Prosthetic foot rollover shapes with implications for alignment of transtibial prostheses

Abstract

Rollover shape is introduced as a significant characteristic of prosthetic feet. The rollover shapes of the Flexwalk, Quantum, SACH, and SAFE prosthetic feet were determined using three methods; two involving quasistatic loading and one dynamic loading. The results show that foot rollover shape properties obtained by quasistatic and by dynamic methods are similar. Relationships between foot rollover shape and the alignment of transtibial prostheses are introduced that suggest ways to align transtibial prostheses without walking trials and iterations. The relationships may explain what prosthetists attempt to accomplish when they dynamically align a transtibial limb. They also explain why prosthetic feet with different mechanical properties usually necessitate different alignments, and may explain why a number of gait studies of transtibial amputees do not show major gait differences when walking is executed on various kinds of prosthetic feet.