The research advances of biomechanics of human knee joint ligaments / 生物医学工程学杂志

Ligaments are the main parts which stabilize the knee joint. How to analog the ligaments in biomechanical model will affect the characteristics of the human knee dynamics and in the computation of the stress in ligaments between two bones. This symposium is aimed at the survey of the simplified method of the ligaments via mechanical parameters, and providing an exact method of constructing model.

Synergic analysis and dynamics pattern of human normal gait during swing phase / 生物医学工程学杂志

A dynamics model of human lower extremity, which combines musculotendon dynamics and muscle excitation-contraction dynamics, is presented. With this model, a motion process of normal gait during swing phase is numerically analyzed by use of the optimal control theory. The model was verified using experimental kinematics, muscles activation, and electromyographic data. The result showed that the tri-phasic activation pattern and synergistic muscles displayed during a normal gait in swing phase. The pattern consists of three distinct phases, i. e., acceleration during moving initiation, braking the moving segment, and posture control at the final specified position.

Dynamic loads at knee joint of trans-tibial amputee on different terrains / 生物医学工程学杂志

Dynamic loads at knee joint of amputee are fundamental for rehabilitation of knee injury and prosthesis design. In this paper, a 3-D model for calculation of dynamic load at knee joint of trans-tibial amputee was developed. Gait analysis was done on three terrains including normal level walking, upstairs and downstairs. Dynamic loads at knee joint were calculated during one gait cycle. The results show that gait patterns and dynamic loads at knee joint were different among these three terrains. Although the general waveforms were about the same, the motion range of knee joint, ground reaction forces and loads at knee joint when walking upstairs or downstairs were larger than those in a normal level walking. The quantitative findings provide the theoretical basis of gait analysis and prosthesis design for trans-tibial amputee.

Inertial effects on interface pressure between prosthetic socket and residual limb / 生物医学工程学杂志

A quantitative understanding of interface pressure distribution between prosthetic socket and residual limb is fundamental for an optimal design of prosthesis. Most of traditional finite element (FE) models were static. In this paper a 3-D nonlinear finite element model was developed according to the data of one transtibial amputee. The interface pressures at residual limb were predicted, and the effect of inertial loads was investigated quantitatively. The results show that interface pressures were mainly distributed at patella tendon, lateral tibia, media tibia and popliteal depression regions. Interface pressure had the similar double-peaked waveform in stance phase. The average difference in interface pressure between the two cases with and without consideration of inertial loads was 8.4% in stance phase, while it was up to 20.1% in swing phase with considerably different change trend. It is found that inertial effects during walking can not be ignored.

Synergic pattern analysis of upper limb grasping movements / 生物医学工程学杂志

In order to discuss the evaluation method of human upper limb movements, the patterns of movement coordination during healthy people prehension have been researched. Eight subjects were asked to perform different reaching-grasping and drinking water from the cup tasks with different indices of difficulty, and the arm movement trajectories and the main muscles group electromyography (EMG) data were collected. To explore the prehension control mechanism, a comparison has been made between the solution of the theoretic calculation and the experimental data. The results show that the topological invariance was observed in the trajectories of different task performance, and the linear relationships between joints covariation were exhibited. Moreover, the different muscles were controlled and combined into units of synergistic muscular group necessary to reach and grasp the goal.

Quantitative gait evaluation using principal component analysis / 生物医学工程学杂志

Evaluation of human gait function is of great significance in clinical medicine and rehabilitation engineering. A quantitative gait evaluation method using principal component analysis was proposed. The evaluation steps included that a series of characteristic index was performed by the gait parameters with a gait detection, and the index was normalized, quantified and summarized by principal component analysis. Then the evaluation results were shown in formulation, figures and tables. The examples showed that this system could evaluate the recovery of the gait by treatment.

The effects of backpack loading on the gait and corresponding compensatory strategy / 生物医学工程学杂志

This study was designed to determine the effect of backpack loading on the gait pattern and corresponding compensatory strategy, which is important to the balance control of biped robot and military training. Five healthy subjects were instructed to walk at their preferred speed on level pathway taking three different loads i.e. 6 kg, 12 kg and 25 kg, on their backs. The results showed that the gait pattern was apparently influenced, and the dominant effects were found to be the flexion of hip, knee joints and pitch angle of torso. The stride speed decreased apparently with loading on their backs, but the stride length showed less changes. Besides, the responses to taking loads might be influenced by the strength of body. An apparent multi-joints coordination motor mode was employed to compensate the influences of loading, however, their contributions are different; hip, knee joints and torso pitch made dominant contributions to the compensation while ankle joints made minor. The anterior pitch of upper torso could be employed to adjust the overall center of mass while loading on their backs, the larger the magnitude of loading on their backs, the larger the anterior pitch angle of torso. After the heel touched the ground, the flexion of hip and knee joints were effective for the shock absorption, which means that the stiffness of hip and knee joints can be used to absorb the shock and avoid the trauma of each joints.

Progress in the study on synergetic control principle of human upper extremity and related issues / 生物医学工程学杂志

Human upper extremity is the most complex and flexible executor during the human movement, coordination analysis of the synergetic control principle of human upper extremity is of great significance in trajectory planning and real-time control of anthropopathy robots and intelligent prosthesis system. Most studies have only been performed within the last 10 years. This paper surveys the research in the structure characteristic and redundancy coordination principle of human upper extremity, and the developments of various prospects of anthropopathy robots, intelligent prosthesis, gymnastic science and rehabilitation evaluation are discussed.

Biomechanical Study of Two Cervical Interbody Cages With Different Surfaces / 中国矫形外科杂志

Objective: To biomechanically compare the initial stability of two cervical interbody cages with different surfaces on human specimens.Methods: Flexibility of twenty-three cervical motion segments (two groups) were tested in axial rotation, flexion/extension and lateral bending, intact and after implantation of a cervical interbody fusion cage (SynCage-C Curved, SynCage-C Wedged). An implant pullout concluded testing. Changes in range of motion (ROM) were analyzed.Results: Both cages were effective at reducing ROM in all directions, with no significant differences in effacency. The pullout force differed significantly between the two cages, the SynCage Curved being higher. Conclusion: Differences of surfaces of the two cages don't affect their initial stability. The cage with a better contoured surface had a higher pullout force.