Fig. 4: Treadmill walking experimental results with the soft knee and the daily-used rigid knee.

The line graphs display the statistical hip and knee joint angles, muscle activity of rectus femoris, ground reaction force (GRF), and vibration forces on the thigh and the shank during one stride. The histograms next to the line graphs show statistical results of the peak knee flexion angle (PKFA), heel strike flexion angle (HSFA), peak hip flexion angle (PHFA), peak hip extension angle (PHEA), swing phase peak muscle activity (SW PMA), heal strike peak ground reaction force (HS PGRF), peak vibration force (PVF), and peak vibration displacement (PVD) during treadmill walking. Data are shown as mean ± std (n = 3). Each data point represents a biologically independent replicate. The histograms at the bottom show the gait symmetry index. The red color represents the soft prosthetic knee, the blue color represents the rigid prosthetic knee, and the gray color represents the corresponding sound knee. For the vibration forces and displacements, the lighter color represents the force on the shank, while the darker color represents the thigh.