RESUMO
Objective To explore the plantar pressure and surface electromyography (sEMG) parameters during human stair walking, so as to provide theoretical support for foot structure design of dynamic walker, selection of power element and distribution of installation location. Methods Ten healthy young males were recruited to perform stair walking trials, respectively. The motion capture system, plantar pressure system and surface myoelectricity acquisition system were used to collect plantar peak pressure, trajectory of COP(center of pressure) and sEMG parameters of lower limb muscles at the same time. Results Compared with level walking, the percentage of stance time in the whole gait cycle increased during stair walking. The peak pressure of forefoot area increased during stair ascent, while the peak pressure of toe area decreased during stair descent. During stair walking, rectus femoris, biceps femoris, medialis and lateralis gastrocnemius played a main role in maintaining the stability of human body. Conclusions The plantar pressure distribution should be fully considered for foot structure design of dynamic walker and the function of main muscles should be considered for selection of power element and distribution of installation location.
RESUMO
Objective To study the effect of stair ascent on insert wear of total knee replacement (TKA) by finite element model, which is of great theoretical and practical significance for improvement of wear evaluation method and guidance of design of artificial knee joint prosthesis. Method A finite element analysis model of TKR wear based on Archard’s law was established and validated. The model was applied with loads under normal level walking (ISO14243) and stair ascent, respectively, to compare and analyze the influence of stair ascent on TKR wear. Results The predicted wear during level walking was consistent with experimental results reported in the literature. The volumetric wear rate during stair ascent was 37.10 mm3 per million cycles (MC), which was significantly higher than that during level walking (16.94 mm3/MC). The linear wear during stair ascent was significantly higher than that during level walking as well. Wear during stair ascent was mainly distributed in the backward area of medial platform, which was obviously different from that during level walking. Conclusions As a common daily activity with high loads and high flexion angles, stair ascent contributes an important part in TKR wear, and more attention should be paid to the testing and evaluation of TKR wear.
RESUMO
Objective To collect the kinematics and kinetics functional parameters of healthy human lower limbs during stair ascent and descent, so as to provide data for designing the gait trajectory and selecting the driving components of the exoskeleton walker to achieve the motion of stair climbing. Methods Common staircase as an experimental setup was designed, and the three-dimensional (3D) motion capture system and 3D force plate were used to simultaneously measure the ankle, knee, hip motion information during stair ascent and descent. The movement characteristics of the lower limb during stair climbing was analyzed by SPSS statistical software and Origin graphics software, and the functional parameters during stair ascent and decent were also compared and analyzed. Results The joint angle at the sagittal plane, joint moment variation with gait and activity limits in lower limbs of healthy youth during stair ascent and descent were obtained by the experiment. The ranges of motion in ankle，knee and hip joints during stair ascent were -10.66°-13.26°, 6.85°-88.92°, 1.31°-50.18°,while those during stair descent were -37.42°-27.18°,9.83°-95.53°,8.01°-31.62°.The maximum ankle, knee and hip joint moment during stair ascent and descent were 1.788, 1.121, 0.946 N•m/kg, respectively. Conclusions The gait parameters variation with gait and the joint range of motion in human lower limb were significantly different during stair ascent and descent. Separate design targeting at stair ascent or stair descent is required for gait planning of walking aids, and the selection of driving element should consider the maximum moment in each joint during stair ascent and descent.