Pub Date : 2024-12-04DOI: 10.1016/j.jmbbm.2024.106847
David Jiang , Andrew J. Robinson , Abbey Nkansah , Jonathan Leung , Leopold Guo , Steve A. Maas , Jeffrey A. Weiss , Elizabeth M. Cosgriff-Hernandez , Lucas H. Timmins
The failure of synthetic small-diameter vascular grafts has been attributed to a mismatch in the compliance between the graft and native artery, driving mechanisms that promote thrombosis and neointimal hyperplasia. Additionally, the buckling of grafts results in large deformations that can lead to device failure. Although design features can be added to lessen the buckling potential (e.g., reinforcing coil), the addition is detrimental to decreasing compliance. Herein, we developed a novel finite element (FE) framework to inform vascular graft design by evaluating compliance and resistance to buckling. A batch-processing scheme iterated across the multi-dimensional design parameter space, which included three parameters: coil thickness, modulus, and spacing – generating 100 unique designs. FE models were created for each coil-reinforced graft design to simulate pressurization, axial buckling, and bent buckling, and results were analyzed to quantify compliance, buckling load, and kink radius, respectively. Validation of the FE models demonstrated that model predictions agreed with experimental observations for compliance ( = 0.99), buckling load ( = 0.89), and kink resistance ( = 0.97). Model predictions demonstrated a broad range of values for compliance (1.1–7.9 %/mmHg × 10−2), buckling load (0.28–0.84 N), and kink radius (6–10 mm) across the design parameter space. Subsequently, data for each design parameter combination were optimized (i.e., minimized) to identify candidate graft designs with promising mechanical properties. Our model-directed framework successfully elucidated the complex mechanical determinants of graft performance, established structure-property relationships, and identified vascular graft designs with optimal mechanical properties, potentially improving clinical outcomes by addressing device failure.
{"title":"A computational framework to optimize the mechanical behavior of synthetic vascular grafts","authors":"David Jiang , Andrew J. Robinson , Abbey Nkansah , Jonathan Leung , Leopold Guo , Steve A. Maas , Jeffrey A. Weiss , Elizabeth M. Cosgriff-Hernandez , Lucas H. Timmins","doi":"10.1016/j.jmbbm.2024.106847","DOIUrl":"10.1016/j.jmbbm.2024.106847","url":null,"abstract":"<div><div>The failure of synthetic small-diameter vascular grafts has been attributed to a mismatch in the compliance between the graft and native artery, driving mechanisms that promote thrombosis and neointimal hyperplasia. Additionally, the buckling of grafts results in large deformations that can lead to device failure. Although design features can be added to lessen the buckling potential (e.g., reinforcing coil), the addition is detrimental to decreasing compliance. Herein, we developed a novel finite element (FE) framework to inform vascular graft design by evaluating compliance and resistance to buckling. A batch-processing scheme iterated across the multi-dimensional design parameter space, which included three parameters: coil thickness, modulus, and spacing – generating 100 unique designs. FE models were created for each coil-reinforced graft design to simulate pressurization, axial buckling, and bent buckling, and results were analyzed to quantify compliance, buckling load, and kink radius, respectively. Validation of the FE models demonstrated that model predictions agreed with experimental observations for compliance (<span><math><mrow><mi>r</mi></mrow></math></span> = 0.99), buckling load (<span><math><mrow><mi>r</mi></mrow></math></span> = 0.89), and kink resistance (<span><math><mrow><mi>r</mi></mrow></math></span> = 0.97). Model predictions demonstrated a broad range of values for compliance (1.1–7.9 %/mmHg × 10<sup>−2</sup>), buckling load (0.28–0.84 N), and kink radius (6–10 mm) across the design parameter space. Subsequently, data for each design parameter combination were optimized (i.e., minimized) to identify candidate graft designs with promising mechanical properties. Our model-directed framework successfully elucidated the complex mechanical determinants of graft performance, established structure-property relationships, and identified vascular graft designs with optimal mechanical properties, potentially improving clinical outcomes by addressing device failure.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106847"},"PeriodicalIF":3.3,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142873743","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 : 2024-12-02DOI: 10.1016/j.jmbbm.2024.106850
Márcia Cristina Bezerra Melo , Bruno Roberto Spirandeli , Lucas Barbosa , Verônica Ribeiro dos Santos , Tiago Moreira Bastos de Campos , Gilmar Patrocínio Thim , Eliandra de Sousa Trichês
3D printing in scaffold production offers a promising approach, enabling precise architectural design that closely mimics the porosity and interconnectivity of natural bone. β-Tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP), with a chemical composition similar to the inorganic component of bone, is a widely used material for scaffold fabrication. Recent advances have made it possible to functionalize ceramic scaffolds to improve bone regeneration and repair while enabling the in situ release of therapeutic agents to treat bone infections. In this study, 3D-printed β-TCP scaffolds were coated with bioactive glasses, 45S5 (45SiO₂ – 24.5Na₂O – 24.5CaO – 6P₂O₅, wt.%) and 58S (58SiO₂ – 33CaO – 9P₂O₅, wt.%), using sol-gel solutions through a vacuum impregnation technique. The β-TCP ink exhibited pseudoplastic behavior, which facilitated its 3D printing. The resulting scaffolds demonstrated high fidelity to the designed model, featuring well-aligned filaments and minimal collapse of the lower layers after sintering. Elemental mapping revealed that 45S5 glass formed a surface coating around the scaffold struts, whereas 58S glass penetrated the internal structure, this occurred due to their differing viscosities at high temperatures. Compared to uncoated β-TCP scaffolds, the coatings significantly improved mechanical strength, with increases of 63% and 126% for scaffolds coated with 45S5 and 58S, respectively. Bioactivity was confirmed through an apatite mineralization assay in simulated body fluid, which demonstrated hydroxyapatite precipitation on both coated scaffolds, albeit with distinct morphologies. Since this study focused on acellular scaffolds, further research is necessary to fully explore the potential of these bioactive scaffolds with optimized mechanical properties in biological systems.
{"title":"Enhanced mechanical strength and bioactivity of 3D-printed β-TCP scaffolds coated with bioactive glasses","authors":"Márcia Cristina Bezerra Melo , Bruno Roberto Spirandeli , Lucas Barbosa , Verônica Ribeiro dos Santos , Tiago Moreira Bastos de Campos , Gilmar Patrocínio Thim , Eliandra de Sousa Trichês","doi":"10.1016/j.jmbbm.2024.106850","DOIUrl":"10.1016/j.jmbbm.2024.106850","url":null,"abstract":"<div><div>3D printing in scaffold production offers a promising approach, enabling precise architectural design that closely mimics the porosity and interconnectivity of natural bone. β-Tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP), with a chemical composition similar to the inorganic component of bone, is a widely used material for scaffold fabrication. Recent advances have made it possible to functionalize ceramic scaffolds to improve bone regeneration and repair while enabling the in situ release of therapeutic agents to treat bone infections. In this study, 3D-printed β-TCP scaffolds were coated with bioactive glasses, 45S5 (45SiO₂ – 24.5Na₂O – 24.5CaO – 6P₂O₅, wt.%) and 58S (58SiO₂ – 33CaO – 9P₂O₅, wt.%), using sol-gel solutions through a vacuum impregnation technique. The β-TCP ink exhibited pseudoplastic behavior, which facilitated its 3D printing. The resulting scaffolds demonstrated high fidelity to the designed model, featuring well-aligned filaments and minimal collapse of the lower layers after sintering. Elemental mapping revealed that 45S5 glass formed a surface coating around the scaffold struts, whereas 58S glass penetrated the internal structure, this occurred due to their differing viscosities at high temperatures. Compared to uncoated β-TCP scaffolds, the coatings significantly improved mechanical strength, with increases of 63% and 126% for scaffolds coated with 45S5 and 58S, respectively. Bioactivity was confirmed through an apatite mineralization assay in simulated body fluid, which demonstrated hydroxyapatite precipitation on both coated scaffolds, albeit with distinct morphologies. Since this study focused on acellular scaffolds, further research is necessary to fully explore the potential of these bioactive scaffolds with optimized mechanical properties in biological systems.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106850"},"PeriodicalIF":3.3,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142792997","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 : 2024-12-02DOI: 10.1016/j.jmbbm.2024.106848
Qing Zhang , Changning Sun , Jibao Zheng , Ling Wang , Chaozong Liu , Dichen Li
Polyether-ether-ketone (PEEK) composites represent one of the most promising approaches to overcoming the weak osseointegration associated with the bioinertness of PEEK, making them highly suitable for clinical translation. Implants with porous structures fabricated by additive manufacturing offer the potential for long-term stability by promoting bone ingrowth. However, despite the importance of porous design, there is still no consensus on the optimal approach for PEEK-based composites. Given the significance of permeability and mechanical properties as functional indicators closely linked to osseointegration, the effects of material composition, structural design, and manufacturing processes on the permeability and mechanical properties of PEEK/hydroxyapatite (HA) scaffolds were systematically investigated in this study. In terms of permeability, the axial permeability of scaffolds with different pore sizes and representative volume elements varied within the range of 0.3–24.8 × 10−9 m2. Among scaffolds with similar relative density, the Gyroid structure exhibited the lowest permeability, while the orthogonal structure demonstrated the highest. For cylindrical scaffolds, circumferential permeability decreased with increasing penetration depth, suggesting a potential reduction in bone ingrowth speed with depth. As for mechanical properties, the experimentally determined effective elastic modulus and effective yield strength of the scaffolds ranged from 675.1 MPa to 65.2 MPa and 43.5 MPa to 4.1 MPa, respectively. The permeability and mechanical properties of PEEK/HA scaffolds with relative density ranging from 35% to 50% were aligned with the those of human cancellous bone. Heat treatment at 240 °C for 120 min increased the crystallinity of PEEK to 37.2%, resulting in a substantial improvement in both the strength and stiffness of the scaffolds. However, excessive crystallinity led to brittle fracture, which in turn reduced the strength of the scaffolds. This study employed a systematic research approach to investigate how material composition, structural design, and manufacturing processes influence the mechanical properties and permeability of PEEK composite bone scaffolds, which are crucial for bone ingrowth. The results offered insights that support the design, manufacturing, and performance evaluation of PEEK-based porous implants.
{"title":"Mechanical behaviour of additive manufactured PEEK/HA porous structure for orthopaedic implants: Materials, structures and manufacturing processes","authors":"Qing Zhang , Changning Sun , Jibao Zheng , Ling Wang , Chaozong Liu , Dichen Li","doi":"10.1016/j.jmbbm.2024.106848","DOIUrl":"10.1016/j.jmbbm.2024.106848","url":null,"abstract":"<div><div>Polyether-ether-ketone (PEEK) composites represent one of the most promising approaches to overcoming the weak osseointegration associated with the bioinertness of PEEK, making them highly suitable for clinical translation. Implants with porous structures fabricated by additive manufacturing offer the potential for long-term stability by promoting bone ingrowth. However, despite the importance of porous design, there is still no consensus on the optimal approach for PEEK-based composites. Given the significance of permeability and mechanical properties as functional indicators closely linked to osseointegration, the effects of material composition, structural design, and manufacturing processes on the permeability and mechanical properties of PEEK/hydroxyapatite (HA) scaffolds were systematically investigated in this study. In terms of permeability, the axial permeability of scaffolds with different pore sizes and representative volume elements varied within the range of 0.3–24.8 × 10<sup>−9</sup> m<sup>2</sup>. Among scaffolds with similar relative density, the Gyroid structure exhibited the lowest permeability, while the orthogonal structure demonstrated the highest. For cylindrical scaffolds, circumferential permeability decreased with increasing penetration depth, suggesting a potential reduction in bone ingrowth speed with depth. As for mechanical properties, the experimentally determined effective elastic modulus and effective yield strength of the scaffolds ranged from 675.1 MPa to 65.2 MPa and 43.5 MPa to 4.1 MPa, respectively. The permeability and mechanical properties of PEEK/HA scaffolds with relative density ranging from 35% to 50% were aligned with the those of human cancellous bone. Heat treatment at 240 °C for 120 min increased the crystallinity of PEEK to 37.2%, resulting in a substantial improvement in both the strength and stiffness of the scaffolds. However, excessive crystallinity led to brittle fracture, which in turn reduced the strength of the scaffolds. This study employed a systematic research approach to investigate how material composition, structural design, and manufacturing processes influence the mechanical properties and permeability of PEEK composite bone scaffolds, which are crucial for bone ingrowth. The results offered insights that support the design, manufacturing, and performance evaluation of PEEK-based porous implants.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106848"},"PeriodicalIF":3.3,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823025","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 : 2024-11-30DOI: 10.1016/j.jmbbm.2024.106840
Rongfang Zou , Xiaohong Han , Yang Meng , Wenbin Chen , Zhiyun Shi , Yilin Lian , Fangping Wang , Mingzhen Wang , Yang Huang
Fixed partial dentures are the primary treatment for dentition defects. Digital light processing (DLP) 3D printing technology is an advanced technique with significant advantages and potential in the field of dental restoration, particularly in cases requiring high precision and personalization. However, challenges persist in printing fixed partial dentures that meet the strength requirements for clinical applications. In this study, we aimed to optimize printing parameters, including exposure time and layer thickness, to enhance dimensional accuracy, reduce warpage, and improve the surface quality of the samples. Additionally, we focused on the rheological and curing properties of the paste. The optimal combination of printing parameters was found to be 5 s of exposure time and 50 μm layer thickness, achieving superior dimensional accuracy, reduced warpage, and improved surface quality. For a slurry with 40% solid content, the dispersant KOS 110 demonstrated the best shear thinning effect, with an optimal addition of 2%. Notably, the Vickers hardness, flexural strength, and fracture toughness of the ZrO2 fixed partial dentures were 13.52 ± 0.21 GPa, 940 ± 20 MPa, and 6.92 ± 0.25 MPa·m1/2, respectively, which surpasses that of human enamel (4 GPa) and is comparable to CAD/CAM ZrO2 (900–1200 MPa). This study demonstrates that DLP technology can be effectively used to fabricate ZrO2 personalized complex fixed partial dentures with excellent mechanical properties and high precision, offering broad application prospects in stomatology.
{"title":"Improved mechanical performance and forming accuracy of ZrO2 fixed partial denture based on the digital light processing technology","authors":"Rongfang Zou , Xiaohong Han , Yang Meng , Wenbin Chen , Zhiyun Shi , Yilin Lian , Fangping Wang , Mingzhen Wang , Yang Huang","doi":"10.1016/j.jmbbm.2024.106840","DOIUrl":"10.1016/j.jmbbm.2024.106840","url":null,"abstract":"<div><div>Fixed partial dentures are the primary treatment for dentition defects. Digital light processing (DLP) 3D printing technology is an advanced technique with significant advantages and potential in the field of dental restoration, particularly in cases requiring high precision and personalization. However, challenges persist in printing fixed partial dentures that meet the strength requirements for clinical applications. In this study, we aimed to optimize printing parameters, including exposure time and layer thickness, to enhance dimensional accuracy, reduce warpage, and improve the surface quality of the samples. Additionally, we focused on the rheological and curing properties of the paste. The optimal combination of printing parameters was found to be 5 s of exposure time and 50 μm layer thickness, achieving superior dimensional accuracy, reduced warpage, and improved surface quality. For a slurry with 40% solid content, the dispersant KOS 110 demonstrated the best shear thinning effect, with an optimal addition of 2%. Notably, the Vickers hardness, flexural strength, and fracture toughness of the ZrO<sub>2</sub> fixed partial dentures were 13.52 ± 0.21 GPa, 940 ± 20 MPa, and 6.92 ± 0.25 MPa·m1/2, respectively, which surpasses that of human enamel (4 GPa) and is comparable to CAD/CAM ZrO<sub>2</sub> (900–1200 MPa). This study demonstrates that DLP technology can be effectively used to fabricate ZrO<sub>2</sub> personalized complex fixed partial dentures with excellent mechanical properties and high precision, offering broad application prospects in stomatology.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106840"},"PeriodicalIF":3.3,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142788236","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 : 2024-11-30DOI: 10.1016/j.jmbbm.2024.106842
Colin R. Firminger , Nicholas C. Smith , W. Brent Edwards , Sean Gallagher
Carpal tunnel syndrome and stenosing tenosynovitis (i.e., trigger finger) are common work-related musculoskeletal disorders (WMSDs) that have been linked to overuse of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons of the hand. These injuries occur in response to repetitive loading; as such, they may be characterized using fatigue failure phenomenon. Current WMSD evaluation tools for carpal tunnel syndrome and trigger finger are built upon fatigue data from lower-limb tendons, however this may lead to inaccurate conclusions when assessing overuse injury risk at the wrist. Therefore, the purpose of this study was to characterize the fatigue behaviour of FDP and FDS tendons. We found that similar to other tendons, cyclically loaded FDP and FDS tendons illustrated a logarithmic relationship between applied stress and fatigue life, however the exact parameters of the FDP/FDS stress-fatigue life relationship were unique and may improve the accuracy of current carpal tunnel syndrome and trigger finger WMSD evaluation tools. We also observed that creep and damage rate had the strongest correlations with fatigue life, suggesting that these metrics may represent promising future directions for WMSD risk evaluation.
{"title":"In vitro fatigue of human flexor digitorum tendons","authors":"Colin R. Firminger , Nicholas C. Smith , W. Brent Edwards , Sean Gallagher","doi":"10.1016/j.jmbbm.2024.106842","DOIUrl":"10.1016/j.jmbbm.2024.106842","url":null,"abstract":"<div><div>Carpal tunnel syndrome and stenosing tenosynovitis (i.e., trigger finger) are common work-related musculoskeletal disorders (WMSDs) that have been linked to overuse of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons of the hand. These injuries occur in response to repetitive loading; as such, they may be characterized using fatigue failure phenomenon. Current WMSD evaluation tools for carpal tunnel syndrome and trigger finger are built upon fatigue data from lower-limb tendons, however this may lead to inaccurate conclusions when assessing overuse injury risk at the wrist. Therefore, the purpose of this study was to characterize the fatigue behaviour of FDP and FDS tendons. We found that similar to other tendons, cyclically loaded FDP and FDS tendons illustrated a logarithmic relationship between applied stress and fatigue life, however the exact parameters of the FDP/FDS stress-fatigue life relationship were unique and may improve the accuracy of current carpal tunnel syndrome and trigger finger WMSD evaluation tools. We also observed that creep and damage rate had the strongest correlations with fatigue life, suggesting that these metrics may represent promising future directions for WMSD risk evaluation.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106842"},"PeriodicalIF":3.3,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bracket fungi sporocarps present promising environmentally friendly alternatives to harmful and wasteful structural applications with their high strength-to-weight ratio mechanical properties. Kingdom Fungi is estimated to have over three million species, yet only 4% of the species have been described by mycologists, and their mechanical behavior has been under-explored. This work aims to characterize the material behavior and mechanical properties of bracket fungi as a whole through micro-mechanical tensile testing combined with microstructural imaging and analysis of two representative species. The context layer from three distinctive fresh bracket sporocarps is used in this study. At the microstructure level, the bracket fungi have a preferred alignment in the hyphal network, which correlates to the radial direction. The bracket fungi exhibit an anisotropic mechanical behavior with higher ultimate tensile strength and elastic modulus in the radial direction, while the strain to failure is higher in the transverse direction. However, the bracket fungi exhibit an isotropic energy absorption, or toughness, behavior, with no statistically significant difference between the radial and transverse directions. The characterization of anisotropic mechanical properties and isotropic energy absorption will inspire the exploration of bracket fungi as a viable alternative to applications in various industries, such as aerospace and agriculture.
{"title":"Material and mechanical behavior of bracket fungi context as a mechanically versatile structural layer","authors":"Ihsan.S. Elnunu , Jessica.N. Redmond , Bryn.T.M. Dentinger , Steven.E. Naleway","doi":"10.1016/j.jmbbm.2024.106841","DOIUrl":"10.1016/j.jmbbm.2024.106841","url":null,"abstract":"<div><div>Bracket fungi sporocarps present promising environmentally friendly alternatives to harmful and wasteful structural applications with their high strength-to-weight ratio mechanical properties. Kingdom <em>Fungi</em> is estimated to have over three million species, yet only 4% of the species have been described by mycologists, and their mechanical behavior has been under-explored. This work aims to characterize the material behavior and mechanical properties of bracket fungi as a whole through micro-mechanical tensile testing combined with microstructural imaging and analysis of two representative species. The context layer from three distinctive fresh bracket sporocarps is used in this study. At the microstructure level, the bracket fungi have a preferred alignment in the hyphal network, which correlates to the radial direction. The bracket fungi exhibit an anisotropic mechanical behavior with higher ultimate tensile strength and elastic modulus in the radial direction, while the strain to failure is higher in the transverse direction. However, the bracket fungi exhibit an isotropic energy absorption, or toughness, behavior, with no statistically significant difference between the radial and transverse directions. The characterization of anisotropic mechanical properties and isotropic energy absorption will inspire the exploration of bracket fungi as a viable alternative to applications in various industries, such as aerospace and agriculture.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106841"},"PeriodicalIF":3.3,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142848727","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 : 2024-11-29DOI: 10.1016/j.jmbbm.2024.106843
Ciaran Neil Pitt , Ariyan Ashkanfar , Russell English , Andrew Naylor , Tahsin T Öpöz , David J. Langton , Thomas J. Joyce
Total Knee Replacements (TKRs) are a commonly used treatment to help patients suffering from severely damaged knee joints, which is normally brought on by osteoarthritis. The aim of the surgery is to reduce pain and regain function of the joint, however, some of these implants fail prematurely with implant wear being one of the main factors of failure. Computational analysis is an efficient tool that can provide an in-depth insight on the evolution of wear, before utilising experimental techniques which are time-consuming and costly. In this study, a bespoke finite element (FE) based wear algorithm has been further developed for TKRs and was used to investigate how location of femoral centre of rotation (CoR) affects the evolution of wear at the bearing surfaces. Three locations of femoral CoR have been investigated: international standards (ISO) CoR, being the location defined in ISO 14243-3, distal CoR being the centre of the femoral component's distal radius, and reference CoR being the middle ground between the two. All investigations were setup in accordance with ISO 14243-3 for displacement-controlled wear testing conditions for knee simulators. The wear algorithm extracts contact pressure and sliding distance from the FE analysis to determine wear depth, wear pattern, volumetric wear, and wear rates on the polymeric insert and femoral component's bearing surfaces using Archard's wear law. The polymeric insert volumetric wear rate after 5 million cycles (Mc) for ISO, reference, and distal CoR are 4.37mm3/Mc, 5.40mm3/Mc, and 6.83mm3/Mc respectively. Furthermore, the wear pattern's location on the bearing surfaces is dependent on the femoral CoR, with ISO CoR wear pattern being positioned more posteriorly, distal CoR being more anteriorly, and reference CoR in between ISO and distal. The ISO CoR investigation showed a region of minimal wear between two wear regions at the middle of the femoral component's wear pattern, on both medial and lateral condyles. This region of minimal wear reduces for the reference CoR and further reduces for the distal CoR. After 5 Mc, the average polymeric insert-femoral component contact area changes with femoral CoR, with the average contact area being 66.53mm2, 68.35mm2, and 71.21mm2 for ISO, reference, and distal CoRs respectively, with distal having around 7% more contact area than ISO. The results from this study show that there is a wide range of wear values for different locations of femoral CoR. As such the choice of femoral CoR should be carefully considered when performing any wear investigation to ensure that the CoR location is consistent for all studies being compared.
{"title":"Development of a bespoke finite element wear algorithm to investigate the effect of femoral centre of rotation on the wear evolution in total knee replacements","authors":"Ciaran Neil Pitt , Ariyan Ashkanfar , Russell English , Andrew Naylor , Tahsin T Öpöz , David J. Langton , Thomas J. Joyce","doi":"10.1016/j.jmbbm.2024.106843","DOIUrl":"10.1016/j.jmbbm.2024.106843","url":null,"abstract":"<div><div>Total Knee Replacements (TKRs) are a commonly used treatment to help patients suffering from severely damaged knee joints, which is normally brought on by osteoarthritis. The aim of the surgery is to reduce pain and regain function of the joint, however, some of these implants fail prematurely with implant wear being one of the main factors of failure. Computational analysis is an efficient tool that can provide an in-depth insight on the evolution of wear, before utilising experimental techniques which are time-consuming and costly. In this study, a bespoke finite element (FE) based wear algorithm has been further developed for TKRs and was used to investigate how location of femoral centre of rotation (CoR) affects the evolution of wear at the bearing surfaces. Three locations of femoral CoR have been investigated: international standards (ISO) CoR, being the location defined in ISO 14243-3, distal CoR being the centre of the femoral component's distal radius, and reference CoR being the middle ground between the two. All investigations were setup in accordance with ISO 14243-3 for displacement-controlled wear testing conditions for knee simulators. The wear algorithm extracts contact pressure and sliding distance from the FE analysis to determine wear depth, wear pattern, volumetric wear, and wear rates on the polymeric insert and femoral component's bearing surfaces using Archard's wear law. The polymeric insert volumetric wear rate after 5 million cycles (Mc) for ISO, reference, and distal CoR are 4.37mm<sup>3</sup>/Mc, 5.40mm<sup>3</sup>/Mc, and 6.83mm<sup>3</sup>/Mc respectively. Furthermore, the wear pattern's location on the bearing surfaces is dependent on the femoral CoR, with ISO CoR wear pattern being positioned more posteriorly, distal CoR being more anteriorly, and reference CoR in between ISO and distal. The ISO CoR investigation showed a region of minimal wear between two wear regions at the middle of the femoral component's wear pattern, on both medial and lateral condyles. This region of minimal wear reduces for the reference CoR and further reduces for the distal CoR. After 5 Mc, the average polymeric insert-femoral component contact area changes with femoral CoR, with the average contact area being 66.53mm<sup>2</sup>, 68.35mm<sup>2</sup>, and 71.21mm<sup>2</sup> for ISO, reference, and distal CoRs respectively, with distal having around 7% more contact area than ISO. The results from this study show that there is a wide range of wear values for different locations of femoral CoR. As such the choice of femoral CoR should be carefully considered when performing any wear investigation to ensure that the CoR location is consistent for all studies being compared.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106843"},"PeriodicalIF":3.3,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142796636","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 : 2024-11-29DOI: 10.1016/j.jmbbm.2024.106844
Naitao Li , Xiaoman Duan , Xiao Fan Ding , Ning Zhu , Xiongbiao Chen
Hydrogel-based scaffolds have been widely used in soft tissue regeneration due to their biocompatible and tissue-like environment for maintaining cellular functions and tissue regeneration. Understanding the mechanical properties and internal microstructure of hydrogel-based scaffold, once implanted, is imperative in tissue engineering applications and longitudinal studies. Notably, this has been challenging to date as various conventional characterization methods by, for example, mechanical testing (for mechanical properties) and microscope (for internal microstructure) are destructive as they require removing scaffolds from the implantation site and processing samples for characterization. Synchrotron radiation propagation-based imaging–computed tomography (SR-PBI-CT) is feasible and promising for non-destructive visualizing of hydrogel scaffolds. As inspired, this study aimed to perform a study on the characterization of mechanical properties and microstructure of hydrogel scaffolds based on the SR-PBI-CT.
In this study, hydrogel biomaterial inks composed of 3% w/v alginate and 1% w/v gelatin were printed to form scaffolds, with some scaffolds being degraded over 3 days. Both degraded and undegraded scaffolds underwent compressive testing, with the strains being controlled at the preset values; meanwhile stresses within scaffolds were measuring, resulting the stress-strain curves. Concurrently, the scaffolds were also imaged and examined by SR-PBI-CT at Canadian Light Source (CLS). During the imaging process, the scaffolds were mechanically loaded, respectively, with the strains same as the ones in the aforementioned compressive testing, and at each strain, the scaffold was scanned with a pixel size of 13 μm.
From the stress-strain curves obtained in the compression testing, the Young's modulus was evaluated to characterize the elastic behavior of scaffolds: with the range between around 5–25 kPa. From the images captured by SR-PBI-CT, the scaffolds microstructures were examined in terms of the strand cross-section area, pore size, and hydrogel volume. Further, from the SR-PBI-CT images, the stress within hydrogel of scaffolds were evaluated, showing the agreement with those obtained from compression testing. These results have illustrated that the mechanical properties and microstructures of scaffolds, ether being degraded or not, can be examined and characterized by the SR-PBI-CT imaging, in a non-destructive manner. This would represent a significant advance for facilitating longitudinal studies on the scaffolds once implanted in-vivo.
{"title":"Characterization of hydrogel-scaffold mechanical properties and microstructure by using synchrotron propagation-based imaging","authors":"Naitao Li , Xiaoman Duan , Xiao Fan Ding , Ning Zhu , Xiongbiao Chen","doi":"10.1016/j.jmbbm.2024.106844","DOIUrl":"10.1016/j.jmbbm.2024.106844","url":null,"abstract":"<div><div>Hydrogel-based scaffolds have been widely used in soft tissue regeneration due to their biocompatible and tissue-like environment for maintaining cellular functions and tissue regeneration. Understanding the mechanical properties and internal microstructure of hydrogel-based scaffold, once implanted, is imperative in tissue engineering applications and longitudinal studies. Notably, this has been challenging to date as various conventional characterization methods by, for example, mechanical testing (for mechanical properties) and microscope (for internal microstructure) are destructive as they require removing scaffolds from the implantation site and processing samples for characterization. Synchrotron radiation propagation-based imaging–computed tomography (SR-PBI-CT) is feasible and promising for non-destructive visualizing of hydrogel scaffolds. As inspired, this study aimed to perform a study on the characterization of mechanical properties and microstructure of hydrogel scaffolds based on the SR-PBI-CT.</div><div>In this study, hydrogel biomaterial inks composed of 3% w/v alginate and 1% w/v gelatin were printed to form scaffolds, with some scaffolds being degraded over 3 days. Both degraded and undegraded scaffolds underwent compressive testing, with the strains being controlled at the preset values; meanwhile stresses within scaffolds were measuring, resulting the stress-strain curves. Concurrently, the scaffolds were also imaged and examined by SR-PBI-CT at Canadian Light Source (CLS). During the imaging process, the scaffolds were mechanically loaded, respectively, with the strains same as the ones in the aforementioned compressive testing, and at each strain, the scaffold was scanned with a pixel size of 13 μm.</div><div>From the stress-strain curves obtained in the compression testing, the Young's modulus was evaluated to characterize the elastic behavior of scaffolds: with the range between around 5–25 kPa. From the images captured by SR-PBI-CT, the scaffolds microstructures were examined in terms of the strand cross-section area, pore size, and hydrogel volume. Further, from the SR-PBI-CT images, the stress within hydrogel of scaffolds were evaluated, showing the agreement with those obtained from compression testing. These results have illustrated that the mechanical properties and microstructures of scaffolds, ether being degraded or not, can be examined and characterized by the SR-PBI-CT imaging, in a non-destructive manner. This would represent a significant advance for facilitating longitudinal studies on the scaffolds once implanted <em>in-vivo</em>.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106844"},"PeriodicalIF":3.3,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142788186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-29DOI: 10.1016/j.jmbbm.2024.106845
Leila Berriche , Jessica Welzel , Svitlana Sirenko , Gabriele Wortmann , Volkmar Vill , Franz J. Wortmann
Fatigue failure testing of materials is an important aspect of assessing their strength and resilience under long-term, oscillatory stresses and/or strains. This also applies to human hair. For this investigation, we decided to complement existing experience on cyclic tests at various levels of constant stress with those at various constant strains (4–30%). For the description and analysis of the data sets, we opted for a non-linear fit of the cumulative two-parameter Weibull distribution (CWD) to the survival data. This gives direct access to the numerical values of the parameters as well as to their standard errors (SE), as measures of precision. As relevant parameters, we identified the lifetime index ln(α) and the shape factor β. All fits showed very high coefficients of determination and normally distributed residuals. Accordingly, precision of the parameter values is very high. It only starts to drop for high constant strains, when significant grouping of data starts to occur. ln(α) drops and β increases both exponentially with strain. β exceeds the value of unity (β ≥ 1) at a strain of 4.3%, indicating a fundamental change of failure mode. The cross-over of the theoretical curves for ln(α) and β occurs around 45% strain, which coincides with the break strain for conventional tensile testing. This agreement supports the validity of our approach and suggests a more than just empirical nature of the CWD-function for modelling the fatigue failure data of human hair.
{"title":"Fatigue failure testing of human hair: Weibull-analysis for constant strain experiments","authors":"Leila Berriche , Jessica Welzel , Svitlana Sirenko , Gabriele Wortmann , Volkmar Vill , Franz J. Wortmann","doi":"10.1016/j.jmbbm.2024.106845","DOIUrl":"10.1016/j.jmbbm.2024.106845","url":null,"abstract":"<div><div>Fatigue failure testing of materials is an important aspect of assessing their strength and resilience under long-term, oscillatory stresses and/or strains. This also applies to human hair. For this investigation, we decided to complement existing experience on cyclic tests at various levels of constant stress with those at various constant strains (4–30%). For the description and analysis of the data sets, we opted for a non-linear fit of the cumulative two-parameter Weibull distribution (CWD) to the survival data. This gives direct access to the numerical values of the parameters as well as to their standard errors (SE), as measures of precision. As relevant parameters, we identified the lifetime index <em>ln(α)</em> and the shape factor <em>β</em>. All fits showed very high coefficients of determination and normally distributed residuals. Accordingly, precision of the parameter values is very high. It only starts to drop for high constant strains, when significant grouping of data starts to occur. <em>ln(α)</em> drops and <em>β</em> increases both exponentially with strain. <em>β</em> exceeds the value of unity (<em>β</em> ≥ 1) at a strain of 4.3%, indicating a fundamental change of failure mode. The cross-over of the theoretical curves for <em>ln(α)</em> and <em>β</em> occurs around 45% strain, which coincides with the break strain for conventional tensile testing. This agreement supports the validity of our approach and suggests a more than just empirical nature of the CWD-function for modelling the fatigue failure data of human hair.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106845"},"PeriodicalIF":3.3,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142788234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-23DOI: 10.1016/j.jmbbm.2024.106825
Qi Li , YanLi Gong , Yingxin Li , Sha Li , WenLang Liang , Y.X. Leng
Poly (vinyl alcohol) (PVA)-based hydrogels are widely regarded as ideal cartilage replacement materials because of their excellent properties. However, they have drawbacks such as high coefficient of friction (COF) and insufficient wear resistance. As important components of the synovial fluid, proteins are involved in counter-pairs and effect their tribological behavior via denaturation. Tannic acid (TA), which is rich in hydroxyl groups, can bind strongly proteins and change their conformation. In this study, the structure and lubrication performance of TA/PVA hydrogels in phosphate buffer saline (PBS) and bovine serum albumin (BSA) solutions were investigated. The results indicated that TA molecules enhanced the stiffness of the hydrogel by forming hydrogen bonds with PVA, reducing its COF in the PBS solution. In BSA solution, the tribological behavior of the PT hydrogels is altered by the BSA adsorbed at the hydrogel interface owing to the addition of TA. The COF of the PVA hydrogels with a TA content of 0.5 wt% is as low as 0.045, which was approximately 2.67 times lower than that of the PVA hydrogel under the same conditions. The benzene rings and hydroxyl groups in TA were connected to BSA molecules through hydrogen bonding, inducing a conformational change in the BSA from an α-helix structure to β-sheet structure, which further improves the lubricating properties of the hydrogel.
{"title":"Study on the lubrication behavior of tannic acid/ poly (vinyl alcohol) hydrogel enhanced by protein adsorption for articular cartilage applications","authors":"Qi Li , YanLi Gong , Yingxin Li , Sha Li , WenLang Liang , Y.X. Leng","doi":"10.1016/j.jmbbm.2024.106825","DOIUrl":"10.1016/j.jmbbm.2024.106825","url":null,"abstract":"<div><div>Poly (vinyl alcohol) (PVA)-based hydrogels are widely regarded as ideal cartilage replacement materials because of their excellent properties. However, they have drawbacks such as high coefficient of friction (COF) and insufficient wear resistance. As important components of the synovial fluid, proteins are involved in counter-pairs and effect their tribological behavior via denaturation. Tannic acid (TA), which is rich in hydroxyl groups, can bind strongly proteins and change their conformation. In this study, the structure and lubrication performance of TA/PVA hydrogels in phosphate buffer saline (PBS) and bovine serum albumin (BSA) solutions were investigated. The results indicated that TA molecules enhanced the stiffness of the hydrogel by forming hydrogen bonds with PVA, reducing its COF in the PBS solution. In BSA solution, the tribological behavior of the PT hydrogels is altered by the BSA adsorbed at the hydrogel interface owing to the addition of TA. The COF of the PVA hydrogels with a TA content of 0.5 wt% is as low as 0.045, which was approximately 2.67 times lower than that of the PVA hydrogel under the same conditions. The benzene rings and hydroxyl groups in TA were connected to BSA molecules through hydrogen bonding, inducing a conformational change in the BSA from an α-helix structure to β-sheet structure, which further improves the lubricating properties of the hydrogel.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"162 ","pages":"Article 106825"},"PeriodicalIF":3.3,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142703612","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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