The objective of this study was to design an orthosis during the exercise of walking in water for the rehabilitation of ACL injury. In the rehabilitation of ACL injury, it is necessary to train the muscles around the knee joint. In particular, compared to the knee flexors, the knee extensors are less exerted in the normal walking form while walking in water. Therefore, the orthosis, by which the knee extensors can be trained, was optimally designed by the simulator which can compute the body load considering the fluid force and force acting on the ACL. The characteristics of the orthosis obtained by the simulation are the large width of the thigh and foot parts and the small density of the shank and foot parts. Second, the orthosis was manufactured based on the simulation design. Finally, the effectiveness of the manufactured orthosis was confirmed by comparing the muscle force analyzed in the simulation with the electromyogram measured in the subjective experiment.
Hand cranking is an alternative method to handrim propulsion for imparting power to a wheelchair. As such it is important that the method does not overload the shoulder or elbow as these joints are at risk of overuse injury in the wheelchair user population. The majority of hand-cycling wheelchair is done under what could be termed ‘autonomous control’. During autonomous control the wheelchair user is travelling at a desired speed and automatically adjusts his or her propulsion/cranking style to the terrain being traversed. Therefore, it is important to understand the loading on the upper limbs during this type of cranking. The experimental system was tested using 3 healthy subjects and the joint powers and torques were measured during the autonomous cranking phase, along with heart rate. From the results it is clear people regulate their hand-cranking in response to increases in heart rate. The maximum cranking power was found to occur at 1.1 rad/s, which produced 3.8W. When the arm was at full stretch from the body (at 180°) the shoulder was working at its hardest. This is because the hand position on the tip of crank is furthest from the shoulder. The elbow was found to be very weak when it travels past 100° flexion angle, this means the elbow joint is having to work hard when cranking between 270° to 70°. It is suggested that adapting the cranking position and cranking length could reduce the maximum power requirements on shoulder and elbow. It is also thought that correct gear ratio settings for individual performances could also reduce overuse injury on shoulder and elbow.
Analyses of the bone mass alone of osteoporotic vertebrae are not sufficient to predict fracture risks and assess the recovery of bone strength during drug treatment. Instead, finite element analyses (FEAs) is superior, because changes in the vertebral strength are strongly dependent on the inner vertebral stress distribution, which is related to the individual bone shape and bone density distribution in cancellous and cortical region. To investigate how FEAs can detect drug effects, we performed patient-specific FEAs of the first lumbar vertebra of osteoporotic patients at five time points (before therapy, and after 6 and 12 months and 2 and 3 years of therapy) during a 3-year drug treatment with alendronate and vitamin D, in four osteoporotic female patients in this study. The FEAs revealed notable decreases in the compressive principal strains in cancellous bone, but these decreases did not necessarily correspond to increases in the bone densities. In addition, statistical analyses by Friedman's test (nonparametric analysis) showed that evaluation based only on the average compressive principal strains over the 3-year treatment identified drug effects significantly, suggesting that compressive principal strain is an useful indicators for monitoring drug effects. Our data implied that compressive fracture of the vertebrae may be prevented as a result of the drug treatment, in a manner that was optimally detectable by patient-specific FEAs.
This paper presents the method to design a novel micro stirrer for high effective dissolution of cerebral thrombus or blood clot. The micro stirrer is a beam with supported one side and the other side is attached to an asymmetrical stirrer. The waves, which were excited by the transducer, propagate through the catheter and impinge to the inclined surface in the stirrer. The reflected waves generate bending mode in the stirrer to dissolve the thrombus. Tip trajectory results are investigated for the simultaneous estimation of all the mode shapes, due to obtain the best drive frequency. It seems that the expected motion is a mode shape which, despite has the bending at tip, there is no significant bending across the catheter. An important parameter has been developed to act as an indicator factor for mode shape detection in simulation analysis. The design algorithm is offered based on the stirrer length and full length of micro stirrer. The accuracy of the estimated design method is evaluated through the some other stirrer length.
This study presents a numerical methodology to clarify the morphology of complex trabecular network architecture in human lumbar vertebra by means of the new post-processing technique for calculated microscopic stress by the homogenization method. Micro-CT image-based modeling technique is used and careful but intuitive and easy-to-use method for microstructure model, in other words region of interest (ROI), is also presented. The macroscopic homogenized properties that include not only the Young's moduli but also shear moduli could explain the difference of morphology between healthy and osteoporotic bones. This paper focuses on the change of degree of anisotropy. Then, the microscopic stress under three basis load cases was analyzed. In this analysis, the homogenization method has a merit in the computational cost. The trabeculae are classified into eight groups from the viewpoint of load bearing function against three loading conditions in the proposed post-processing of numerical results. It contributes to the understanding of the mechanical role of trabecular bone in vertebra. The primary trabecular bone that has been supposed to support the self-weight and secondary bone that connects the primary bone are successfully visualized. The discussion on the mechanical role of plate-like trabecular bone in the load path network system is also highlighted.
Staphylococcal γ-hemolysin (Hlg), consists of two separate proteins, Hlg1 (LukF) of 34 kDa and Hlg2 of 32 kDa, which cooperatively lyse mammalian erythrocytes. Hlg is an illustrative molecule for the study of the assembly and membrane insertion of transmembrane proteins having the unique characteristic of being composed of two separate proteins. Our previous studies revealed that LukF and Hlg2 assemble alternately on a membrane to form ring-shaped heteroheptameric transmembrane pores, which form funnel-shaped structure with a subunit mismatch arrangement in which the distance between two of the adjacent subunits is significant larger than the others. In the present study, further analysis of the subunit mismatch arrangement in Hlg heteroheptameric pores was conducted by two-dimensional (2-D) image analysis. The distances between two adjacent subunits were numbered according to the size of the distance between adjacent subunits, and how each distance was arranged in the pore was investigated. As a result, the following results were clarified: (1) Not all distances between two adjacent subunits are even. This indicates that a mismatch arrangement exists at not only one site but also at other sites. (2) There is a high probability leading several patterns of mismatch arrangement. (3) These mismatch patterns tend to be polarized into a region in which the distance between subunits is great and a region in which such distance is small. The probabilistic analysis used in this study revealed that there is the intrinsic geometry with subunit arrangements in the heteroheptameric pore consists of two differential subunits.
Human foot is a complex musculoskeletal system. As it is inconvenient to directly measure tension forces of muscles attaching on limbs, a new quantitative method for dynamics analysis of muscle forces of ankle joint was presented based on a developed wearable motion, ground reaction force (GRF) sensor system and AnyBody Modeling System. In the AnyBody Modeling System, which professionally concerns on musculoskeletal kinematic modeling and analysis, quantitative results of muscle forces can be calculated through an inverse dynamics method. In this study, a musculoskeletal model composed of the shank and multiple-units foot was established in the AnyBody Modeling System, and an experiment was implemented with the wearable sensor system on eight volunteers during their normal gait. Tension forces of muscles of ankle joint were calculated through the inverse dynamics analysis, and the results matched the muscle activation level tendency of electromyography (EMG) method, which was implemented in the experiment as a contradistinction. The method for estimating muscle forces of ankle joint in the study appears to be a practical means to determine muscle forces in musculoskeletal analysis of human limb, and the system may be used as a convenient instrument for on-the-spot medical applications.
Although several histological studies in mice have examined healing of fractures secured with bone plates, no data are available at present on the mechanical response of fractured bone or callus tissue. Here, we simulated the healing response of fractures secured with rigid and flexible bone plate-designs. Using finite element methods, we simulated the maximum principal strain, stress, and strain energy density in the fractured region of mouse femurs under three loading conditions. In the rigid plate-design, the strain energy density increased when compression and bending were loaded and decreased when torsion was loaded. In the flexible plate-design, the strain energy density increased under all loading conditions. Since an increase in the strain energy density indicates an increase in mechanical stimulation, the simulation suggests that the flexible plate design may stimulate bone growth more than the rigid plate design. A favorable bone plate design must be stiff enough to avoid dislocation but flexible enough to provide mechanical stimulation.
Background. “Rise-to-Peak time” has been proposed as an index of the probe angle during ultrasound measurement. The aim of this study is to quantitatively evaluate the effectiveness of this index as a guide for ultrasound evaluation of articular cartilage. Methods. “Acceptance”, defined as the normalized difference between the index value at a target position and the index value at a deviated position, was calculated using the “Rise-to-Peak time” for materials with varying surface roughness. Findings. Echoes from rough surfaces had lower amplitude values compared with those from flat surfaces. Meanwhile, “Rise-to-Peak time” was little-affected by the surface roughness of the reflection surface. Also, echo amplitude had a large negative “Acceptance” compared with Rise-to-Peak time. Interpretation. These results suggest that the “Rise-to-Peak time” index is effective in reducing measurement time and measurement error during articular-cartilage evaluation.
Pulse diagnosis in traditional Chinese medicine is said to be able to detect not only illness but also decline of health in the patients from tactile sense of the pulse in the radial artery at the wrists. This diagnosis, however, is not supported by concrete scientific evidence. The authors have proposed a non-linear spring model of subcutaneous tissue on the radial artery and one-dimensional arterial blood flow model in an arm for the purpose of scientific verification of the pulse diagnosis. They performed, in the former study, a numerical experiment with this mathematical model in which the radial artery was indented in a stepwise manner by a pressure sensor, which extract the fundamental mechanism of the pulse diagnosis, to validate the subcutaneous tissue model and to find the appropriate coefficient to fit the experimental result. They investigated, in this research, contribution of parameters of supply pressure of the blood and tube law of the artery on the change in the pressure pulse waves with the indentation steps with respect to mean value Poav and amplitude ΔPo of the pressure. It was shown that mean supply pressure affects both Poav and ΔPo, while amplitude of the supply pressure affects ΔPo. It was also shown that profile of ΔPo vs. distance of the indentation changes drastically as the artery becomes hard. Lastly, it was examined to reproduce the experimentally obtained pressure pulse waves during the indentation in their former work with the mathematical model by adjusting the parameters. The result showed better agreement than the former result, but it implied that ulnar artery had to be taken into consideration for quantitative fitting of the pulse waves to the range where the radial artery was nearly flattened by the indentation.
Designing robots with human characteristics is a great challenge to researcher to fulfill the needs of robotic technology in human occupied environment. This research aims to enable a smooth and natural cooperative object transfer by a human hand and a robot manipulator mimicking the same task performed by two humans. Prior to the development of the human-robot system, investigation on characteristics which generate a smooth cooperative object transfer in a human-human system is crucial. Perceiving certain part of an object in transfer, acts as a medium for the exchange of object's motion information between subjects. We have investigated the effect of perceiving different parts of the object in transfer to the cooperative motion smoothness (smoothness is quantitatively evaluated using Minimum Jerk Model). The result suggests that observing the center part of the experimental object produced more frequent, a smooth and natural motion for task executed in leftward/rightward and upward/downward direction. Moreover, the center part was associated with less object rotation during smooth task in these directions. However, there is no significant difference between End and Center case for the same task executed in forward/backward direction. We also considered the importance of having information of cooperative task initiation signal and a target position to the cooperative task smoothness. Regardless of which part of the object being perceived, smoother task is frequently generated when both signals are available to both subjects. Although the effect of End and Center case may be significant in human-human system; in human-robot system, both cases should be further tested and evaluated.