Keywords

Biomechanics, Orthopaedics, Deep knee flexion, Patellofemoral joint, Mathematical model, Three-dimensional analysis, Kinetics

Paper information

- [Advance Publication] (Proper information for citation will be announced after formal publication)

Severe head injuries can occur in cyclists involved in traffic accidents. In Japan, head injuries accounted for 62% of cyclist fatalities in 2015 (ITARDA, 2016). The purpose of this study is to estimate head injuries for cyclists and quantify the effectiveness of a bicycle helmet by performing finite element (FE) simulations of head impacts against roads. Impacts with and without a helmet over a range of relative head velocities and head impact angles were simulated. A number of possible head injuries were assessed; skull fracture by skull strain, traumatic intracerebral hematoma (ICH) by brain pressure, brain contusion by brain negative-pressure and von Mises stress, and moderate and severe diffuse axonal injuries (DAIs) by von Mises stress. Results showed that without a helmet, the peak values of all metrics exceeded the 50% probability point for head injury in all impacts. The 50% probability points of moderate and severe DAIs were exceeded under impacts of 8.22 m/s at 26.5 degrees and 10.33 m/s at 15.0 degrees for moderate DAI, and 10.33 m/s at 15.0 degrees for severe DAI, without a helmet. All the peak values were reduced when a bicycle helmet was worn, and the largest reduction was found in the skull strain. These results predict that the risks of head injuries due to road impacts may be considerably decreased by helmet use.

Keywords

Bicycle helmet, Cyclist, Head injuries, Impact against road, Finite element simulation

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- [Advance Publication] (Proper information for citation will be announced after formal publication)

For cycling competitors, the pedaling exercise is typically accompanied by a binding pedal system. The purpose of this pedal system is to attach the body of the pedal and the sole of the cycling shoe together in order to allow the cyclist to rotate the crank efficiently. Although the importance of a pedaling skill that streamlines the muscle activity of the leg muscles recruited in the pedaling exercise has been widely recognized in the field of cycling, no instructional method based on scientific evidence has been established yet. Hence, this study first proposes an evaluation standard for the pedaling skill by using the muscle activity data of a skilled cyclist. Subsequently, the training system based on the proposed evaluation standard is developed. The system measures the surface electromyogram of the leg muscles and the angle of crank rotation during the pedaling exercise. In addition, the system employs principal component analysis to extract the features of the muscle activity pattern from a beginner and an intermediate cyclist. Furthermore, the online visualization of their pedaling skill, based on the results of the principal component analysis, is implemented to enable cyclists to objectively monitor their pedaling skill. The experimental results obtained from the developed training system and the relationship between the pedaling skill and the consistency of the muscle activity pattern are discussed. The experimental results revealed the significant aspects of the pedaling skills, in which the consistency of the muscle activity pattern and the motion of pulling the pedal up were relatively clear in the pedaling of the skilled cyclist.

Keywords

Principal component analysis, Electromyography, Pedaling exercise, Real-time assessment

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- [Advance Publication] (Proper information for citation will be announced after formal publication)

Various catheter simulators using a computer or blood vessel biomodels have been developed for training of medical students and young physicians. Moreover, we have developed a system to simulate a guidewire in blood vessels that uses both numerical analysis and experimental observation for the quantitative analysis of treatment technique, surgical planning, intra-operative assistance, and to facilitate the design of new guidewires. However, not limited to our group, there is a lack of studies evaluating the motions of both the guidewire and catheter and their interaction in a blood vessel. Therefore, in the present study, we modified our computer-based system and experimental apparatus to evaluate the catheter motion and compared both results. First, we added a mechanism to the experimental apparatus to move and evaluate the catheter in a poly (vinyl alcohol) hydrogel blood vessel model. Second, we added a new catheter model to the calculation. We subsequently evaluated the behaviors of the medical devices (the guidewire and the catheter) by measuring the three-dimensional position and the contact force between the medical devices and the vessel wall. Comparison of the calculation and experimental results showed that the trajectories and the contact forces of both the experimental and numerically analyzed medical devices had the same tendencies. By considering the flexibility of the catheter in both the experimental and numerical analysis methods, we could reproduce the phenomena seen in clinical situations, such as movement of the catheter during the insertion or removal of the guidewire, and movement of the guidewire during the insertion of the catheter.

Keywords

Endovascular treatment, Simulation, Guidewire, Catheter, Phantom, Numerical analysis

Paper information

- [Advance Publication] (Proper information for citation will be announced after formal publication)

Currently, there is no definite mathematical model to evaluate damage to blood cells, especially for cardiovascular devices with complex flow profiles due to turbulent flow and moving parts. This paper describes a finite volume technique that can more accurately predict damage of red blood cells and platelets by tracking their shear stress history and calculating their accumulated damage. Three standard power-law models for calculating the damage to the blood cells are compared to a novel modified model which takes into account a particle accumulated history and corrects for issues in previous models that miscount for decreasing shear stress. As an example, the damage to blood cells are determined for specific streamlines along a prosthetic polymer-based aortic valve, which is a cardiac device with low levels of damage, allowing for the sensitivity of these models to be tested. The results suggest that the new modified model provides the most accurate prediction of damage.

Keywords

Blood damage index, Hemolysis, Shear stress-exposure time, Prosthetic valve assessment

Paper information

- [Advance Publication] (Proper information for citation will be announced after formal publication)