{"title":"Integrated Workflow Finite Element Modeling of the Temporomandibular Joint: Toward a Methodical and Reproducible Approach.","authors":"Lilian Baugnon, Romain Nicot, Nicolas Bethune, Pauline Lecomte-Grosbras, Jean-François Witz, Olivier Mayeur","doi":"10.1115/1.4071534","DOIUrl":"10.1115/1.4071534","url":null,"abstract":"<p><p>This study presents a patient-specific parametric model of the temporomandibular joint, designed to be semi-automated, and reproducible for multiple patients. The numerical model is used to evaluate mandibular stress distribution under different interaction and loading conditions. The main contribution is to demonstrate the feasibility of an integrated, fast, and streamlined workflow for generating accurate biomechanical models tailored to each patient. The proposed method, which relies on standard clinical images complemented by artificial intelligence-assisted segmentation of bone and muscles, enables the integration of patient-specific anatomical features and mechanical variability. A finite element model of the skull, mandible, teeth, and articular disks was constructed from calibrated computed tomography data. Material properties were automatically assigned using Hounsfield units, distinguishing between cortical bone, cancellous bone, and dental tissue. Sensitivity of key modeling parameters (mesh density, material, friction coefficients, muscle force vectors) was evaluated using abaqus/standard. Hounsfield-units-driven material assignment provides a Young modulus distribution aligned with the literature, while maintaining patient specificity. Artificial intelligence-based muscle reconstruction reveals that stress fields stabilize with increased directional vector refinement, reinforcing biomechanical accuracy and confirming the necessity of multivector muscle loading. This patient-specific parametric model accurately reproduces the distribution of mandibular stresses and offers a promising tool for surgical planning, pathology simulation, and the evaluation of personalized treatment strategies.</p>","PeriodicalId":54871,"journal":{"name":"Journal of Biomechanical Engineering-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147534515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yamnesh Agrawal, Masoud Zamani, James R Thunes, Spandan Maiti, Anne M Robertson
{"title":"Load Transfer Along Continuous Collagen Fibers Reduces the Importance of Wall Thickness Variations.","authors":"Yamnesh Agrawal, Masoud Zamani, James R Thunes, Spandan Maiti, Anne M Robertson","doi":"10.1115/1.4071368","DOIUrl":"10.1115/1.4071368","url":null,"abstract":"<p><p>The mechanical response of biological soft tissues is influenced by wall heterogeneity, including spatial variations in wall thickness. Traditional models for homogeneous soft tissues under uniaxial loading predict higher stretch and stress in thinner regions. In prior studies, the role of collagen fibers in regions of thickness transition has been largely neglected or only considered in terms of their effect on anisotropy. Here, we explore the role of collagen fibers as primary load-bearing components across regions of varying wall thickness, using a three-dimensional mesoscale model incorporating explicit collagen fiber architecture and a gradual thickness gradient. We examined two distinct collagen fiber configurations across the thickness transition: one featuring abrupt fiber termination and another with fiber continuity. Finite element analysis under uniaxial tension revealed that load transfer by the continuous fibers markedly reduced the importance of the change in wall thickness, with stretch differentials dropping from 20.97% (fiber-termination network) to 0.68% (continuous fibers) and stress differentials dropping from ∼65% (fiber-termination network) to 2.3% (continuous fibers). Fiber tortuosity delayed the point at which mechanical response was governed by fiber structure. These findings demonstrate the critical role of fiber continuity in reducing stretch and stress gradients across regions of varying wall thickness and clarify the importance of accurately representing fiber architecture when modeling soft tissues with heterogeneous wall thickness.</p>","PeriodicalId":54871,"journal":{"name":"Journal of Biomechanical Engineering-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13313125/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147437768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jason A Franzman, Joshua Do, Manali Rajendra Kulkarni, John-Paul Heinzen, Hadi Wiputra, Victor Barocas
{"title":"Benchtop Pulse Wave Velocity Measurement From Spatial Wavelength Rather Than Pulse Arrival Time: Feasibility Studies.","authors":"Jason A Franzman, Joshua Do, Manali Rajendra Kulkarni, John-Paul Heinzen, Hadi Wiputra, Victor Barocas","doi":"10.1115/1.4071257","DOIUrl":"10.1115/1.4071257","url":null,"abstract":"<p><p>Arterial stiffness is a significant predictor of cardiovascular disease, commonly assessed using pulse wave velocity (PWV). Traditional PWV measurement methods, such as time-of-flight, become unreliable in highly reflective systems due to the presence of standing waves and measurement noise, complicating accurate determination of wave arrival times. To address these limitations, we developed and validated a spatial wavelength-based PWV measurement approach. Our objective was to evaluate the capability of this method in nonbiological systems and compare its performance directly to standard methods. Experimental measurements were conducted using latex tubes in a benchtop pulsatile flow system across multiple frequencies (20-47 Hz). High-speed video analysis tracked spatial diameter changes, allowing identification of the spatial wavelength. Computational fluid-structure interaction (FSI) simulations, replicating experimental conditions, provided validation. Measuring PWV via spatial wavelength showed consistent accuracy when compared to traditional methods (phase-slope, peak-slope, and pressure arrival time), remaining within 12% error relative to theoretical predictions derived from the Moens-Korteweg equation. Spatial wavelength-based calculation has practical limitations, including reduced reliability near resonant frequencies and the requirement for at least one full wavelength within the length of measured region, constraining clinical usability. This method can be used in laboratory conditions at higher frequencies, potentially allowing quantification of how vascular implants and prosthetics could alter arterial wall dynamics.</p>","PeriodicalId":54871,"journal":{"name":"Journal of Biomechanical Engineering-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13313132/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147319016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Influence of Passively Modeled Paraspinal Soft Tissues on Spinal Geometric Compensation: A Finite Element Analysis.","authors":"Adi Mithani, Ahmed Aoude, Mark Driscoll","doi":"10.1115/1.4071533","DOIUrl":"10.1115/1.4071533","url":null,"abstract":"<p><p>Alterations in the contributions of paraspinal soft tissues can influence the geometric profile of the spine. This study investigated the effects of passively modeled paraspinal soft tissues (i.e., paraspinal muscles and the thoracolumbar fascia (TLF)), on lumbar segmental mobility and geometric compensation, using a credible and previously validated finite element model (FEM) of the thoracolumbar spine. The model included the vertebrae, rib cage, intervertebral discs (IVDs), pelvis, ligaments, spinal and abdominal muscles, and the TLF. The model was subjected to 30 deg and 60 deg flexion rotation with a fixed pelvic support, and an applied follower load of 1175 N, increasing by 2.4% at each segmental level. Changes in lumbar L2-S1 intervertebral rotation (IVR), lumbar and thoracic range of motion (RoM), and curvature were analyzed for cases involving removal and increased stiffening of the paraspinal muscles and the TLF. Increasing TLF stiffness reduced lumbar RoM (5.1 deg) at 60 deg flexion relative to the validated model, with compensatory increases of 3.6 deg in thoracic RoM. Increases in lumbar lordosis (3.6 deg) were proportional to increases in thoracic kyphosis (3.3 deg). Similar effects of reduced magnitude were observed in 30 deg flexion. Inverse effects were observed following TLF removal. However, no changes were observed with changes in paraspinal muscle contribution. These findings suggest that changes in TLF stiffness influence lumbar segmental mobility and drive compensatory adjustments in the spinal geometric profile.</p>","PeriodicalId":54871,"journal":{"name":"Journal of Biomechanical Engineering-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147534499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
George Morgan, Jennifer Frattolin, Lamis Elsawah, Amelie Daudet, Daniel Watson, Nicola Contessi Negrini, Adam D Celiz, James E Moore
{"title":"Excessive Shear Rate, Not Shear Stress, Influences Cell Mechanical Damage in Small-Bore Needle Injections.","authors":"George Morgan, Jennifer Frattolin, Lamis Elsawah, Amelie Daudet, Daniel Watson, Nicola Contessi Negrini, Adam D Celiz, James E Moore","doi":"10.1115/1.4071455","DOIUrl":"10.1115/1.4071455","url":null,"abstract":"<p><p>Cell therapies and 3D bioprinting often require suspended cells to be delivered through needles of 20-gauge and smaller. This often damages cells, affecting their short and long-term viability. Most researchers have attributed this to excessive viscous stresses encountered entering or within the needle, but the experimental evidence contradicts that, as higher viscosity suspension fluids generally yield higher cell viabilities when injected at the same flow rate. We therefore sought to determine the most relevant fluid flow parameter influencing cell mechanical damage. A combination of reprocessing published results and cell injection experiments were conducted. Human umbilical vein endothelial cells (HUVECs) were suspended in Newtonian fluids of varying viscosities and injected through 30-gauge syringe needles in experiments that controlled for either shear stress or shear rate (a kinematic quantity expressing relative velocity of adjacent fluid layers). Based on evidence from injection experiments using a variety of fluids, it is shown that increasing shear rate better explains reductions in cell viability than increasing shear stress. Knowledge that shear rate is a more relevant fluid mechanical parameter governing mechanical damage provides a rational basis for designing injection protocols (injectors and suspension fluid rheological properties) to maximize cell viability.</p>","PeriodicalId":54871,"journal":{"name":"Journal of Biomechanical Engineering-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147488517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Vertebral Body Kinematics Measured From T1-Weighted Magnetic Resonance Imaging With Optimized Rigid Registration.","authors":"John M Peloquin, Harrah R Newman, Dawn M Elliott","doi":"10.1115/1.4071578","DOIUrl":"10.1115/1.4071578","url":null,"abstract":"<p><p>Magnetic resonance imaging (MRI) is a useful method to noninvasively measure vertebral kinematics (rotations and translations). Measurement of vertebral kinematics should be both fast and accurate, a need potentially satisfied by automatic registration of reference-deformed image pairs. So far, MRI registration has not been systematically optimized for this application. The objective of this study therefore was to apply automatic 3D image registration methods to the measurement of vertebral kinematics from MRI: first, to systematically optimize all registration parameters to minimize registration error across a representative dataset; second, to reanalyze a separate, previously published, MRI dataset of diurnal, flexion, and extension vertebral body (VB) mechanics using the optimized registration to reduce the dataset's measurement error and clarify its interpretation. Validation against manual registrations indicated that midsagittal vertebral body marker position error in the sagittal plane was 0.10±0.08 mm, well below the pixel size of 0.5 mm, with corresponding negligible errors in change in wedge angle (Δ wedge angle), change in disc height (Δ disc height), and A-P translation. Reanalysis of diurnal mechanics data revealed that diurnal Δ wedge angle, with subjects scanned supine, is essentially zero despite significant A-P translation and disc height loss. Distinct kinematics at the L5-S1 disc level were also observed. Relative to manual marker-based methods, use of this image registration method in future work would allow sample size to be halved with no change in statistical power. This optimized registration method will increase the efficiency of future research and may allow detection of effects that would otherwise be overlooked.</p>","PeriodicalId":54871,"journal":{"name":"Journal of Biomechanical Engineering-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13313121/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147619267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jianing Wang, Niko Burger, Bo Wang, Linxia Gu, Pengfei Dong
{"title":"Effects of Overcorrection on Mitigating Uncontrolled Tipping During Incisor Retraction Using Clear Aligners: Finite Element Analysis and in vitro Experiment.","authors":"Jianing Wang, Niko Burger, Bo Wang, Linxia Gu, Pengfei Dong","doi":"10.1115/1.4071380","DOIUrl":"10.1115/1.4071380","url":null,"abstract":"<p><p>Uncontrolled tipping during incisor retraction with clear aligners continues to limit orthodontic treatment. Different countermeasures have been proposed to improve the predictability of aligners, such as power ridges and attachments, while their efficacy requires further investigation. This work investigated the biomechanics of the overcorrection in reducing the tipping angle and moment during incisor retraction with a clear aligner, through in vitro experiments and finite element analysis (FEA). Specifically, the influence of overcorrection angle (1 deg), retraction distance (0.15 mm), and the combination of both were assessed through in vitro experiments and the finite element simulation. Further computational simulations were conducted to inspect the mechanical performance of clear aligners with different overcorrection angles (from 0 deg to 1 deg and 2 deg) for a fixed retraction distance of 0.15 mm. As the overcorrection angle increased from 0 deg to 1 deg and 2 deg for the clear aligner with a retraction of 0.15 mm, the tipping angle of the incisor decreased from 0.29 deg to 0.25 deg and 0.21 deg, and the tipping moment at the tooth root decreased from 13.60 N·mm to 9.38 N·mm and 6.27 N·mm. However, the retraction force also decreased from 0.84 N to 0.73 N and 0.47 N, indicating a tradeoff between tipping control and retraction efficiency, likely due to increased counteractive moment and the decreased force exerted by the aligner on the tooth crown. In conclusion, this study presents both the benefits and limitations of overcorrection strategies in reducing the tipping angle and moment during incisor retraction using clear aligners, providing biomechanical insight for the optimal design of clear aligners for improving treatment outcomes.</p>","PeriodicalId":54871,"journal":{"name":"Journal of Biomechanical Engineering-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147445859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carlos Pagès Sanchis, Filippo Maceratesi, Míriam Febrer-Nafría
{"title":"Predicting the Effects of Walker Height and Weight Support on Assisted Gait Using Physics-Based Predictive Simulations.","authors":"Carlos Pagès Sanchis, Filippo Maceratesi, Míriam Febrer-Nafría","doi":"10.1115/1.4071579","DOIUrl":"10.1115/1.4071579","url":null,"abstract":"<p><p>Walker-assisted gait is widely used in clinical rehabilitation for individuals with muscle weakness and balance impairments. This study presents a first step toward developing a predictive simulation framework that integrates a 3D full-body musculoskeletal model driven by muscle torque generators within an optimal control problem. We calibrated the muscle torque generators model using experimental isometric and isokinetic data from a healthy participant, obtained from a biodex dynamometer equipment. To assess the predictive capability of the framework, we evaluated the effects of walker height and percentage of body weight support on walker-assisted gait patterns by running nine predictive simulations across varying walker configurations. Results showed that effects of walker height were well predicted (e.g., elbow flexion increased with walker height from a mean value of 81.59 deg to 93.86 deg), while effects of weight support were only partially predicted (e.g., upper body joints did not show a clear trend with changes in weight support). Results suggest that developing a detailed hand-walker interaction model would significantly improve the realism of the simulations. This study provides an important step toward optimizing walker-assisted gait through simulation-based design and personalization.</p>","PeriodicalId":54871,"journal":{"name":"Journal of Biomechanical Engineering-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147619197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Henry Tien, Yun Seong Song, Devin Burns, Mohsen Mohammadi Beirami, Khosro Ghorbani Zadeh, Riley Still
{"title":"Development of a Force Perturbation Handle for Physical Interaction Research in Humans.","authors":"Henry Tien, Yun Seong Song, Devin Burns, Mohsen Mohammadi Beirami, Khosro Ghorbani Zadeh, Riley Still","doi":"10.1115/1.4071214","DOIUrl":"10.1115/1.4071214","url":null,"abstract":"<p><p>The vision of advancing robots capable of direct physical engagement with humans begins with an understanding of how humans interact with each other. Even rudimentary interactive tasks, such as shaking hands, provide tremendous challenges for modern robotics, and current research into the biomechanics of such interactions is limited. Thus, further analysis of physical human-human interaction (HHI) will bolster efforts to enhance collaborative robot capabilities. To this end, a custom force perturbation handle (FPH) was developed, including the requisite mechanical, electrical, and software systems, to investigate the unique role of arm stiffness modulation in haptic communication between humans. The novel device records force and torque values generated by an interacting dyad and administers controlled force perturbations for estimating arm impedance metrics while maintaining a compact configuration that facilitates natural manipulation during pHHI tasks. To evaluate the capabilities of the FPH, a pilot experiment was conducted where subjects were instructed to exhibit specified levels of arm stiffness to which the calculated values from the FPH were compared. The results from four unbalanced two-way analysis of variance (ANOVA) analyses indicated a strong correspondence between the subjects' stiffness instruction and the estimated values from the FPH. The data were further validated through a qualitative analysis of arm displacement and actuation length. Considerations were addressed for deploying the FPH in future dynamic pHHI tasks to acquire valuable insight into motor communication strategies between humans and its applications for future interactive robotics.</p>","PeriodicalId":54871,"journal":{"name":"Journal of Biomechanical Engineering-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147291736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The 2026 Richard Skalak Award and Editors' Choice Papers.","authors":"Andrew Feola","doi":"10.1115/1.4072062","DOIUrl":"https://doi.org/10.1115/1.4072062","url":null,"abstract":"","PeriodicalId":54871,"journal":{"name":"Journal of Biomechanical Engineering-Transactions of the Asme","volume":" ","pages":"1-4"},"PeriodicalIF":1.7,"publicationDate":"2026-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148058401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}