Figure 2.

Ankle moment plotted against ankle rotation during stance phase from one subject walking with and without the ankle units at their freely-selected speed. The initial contact (IC) of the foot with the ground for each condition occurred at approximately the same ankle moment-angle position in each curve. The arrows indicate time progression during stance. Ankle “stiffness” (24) can be determined at each point in time from the slope of the lines that are tangent to this curve. These curves illustrate that ankle stiffness was reduced with the prosthetic ankle unit.