to axial strain ratio in semi-dilute polyacrylamide hydrogels","authors":"Satya Pal , Thomas E. Angelini , Abir Bhattacharyya","doi":"10.1016/j.jmbbm.2025.107244","DOIUrl":"10.1016/j.jmbbm.2025.107244","url":null,"abstract":"<div><div>Regulating elastic modulus of basic synthetic hydrogels, such as polyacrylamide, is crucial for their application in various fields of biotechnology. However, the measurement of elastic modulus and stress-strain response under different deformation modes is challenging in soft and fragile hydrogels. In this study, a non-contact, 2-dimensional digital image correlation (2D-DIC) technique is used to measure tensile and simple shear stress-strain responses of fully swelled polyacrylamide hydrogels at semi-dilute concentrations, over strain rates ranging between 10<sup>−3</sup>-10<sup>−1</sup>/s. The measured strain fields exhibit uniformity across all the deformation modes up to threshold strain levels. The elastic moduli were found to be strain-rate insensitive, except at small strains for 10<sup>−1</sup>/s due to strain acceleration and inertia of the specimen. The <em>E</em> and <em>G</em> determined from the initial slopes of stress-strain responses of lower strain-rate experiments followed De Genne's <em>c</em><sup>9/4</sup> power law scaling with equilibrium gel concentrations. The Poisson's ratio determined from the measured axial and lateral strains at small strains was found to closely match with the Poisson's ratio determined from <em>E/G</em>, indicating that the gels follow linear elasticity for nearly incompressible solids at small strains, but deviate from linear elasticity and becoming compressible at higher tensile strains leading to nonlinearity in tensile stress-strain response marked by reduction in instantaneous tensile modulus. The simple shear stress-strain response remains linear throughout. Finally, a polymer physics-based explanation connecting hydrogel concentration, mesh size and elastic moduli is proposed to explain strain-dependent evolution of stresses in semi-dilute polyacrylamide hydrogels for different deformation modes. Therefore, design of technologies using hydrogels must consider active deformation mode.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107244"},"PeriodicalIF":3.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145395825","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 : 2026-01-01Epub Date: 2025-09-16DOI: 10.1016/j.jmbbm.2025.107187
Muhammad Asif , Mohsin Islam Tiwana , Waqar Shahid Qureshi , Syed Tayyab Hussain , Umar Shahbaz Khan , Noman Naseer , Amir Hamza , Zeeshan Abbas
This research addresses the challenges faced by amputees who struggle while performing daily activities due to a missing limb. The objective is to create a bio-inspired framework that intelligently adapts to compensate for lost mobility and mimics natural walking for passive knee users. We have developed a framework that takes input power from human femur and drives the passive knee with the help of sensors and damping control mechanism. Our deep learning architecture achieved a high classification accuracy 94.44% for gait phase events. The proposed framework demonstrated optimized movement with reduced hip hikes and less fatigue, maintaining normal knee flexion , and achieving a good fall prevention rate of 95%. This research presents a promising solution to improve the functionality and comfort of passive knee prostheses, significantly improving the quality of an amputee’s life.
{"title":"Bio-inspired auto-adaptive framework for optimized movement of passive knee prosthesis","authors":"Muhammad Asif , Mohsin Islam Tiwana , Waqar Shahid Qureshi , Syed Tayyab Hussain , Umar Shahbaz Khan , Noman Naseer , Amir Hamza , Zeeshan Abbas","doi":"10.1016/j.jmbbm.2025.107187","DOIUrl":"10.1016/j.jmbbm.2025.107187","url":null,"abstract":"<div><div>This research addresses the challenges faced by amputees who struggle while performing daily activities due to a missing limb. The objective is to create a bio-inspired framework that intelligently adapts to compensate for lost mobility and mimics natural walking for passive knee users. We have developed a framework that takes input power from human femur and drives the passive knee with the help of sensors and damping control mechanism. Our deep learning architecture achieved a high classification accuracy 94.44% for gait phase events. The proposed framework demonstrated optimized movement with reduced hip hikes and less fatigue, maintaining normal knee flexion <span><math><mrow><mo>(</mo><mn>6</mn><msup><mrow><mn>4</mn></mrow><mrow><mo>∘</mo></mrow></msup><mo>±</mo><mn>6</mn><mo>)</mo></mrow></math></span>, and achieving a good fall prevention rate of 95%. This research presents a promising solution to improve the functionality and comfort of passive knee prostheses, significantly improving the quality of an amputee’s life.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107187"},"PeriodicalIF":3.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145119092","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 : 2026-01-01Epub Date: 2025-10-10DOI: 10.1016/j.jmbbm.2025.107226
Jessica Faber , Alexander Greiner , Paula Büttner , Chiara Schoppe , Lars Bräuer , Friedrich Paulsen , Torsten Blunk , Mario Perl , Marcel Betsch , Silvia Budday
Articular cartilage serves an important mechanical function in the human body. For the design of implants for cartilage repair after injury or disease, it is key to thoroughly understand the unique mechanical properties of the native tissue. Here, we use multimodal mechanical testing combined with poro-viscoelastic modeling, finite element simulations, and histology to characterize the region-specific macroscopic large-strain mechanical properties of healthy and osteoarthritic human articular cartilage as well as their relation to the underlying microanatomy. We individually characterize tissue from medial and lateral sides, respectively, of the human femoral condyle and tibial plateau. Our results show that there are no significant differences between the medial and lateral sides, but tissue from the tibial plateau is slightly softer than tissue from the femoral condyle. Osteoarthritis leads to a significantly softened mechanical response, which correlates with corresponding microstructural changes. Through the presented combination of experiments and poro-viscoelastic material parameter identification for healthy and osteoarthritic cartilage, we confirm a reduction in stiffness and an increase in permeability due to the disease. The parameters can be valuable for future finite element simulations of the knee joint The presented results will help guide the design of implants that are able to restore cartilage structure and function, bridging biomechanics and regenerative medicine for osteoarthritis treatment.
{"title":"Poro-viscoelastic mechanical characterization of healthy and osteoarthritic human articular cartilage","authors":"Jessica Faber , Alexander Greiner , Paula Büttner , Chiara Schoppe , Lars Bräuer , Friedrich Paulsen , Torsten Blunk , Mario Perl , Marcel Betsch , Silvia Budday","doi":"10.1016/j.jmbbm.2025.107226","DOIUrl":"10.1016/j.jmbbm.2025.107226","url":null,"abstract":"<div><div>Articular cartilage serves an important mechanical function in the human body. For the design of implants for cartilage repair after injury or disease, it is key to thoroughly understand the unique mechanical properties of the native tissue. Here, we use multimodal mechanical testing combined with poro-viscoelastic modeling, finite element simulations, and histology to characterize the region-specific macroscopic large-strain mechanical properties of healthy and osteoarthritic human articular cartilage as well as their relation to the underlying microanatomy. We individually characterize tissue from medial and lateral sides, respectively, of the human femoral condyle and tibial plateau. Our results show that there are no significant differences between the medial and lateral sides, but tissue from the tibial plateau is slightly softer than tissue from the femoral condyle. Osteoarthritis leads to a significantly softened mechanical response, which correlates with corresponding microstructural changes. Through the presented combination of experiments and poro-viscoelastic material parameter identification for healthy and osteoarthritic cartilage, we confirm a reduction in stiffness and an increase in permeability due to the disease. The parameters can be valuable for future finite element simulations of the knee joint The presented results will help guide the design of implants that are able to restore cartilage structure and function, bridging biomechanics and regenerative medicine for osteoarthritis treatment.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107226"},"PeriodicalIF":3.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145314493","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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