Acta of bioengineering and biomechanics最新文献

Purpose: This study aims to investigate whether unilateral low-volume, high-intensity isometric strength activation (ISA) can enhance jump performance and bilateral isokinetic flexion and extension strength within 24 and 48 hours post-intervention. Methods: A total of 68 participants (40 males and 28 females) were included, all free from muscle, ligament or skeletal disorders that could affect physical performance, and none had undergone lower limb surgery due to injury in the past year. Participants were randomly assigned to either the experimental group or the control group using a balanced randomization scheme. Athletic performance was assessed using unloaded countermovement jump (CMJ), unloaded squat jump (SJ), and isokinetic knee flexion and extension strength tests. The experimental group received an isometric activation protocol, while the control group maintained their regular exercise routines. Results: The isometric activation protocol led to varying degrees of improvement across genders in the experimental group. Among male participants, there were significant increases in CMJ performance 24 hours post-activation, with flight time ((FT): +5%) and jump height ((JH): +9%) both showing statistical significance ( p < 0.05). SJ performance also improved significantly, with FT ( p < 0.01, ES = 1.101) and JH ( p < 0.01, ES = 1.335) demonstrating large effect sizes. Furthermore, SJ performance remained significantly elevated 48 hours post-intervention compared to baseline ( p < 0.05, JH: ES = 0.829). For female participants, SJ performance showed significant improvement 24 hours after activation ( p < 0.05, FT: ES = 1.847; JH: ES = 1.789), although no other significant changes were observed. Regarding knee flexion and extension strength, at an angular velocity of 60°/s, the male group exhibited significantly greater strength at 48 hours post-intervention compared to 24 hours ( p < 0.05, ES = 1.791). In the female group, bilateral knee strength significantly improved at both 24 and 48 hours post-intervention ( p < 0.05, ES = 0.152). Conclusions: ISA interventions can enhance knee joint strength in both male and female participants within 24 and 48 hours post-intervention, and also induce a cross-activation effect. Therefore, when coaches aim to improve athletes' performance in subsequent training sessions or competition days, ISA can be considered as an effective method to activate lower limb strength.

Purpose: This study examined the biomechanical effects of running-induced fatigue on the kinematic and kinetic changes of the lower limb during a countermovement jump (CMJ) via analyzing variations in joint biomechanics during landing. Methods: A running-induced fatigue protocol was employed to explore changes in joint angle, moments, stiffness and loading rate during the CMJ landing pre and post-fatigue. Paired-sample t-tests assessed changes in discrete parameters of joint stiffness, loading rates, and time-varying parameters were compared with one-dimensional statistical parametric mapping. Results: Fatigue significantly reduced the range of motion (ROM) during landing, with significant differences in angles, specifically the dorsi-plantar flexion of right ankle, flexion-extension of left hip, rotation of left knee, and adduction-abduction of right knee (P < 0.001). The first loading rate at touchdown decreased by 10%, and the time intervals between the first and second peak and the second and third peak reduced by 40 and 80%, respectively. Joint loading increased and the sagittal joint stiffness of left hip, right knee, and right ankle exhibited significant differences post-fatigue (P < 0.001). Knee joint reduced the flexion angle (P < 0.001) and the load of knee joint (P < 0.001) during post-fatigue, with the role compensated by hip and ankle joints to achieve balance in the lower limb kinetic chain. Conclusions: These findings provide pilot evidence that running fatigue may lead to changes in lower limb joint loadings and provide a scientific foundation for fatigue prediction and injury assessment.

Purpose: In this study, the authors attempted to determine whether and to what extent the vibrations generated while driving a baby stroller could pose a potential hazard to an infant. For this purpose, the measurement of whole body vibrations inside a baby stroller was carried out, using a dummy infant weighing 5 kg. Methods: The study was conducted using four baby strollers of similar overall weight and design. Based on the results, it was concluded that the vibrations occurring in the baby stroller exceed the comfort limit defined by ISO 2631 and could be potentially dangerous to children. Results: The comfort limit for the vertical axis is exceeded in the frequency range that corresponds to the resonant frequencies of the head (6-8 Hz), torso (6-17 Hz) or pelvis (6-17 Hz). For this type of study, the ISO 2631 standard can only be considered as a guideline in analyzing the results since the standard is intended for adults. There is no norm in the literature that defines the limit of vibrations acting on children. Conclusions: It seems necessary to develop a standard specifically for children. Based on the results obtained, the effect of speed and the way of driving a baby carriage on the magnitude of vibration received is evident.

Purpose: Fluid-structure interaction (FSI) techniques have become widely accepted numerical tools for analysing transient flows through compliant channels and tubes. However, FSI remains computationally demanding and requires assumptions about certain parameters that are often difficult to determine, particularly in biomedical applications. This study aimed to demonstrate the importance of key decisions required to conduct FSI simulations. Methods: Appropriate material properties were selected and parameters that define the magnitude of external reactions and cushioning effects (which are usually unknown but can be discovered through reverse engineering were set). Using a simplified model of an elastic straight tube, which represents a high-flow artery, reduced the influence of shape and associated mesh imperfections on the results. Results: Wall deformation, von Mises stress, wall shear stress and the pressure drop along the tube were analysed. Verification with various mesh densities for the compliant wall demonstrated that mesh fidelity significantly affects von Mises stress and computation time on a standard PC but has a negligible effect on wall deformation, wall shear stress and pressure drop. Conclusions: Varying wall stiffness and foundation stiffness affected the resulting compliance and all monitored parameters. Additionally, applying different mass and stiffness coefficients to define Rayleigh damping identified a safe range of applicability of this type of damping, however, experimental validation is necessary to determine appropriate values for specific applications and avoid overdamping. Finally, the results were discussed in the context of other FSI research and relevant in vivo and in vitro blood flow studies.

Purpose: The aim of this study was to investigate a novel data mining approach for early and effective diagnosis of Gestational Diabetes Mellitus (GDM). Methods: Gestational Diabetes Mellitus (GDM) data contains two classes (healthy and diabetic), 15 features and 3525 instances. In the first stage, the widely used and effective KNN and regression methods were employed for the filling of missing data. Then, the data source transformed into grayscale images as primary images and multiplexed images. Finally, both original data and transformed data are classified with KNN, SVM and CNN using k-fold cross validation technique. Performance metrics were compared to extract the best suitable system. Results: The original GDM source and the missing values replacement of GDM are classified with KNN and SVM methods. Also, primary images of this dataset and multiplexed images are classified with CNN 50%-50% and 70%-30% train-test respectively. The results of classification performance demonstrated that reaching up to 97.91% with CNN, recall of 97.61%, specificity of 97.61%, precision of 97.97% and F1-score of 97.79%. This result outperformed all previous studies conducted on the same dataset in the literature. Conclusions: This work is demonstrated a new approach that the best results of classification accuracy when compared with previous studies related to proposed methods to identify GDM disease. It can be clearly stated that applying a data mining method to impute missing values, followed by converting the dataset into images based on certain criteria and classifying with CNN, is the most effective approach for predicting GDM.

Purpose: The implantation angle of Bileaflet Mechanical Heart Valve (BMHV) is critical issue in valve replacement surgery. Investigating the local hemodynamic characteristics and analyzing the postoperative flow dynamics can provide valuable insights for determining the optimal implantation angle, thereby offering clinical guidance for improved surgical outcomes. Methods: Three-dimensional anatomical model of the Left Ventricle (LV) and BMHV was reconstructed based on patient-specific medical imaging data and anatomical parameters. The hemodynamic effects of varying implantation angles were investigated using Computational Fluid Dynamics (CFD) integrated with a Fluid-Structure Interaction (FSI) framework. Results: The key analyses focused on the downstream shear stress distribution, vortex dynamics, clinically relevant hemodynamic indicators. When the valve was implanted along the axis of the aortic outflow tract (referred to as the AO angle), several benefits were observed. Blood flow penetrability improved, high shear stress regions were reduced, mechanical trauma to blood cells was significantly lessened. Quantitative metrics further demonstrated that the AO angle minimized values of Time-Averaged Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI) and Relative Residence Time (RRT). These metrics indicate more stable hemodynamics and a lower risk of ventricular wall inflammation and thrombosis. Furthermore, the Hemolysis Index (HI) reached its lowest level under the AO angle, suggesting optimal mitigation of hemolysis. This study systematically examines how the orientation of BMHV implantation affects LV hemodynamics. It identifies the AO angle as the most effective strategy for positioning. Conclusions: These findings provide quantitative evidence that can inform preoperative planning and support the advancement of precision-guided cardiac valve interventions based on hemodynamics considerations.

Purpose: Image-guided biopsy is essential for safe and precise procedures. Our primary objective was to develop a software-hardware platform to automate planning and assist the procedure intraoperatively. The novelty lies in a unique combination of modern computational approaches - a voxel-based needle representation on a DICOM-based cost-map with target insertion safety represented in a continuous way by a largest empty sphere, optimized with Differential Evolution, with partial experimental validation. Methods: This study presents a prototype hardware-software platform for biopsy assistance, featuring an optimization tool for preplanning and the MentorEye system for real-time needle navigation using a simple support setup. Evaluation was conducted on a custom skull phantom with brain tissue and cancerous lesions. The system optimizes needle paths while considering surrounding structures and provides intraoperative guidance. Results: The planning tool successfully generated viable trajectories for all lesions, typically aligning with the shortest insertion paths. The mean Target Registration Error between CT and optical navigation was 2.08 ± 0.43 mm, similar to that obtained in typical computer-assisted procedures. In seven simulations, all biopsies were successful, with a mean deviation of 2.15 ± 0.84 mm and an nRMSE of 3.7%, comparable even to that reported for robotic-assisted systems. Conclusions: The experiment results confirmed the good efficiency of the developed tools for automatic planning and image-guided biopsy aiding.

Purpose: Joint angle analysis during gait is crucial for identifying pathological conditions and estimating joint loading, thereby supporting clinical decision-making for injury prevention. Although various methods are available for analyzing joint angles, webcam-based motion capture systems (MoCap) are gaining attention due to their affordability and user-friendliness. This study aimed to evaluate and compare the inter-rater and intra-trial reliability of a webcam-based MoCap with that of a conventional inertial measurement unit (IMU)-based system. Methods: Gait analysis was conducted on 15 participants (6 males, 9 females; mean age: 28.1 ± 5.26 years). While participants walked a 3-meter distance, hip and knee joint angles in the sagittal plane were simultaneously recorded using both inertial measurement unit (IMU) sensors and a webcam-based MoCap. Inter-rater and intra-trial reliability were assessed using intraclass correlation coefficients (ICCs), and agreement between the two systems was evaluated using Bland-Altman analysis. Results: For intra-trial reliability, most IMU-based systems demonstrated excellent reliability (ICC > 0.8). Although slightly lower, the webcam-based MoCap also achieved substantial to almost perfect reliability (ICC = 0.652 - 0.838). Inter-rater reliability between the IMU and webcam-based MoCap generally showed moderate to substantial agreement (ICC = 0.466 - 0.696). Conclusions: These findings suggest that the webcam-based MoCap may serve as a viable alternative in settings where IMU systems are unavailable or impractical. Future studies should aim to refine webcam-based tracking algorithms to improve event detection, assess reliability across diverse populations and movement tasks, and further validate such systems against gold-standard marker-based 3D optical MoCap.

Purpose: The aim of this study was to compare the biomechanical parameters of runners during overground and treadmill running, to assess the significance of these differences for treadmill training, and to evaluate their relevance for physiotherapy. Methods: Ten professional runners (mean age of 31.2 ± 6.8 years) were evaluated using a 10-camera Vicon motion capture system and a Phantom V12 high-speed camera. After completing a 200-meter overground run at a self-selected pace, each athlete entered the calibrated capture volume, where their running velocity and kinetic data were recorded. The individual mean velocities were then replicated on a treadmill positioned within the same capture space. Results: Treadmill running altered lower limb biomechanics compared to over-ground running. Median step length was 3% longer and markedly less variable on the treadmill than over-ground ( p < 0.001). The knee-flexion angle differed by surface and side ( p < 0.0001), changes were (1° for left, -2° right) but variability narrowed on the treadmill, while the knee-impact angle remained unchanged. Relative to over-ground running treadmill running reduced the horizontal distance between the center of gravity and foot initial contact; ground-contact time (12%) and heel velocity after toe-off by 19% ( p < 0.0001). Conclusions: Treadmill running alters lower limb biomechanics by reducing ground contact time, heel velocity, and variability in movement patterns. The consistent mechanics observed on the treadmill may support its use in physiotherapy, particularly for hamstring rehabilitation. However, due to limited replication of natural conditions, treadmill training should complement rather than replace overground running.

Purpose: Portal hypertension (PHT) leads to complications such as variceal bleeding, hepatic remodeling and thrombosis, driven by altered hemodynamics. This study aims to elucidate flow structure, shear stress and helicity changes under PHT, and their potential roles in promoting thrombosis and vascular remodeling. Methods: A patient-specific portal venous system model was reconstructed from CT images. Computational fluid dynamics (CFD) simulations were conducted to evaluate flow velocity, wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT) and helicity. Results: Compared to the healthy model, the PHT condition demonstrated reduced flow velocity, lower TAWSS and elevated RRT, particularly near bifurcations. Moreover, the strength and symmetry of helical flow were significantly impaired in PHT, especially at the main portal vein bifurcation - an area frequently associated with thrombosis. Conclusions: This study highlights the role of hemodynamic disruption, particularly helicity loss, in the pathogenesis of PHT-related complications. CFD-based helicity analysis offers novel insight into biomechanical risk assessment and may inform future interventional strategies.