Article

Over the last half-century, the field of prosthetic engineering has continuously
evolved with much attention being dedicated to restoring the mechanical energy
properties of ankle joint musculatures during gait. However, the contributions of
'distal foot structures' (e.g., foot muscles, plantar soft tissue) have been
overlooked. Therefore, the purpose of this study was to quantify the total
mechanical energy profiles (e.g., power, work, and work-ratio) of the natural
ankle-foot system (NAFS) by combining the contributions of the ankle joint and
all distal foot structures during stance in level-ground steady state walking
across various speeds (0.4, 0.6, 0.8 and 1.0 statures/s). The results from eleven
healthy subjects walking barefoot indicated ankle joint and distal foot
structures generally performed opposing roles: the ankle joint performed net
positive work that systematically increased its energy generation with faster
walking speeds, while the distal foot performed net negative work that
systematically increased its energy absorption with faster walking speeds.
Accounting for these simultaneous effects, the combined ankle-foot system
exhibited increased work-ratios with faster walking. Most notably, the work-ratio
was not significantly greater than 1.0 during the normal walking speed of 0.8
statures/s. Therefore, a prosthetic design that strategically exploits
passive-dynamic properties (e.g., elastic energy storage and return) has the
potential to replicate the mechanical energy profiles of the NAFS during
level-ground steady-state walking.
CI - Copyright (c) 2013 Elsevier B.V. All rights reserved.

Langue : ANGLAIS