The thoracolumbar fascia (TLF) and the erector spinae aponeurosis (ESA) play an important role in the biomechanics of the spine and could be a source of low back pain. Although the TLF and ESA are key structures in several musculoskeletal dysfunctions and in tissue engineering, there is still a lack of evidence in the literature to prove that they have different mechanical properties and roles when considered as a single tissue. Furthermore, no methods are currently available to study these structures in vivo. The objective of this study was to analyze the ex-vivo tensile properties TLF and ESA, and to test the potential of ultrasound shearwave elastography (SWE) to characterize these tissues. Hundred samples from N = 10 fresh-frozen human donors were studied. Shear wave speed (SWS) was measured in all samples with SWE, and their tensile properties were measured with mechanical testing. Results show that TLF is anisotropic, and more compliant than ESA. SWS was not significantly correlated to tensile moduli.
These findings could potentially aid surgeons in their daily practices, assist engineers with in silico simulations, and support physiotherapists in musculoskeletal rehabilitation by enabling them to customize medical interventions for each specific patient and clinical condition. However, further research is necessary to further investigate the behavior in terms of time-dependent response and link between the tissue anisotropy and microstructural organization.
{"title":"Ex vivo mechanical properties of human thoracolumbar fascia and erector spinae aponeurosis under traction loading and shear wave elastography","authors":"Maud Creze , Alexandre Lagache , Fabrice Duparc , Mila Broqué , Sylvain Persohn , Camille Slama , Claudio Vergari , Pierre-Yves Rohan","doi":"10.1016/j.jmbbm.2025.107028","DOIUrl":"10.1016/j.jmbbm.2025.107028","url":null,"abstract":"<div><div>The thoracolumbar fascia (TLF) and the erector spinae aponeurosis (ESA) play an important role in the biomechanics of the spine and could be a source of low back pain. Although the TLF and ESA are key structures in several musculoskeletal dysfunctions and in tissue engineering, there is still a lack of evidence in the literature to prove that they have different mechanical properties and roles when considered as a single tissue. Furthermore, no methods are currently available to study these structures <em>in vivo</em>. The objective of this study was to analyze the ex-vivo tensile properties TLF and ESA, and to test the potential of ultrasound shearwave elastography (SWE) to characterize these tissues. Hundred samples from N = 10 fresh-frozen human donors were studied. Shear wave speed (SWS) was measured in all samples with SWE, and their tensile properties were measured with mechanical testing. Results show that TLF is anisotropic, and more compliant than ESA. SWS was not significantly correlated to tensile moduli.</div><div>These findings could potentially aid surgeons in their daily practices, assist engineers with in silico simulations, and support physiotherapists in musculoskeletal rehabilitation by enabling them to customize medical interventions for each specific patient and clinical condition. However, further research is necessary to further investigate the behavior in terms of time-dependent response and link between the tissue anisotropy and microstructural organization.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"168 ","pages":"Article 107028"},"PeriodicalIF":3.3,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143854956","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 : 2025-04-19DOI: 10.1016/j.jmbbm.2025.107027
Jun Li , Chuang Zhang , Weiwei Lan , Weiyi Chen , Di Huang
Polyvinyl alcohol (PVA) hydrogels have garnered increasing interest in the field of biomedical materials due to their excellent biocompatibility and controllable mechanical properties. Although various preparation strategies such as freeze-thaw cycles, solvent-exchange, salting-out and annealing treatments have been extensively employed in the preparation of PVA hydrogels, the current literature lacks systematic comparisons under the same PVA molecular weight and mass fraction conditions. It limited the in-depth understanding of the mechanism of optimizing the properties of PVA hydrogels and could not provide guidance for the construction of high strength pure PVA hydrogels. In this study, PVA with a molecular weight of 145,000 was utilized to prepare hydrogels with mass fraction of 10 wt%, 15 wt%, and 20 wt% using the aforementioned four preparation strategies. We thoroughly investigated the effects of preparation strategies and mass fraction on the mechanical properties of PVA hydrogels by employing the eXtreme Gradient Boosting (XGboost) machine learning model for precise data analysis and predictions. Additionally, we also investigated the effects of different preparation strategies and mass fraction on the microstructure and surface properties of PVA hydrogels. The results indicated that the choice of preparation strategies significantly influenced the mechanical properties of PVA hydrogels, surpassing the effects of PVA mass fraction. Notably, under the same preparation conditions, the 20 wt% annealing-PVA hydrogels exhibited the best tensile strength (3.96 ± 0.511 MPa), tensile modulus (4.36 ± 0.160 MPa), and compressive modulus (3.17 ± 0.644 MPa), representing increases of 10 times, 62 times, and 26 times, respectively, compared to freeze-thaw cycles-PVA, while also demonstrating the lowest friction coefficient (0.05). According to the XGboost machine learning model, it showed that the PVA mass fraction had 26.21 % of the effect on the variation of mechanical properties, while the preparation strategy accounted for the remaining 73.79 %. In summary, we successfully established the correlation between the mechanical properties of PVA hydrogels and preparation parameters, providing a solid technical foundation for the development of high strength pure PVA hydrogels.
{"title":"Machine learning-assisted strategies to enhance the mechanical properties of PVA hydrogels","authors":"Jun Li , Chuang Zhang , Weiwei Lan , Weiyi Chen , Di Huang","doi":"10.1016/j.jmbbm.2025.107027","DOIUrl":"10.1016/j.jmbbm.2025.107027","url":null,"abstract":"<div><div>Polyvinyl alcohol (PVA) hydrogels have garnered increasing interest in the field of biomedical materials due to their excellent biocompatibility and controllable mechanical properties. Although various preparation strategies such as freeze-thaw cycles, solvent-exchange, salting-out and annealing treatments have been extensively employed in the preparation of PVA hydrogels, the current literature lacks systematic comparisons under the same PVA molecular weight and mass fraction conditions. It limited the in-depth understanding of the mechanism of optimizing the properties of PVA hydrogels and could not provide guidance for the construction of high strength pure PVA hydrogels. In this study, PVA with a molecular weight of 145,000 was utilized to prepare hydrogels with mass fraction of 10 wt%, 15 wt%, and 20 wt% using the aforementioned four preparation strategies. We thoroughly investigated the effects of preparation strategies and mass fraction on the mechanical properties of PVA hydrogels by employing the eXtreme Gradient Boosting (XGboost) machine learning model for precise data analysis and predictions. Additionally, we also investigated the effects of different preparation strategies and mass fraction on the microstructure and surface properties of PVA hydrogels. The results indicated that the choice of preparation strategies significantly influenced the mechanical properties of PVA hydrogels, surpassing the effects of PVA mass fraction. Notably, under the same preparation conditions, the 20 wt% annealing-PVA hydrogels exhibited the best tensile strength (3.96 ± 0.511 MPa), tensile modulus (4.36 ± 0.160 MPa), and compressive modulus (3.17 ± 0.644 MPa), representing increases of 10 times, 62 times, and 26 times, respectively, compared to freeze-thaw cycles-PVA, while also demonstrating the lowest friction coefficient (0.05). According to the XGboost machine learning model, it showed that the PVA mass fraction had 26.21 % of the effect on the variation of mechanical properties, while the preparation strategy accounted for the remaining 73.79 %. In summary, we successfully established the correlation between the mechanical properties of PVA hydrogels and preparation parameters, providing a solid technical foundation for the development of high strength pure PVA hydrogels.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"168 ","pages":"Article 107027"},"PeriodicalIF":3.3,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143859056","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 : 2025-04-18DOI: 10.1016/j.jmbbm.2025.107026
Jens Hachenberg , Babak Behbahanian , Sebastian Ludwig , Wolfram Malter , Lena Steinkassserer , Agnieszka Denecke , Mathieu Pfleiderer , Christian Eichler
Purpose
Pelvic organ prolapse (POP) in women is a common condition. Polypropylene meshes have an important place in the treatment. To date, a biomechanical comparison with a specific mesh design has not been performed for cervical fixation. The purpose of this study was to evaluate the biomechanical properties of different polypropylene mesh shapes and their fastening.
Methods
Biomechanical testing was performed with a porcine model using the Tension Testing machine Instron 5565®. The cervix was fixated in the Instron 5565® to measure its biomechanical properties. Measurement parameters comprised the maximum load (N), displacement at failure (mm), and stiffness (N/mm). In total, sixty trials were performed. These trials were subdivided into three groups. The first group used Y-shaped meshes fixated with 4 sutures (Y4). The second group used a Y-shaped mesh with 6 sutures (Y6). The third group comprised the standard cervical fixation (SF) utilizing a rectangular mesh with three sutures fixed horizontally on the anterior of the cervix.
Results
Y6 displayed the highest maximum load of 114 ± 19.4 N with displacement at failure 53.2 ± 12.3 mm. SF yielded the highest stiffness value 2.7 ± 0.74 N/mm with the second lowest maximum load and lowest displacement at failure. Y4 displayed the lowest maximum load 73,3 ± 20.5 N, second highest displacement at failure 40.5 ± 9.2 mm, and lowest stiffness 1.99 ± 0.85 N/mm.
Conclusion
Y6 displayed the overall highest results for maximum load and displacement at failure. The data derived from this study show that factors such as the shape of the mesh, number of sutures, and location of sutures play an important role in the uniaxial biomechanical properties.
{"title":"A biomechanical analysis of cervical fixation methods using shaped meshes for pelvic floor reconstruction in a porcine model","authors":"Jens Hachenberg , Babak Behbahanian , Sebastian Ludwig , Wolfram Malter , Lena Steinkassserer , Agnieszka Denecke , Mathieu Pfleiderer , Christian Eichler","doi":"10.1016/j.jmbbm.2025.107026","DOIUrl":"10.1016/j.jmbbm.2025.107026","url":null,"abstract":"<div><h3>Purpose</h3><div>Pelvic organ prolapse (POP) in women is a common condition. Polypropylene meshes have an important place in the treatment. To date, a biomechanical comparison with a specific mesh design has not been performed for cervical fixation. The purpose of this study was to evaluate the biomechanical properties of different polypropylene mesh shapes and their fastening.</div></div><div><h3>Methods</h3><div>Biomechanical testing was performed with a porcine model using the Tension Testing machine Instron 5565®. The cervix was fixated in the Instron 5565® to measure its biomechanical properties. Measurement parameters comprised the maximum load (N), displacement at failure (mm), and stiffness (N/mm). In total, sixty trials were performed. These trials were subdivided into three groups. The first group used Y-shaped meshes fixated with 4 sutures (Y4). The second group used a Y-shaped mesh with 6 sutures (Y6). The third group comprised the standard cervical fixation (SF) utilizing a rectangular mesh with three sutures fixed horizontally on the anterior of the cervix.</div></div><div><h3>Results</h3><div>Y6 displayed the highest maximum load of 114 ± 19.4 N with displacement at failure 53.2 ± 12.3 mm. SF yielded the highest stiffness value 2.7 ± 0.74 N/mm with the second lowest maximum load and lowest displacement at failure. Y4 displayed the lowest maximum load 73,3 ± 20.5 N, second highest displacement at failure 40.5 ± 9.2 mm, and lowest stiffness 1.99 ± 0.85 N/mm.</div></div><div><h3>Conclusion</h3><div>Y6 displayed the overall highest results for maximum load and displacement at failure. The data derived from this study show that factors such as the shape of the mesh, number of sutures, and location of sutures play an important role in the uniaxial biomechanical properties.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"168 ","pages":"Article 107026"},"PeriodicalIF":3.3,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143859057","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 : 2025-04-17DOI: 10.1016/j.jmbbm.2025.107006
Moslem Mohammadi , Abbas Z. Kouzani , Mahdi Bodaghi , Ali Zolfagharian
This research proposes a computational framework for designing a compliant bistable mechanism and fabricating it using 3D printing for customized medical applications. The proposed method reduces upper limb tremors, taking advantage of the nonlinear mechanical properties of flexible structures. The model's development and execution on a single platform streamlines integrated inverse design and simulation, simplifying the customization process. A synthetic human arm model, built to imitate a human wrist, was scanned with a light detection and ranging (LiDAR) sensor to customize the 3D model of the bistable structure. Afterwards, the arm model was used to test the bistable mechanism. Automating the inverse design process with a deep neural network (DNN) and evolutionary optimization decides the optimal bistable mechanism configurations for stiffness and vibration attenuation. The pseudo-rigid-body model (PRBM) of the bistable mechanism was developed to train the machine learning (ML) model in the inverse design, making it computationally affordable to find the optimal parameters of bistable structure for a specific mechanical response based on tremor characteristics. Experimental results showing up to 87.11 % reduction in tremor power while weighing only 27 g to reduce vibrations in various situations suggest its use in 4D printing of wearable orthotic devices for Parkinsonian tremors and related diseases.
{"title":"3D-printed programmable bistable mechanisms for customized wearable devices in tremor attenuation","authors":"Moslem Mohammadi , Abbas Z. Kouzani , Mahdi Bodaghi , Ali Zolfagharian","doi":"10.1016/j.jmbbm.2025.107006","DOIUrl":"10.1016/j.jmbbm.2025.107006","url":null,"abstract":"<div><div>This research proposes a computational framework for designing a compliant bistable mechanism and fabricating it using 3D printing for customized medical applications. The proposed method reduces upper limb tremors, taking advantage of the nonlinear mechanical properties of flexible structures. The model's development and execution on a single platform streamlines integrated inverse design and simulation, simplifying the customization process. A synthetic human arm model, built to imitate a human wrist, was scanned with a light detection and ranging (LiDAR) sensor to customize the 3D model of the bistable structure. Afterwards, the arm model was used to test the bistable mechanism. Automating the inverse design process with a deep neural network (DNN) and evolutionary optimization decides the optimal bistable mechanism configurations for stiffness and vibration attenuation. The pseudo-rigid-body model (PRBM) of the bistable mechanism was developed to train the machine learning (ML) model in the inverse design, making it computationally affordable to find the optimal parameters of bistable structure for a specific mechanical response based on tremor characteristics. Experimental results showing up to 87.11 % reduction in tremor power while weighing only 27 g to reduce vibrations in various situations suggest its use in 4D printing of wearable orthotic devices for Parkinsonian tremors and related diseases.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"168 ","pages":"Article 107006"},"PeriodicalIF":3.3,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143859158","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 : 2025-04-17DOI: 10.1016/j.jmbbm.2025.106996
Michael S. Sacks , Benjamin Thomas , Christian Goodbrake , Aldan Webb , Charles V. Kingsley , Jason Stafford , Gregory P. Reece , Kristy Brock
There is a lack of understanding how human breast tissue internal structure connects to its bulk level 3D mechanical behaviors. An attractive method to quantify tissue structure is diffusion tensor imaging (DTMRI), which produces compact, local, quantitative information in the form of a second rank symmetric tensor D. As D contains rich information about local 3D tissue structure, we developed a novel constitutive model form for human fibroglandular (FG) and adipose (AD) breast tissues that directly utilized the complete . Our modeling approach included separate extensional/compression and shear-like interactions terms. To develop the necessary mathematical forms we utilized a neural network modeling approach trained using pure-shear loading paths from the extant triaxial data for the AD and FG groups. A final model form was formulated and model parameters determined using the same data set. The resultant constitutive model was able to simulate the unique anisotropic tension/compression behaviors, including directionally dependent non-linearities for the FG tissue group. The constitutive model was validated in two steps. First, we used the model to predict D and compared it to D as measured directly by DTMRI on excised breast tissue, which compared very well. Secondly, validation of the predictive capabilities of the model were demonstrated by accurate predictions of breast tissue in simple compression for both AD and FG tissue groups. The present modeling approach was able to predict human breast tissue 3D mechanical behavior accurately, as well as shed insight into connections to the underlying tissue structure via the use of D.
{"title":"A novel diffusion tensor based three-dimensional constitutive model for human breast tissue","authors":"Michael S. Sacks , Benjamin Thomas , Christian Goodbrake , Aldan Webb , Charles V. Kingsley , Jason Stafford , Gregory P. Reece , Kristy Brock","doi":"10.1016/j.jmbbm.2025.106996","DOIUrl":"10.1016/j.jmbbm.2025.106996","url":null,"abstract":"<div><div>There is a lack of understanding how human breast tissue internal structure connects to its bulk level 3D mechanical behaviors. An attractive method to quantify tissue structure is diffusion tensor imaging (DTMRI), which produces compact, local, quantitative information in the form of a second rank symmetric tensor <strong>D</strong>. As <strong>D</strong> contains rich information about local 3D tissue structure, we developed a novel constitutive model form for human fibroglandular (FG) and adipose (AD) breast tissues that directly utilized the complete <span><math><mi>D</mi></math></span>. Our modeling approach included separate extensional/compression and shear-like interactions terms. To develop the necessary mathematical forms we utilized a neural network modeling approach trained using pure-shear loading paths from the extant triaxial data for the AD and FG groups. A final model form was formulated and model parameters determined using the same data set. The resultant constitutive model was able to simulate the unique anisotropic tension/compression behaviors, including directionally dependent non-linearities for the FG tissue group. The constitutive model was validated in two steps. First, we used the model to predict <strong>D</strong> and compared it to <strong>D</strong> as measured directly by DTMRI on excised breast tissue, which compared very well. Secondly, validation of the predictive capabilities of the model were demonstrated by accurate predictions of breast tissue in simple compression for both AD and FG tissue groups. The present modeling approach was able to predict human breast tissue 3D mechanical behavior accurately, as well as shed insight into connections to the underlying tissue structure via the use of <strong>D</strong>.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"168 ","pages":"Article 106996"},"PeriodicalIF":3.3,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851684","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 : 2025-04-16DOI: 10.1016/j.jmbbm.2025.107017
Alexandre Segain , Helene Pillet , Stefano Zappalá , Giuseppe Sciume , Pierre-Yves Rohan
Basic research into the aetiology of pressure ulcers suggests that the concentration of mechanical strain in biological soft tissues is critical to their development. Direct measurement of in vivo strain is not compatible with clinical routine. To overcome this problem, several finite element models (FEM) have been proposed by the biomechanical community to estimate strain from imaging data. However, no direct experimental validation of the underlying relationships between mechanical loading and soft tissue strain distribution predicted by the model has been performed, and such validation evidence must be obtained prior to any clinical evaluation. Building on the experimental results obtained in N = 10 healthy volunteers (Zappalá et al., 2024), the relevance of the modelling hypotheses of the finite element model proposed in this study, which is based on a simplified geometric representation of the ischial region (Macron et al., 2020), was investigated. A methodology was proposed to estimate the different parameters needed to construct the model from the available MRI masks. The FEM was then used to estimate in vivo compressive and shear strains. The resulting strains were then compared with experimental data. The results show that the model assumptions lead to an overall overestimation of the compressive and shear strains in the muscle tissue, especially directly under the ischial tuberosity. Similarly, the model underestimates the strain in adipose tissue (mean error in shear strain of −0.2). This study highlights the fact that the assumptions usually made for the geometric modelling of muscle tissue (homogeneous soft tissue layer) lead to an incorrect estimation of peak strain localisation. Further work should be done to improve the representation of muscle tissue.
{"title":"Corroboration in vivo mechanical strain distribution in soft tissues for pressure ulcer prevention: A comparative analysis between a simplified finite element analysis and experimental strain fields","authors":"Alexandre Segain , Helene Pillet , Stefano Zappalá , Giuseppe Sciume , Pierre-Yves Rohan","doi":"10.1016/j.jmbbm.2025.107017","DOIUrl":"10.1016/j.jmbbm.2025.107017","url":null,"abstract":"<div><div>Basic research into the aetiology of pressure ulcers suggests that the concentration of mechanical strain in biological soft tissues is critical to their development. Direct measurement of <em>in vivo</em> strain is not compatible with clinical routine. To overcome this problem, several finite element models (FEM) have been proposed by the biomechanical community to estimate strain from imaging data. However, no direct experimental validation of the underlying relationships between mechanical loading and soft tissue strain distribution predicted by the model has been performed, and such validation evidence must be obtained prior to any clinical evaluation. Building on the experimental results obtained in N = 10 healthy volunteers (Zappalá et al., 2024), the relevance of the modelling hypotheses of the finite element model proposed in this study, which is based on a simplified geometric representation of the ischial region (Macron et al., 2020), was investigated. A methodology was proposed to estimate the different parameters needed to construct the model from the available MRI masks. The FEM was then used to estimate <em>in vivo</em> compressive and shear strains. The resulting strains were then compared with experimental data. The results show that the model assumptions lead to an overall overestimation of the compressive and shear strains in the muscle tissue, especially directly under the ischial tuberosity. Similarly, the model underestimates the strain in adipose tissue (mean error in shear strain of −0.2). This study highlights the fact that the assumptions usually made for the geometric modelling of muscle tissue (homogeneous soft tissue layer) lead to an incorrect estimation of peak strain localisation. Further work should be done to improve the representation of muscle tissue.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"168 ","pages":"Article 107017"},"PeriodicalIF":3.3,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850662","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 : 2025-04-16DOI: 10.1016/j.jmbbm.2025.107023
Kyosuke Hoshikawa , Maria Prado , Nariyuki Mura , Takuma Yuri , Philip M. Jacobs , Hugo Giambini
Supraspinatus (SSP), infraspinatus (ISP), and subscapularis (SSC) muscles from the rotator cuff (RC) are comprised of anatomical subregions based on muscle fiber alignment and tendon attachments. Previous studies have shown mechanical interactions between the SSP and ISP tendons, with abduction angle influencing these interactions. However, changes in strain distribution originating from the RC muscle subregions, including the SSC, due to differences in abduction angle have not been investigated. Therefore, this study aimed to determine the strain distribution in intact RC cadaveric shoulders with loading from the SSP, ISP, and SSC muscles and their subregions at different abduction angles. Surface strains in the bursal side of the SSP, ISP and SSC tendons of eight fresh frozen cadaveric intact shoulders were obtained by applying tension on these muscles and on their subregions at 25° and 45° glenohumeral abduction using an MTS system. When the SSP muscle or anterior region was loaded, no significant strain differences were observed within the footprint regions at 45° abduction. However, when the posterior region was loaded, strains concentrated on the middle facet as the abduction angle increased. Significantly higher strains were also observed in the inferior portion of the footprint with increasing abduction angle when the ISP or SSC muscles, or their subregions, were loaded. The differences in strain distribution patterns observed between the anterior and posterior regions of the SSP muscle highlight the importance of addressing each region and tendon separately when managing RC tears and repairs.
{"title":"Rotator cuff tendon strain distribution changes from the superior to the inferior tendon attachments with increasing shoulder abduction","authors":"Kyosuke Hoshikawa , Maria Prado , Nariyuki Mura , Takuma Yuri , Philip M. Jacobs , Hugo Giambini","doi":"10.1016/j.jmbbm.2025.107023","DOIUrl":"10.1016/j.jmbbm.2025.107023","url":null,"abstract":"<div><div>Supraspinatus (SSP), infraspinatus (ISP), and subscapularis (SSC) muscles from the rotator cuff (RC) are comprised of anatomical subregions based on muscle fiber alignment and tendon attachments. Previous studies have shown mechanical interactions between the SSP and ISP tendons, with abduction angle influencing these interactions. However, changes in strain distribution originating from the RC muscle subregions, including the SSC, due to differences in abduction angle have not been investigated. Therefore, this study aimed to determine the strain distribution in intact RC cadaveric shoulders with loading from the SSP, ISP, and SSC muscles and their subregions at different abduction angles. Surface strains in the bursal side of the SSP, ISP and SSC tendons of eight fresh frozen cadaveric intact shoulders were obtained by applying tension on these muscles and on their subregions at 25° and 45° glenohumeral abduction using an MTS system. When the SSP muscle or anterior region was loaded, no significant strain differences were observed within the footprint regions at 45° abduction. However, when the posterior region was loaded, strains concentrated on the middle facet as the abduction angle increased. Significantly higher strains were also observed in the inferior portion of the footprint with increasing abduction angle when the ISP or SSC muscles, or their subregions, were loaded. The differences in strain distribution patterns observed between the anterior and posterior regions of the SSP muscle highlight the importance of addressing each region and tendon separately when managing RC tears and repairs.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"168 ","pages":"Article 107023"},"PeriodicalIF":3.3,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848030","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 : 2025-04-15DOI: 10.1016/j.jmbbm.2025.107011
Telma de Souza Pires , Felipe Somavilla Binotto , Maria Gabriela Packaeser , Rafael R. Moraes , Gabriel Kalil Rocha Pereira , Rafaela Oliveira Pilecco
This in vitro study evaluated how different surface treatments during try-in affect the fatigue behavior of lithium disilicate ceramic. Disc-shaped lithium disilicate specimens were fabricated and allocated into 4 groups: (1) CTRL – try-in paste removed with 37% phosphoric acid (H3PO4), followed by etching with 5% hydrofluoric acid (HF) and silane treatment; (2) HFSIL PRE – HF and silane applied before try-in, followed by H3PO4 cleaning; (3) HFSIL PRE + SIL POST – same as HFSIL PRE, with an additional silane application after paste removal; and (4) HFSIL PRE + HFSIL POST – HF and silane applied both before and after try-in. Specimens were bonded to fiber-reinforced epoxy resin discs with resin cement. Baseline (24-h water storage) and aged (25,000 thermal cycles) samples underwent fatigue testing (n = 15; 20 Hz, initial load 200 N, step size 50 N, 10,000 cycles per step) to measure fatigue failure load (FFL) and cycles for failure (CFF). Monotonic test (1 mm/min) was also performed to determine maximum load. At baseline, no significant differences in fatigue behavior were observed among the groups. After aging, HFSIL PRE group demonstrated superior fatigue behavior compared to HFSIL PRE + HFSIL POST group. No significant differences were found between CTRL, HFSIL PRE, and HFSIL PRE + SIL POST. Aging significantly reduced FFL and CFF across all groups. These results suggest that a surface treatment protocol involving single etching and silane application during try-in optimizes the mechanical performance of lithium disilicate restorations. Re-etching with HF after try-in is unnecessary and may impair fatigue performance.
{"title":"Try-in procedure and surface treatment strategies: Optimizing the fatigue behavior of lithium disilicate restorations","authors":"Telma de Souza Pires , Felipe Somavilla Binotto , Maria Gabriela Packaeser , Rafael R. Moraes , Gabriel Kalil Rocha Pereira , Rafaela Oliveira Pilecco","doi":"10.1016/j.jmbbm.2025.107011","DOIUrl":"10.1016/j.jmbbm.2025.107011","url":null,"abstract":"<div><div>This <em>in vitro</em> study evaluated how different surface treatments during try-in affect the fatigue behavior of lithium disilicate ceramic. Disc-shaped lithium disilicate specimens were fabricated and allocated into 4 groups: (1) CTRL – try-in paste removed with 37% phosphoric acid (H<sub>3</sub>PO<sub>4</sub>), followed by etching with 5% hydrofluoric acid (HF) and silane treatment; (2) HFSIL PRE – HF and silane applied before try-in, followed by H<sub>3</sub>PO<sub>4</sub> cleaning; (3) HFSIL PRE + SIL POST – same as HFSIL PRE, with an additional silane application after paste removal; and (4) HFSIL PRE + HFSIL POST – HF and silane applied both before and after try-in. Specimens were bonded to fiber-reinforced epoxy resin discs with resin cement. Baseline (24-h water storage) and aged (25,000 thermal cycles) samples underwent fatigue testing (n = 15; 20 Hz, initial load 200 N, step size 50 N, 10,000 cycles per step) to measure fatigue failure load (FFL) and cycles for failure (CFF). Monotonic test (1 mm/min) was also performed to determine maximum load. At baseline, no significant differences in fatigue behavior were observed among the groups. After aging, HFSIL PRE group demonstrated superior fatigue behavior compared to HFSIL PRE + HFSIL POST group. No significant differences were found between CTRL, HFSIL PRE, and HFSIL PRE + SIL POST. Aging significantly reduced FFL and CFF across all groups. These results suggest that a surface treatment protocol involving single etching and silane application during try-in optimizes the mechanical performance of lithium disilicate restorations. Re-etching with HF after try-in is unnecessary and may impair fatigue performance.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"168 ","pages":"Article 107011"},"PeriodicalIF":3.3,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850663","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 : 2025-04-15DOI: 10.1016/j.jmbbm.2025.107015
Sabrina I. Sinopoli , Mitchel C. Whittal , Noah Chow , Diane E. Gregory
Purpose
As humans age, the intervertebral disc begins to deteriorate and lose structural integrity. The purpose of this study was to examine age-related mechanical differences of the annulus fibrosus in a human cadaveric model.
Methods
Twenty-two discs were removed from eight soft fixed human cadaveric spine segments (T10-S1) ranging from 53 to 90 years of age; 5 male, 3 female. All discs were a degenerative grade of 3 or higher. Single layer (n = 22), bilayer (n = 22), and multilayer annulus samples (n = 37) were mechanically tested from of the excised discs. Single layer and bilayer samples were mechanically tested in tension; single layer testing isolated the intralamellar matrix while bilayer testing provided a more holistic measure of the annular mechanical properties. The multilayer samples were tested via a 180° peel test to investigate the interlamellar matrix. From these tests, numerous mechanical properties were quantified.
Results
Age was found to significantly affect single and bilayer stiffness and numerous stress properties including single layer failure stress, bilayer end of toe-region stress, and bilayer stress at 15 % strain such that as age increased, the magnitude of these mechanical properties decreased. In contrast, age did not affect any peel test mechanical property (p > 0.05).
Conclusion
This study demonstrated that, with increasing age, the annulus fibrosus becomes more compliant and weaker. However, the adhesive matrix found between the lamellae of the annulus does not appear to be impacted by age.
{"title":"Mechanical age-related differences in the human cadaveric annulus fibrosus","authors":"Sabrina I. Sinopoli , Mitchel C. Whittal , Noah Chow , Diane E. Gregory","doi":"10.1016/j.jmbbm.2025.107015","DOIUrl":"10.1016/j.jmbbm.2025.107015","url":null,"abstract":"<div><h3>Purpose</h3><div>As humans age, the intervertebral disc begins to deteriorate and lose structural integrity. The purpose of this study was to examine age-related mechanical differences of the annulus fibrosus in a human cadaveric model.</div></div><div><h3>Methods</h3><div>Twenty-two discs were removed from eight soft fixed human cadaveric spine segments (T10-S1) ranging from 53 to 90 years of age; 5 male, 3 female. All discs were a degenerative grade of 3 or higher. Single layer (n = 22), bilayer (n = 22), and multilayer annulus samples (n = 37) were mechanically tested from of the excised discs. Single layer and bilayer samples were mechanically tested in tension; single layer testing isolated the intralamellar matrix while bilayer testing provided a more holistic measure of the annular mechanical properties. The multilayer samples were tested via a 180° peel test to investigate the interlamellar matrix. From these tests, numerous mechanical properties were quantified.</div></div><div><h3>Results</h3><div>Age was found to significantly affect single and bilayer stiffness and numerous stress properties including single layer failure stress, bilayer end of toe-region stress, and bilayer stress at 15 % strain such that as age increased, the magnitude of these mechanical properties decreased. In contrast, age did not affect any peel test mechanical property (p > 0.05).</div></div><div><h3>Conclusion</h3><div>This study demonstrated that, with increasing age, the annulus fibrosus becomes more compliant and weaker. However, the adhesive matrix found between the lamellae of the annulus does not appear to be impacted by age.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"168 ","pages":"Article 107015"},"PeriodicalIF":3.3,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143859054","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 : 2025-04-12DOI: 10.1016/j.jmbbm.2025.106984
Nicole Cindy Fontinele Miranda , Ivan Onone Gialain , Marlene Kasumi Gantier-Takano , Rafael Yagüe Ballester , Bruno Agostinho Hernandez , Alex Fok , Josete Barbosa Cruz Meira
The load-to-fracture test is widely used to evaluate crowns made of new CAD/CAM materials, even though its validity in predicting clinical performances is often questioned. Despite its limitations, the test is useful in assessing the load-bearing capacity of crowns subjected to accidental overloads and setting up step-stress regimes for fatigue testing. This study combined a systematic review (SR) and finite element analysis (FEA) to assess whether the test should be standardized and how.
The SR evaluated load-to-fracture studies of monolithic CAD/CAM molar crowns published in Q1 and Q2 journals. Findings from 85 studies highlighted the lack of standardization in test methods, particularly regarding loading head type and die material. This variability led to a wide dispersion of fracture load results, limiting the utility of the load-to-fracture test.
The FEA evaluated the influence of loading head type and die material on tensile stress distribution in lithium disilicate (LD) and polymer-infiltrated ceramic network (PICN) crowns. Eight in vitro conditions were simulated, varying the loading head (4 mm and 10 mm spheres, inverse V-shaped device, opposing teeth) and die material (stiff, E = 207 GPa; non-stiff, E = 13 GPa). The FEA confirmed that the stress distribution and peak tensile stress in LD and PICN crowns depend significantly on these factors as well as the crown material properties, with the peak stress variation from LD to PICN ranging from −4 % to 237 %. Using larger-diameter spheres with a die material approximating dentin in stiffness resulted in stress distributions more representative of clinical conditions.
{"title":"Should the load-to-fracture test for CAD/CAM monolithic molar crowns be standardized and how? A systematic review and finite element analysis","authors":"Nicole Cindy Fontinele Miranda , Ivan Onone Gialain , Marlene Kasumi Gantier-Takano , Rafael Yagüe Ballester , Bruno Agostinho Hernandez , Alex Fok , Josete Barbosa Cruz Meira","doi":"10.1016/j.jmbbm.2025.106984","DOIUrl":"10.1016/j.jmbbm.2025.106984","url":null,"abstract":"<div><div>The load-to-fracture test is widely used to evaluate crowns made of new CAD/CAM materials, even though its validity in predicting clinical performances is often questioned. Despite its limitations, the test is useful in assessing the load-bearing capacity of crowns subjected to accidental overloads and setting up step-stress regimes for fatigue testing. This study combined a systematic review (SR) and finite element analysis (FEA) to assess whether the test should be standardized and how.</div><div>The SR evaluated load-to-fracture studies of monolithic CAD/CAM molar crowns published in Q1 and Q2 journals. Findings from 85 studies highlighted the lack of standardization in test methods, particularly regarding loading head type and die material. This variability led to a wide dispersion of fracture load results, limiting the utility of the load-to-fracture test.</div><div>The FEA evaluated the influence of loading head type and die material on tensile stress distribution in lithium disilicate (LD) and polymer-infiltrated ceramic network (PICN) crowns. Eight in vitro conditions were simulated, varying the loading head (4 mm and 10 mm spheres, inverse V-shaped device, opposing teeth) and die material (stiff, E = 207 GPa; non-stiff, E = 13 GPa). The FEA confirmed that the stress distribution and peak tensile stress in LD and PICN crowns depend significantly on these factors as well as the crown material properties, with the peak stress variation from LD to PICN ranging from −4 % to 237 %. Using larger-diameter spheres with a die material approximating dentin in stiffness resulted in stress distributions more representative of clinical conditions.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"168 ","pages":"Article 106984"},"PeriodicalIF":3.3,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824328","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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