Acta of bioengineering and biomechanics最新文献

Purpose: Plantar pressure distribution is a crucial indicator in gait analysis, with significant value in clinical diagnoses and sports optimization. Traditional measurement methods, however, are often limited by expensive equipment and laboratory settings. This study aimed to develop an accurate, portable and cost-effective method using a deep learning model based on data from wearable Inertial Measurement Units (IMU) to predict comprehensive plantar pressure distributions. Methods: We proposed a hybrid model combining a Convolutional Neural Network (CNN) and a Bidirectional Long Short-Term Memory (BiLSTM) network. The CNN extracts local features from IMU data; the BiLSTM captures temporal dependencies; a temporal attention mechanism optimizes the prediction of key time steps; and body weight information is integrated to accommodate individual differences. Results: Experimental results show that in 10-fold cross-validation, the model achieves a Mean Squared Error of 0.98 and a Structural Similarity Index of 0.89, demonstrating excellent prediction accuracy and distribution similarity. Conclusions: This study provides a cost-effective method for plantar pressure analysis, which is expected to be integrated into wearable devices for real -time gait monitoring, with applications in rehabilitation and sports optimization.

Purpose: The aim of this study was to determine how solid ankle-foot orthoses (AFO) influence the symmetrization of free standing posture in children with hemiplegic cerebral palsy (CP). Methods: In the analysis, we examined the body posture of children (n = 43, mean age of 7 years) who did not wear any orthopedic equipment on a daily basis (Group 1). We also studied those who used unilateral (Group 2) or bilateral AFOs (Group 3). The BTS SMART D-140 6 TVC optoelectronic system was implemented in the research. Results: There were no significant differences between the study groups in terms of obliqueness, rotation or pelvic inclination in standing position, or in hip joint angle on the (un)affected sides with and without AFOs. However, differences could be observed in obliqueness and rotation after applying AFOs (0.1 > p > 0.05). In all study groups, knee flexion angle on the affected side was greater. After putting on the orthoses (Groups 2 and 3), knee joint flexion decreased. Analysis of measurements without orthoses showed significantly less dorsiflexion and greater external rotation of the ankle joint on the affected side ( p < 0.05). After putting on the orthoses (Groups 2 and 3), the differences in dorsiflexion noted in the ankle joints of both feet did not exceed 1°. In such conditions, the rotation in these joints also became equal. Conclusions: The results of the study made it possible to indicate that the use of AFOs in children with hemiplegic CP demonstrates a beneficial effect on the joint to which they are directly applied. They also aid other joints of the lower limbs and pelvis. The use of bilateral AFOs provides greater positive changes in standing symmetry compared to unilateral AFO implementation.

Objective: The objective of this research was to show a potential use of computational fluid dynamics tools in supporting the medical personnel by offering objective data regarding the hemodynamic changes in the aneurysm caused by implanting different models of the stent. Methods: The authors reconstructed patient-specific model of the cerebral arteries with diagnosed aneurysm. Then, four virtual models of the Flow Diverter stent (with varied nominal diameters) were prepared. During the numerical analyses, the Immersed Solid Method was used to model the presence of the stent wirebraid. After performing steady state and transient simulations of non-Newtonian blood flow in pre- and post-treatment models, changes in numerous hemodynamic parameters were analysed. Results: The results confirmed that stent porosity influences hemodynamic changes inside the aneurysm (for presented case studies). The less porous the stent, the more it promotes the possible intrasaccular thrombosis. This could be concluded by observing larger regions of stagnant blood with higher viscosity. Additionally, the denser the stent, the lower and more uniform the stress exerted on the aneurysm wall. Conclusions: Numerical simulations can provide valuable insight into phenomena occurring inside the blood flow after implanting the stent. This can support selecting optimal stent configuration for the particular patient and, consequently, can help in planning the endovascular procedure.

Purpose: Regular training causes the human body to adapt to the load, and specific changes occur in the soft tissues affecting the body composition. In this study, we analyzed differences in body composition, segmental muscle mass and isometric strength in soccer players, basketball players, handball players and volleyball players. Methods: Height and weight were measured in 96 men aged 20.7 ± 1.88 years training in academic sports clubs in Wrocław (Poland): football (n = 24, age: 20.3 ± 1.08 years), basketball (n = 24, age: 20.9 ± 1.83 years), handball (n = 24, age: 21.2 ± 1.90 years) and volleyball (n = 24, age: 20.3 ± 1.06 years). Body composition was assessed using BIA and SBIA. Motor tests were conducted to assess grip strength and back strength. Results: It occurred that soccer players are characterized by significantly lower height. Handball players have higher body cell mass and better results in strength tests. Additionally, they have a less muscular torso and more strongly muscled legs. Basketball players, handball players and volleyball players are characterized by a more muscular right side of the torso. Football players are distinguished by greater muscularity of the right lower limb. Among volleyball players, greater muscularity of the right upper limb was noted. In football, handball and basketball players, significantly greater right hand strength was observed. Conclusions: It can be concluded that training load in team games shapes specific differences in body composition and isometric strength. Team game players also tend to develop directional asymmetries in the musculature of body segments and grip strength.

Purpose: The purpose of the current study was to compare the protective performance of helmet designs with different sizes and cushion materials for skull and brain injuries in children. Methods: A 6-year-old child head finite element (FE) model with high biofidelity was used to conduct impact simulations under the protection of helmets with different sizes (small, medium and large) and cushion materials (EPS-expanded polystyrene, PU-polyurethane and airbag) according to the testing conditions specified by the standard. Then, the protective performance of different helmet designs was evaluated by assessing skull and brain injury risk calculated based on the kinematic and biomechanical response of the child head model. Results: The skull fracture risk of children under the protection of airbag helmets is lower than that of EPS and PU helmets by more than 50%. Large-sized helmets, with thicker padding, show better protective capability for skull injury compared to small-sized helmets. The risk of brain injury under airbag helmet protection is significantly lower than EPS and PU helmet under 4.8 m/s sharp anvil impact test condition, and small sized helmet could generally reduce brain injury risk under the 6.2 m/s flat anvil impact test condition. However, no obvious effect has been found of helmet size and material to brain injury risk in the impact scenarios at 6.2 m/s. Conclusions: The size and cushion material of the helmet have a significant influence on its skull injury protection performance, but their effect pattern on brain injury protection capability is not obvious. The use of airbag helmets with larger buffering stroke can effectively reduce both the risk of skull and brain injuries under relatively low impact loads.

Purpose: Exoskeleton robots are becoming increasingly popular due to improved robotic technologies and the positive perception of users. Lower limb exoskeletons are the most widely used as assistive devices for people with disabilities. The aim of the study was to determine the magnitude of forces necessary to induce the fall of a person using the Polish prototype of the exoskeleton robot. Methods: Sixteen volunteers used DreamMotion prototype designed to perform medical tasks was tested. Measurements of the fall-inducing forces were performed in compliance with safety standards. Assessed were fall-inducing forces acting in various directions in 3 static, vertical body positions. In each test position, 10 trials were completed resulting in the effective measurement. Results: In the 2-leg standing with posterior vector direction, the lowest value of fall-inducing force was recorded (mean 1.50 kG). Also, in 1-leg standing position, the lowest value of the fall-inducing force was recorded with posterior vector direction (1.66 kG). In the step position, the highest fall-inducing forces were recorded with the posterior (8.58 kG) and anterior (6.37 kG) vector directions, the lowest - with the lateral vector direction towards the stepping limb (3.26 kG). Conclusions: The forces required to induce a fall in a person wearing the exoskeleton robot are relatively low, with relative forces ranging from 1.45% to 8.30% of the subject-ER setup weight. In both the 2-leg and 1-leg standing positions, the lowest fall-inducing forces were recorded when the force vector was directed posteriorly. The exoskeleton robot's design will likely need to be modified to enhance safety in this particular direction.

Purpose: The design of three-dimensional scaffolds for bone regeneration poses challenges in balancing mechanical strength, porosity and degradability. This study aimed to optimize the geometric parameters of polylactic acid (PLA) scaffolds fabricated via 3D printing, focusing on pore size, porosity, and geometric configurations to enhance mechanical performance and biological functionality. Methods: Two geometric configurations - orthogonal and offset orthogonal - were evaluated with pore sizes ranging from 400-1000 µm and porosities between 55-70%. Finite element analysis (FEA) in ANSYS Workbench was used to simulate mechanical behavior, while the Taguchi experimental design determined the optimal parameter combinations. Statistical analyses, including ANOVA, assessed the significance of each factor. Results: The study identified a pore size of 400 µm as optimal for structural strength, while a porosity of 70% provided a balance between stability and cell growth. Orthogonal geometries distributed stress more uniformly, reducing critical stress concentrations compared to offset configurations. ANOVA revealed that pore size was the most significant factor, followed by porosity and geometry, achieving a model reliability of R ² = 98.42%. Conclusions: The findings highlight the importance of geometric optimization for improving scaffold mechanical properties while maintaining biological functionality. This study offers a robust framework for designing patient-specific scaffolds tailored to bone tissue engineering applications.

Purpose: This study aimed to investigate the immediate effects of cognitive tasks on static and dynamic balance in gymnasts, handball players and video gamers under the age of 12 years, using dual-task paradigm. Methods: A sample of 50 children under the age of 12 years was divided into three groups (i.e., gymnasts, handball players and video gamers). They participated in a dual-task experiment involving mental rotation tasks with static and dynamic balance assessments. Participants performed mental rotation tasks (i.e., object- based 3D cube and human body conditions) while simultaneously maintaining static and/or dynamic balance on a stabilometric platform. Center of pressure sway, acceleration and displacement were measured. Performance in both cognitive and balance tasks was recorded and analyzed. Results: The results revealed significant immediate beneficial effects of cognitive tasks on dynamic balance. Specifically, dual tasks led to improved performance in mental rotation tasks and enhanced postural control, as evidenced by a reduced center of pressure sway ( p < 0.01). Athletes demonstrated greater improvements than non-athletes, highlighting the effectiveness of cognitive engagement in improving postural control. Conclusion: These results suggest that participation in sports during childhood can significantly enhance neuromuscular control and balance, which are critical for maintaining stability. The findings highlight the importance of integrating cognitive challenges into physical training. This approach enhances both cognitive and motor performance in young athletes.

Purpose: The objective of this study is to ascertain how specific somatic traits and kinematic indices influence the force of a punch, contingent on the type of kick (i.e., turning kick and side kick). Methods: One hundred kicks were performed by five female elite ITF taekwon-do (International Taekwon-do Federation) athletes (aged 27.0 ± 4.8 years, body mass 64.2 ± 5.8 kg, height 163.0 ± 6.5 cm). To record the force of the impact, a strain gauge platform padded with a training disc was used as a target to protect the participants from direct impact on a force plate mounted on a stable structure. Results: The study demonstrated that the side kicks of female taek- won-do athletes achieved, on average, a higher peak pressure force (1770 N) than the turning kick (1379 N) ( p < 0.01). Conversely, the lower limb segments demonstrate an inverse trend in terms of average peak acceleration values. The effective mass values recorded in this study expressed as a percentage of the athletes' total body mass, were approximately 18% for the turning kick and 85% for the side kick. Conclusions: The findings of these studies demonstrate that pressure force evidently increases with rising effective mass. However, no correlation was observed between the acceleration of the foot and the other segments of the lower limb. The calculated β* factor indicates that there are no lateralisation differences in pressure force between kicks performed with the right and left leg.

Purpose: The fluid shear stress (FSS) generated by fluid flow after scaffold implantation is an important factor affecting the osteogenic ability of scaffolds and the proliferation and differentiation of osteoblasts are also affected by FSS. When the bone injury occurs, the blood flow at the defect changes from laminar flow to turbulent flow. Consequently, it is essential to employ a numerical simulation method that accurately reflects the actual conditions to study and analyze the surface FSS experienced by scaffolds and cells, thereby enhancing the osteogenic properties of the scaffolds. Methods: In this research, nine scaffolds with different structures and pore sizes were designed. The two-way fluid-structure interaction (FSI) method was used to evaluate scaffolds' internal flow field velocity and the surface FSS of scaffolds and cells. Results: The results show that the velocity distribution of different scaffolds is basically the same. FSS on the scaffold surface and FSS on cell surface decreased with the increase of scaffold pore size. FSS accepted by cells was much larger than that received by scaffolds, and FSS was distributed in a stepped pattern on the cell surface. Conclusions: Based on the FSS of the scaffold and cell surface, the triangle-600 and triangle-800 scaffolds have better osteogenic differentiation ability. This provides a more practical strategy for tissue engineering to design better scaffolds.