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Because in patients with knee osteoarthritis (OA), the knee joint properties such as cartilage, meniscus, soft tissue and bone formation are assumed to degeneration change, the shock absorb might also decrease. The transmission of impulse from femur and tibia is thought to change in the knee joint. The purpose of the present study was to determine the differences between young healthy women and elderly women with knee OA using the impulse response method. Twenty-six older women with clinically diagnosed knee OA (OA group, age: 69 ± 6 years) and 26 young women without knee OA (young control [YC] group, age: 21 ± 1 years) participated in the study. The OA group fulfilled the knee OA classification criteria based on clinical findings. An input device provided an impulse to the subject while standing. The output value was measured using a single-axis accelerometer. The outcome measures were the input–output ratio and power spectrum. The input–output ratio did not significantly differ between the groups. The power spectrum at 21–30 Hz was significantly greater (p = 0.036) in the OA group than in the control group. Additionally, the power spectrum at 21–30 Hz correlated with knee pain (r = 0.39, p = 0.049). At 21–30 Hz, transmission of impulse from femur and tibia in the knee joint was lower in the OA group than in the control group. The IR method used in the present study could detect the transmission of impulse in early knee OA.

Knee disorders are a common but easily overlooked disease and are often caused by natural or early aging. However, the aging process is difficult for the patient to self-diagnose until it deteriorates to osteoarthritis (OA). Vibroarthrographic (VAG) signals make the aging process visible and may contribute to reducing the incidence of disability caused by delayed medical diagnosis. Recently, although many studies have used VAG signals to diagnose knee joint disease, they have not yet been used in the diagnosis of knee aging. In this paper, a method is proposed to observe the aging process of the knee through VAG signal analysis. The accuracy of classifying naturally aging and healthy knees with this method is 0.9275, and the area under the receiver operating characteristic curve is 0.8928. The paper has filled the gap of using VAG signal to diagnose the natural knee aging process and laid the foundation for the non-invasive diagnosis of early knee aging.

[Purpose] The aims of the present study were to investigate the most suitable location for vibroarthrography measurements of the knee joint to distinguish a healthy knee from knee osteoarthritis using Wavelet transform analysis. [Subjects and Methods] Participants were 16 healthy females and 17 females with severe knee osteoarthritis. Vibroarthrography signals were measured on the medial and lateral epicondyles, mid-patella, and tibia using stethoscopes with a microphone while subjects stood up from a seated position. Frequency and knee flexion angles at the peak wavelet coefficient were obtained. [Results] Peak wavelet coefficients at the lateral condyle and tibia were significantly higher in patients with knee osteoarthritis than in the control group. Knee joint angles at the peak wavelet coefficient were smaller (more extension) in the osteoarthritis group compared to the control group. The area under the receiver operating characteristic curve on tibia assessment with the frequency and knee flexion angles was higher than at the other measurement locations (both area under the curve: 0.86). [Conclusion] The tibia is the most suitable location for classifying knee osteoarthritis based on vibroarthrography signals.

Many methods for physical medicine and rehabilitation strategies have been developed for physically disabled people. Most of them have been determined by physical therapists based on anatomical and physiological assessment of the subject. With application of robot technology which allows smooth achievement of complex trajectories, and with loading or assisting designated muscles in an accurate manner, a better rehabilitation strategy can be developed. In this paper, we propose a new method to design the motion trajectory of lower limbs and the applied forces acting on the foot. In order to improve the rehabilitation effect in full consideration of biomechanical stability of the trajectory and musculo-skeletal model of each subject, we have applied genetic algorithm to search the parameters of spline curves for the trajectory and the applied force acting on subject's foot. The usefulness of the proposed method is confirmed through simulation results and the comparison with a conventional training trajectory.

We propose a method for the comprehensive identification of spastic and intrinsic properties of spastic knee joints using multiple pendulum tests. The stretch reflex system was modeled as a velocity feedback loop where the key component was the muscle spindle model generating the afferent signals with a constant threshold and gain of the lengthening velocity. For the comprehensive identification, multiple trajectories from one session of pendulum trials with different release angles were used as the reference trajectories that the model must reproduce. The identification was successful based on the results that the identified model represented the various features of pendulum trajectories and the simulated spastic torque closely matched the experimental EMG. The identified velocity threshold showed a remarkable correlation with the EMG duration and peak. The session-based method was effective in the identification of the spastic musculoskeletal system and the velocity threshold of the stretch reflex was suggested as a reliable and intuitive indicator of spastic severity.

我々は，草鞋の機能を模擬したとされる足部装具が歩行運動や立位姿勢に与える影響を明らかにするため，光学式運動計測装置，床反力計などを用いた運動力学計測を以前において行った．本研究ではさらに，足部装具の装着方法を変化させ，筋骨格モデルや足圧分布計などを用いて，より詳細に足部装具，足指の運動，歩行の関係を明らかにすることを目的とする．実験では被験者10名に対して，第1・2指間刺激，第2－5指拘束，全指拘束の3種類の装着法にて足部装具を装着させ，歩行動作と立位姿勢の運動力学計測を行った．また別途，足圧分布計上での歩行実験を行った．第1・2指間刺激の方法では足指の屈曲位，足指間距離の増大などが見られ，足関節まわりの筋活動が増大した．他の装着法でもそれに応じた足部形状の変化，歩容の変化が見られ，これらの結果に基づき本装具が身体動作に与える効果について議論した．

The purpose of the present study was to investigate the causal relationship between walking pattern and physical malfunction using a computer simulation method with a biomechanical walking model. In this computer simulation, the musculoskeletal system was represented by a three-dimensional 14-rigid-link model and 60 muscle models. Muscular forces were controlled by a neuronal system model consisting of 16 pairs of neural oscillators. In the computational experiment, five types of walking models were constructed: an intact model, a delayed response model, a weak muscle model, an inclined posture model, and a joint contracture model. These malfunction factors were hypothesized to have a causal relationship with walking characteristics in older adults. The simulation revealed that the delayed response in the neuronal system was primarily related to walking stability. In addition, the weakening of muscles was strongly related to the reduction of the walking step length. The inclined posture and joint contracture also influenced the walking pattern, but not significantly. The use of such a computer simulation method is essential in order to clarify the causal relationship between body function and walking pattern in older adults.

本研究では, リハビリテーションや一般的な運動施設での利用を念頭に, センサを装着した自転車エルゴメータと筋骨格モデルを用いた下肢運動評価システムの開発を行った. ペダル位置から関節角度を推定する逆運動学モデルを構築し, その妥当性を示すため, 動作計測装置より計測した値と比較した. 次に筋力などの生体内負荷を推定する筋骨格モデルを構築し, その妥当性を示すため, 筋電位波形と推定筋力波形とを比較した. さらに開発したシステムを用いて, サドル高さを変化させた際の膝蓋大腿関節に与える影響を考察した. その結果, 推定関節角度は相関係数0.98以上の精度で動作計測装置での計測結果と一致し, 推定筋力波形も筋電位波形と類似する傾向を示すなど, 開発システムの妥当性が確認された. ただし, サドル高さに応じた膝蓋大腿関節負荷推定では明確な傾向は示せなかった.

In case of a lower limb prosthesis, the most important parameter is the fitting between the cut section of the leg (stump) and the socket. It has been observed that the contact pressure between the socket and the stump changes after the alignment of the lower limb prosthesis changes and also during dynamic movement such as walking or running. The main aim of this research is to design a novel socket using smart materials, such as magneto-rheological (MR) fluid, which can transform the rigidity and capacity of the socket to accommodate the dynamic movement and alignment changes. In order to determine design parameters of the socket, we conducted various experiments such as subjective evaluation of pain by the contact pressure, measurement of the stiffness of the MR bag in which MR fluid was filled up. The MR socket was actually developed as a prototype based on the above experiments. The fitting between the stump and the socket was investigated subjectively and also based on the pressure sensors. The contact pressure and the pain felt by the amputee using a lower limb prosthesis have become smaller in the proposed MR socket, especially, on the patellar tendon. The proposed MR socket had a possibility to improve the fitting between the stump and the socket.

In the present clinical fields, medical doctors mainly use Modified Ashworth Scale (MAS) to evaluate spasticity. However, MAS is manual and qualitative method and results depend on doctors. The purpose of this paper is to propose a method to quantitatively evaluate spasticity using a neuro-musculo-skeletal model. The proposed model consisted of the muscular activation model, variable viscoelastic model of the muscles, musculoskeletal model, muscle spindle model and alpha motoneuron model. This model could represent spasticity patient’s knee pendulum well. A parameter related with sensitivity of the muscle spindle was a factor to evaluate spasticity quantitatively.

The quantitative and objective evaluation of spasticity is desirable in rehabilitation and orthopedics where subjective evaluations are mostly used. In the present study, data from a simple pendulum test are used for the evaluation of the spasticity with the help of biomechanical modeling. The spasticity of a knee joint is modeled as nonlinear feedback of muscle lengthening velocity and the muscle length. Through the optimization of the modeling error, the feedback parameters are determined. The threshold of muscle lengthening velocity in the reflex system is suggested as a severity index of the spasticity.

本研究では，股義足を使用した歩行を再現することのできるシミュレーションモデルを開発した．まず，股義足歩行の動作分析を行い，股義足歩行の特徴を調べた．その結果から，妥当な股義足歩行をシミュレーションで再現するには3次元で全身のモデルが必要であることがわかった．そこで，股義足の機械的モデルを導入した股義足・筋骨格系モデルと股離断者の神経系モデルを統合した3次元股義足歩行シミュレーションモデルを構築した．数値シミュレーションにおいて，20,000試行の神経系のパラメータ探索計算を経て，3次元，多数歩，全身動作の股義足歩行を生成した．生成された歩行は，実際の股義足歩行の特徴を定性的に再現していた．

This work was designed to investigate biomechanical aspects of the evolution based on the hypothesis of dynamic cooperative interactions between the locomotion pattern and the body shape in the quadrupedal hopping and the bipedal hopping. The musculoskeletal sagittal-plane model used in the computer simulation consisted of several segments; foot, shank, thigh, trunk, forearm, upper arm, and tail. Two adjacent segments were connected by a hinge joint, and each joint angle was controlled by an extensor and a flexor muscle. The nervous system was represented by a rhythm pattern generator which consisted of 12 neuron models. The genetic algorithm was employed based on the natural selection theory to represent the evolutionary mechanism. The simulation results showed that although hopping could not be seen in the early evolution process, repeated manipulations of the selection and multiplication increased the step length and the locomotion speed and that the resulting hopping motion was close to that of living animals. It was suggested that the advantage of the quadrupedal hopping is high energy efficiency and that of the bipedal hopping is high stability due to the simple and easy motion control. The computational evolution method employed in this study can be a new powerful tool for investigation of the evolution process mostly due to its versatility.

Halliday SE, Zavatsky AB, Hase K. Can functional electric stimulation-assisted rowing reproduce a race-winning rowing stroke? Arch Phys Med Rehabil 2004;85:1265–72. Objective To compare the ergometer rowing technique of a person with spinal cord injury (SCI), using functional electric stimulation (FES) of his leg muscles, with that of a well-defined group of able-bodied rowers. Design Whole-body kinematics and kinetics and electric activity of selected muscles were measured during ergometer rowing. Setting A hospital-based motion analysis laboratory. Participants Five male university varsity-level rowers and 1 male rower with SCI. Interventions Eight rowing trials were collected on the university-level rowers, 2 trials each at 20, 24, 28, and 32 strokes/min. The rower with SCI had surface electrodes applied to his medial hamstrings and medial quadriceps muscle bellies. The electrodes were attached to a stimulator that was activated using a button in the ergometer handle. The subject with SCI rowed at a self-selected stroke rate. Main outcome measures Forces at the ergometer handle and foot cradle, 3-dimensional whole-body kinematics, net joint moments, and phasic activity of muscles. Results Motion of the arms, ankles, and knees of the rower with SCI was similar to those of the university-level rowers; other joint motions and forces applied to the ergometer differed. Conclusions FES-assisted rowing in its current implementation cannot reproduce a race-winning rowing stroke. Further development work is required.

Objective: To investigate the difference in knee joint kinematics and kinetics during gait and T2 mapping values in a healthy female population in their twenties and forties in order to determine the knee motion changes related to early knee OA change. Methods: Thirty healthy women, 15 in their 20s and 15 in their 40s, participated (average ages 22.1 ± 2.4 and 45.7 ± 2.5 years old, respectively). Knee joint kinematic and kinetic data during gait and T2 measurements of the medial femorotibial joint cartilage using a 3T MR system were assessed. Results: The first peaks of knee adduction moment (KAM) in women in their 20s and 40s were not significantly different, although the first peaks of knee flexion moment in their 40s (5.7×10-2 ± 1.7×10-2) were significantly greater than the values in their 20s (3.2×10-2 ± 2.6×10-2, P

Compared with the other exercise, such as walking and cycling, rowing was expected to have some fitness advantage, while there were some misgivings about the risk of injury. The objectives of this study were to quantify biomechanical characteristics of rowing for fitness and rehabilitation and to offer normative data for the prevention of injury and for determining effective exercise. An experiment was performed to collect the kinematic and kinetic data during rowing by experienced and non-experienced subjects. A three-dimensional whole-body musculo-skeletal model was used to calculate the biomechanical loads, such as the joint moments, the muscular tensions, the joint contact forces and the energy consumption. The results of this study indicate that rowing is an effective exercise for rehabilitation and fitness. However, the non-experienced rower should acquire considerable skill to obtain sufficient exercise. The rowing cadence should be decided according to the purpose of the exercise.

Computer simulations of human infant walking, changing from supported walking with weight support to independent bipedal walking, were conducted to identify the biomechanical factors of the neuro-muscular system necessary to acquire bipedal walking. We simulated the autonomous acquisition of independent walking by repeating walking trials and modifying neuronal structures and parameters so that walking efficiency is maximized, and forces supporting the upper body are minimized. The results of simulation showed that reinforced interaction with the system of body dynamics, such as feedback from somatic senses, especially information concerning angular velocities of joints, is essential to the development of walking. Other significant factors for bipedal walking are the development of neuronal feedback about the hip joint position, which determines the posture of the upper body, and improvements in the extensors' ability to produce joint moments.

A simulation model for biomechanical analysis was developed in order to calculate the internal loads, such as muscular tension and energy consumption, from measured kinesiological data for various kinds of motion. In this model, the human body is divided into a maximum of nineteen rigid segments connected to each other with ball joints. A maximum of 156 skeletal muscles throughout the body are modeled as tensile force generators which include physiological elements that consume mechanical energy. The component ratio among muscle fiber types, number of body segments and number of degrees of jointfreedom can be changed easily, and according to the alteration of the segment number, the musculoskeletal system is changed automatically. This flexibility is of benefit in application of the method to various motion analyses. Three-dimensional bipedal walking was analyzed using a simplified model, and rowing motions were analyzed using the whole-body model.

A new computer simulation method, using a neuro-musculo-skeletal model, is used to clarify the process of acquisition of erect bipedal walking during human ontogeny. Walking was autonomously generated as a dynamic interaction called ‘mutual entrainment’ between the neural oscillation and the pendular movement of differently proportioned bodies. Walking patterns of humans with 8 different sets of alternative body proportions, varying from those of 8-month-old children to those of 22 years old adults, were simulated. The development of bipedal walking is characterized as the change from a forced oscillation controlled by the nervous system to the natural oscillation of pendular motion, determined by body proportions. Body proportions are the fundamental factor in the development of bipedal walking.

In order to calculate the mechanical load on living tissues from measured kinesiological data, the human musculoskeletal system was modeled three-dimensionally by nineteen rigid segments and one hundred fifty -six muscles. The length, mass, and moment of inertia of each segment can be adjusted according to the subject's stature and weight. The muscle model includes several physiological elements that consume mechanical energy. The component ratio of muscle fibers can be changed arbitrarily. The proposed musculoskeletal model can be modified easily to a system with fewer segments or a two-dimensional system to suit the purpose of analysis. This flexibility increases the applications of the method to various motion analyses. As examples, we analyzed three-dimensional bipedal walking by a model without upper extremities, and rowing motion of whole body segments.

Many of walking assist devices have been developed to support the general walking style in the sagittal plane. These assist flexion-extension of the knee and hip joints. However, the theory called the Spinal Engine describes that the essence of walking is in a motion of the spinal column. This paper presents the new walking assist device focusing on twist motion of the trunk and waist.

Endothelium-dependent relaxations mediated by Gi protein are prominently impaired in atherosclerotic coronary arteries. However, it remains to be determined whether the expression of endothelial Gi protein per se is reduced in coronary atherosclerosis. Thus, in the present study the expression of endothelial Gi protein was examined by immunohistochemical staining using a specific antibody against human Gi protein (alpha-subunits of Gi-1 and Gi-2 proteins) in the proximal segment of the left anterior descending coronary arteries (segment 6) from 40 consecutive autopsy cases. The immunoreactive level of the Gi protein was semi-quantitated in four grades (none, 0; slight, +; moderate, +2; high, +3) and the mean value of the ratings of all endothelial cells was used as an index of the endothelial Gi protein expression of the artery. The immunoreactive level of the Gi protein in human coronary arteries was significantly reduced with ageing and extent of coronary atherosclerosis (both P0.05), and was lower in patients with than in those without hypertension (P0.01) or hyperlipidaemia (P0.05). In addition, the level was significantly lower in the eccentric portions than in the concentric ones in each atherosclerotic coronary artery (P0.0001). These alterations in the immunoreactive level of endothelial Gi protein in human coronary arteries may explain, in part, why Gi protein-mediated, endothelium-dependent relaxations are prominently impaired in atherosclerosis.

We introduce a method for lower-limb physical rehabilitation by means of a robot that applies preliminary defined forces to a patient's foot while moving it on a preliminary defined trajectory. We developed a special musculoskeletal model that takes into consideration the generated muscle forces of 27 musculotendon actuators and joint stiffness of the leg and allows the calculation of the motion trajectory of the robot and the forces that the robot needs to apply to the foot in each moment of the therapeutic exercise. Robotic treatment programs are customized for the individual patient by using a genetic algorithm (GA) that refers to the musculoskeletal model and calculates the parameters of the spline curves of the motion trajectory of the robot and forces acting on the foot.

Functional electrical stimulation (FES) is useful to improve the gait of patients with peroneal nerve palsy or spastic hemiparesis after stroke. So as to apply FES to such patients, we have to have estimators for detecting the timing of phase switching in walking motion. We designed a wearable device for state estimating of walking and functional electrical stimulation. We consider the implementation of artificial neural network (ANN) into the device, and propose a method for supervised learning of the ANN. Two experiments have been conducted to show the effectiveness of the wearable device. The accuracy of estimating the timing for FES is good enough for the practical application.