Biomechanical Model Research Articles

A biomechanical model for cell sensing and migration

We developed an original computational model for cell deformation and migration capable of accounting for the cell sensitivity to the environment and its appropriate adaptation. This cell model is ultimately intended to be used to address tissue morphogenesis. Hence it has been designed to comply with four requirements: (1) the cell should be able to probe and sense its environment and respond accordingly; (2) the model should be easy to parametrize to adapt to different cell types; (3) the model should be able to extend to 3D cases; (4) simulations should be fast enough to integrate many interacting cells. The simulations carried out focused on two aspects: first, the general behaviour of the cell on a homogeneous substrate, as observed experimentally, for model validation. This enabled us to decipher the mechanisms by which the cell can migrate, highlighting respective influences of the adhesions lifetimes and their sensitivity to traction; second, it predicts the sensitivity of the cell to an anisotropic patterned substrate, in agreement with recently published experiments. The results show that mechanosensors simulated by the model make it possible to reproduce such experiments in terms of migration bias generated by the substrate anisotropy. Here again, the model provides a biomechanical explanation of this phenomenon, depending on cell-matrix interactions and adhesion maturation rate.

Finite element simulation of knee joint pressure and surface displacement: relationship and influencing factors

Knee sleeves are widely used functional pressure garments that exert pressure on the knee, causing body surface displacement and deformation. Understanding the relationship between knee joint pressure distribution and body surface displacement, along with the factors affecting this displacement, is crucial for optimizing knee sleeves. This study established a biomechanical model of the human knee joint using three-dimensional reconstruction and finite element analysis. The study simulated the pressure distribution and body surface displacement after wearing five different knee sleeve designs. Using SPSS software, it analyzed clothing and human factors to determine the main influences on displacement, resulting in linear regression equations linking knee physiological characteristics and skin displacement. Findings indicated that skin curvature radius and the distance between skin and bone significantly affect displacement, while knee sleeve structure design shows less correlation. The study also divided the knee joint into eight sections to calculate volume shrinkage after compression, providing insights for designing knee sleeves that enhance comfort and functionality based on human physiology.

Progress of fracture mapping technology based on CT three-dimensional reconstruction

Fracture Mapping is a new technology developed in recent years. This technology visually representing the morphology of fractures by overlaying fracture lines from multiple fracture models onto a standard model through three-dimensional reconstruction. Fracture mapping has been widely used in acetabular fracture, proximal humerus fractures, Pilon fracture, tibial plateau fractures, and so on. This technology provides a new research method for the diagnosis, classification, treatment selection, internal fixation design, and statistical analysis of common fracture sites. In addition, the fracture map can also provide a theoretical basis for the establishment of a biomechanical standardized fracture model. Herein, we reviewed various methods and the most advanced techniques for fracture mapping, and to discuss the issues existing in fracture mapping techniques, which will help in designing future studies that are closer to the ideal. Moreover, we outlined the fracture morphology features of fractures in various parts of the body, and discuss the implications of these fracture mapping studies for fracture treatment, thereby providing reference for research and clinical decision-making on bone and joint injuries to improve patient prognosis.

Statistical evaluation of mechanical load on technicians during electric vehicle battery replacement using Python simulation

Electric vehicle (EV) battery replacement poses significant mechanical strain on technicians, increasing the risk of musculoskeletal disorders (MSDs). This study uses Python-based simulations and biomechanical modeling to evaluate the mechanical load distribution during the battery replacement process, focusing on joint stress and technician posture. The analysis covers different task phases, including battery removal, transport, and installation, with statistical methods used to assess forces and torques applied to critical joints. The results indicate that the removal and installation phases exert the highest mechanical loads on the lower back and shoulders. The study suggests ergonomic interventions such as workstation redesign, lifting tools, and improved posture techniques to reduce the risk of injury and enhance the safety and efficiency of EV maintenance tasks.

Step Length and Gait Speed Estimation Using a Hearing Aid Integrated Accelerometer: A Comparison of Different Algorithms.

Gait is an indicator of a person's health status and abnormal gait patterns are associated with a higher risk of falls, dementia, and mental health disorders. Wearable sensors facilitate long-term assessment of walking in the user's home environment. Earables, wearable sensors that are worn at the ear, are gaining popularity for digital health assessments because they are unobtrusive and can easily be integrated into the user's daily routine, for example, in hearing aids. A comprehensive gait analysis pipeline for an ear-worn accelerometer that includes spatial-temporal parameters is currently not existing. Therefore, we propose and compare three algorithmic approaches to estimate step length and gait speed based on ear-worn accelerometer data: a biomechanical model, feature-based machine learning (ML) models, and a convolutional neural network. We evaluated their performance on a step and walking bout level and compared it with an optical motion capture system. The feature-based ML model achieved the best performance with a precision of 4.8cm on a walking bout level. For gait speed, the machine learning approach achieved an absolute percentage error of 5.4 % ( ± 4.0 %). We find that the ML model is able to estimate step length and gait speed with clinically relevant precision. Furthermore, the model is insensitive to different age groups and sampling rates but sensitive to walking speed. To our knowledge, this work is the first contribution to estimating step length and gait speed using ear-worn accelerometers. Moreover, it lays the foundation for a comprehensive gait analysis framework for ear-worn sensors enabling continuous and long-term monitoring at home.

Functional and Character Disparity Are Decoupled in Turtle Mandibles.

Turtles have high shape variation of their mandibles, likely reflecting adaptations to a broad variety of food items and ingestion strategies. Here, we compare functional disparity measured by biomechanical proxies and character disparity measured by discrete morphological characters. Functional and character disparities vary between clades and ecological groups and are thus decoupled. Comparisons with cranial disparity also indicate decoupled patterns within the turtle skull. Exploration of mandibular patterns reveals that several biomechanical configurations or character state combinations can lead to the same feeding type (i.e., convergence) or that high functional disparity can be achieved at a low exhaustion of character state combinations (e.g., cryptodires). Dietary specialists show larger functional disparity than generalists, but the phylogenetically widespread generalist ecology leads to high character disparity signals in the ecotype. Whereas character disparity generally shows high phylogenetic signal, functional disparity patterns correspond to dietary specializations, which may occur convergently across different groups. Despite this, individual functional measurements have overlapping ranges across ecogroups and do not always conform to biomechanical expectations. Jaw opening and closing biomechanical advantages model trade-offs between force transmission and opening/closing speeds, and turtles show a variety of combinations of values that we try to synthesize into several "jaw types". Closing mechanical advantage shows that turtles retain high levels of force transmission at the anterior jaw end compared with other groups (e.g., pseudosuchians). This can possibly be explained as an evolutionary adaptation to retain high bite forces at small head sizes.

Velocity prediction program for windsurfing: A hierarchical approach integrating biomechanical insights

Windsurfing sails have three degrees of controllable angular freedoms and rely heavily on the sailor’s gravity to balance the heeling moments. The position of the sailor’s centre of gravity that affect the moment generation is greatly influenced by the posture. These factors result in the complexity of predicting windsurfing velocity during steady sailing, which is shown to be an under-defined problem. To address the challenges, this study proposes a hierarchical approach. At the lower levels of the hierarchy, a mechanical model of windsurfing is constructed by incorporating a tailor-made biomechanical model of the sailor, as well as the aero- and hydrodynamic properties of the sail, board, and sailor. The mechanical model allows the investigation of control variables that lead to different steady states, including sail roll, yaw and hydrofoil roll. At a higher level, these variables are optimized to maximize sailing speed. The proposed approach provides intermediate results that explore factors affecting sailing velocity, such as sail and board orientation angles, the sailor’s center of gravity, and wind conditions. Furthermore, the approach generates a velocity polar chart that illustrates the maximum sailing speed for different travel directions. The chart indicates the maximum VMG and optimal sailing angle for achieving an upwind or downwind mark. This study contributes to a deeper understanding of the critical variables influencing windsurfing velocity and provide insights for improving sailing performance.

Global and local identifiability analysis of a nonlinear biphasic constitutive model in confined compression.

Application of biomechanical models relies on model parameters estimated from experimental data. Parameter non-identifiability, when the same model output can be produced by many sets of parameter values, introduces severe errors yet has received relatively little attention in biomechanics and is subtle enough to remain unnoticed in the absence of deliberate verification. The present work develops a global identifiability analysis method in which cluster analysis and singular value decomposition are applied to vectors of parameter-output variable correlation coefficients. This method provides a visual representation of which specific experimental design elements are beneficial or harmful in terms of parameter identifiability, supporting the correction of deficiencies in the test protocol prior to testing physical specimens. The method was applied to a representative nonlinear biphasic model for cartilaginous tissue, demonstrating that confined compression data does not provide identifiability for the biphasic model parameters. This result was confirmed by two independent analyses: local analysis of the Hessian of a sum-of-squares error cost function and observation of the behaviour of two optimization algorithms. Therefore, confined compression data are insufficient for the calibration of general-purpose biphasic models. Identifiability analysis by these or other methods is strongly recommended when planning future experiments.

A set of anatomical databases for developing biomechanical models of the lower human limb

A set of anatomical databases for developing biomechanical models of the lower human limb

Modeling and control of dynamical biomechanical arm systems with elastic joints sensitive to the effect of an external load

In this study, a biomechanical model mimicking the human hand-arm system under heavy disk excitation is developed to define the stability threshold between the preload vibration and the stress of the human hand-arm system. The fully electromechanical system, consisting of a DC motor, a transmission system, and three discrete masses representing the upper arm, forearm, and hand lifting a heavy disk, is connected by shock absorbers and various springs. The challenge of mimicking the angular activity of the elbow joint in torsion and flexion was also included to assess its contribution to system stability and to study the absorption of mechanical energy in the human hand-arm system. Finally, the movements of the model were described by a differential matrix equation, and its analysis facilitates the understanding of the threshold of the chaotic behaviors observed in an oscillating arms system. Specifically, it explores how the motion of a DC motor can be regulated using a single controller parameter within the context of a multi-degree-of-freedom human hand-arm system. The study uses numerical integrations to analyze system behaviors, with an emphasis on the use of frequency spectra, Poincaré maps, and bifurcation diagrams for visualization and interpretation. The results indicate that the system exhibits chaotic behavior when subjected to certain conditions, particularly when the mass load exceeds 35 kg. Imposing motion on the mass block further intensifies the chaos, leading to manifestations such as strong oscillations and frequency-synchronization effects. These characteristics, exhibited by the idealized model, which imitates the human body through a mechanical model and computation of the motions of the body, play a vital role in various fields of ergonomics and sports biomechanics. Understanding the dynamic behaviors of such systems, especially in response to varying conditions, has significant implications for engineering applications.

Towards realistic blood cell biomechanics in microvascular thrombosis simulations

Abstract The paper is devoted to a three-dimensional mesoscale hemodynamic model for simulations of microvascular blood flows at cellular resolution. The focus is on creating a more accurate biomechanical model of red blood cells for further use in models of hemostasis and thrombosis. The presented model effectively and accurately reproduces peculiarities of blood flow under realistic hydrodynamic conditions in arterioles, venules, and capillaries, including the Fahraeus–Lindquist effect and subsequent platelet margination. In addition, shear-dependent platelet aggregation can also be captured using the proposed approach.

A Computational Model Reveals How Varying Muscle Activation in the Lateral Pharyngeal Wall and Soft Palate Differentiates Velopharyngeal Closure Patterns.

Finite element (FE) models have emerged as a powerful method to study biomechanical complexities of velopharyngeal (VP) function. However, existing models have overlooked the active contributions of the lateral pharyngeal wall (LPW) in VP closure. This study aimed to develop and validate a more comprehensive FE model of VP closure to include the superior pharyngeal constrictor (SPC) muscle within the LPW as an active component of VP closure. The geometry of the velum and the lateral and posterior pharyngeal walls with biomechanical activation governed by the levator veli palatini (LVP) and SPC muscles were incorporated into an FE model of VP closure. Differing muscle activations were employed to identify the impact of anatomic contributions from the SPC muscle, LVP muscle, and/or velum for achieving VP closure. The model was validated against normative magnetic resonance imaging data at rest and during speech production. A highly accurate and validated biomechanical model of VP function was developed. Differing combinations and activation of muscles within the LPW and velum provided insight into the relationship between muscle activation and closure patterns, with objective quantification of anatomic change necessary to achieve VP closure. This model is the first to include the anatomic properties and active contributions of the LPW and SPC muscle for achieving VP closure. Now validated, this method can be utilized to build robust, comprehensive models to understand VP dysfunction. This represents an important advancement in patient-specific modeling of VP function and provides a foundation to support development of computational tools to meet clinical demand.

Reduction of material groups for vertebral bone finite element simulation: cross comparison of grouping methods

In patient-specific biomechanical modeling, the process of image-to-mesh-material mapping is important, and various strategies have been explored for assigning the number of groups of unique material properties to the mesh. This study aims to cross-compare different grouping strategies to identify the minimum number of unique groups necessary for accurately calculating the fracture load of vertebral bones. We analyzed 12 vertebral specimens by experimentally determining the biomechanical fracture load and acquiring corresponding CT scans. After geometry extraction and meshing, we applied commonly used fixed-value strategies for reducing the number of unique groups, such as Modulus Gaping and Percentual Thresholding. Additionally, we introduced a patient-specific adaptive grouping method based on K-means clustering, which allowed us to maintain a consistent number of groups of unique material properties across the study. A total of 204 simulations were performed, achieving a potential 98% reduction in the number of individual material parameters while maintaining a strong correlation with experimental results when utilizing Percentual Thresholding or Adaptive Clustering, compared to Modulus Gaping. The findings demonstrate the feasibility of significantly reducing simulation complexity while maintaining the accuracy of patient-specific models that strongly correlate with experimental results. This reduction enables efficient processing of patient-specific biomechanical models derived from image data, offering potential benefits for clinicians, particularly in resource-constrained settings.

Biomechanical Analysis and Modeling of Different Traction Patterns in Adolescent Idiopathic Scoliosis

Objective: Traction is a valuable treatment for Adolescent idiopathic scoliosis; however, assessing its biomechanical effects, particularly with new methods, presents challenges. This study aims to explore the biomechanics using finite element analysis, with the goal of enhancing safety and effectiveness. Methods: Based on CT images, two different boundary and loads were applied to simulate two traction methods. The effects of these two traction methods on stress and deformation of lumbar vertebral bodies and intervertebral discs were compared. Results: Under two traction methods, the stress was concentrated on the posterior side. Multi-point traction resulted in higher stress and deformation, and concentrated stress on the convex side as well. However, there is some stress concentration on the vertebral arch, which may lead to injury. Conclusion: Compared to longitudinal traction, multi-point traction can better reduce stress on the vertebral bodies and intervertebral discs, focusing the pulling force on the concave side and achieving greater deformation. Multi-point traction might better suit specific patients needing more correction and pressure relief compared to longitudinal traction.

The paradox of CAC score and plaque vulnerability

Abstract Introduction The effect of coronary artery calcification on plaque vulnerability remains unclear. The coronary artery calcium (CAC) score, quantified using coronary computed tomography, has a strong correlation with total atherosclerotic burden and risk of adverse cardiac events. Nevertheless, different patterns in the distribution of coronary artery calcium have been reported to convey different effects on plaque stability. Some biomechanical models suggest that microcalcifications can intensify stress in the fibrous cap, promoting plaque rupture. On the other hand, large calcium deposits are hypothesized to promote plaque stability, as statin therapy has been shown to promote the calcification of atherosclerotic lesions. The purpose of this study is to investigate the relationship between CAC score and vulnerable plaque using coronary computed tomographic angiography (CCTA) in patients with an acute coronary syndrome (ACS). Methods CCTA was performed in 444 patients; these patients were divided into two groups (those with vulnerable plaque and those without). CAC score of each patient was obtained. We calculated median value of CAC score of both groups and compared them using Two Sample Mann-Whitney U Test. All tests were 2-sided, p values below a threshold of 0.05 were considered to be significant. All statistical analyses were performed using IBM SPSS Statistics 29.0 (SPSS Inc, Chicago, IL). Results Out of 444 patients with an ACS and evaluated with CCTA, vulnerable plaques were found in 57 patients (13%). The median value of CAC score in patients with vulnerable plaques was significantly higher compared with patients without vulnerable plaques (mean CAC score 1065,07 AU (95% Confidence Intervals 526,26-2656,40 AU) vs 444,03 AU (95% CI 120,18-766,88 AU, p < 0.001). Using Mann–Whitney U test, we found a statistically significant difference between CAC score of patients with vulnerable plaques and those that did not have such plaques. Conclusion Although CAC score is a reliable marker of atherosclerosis it is still uncertain whether CAC score is an indicator of plaque vulnerability. In our study, CAC score was higher in patients with vulnerable plaque compared to those without such plaques. A highly statistically significant difference was found between the median value of CAC score between these two groups of patients.Boxplot

Late acquisition of erect hindlimb posture and function in the forerunners of therian mammals.

The evolutionary transition from early synapsids to therian mammals involved profound reorganization in locomotor anatomy and function, centered around a shift from "sprawled" to "erect" limb postures. When and how this functional shift was accomplished has remained difficult to decipher from the fossil record alone. Through biomechanical modeling of hindlimb force-generating performance in eight exemplar fossil synapsids, we demonstrate that the erect locomotor regime typifying modern therians did not evolve until just before crown Theria. Modeling also identifies a transient phase of increased performance in therapsids and early cynodonts, before crown mammals. Further, quantifying the global actions of major hip muscle groups indicates a protracted juxtaposition of functional redeployment and conservatism, highlighting the intricate interplay between anatomical reorganization and function across postural transitions. We infer a complex history of synapsid locomotor evolution and suggest that major evolutionary transitions between contrasting locomotor behaviors may follow highly nonlinear trajectories.

An Exploratory Study of a Choreographic Approach to Golf Swing Dynamics: Bridging Biomechanics and Laban Movement Analysis.

This study introduces an innovative integration of Laban Movement Analysis (LMA) with biomechanical principles to examine the golf swing dynamics from an ecological perspective. Traditionally, LMA focuses on the qualitative aspects of movement, often isolated from external influences. This research bridges that gap by investigating how golfers manage and adapt to the inertial forces of the club throughout the swing. Using motion tracking sensors and screw theory, we analyzed the spatial movement pattern in the Kinesphere (mapped as an icosahedron) and related it to force dynamics in the Effort Cube through the inertia tensor. The results showed significant differences between skilled and novice golfers in terms of how efficiently they align their movements with the club's inertia. Skilled golfers demonstrated smoother Instantaneous Screw Axes (ISAs) and better synchronization with inertia forces, while novice golfers exhibited more abrupt deviations. These findings suggest that integrating qualitative movement descriptors with biomechanical models provides deeper insights into swing efficiency, performance improvement, and injury prevention. This combined framework offers a novel method to enhance both qualitative and quantitative analysis of golf swings.

Experimental verification of multifunctional biomechanical models effectiveness regarding main elements of technical actions, applied by track and field athletes specialized in sports walking, in the process of their technical training

Current training system for track and field athletes specialized in sports walking requires application of the latest technologies for modelling athletes’ technical actions. The approach suggested by the authors presupposes the use of multifunctional biomechanical models of the main elements of the technical actions by track and field athletes, who specialize in sports walking, as far as it has a beneficial effect on athletes’ chances to achieve high sports results. The authors suggest improving the process of technical training of track and field athletes based on the use of multifunctional biomechanical models of the main elements of the athletes' technical actions. The study contributes to the improvement of the process of technical training of track and field athletes who specialize in sports walking. The developed approach regarding use of multifunctional biomechanical models of the main technique elements within athletic walking in the process of track and field athletes’ technical training has proven its effectiveness in terms of a favourable effect on the level of technical preparation and sports results. In the main group, at the end of the experiment, there was an improvement of sports results from 1:27:18 (S = 0:01:41) to 1:23:44 (S = 0:02:07), which comprised 4.3% with statistically significant differences being p<0.05, while relatively to statistics (p<0.05) almost all informative biomechanical indicators of the technique have also improved. At the end of the experiment, the athletes of the control group also improved their sports results from 1:27:45 (S = 0:02:02) to 1:27:32 (S = 0:03:48), which represented 0.3% of statistically significant difference (p > 0.05). Almost all informative biomechanical indicators of the technique have also improved, however, statistically significant differences were not found (p > 0.05).

Modeling the Dynamics of Prosthetic Fingers for the Development of Predictive Control Algorithms

In the field of biomechanical modeling, the development of a prosthetic hand with dexterity comparable to the human hand is a multidisciplinary challenge involving complex mechatronic systems, intuitive control schemes, and effective body interfaces. Most current commercial prostheses offer limited functionality, typically only one or two degrees of freedom (DoF), resulting in reduced user adoption due to discomfort and lack of functionality. This research aims to design a computationally efficient low-level control algorithm for prosthetic hand fingers to be able to (a) accurately manage finger positions, (b) anticipate future information, and (c) minimize power consumption. The methodology employed is known as model-based predictive control (MBPC) and starts with the application of linear identification techniques to model the system dynamics. Then, the identified model is used to implement a generalized predictive control (GPC) algorithm, which optimizes the control effort and system performance. A test bench is used for experimental validation, and the results demonstrate that the proposed control scheme significantly improves the prosthesis’ dexterity and energy efficiency, enhancing its potential for daily use by people with hand loss.

Influence of Screw Angulation on the Mechanical Properties on a Polyaxial Locking Plate Fixation.

Polyaxial locking systems are widely used for strategic surgical placement, particularly in cases of osteoporotic bones, comminuted fractures, or when avoiding pre-existing prosthetics. However, studies suggest that polyaxiality negatively impacts system stiffness. We hypothesize that a new plate design, combining a narrow plate with asymmetric holes and polyaxial capabilities, could outperform narrow plates with symmetric holes. Three configurations were tested: Group 1 with six orthogonal screws, and Groups 2 and 3 with polyaxiality in the longitudinal and transverse axes, respectively. A biomechanical model assessed the bone/plate/screw interface under cyclic compression (5000 cycles) and torsion loads until failure. Screws were inserted up to 10° angle. None of the groups showed a significant loss of stiffness during compression (p > 0.05). Group 1 exhibited the highest initial stiffness, followed by Group 3 (<29%) and Group 2 (<35%). In torsional testing, Group 1 achieved the most load cycles (29.096 ± 1.342), while Groups 2 and 3 showed significantly fewer cycles to failure (6.657 ± 3.551 and 4.085 ± 1.934). These results confirm that polyaxiality, while beneficial for surgical placement, reduces biomechanical performance under torsion. Despite this, no group experienced complete decoupling of the screw-plate interface, indicating the robustness of the locking mechanism even under high stress.