2016 Volume 23 Pages 213-222
A prosthetic foot-ankle unit is one of the key components in a stable and efficient amputee gait. The characteristics of an amputee’s gait depend on the mechanical properties of the units. Thus, several measurement methods have been proposed to evaluate the rollover characteristics of prosthetic foot-ankle units using static or quasi-static loading test devices. To clarify the effects of a dynamic amputee gait on prosthetic foot-ankle units, this study developed a dynamic gait simulated loading device based on concepts found in ISO22675 and ISO/TR22676. The advantage of this approach enables the measurement of the individual dynamic rollover characteristics of various prosthetic foot-ankle units unlike the conventional methods with a prosthesis applied to able-bodied persons or static/quasi-static loading test devices.
From this viewpoint, in this study, we evaluated the effects of dynamic rollover properties on prosthetic foot-ankle units and stable/unstable shoe combinations under a loading level of 70.0 kg and cyclic loading period of 2.0 s. Based on the dynamic rollover analysis of six kinds of prosthetic foot-ankle units and shoe combinations, we reached the following conclusions. (1) In the middle period of the stance phase, the rollover shape of a SACH foot (1S49) shows a large curvature than that of a SACH foot (1D10). This indicates that a SACH foot (1S49) is suitable for low-activity users to support a stable amputee gait because it has low mechanical deformation. (2) In the stance phase, the rollover shape of a combination with a prosthetic foot-ankle unit and an unstable shoe shows constant curvature in comparison to prosthetic foot-ankle units. This demonstrates that an unstable shoe is one of the key components in amputee gait training because it can improve user activity level without a change in a prosthetic foot-ankle unit. The effectiveness of the dynamic rollover analysis for prosthetic foot-ankle units based on the ISO22675 gait simulated loading device was ascertained through a series of experiments.
