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Objective To study the effect of lateral wedge insoles with different stiffness on the knee adduction moment (KAM) under walking condition. Methods The gait of 15 healthy males wearing lateral wedge insoles with different stiffness was tested. The kinetics and kinematics data were collected by optical motion capture system and ground reaction force platform. The KAM and its peak values were calculated by Visual 3D software. The differences in peak KAM under 3 walking conditions (shoes only, shoes with softer or harder lateral wedge insoles) were analyzed. Results Compared with walking with the softer lateral wedge insoles, walking with the harder lateral wedge insoles could reduce the 1st and 2nd peak KAM by 9.3% and 9.7%, respectively, with significant statistic differences. Conclusions Increasing some stiffness of lateral wedge insoles can further reduce the pressure and wear on medial compartment of the knee joint, which may relieve the symptom of knee osteoarthritis.
ABSTRACT
Objective To study the effect of lateral wedge insoles with different stiffness on the knee adduction moment (KAM) under walking condition.Methods The gait of 15 healthy males wearing lateral wedge insoles with different stiffness was tested.The kinetics and kinematics data were collected by optical motion capture system and ground reaction force platform.The KAM and its peak values were calculated by Visual 3D software.The differences in peak KAM under 3 walking conditions (shoes only,shoes with softer or harder lateral wedge insoles) were analyzed.Results Compared with walking with the softer lateral wedge insoles,walking with the harder lateral wedge insoles could reduce the 1st and 2nd peak KAM by 9.3％ and 9.7％,respectively,with significant statistic differences.Conclusions Increasing some stiffness of lateral wedge insoles can further reduce the pressure and wear on medial compartment of the knee joint,which may relieve the symptom of knee osteoarthritis.
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Objective To compare biomechanical characteristics of the knee joint during forward walking and backward walking. Methods Temporal-spatial, kinematics, kinetics parameters of 13 healthy young male volunteers were collected and compared by 3D motion capture system Vicon T40 and force platforms AMTI OR6-7. Results Compared with forward walking, the speed, cadence and stride length significantly decreased, while the gait cycle and stance phase percentage in gait cycle significantly increased during backward walking. In the sagittal plane, the range of motion (ROM), the maximum flexion/extension moment of the knee were smaller during backward walking. In the frontal plane, the ROM of knee varus/valgus during backward walking decreased, and the peak value of knee adduction moment significantly reduced in the early stance phase while significantly increased in the late stance phase of backward walking. The peak value of ground reaction force (GRF) was significantly larger in the early stance phase while smaller in the late stance phase during backward walking than that during forward walking. Conclusions The biomechanical characteristics of the knee joint during forward walking and backward walking are significantly different. Compared with forward walking, backward walking is helpful to reduce the medial compartment load in the early stance phase. Further study will be needed to investigate the effects of backward walking on knee joint loading in the late stance phase.
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Objective To study dynamic characteristics of the ankle gait simulator, simulate plantar forces in the vertical, anterior-posterior, right-left direction during the stance phase, and validate such forces in the experimental setup. Methods The Adams virtual prototype and ankle model (including tendons, ligaments and soft tissues of foot) were established for dynamic simulation based on the self-developed 5 DOF gait simulator. The dynamic results from both the prototype and gait simulator were compared with the real plantar forces. Results The simulated plantar force could accurately fit the normal in vivo ankle position curves during a stance phase in three directions, and the tendons, ligaments and soft tissues had important influences on the correct gait. The simulated plantar force by the gait simulator could be repeatedly fit for the real stance plantar force. Conclusions The gait simulator was proved to simulate the human gait stance well and can provide a clinical research platform for those experiments which are incapable of in vivo measurement.
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Objective To study the control problem in dynamic foot biomechanical simulator and propose a complete multi-axis control algorithm which could be more competitive than that of current gait simulators in aspects as simulations in degree-of-freedom (DOF), velocity, precision, weight-bearing and trial efficiency. Methods A novel custom-made foot and ankle biomechanical simulator was developed to simulate both motion and force characteristics in a stance phase with 5 DOF. A model of the simulator was built in Matlab based on gait analysis and reasonable simplification. Iteration learning control (ILC) was proposed to control multi-axis forces and was verified in Simulink. Finally, the control strategy was validated in the simulation platform with a prosthetic foot. Results The novel simulator could complete the motion and force loading process within 5 seconds in one stance after 4-5 iterations. All 3D ground reaction forces (Fz, Fy and Fx) had high verified repeatability. The tracking curves of Fz and Fy with 50% of real body weight could converge to the target ones with root mean square (RMS) error of 20 N and 8 N using ILC, respectively, which was smaller than 10% of simulated loads. Conclusions The proposed control strategy greatly improved intelligence of the simulator and provided a good foundation to further improve the simulation speed and accuracy. The development of the simulator is of great significance to the cadaveric experiments on foot and ankle biomechanics.
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Objective To study the association between clinical symptoms,psychosomatic factors and autonomic nervous function in patients with gastroesophageal reflux disease (GERD).Methods Thirty-four patients with GERD diagnosed by reflux disease questionnaire (RDQ) and endoscopy and 15 healthy control subjects were enrolled in this study.All the subjects were divided into two groups,one with normal scores of Zung's self-rating anxiety scale (SAS) and Zung's depression scale (SDS) as GERD (-) and the other with abnormal scores of SAS and SDS as GERD (+).Reflux symptom score was recorded for both groups at the same time.Autonomic nervous function was assessed by their heart rate variability (HRV) on dynamic electrocardiogram (DCG).The time domain parameters analyzed included standard deviation (SD) of average R-R interval during 24 hours (SDNN),SD of average 5-minute sinus heart rate (SDANN),mean square root of the difference of adjoining two R-R interval (rMSSD),and proportion of the heart beats with difference of R-R interval more than 50 ms from the total heart beats (PNN 50),and the frequency domain parameters analyzed included low-frequency (LF),high-frequency (HF) and ratio of LF to HF.Results Average scores of SAS and SDS were significantly higher in patients with GERD than those in healthy controls (48?9 vs 38?6 and 48?11 vs 41?6,respectively,P