Individuals with transtibial amputations show a greater peak prosthetic ankle power (push-off) when using energy storing and returning (ESAR) prosthetic feet compared to SACH feet. Since ESAR feet further contribute to the users’ body support, prosthetic ankle motion is limited. Articulating prosthetic feet improve ankle motion but may diminish push-off.
A study published online in Gait & Posture in May considered the kinematic and kinetic advantages of a novel foot prosthesis with a serial layout of carbon fiber leaf springs connected by a multi-center joint construction may have over a conventional ESAR prosthetic foot.
Eleven individuals with unilateral transtibial amputations were fitted with the novel foot and a conventional ESAR foot (CF) and underwent 3D gait analysis. As an additional power estimate of the prosthetic ankle, a unified, deformable segment model approach was applied. Eleven matched individuals without impairments served as a reference. Results determined that the novel foot showed an effective prosthetic ankle range of motion (ROM) that was closer to a physiologic ankle ROM, at 31.6 degrees compared to 15.2 degrees with CF, without reducing the maximum prosthetic ankle joint moment. The novel foot also showed a greater increase in prosthetic ankle power and a reduction of 19 percent in the peak knee varus moment and 13 percent in vertical ground reaction forces on the sound side for novel foot in comparison to CF, the study found.
The novel foot prosthesis showed that serial carbon fiber leaf springs connected by a multi-center joint construction allow for larger ankle joint ROM and higher ankle power than only a conventional carbon fiber structure. Consequently, load is taken off the contralateral limb, as measured by the decrease in vertical ground reaction forces and peak knee varus moment, the study showed.
