Though mechanical properties of prosthetic feet can significantly influence the gait of an individual with an amputation, how they vary with respect to limb loading and orientation is infrequently reported.
A study published online January 28 in Prosthetics and Orthotics International measured stiffness and energy-storage characteristics of prosthetic feet across limb loading and a range of orientations experienced in typical gait.
Force-displacement data was collected at combinations of 15 sagittal and five coronal orientations and used to calculate stiffness and energy storage across prosthetic feet, stiffness categories, and heel wedge conditions.
The study found that stiffness and energy storage were highly non-linear in the sagittal and coronal planes. Across all prosthetic feet, stiffness decreased with greater heel, forefoot, medial, and lateral orientations, while energy storage increased with forefoot, medial, and lateral loading orientations. Stiffness category was proportional to stiffness and inversely proportional to energy storage, the study found. Heel wedge effects were also prosthetic foot–dependent, and orientation, manufacturer, stiffness category, and heel wedge inclusion influenced stiffness and energy storage characteristics of prosthetic feet.
