Article

Passive-dynamic ankle-foot orthoses (AFOs) are commonly prescribed to improve
locomotion for people with lower limb musculoskeletal weakness. The clinical
prescription and design process are typically qualitative and based on
observational assessment and experience. Prior work examining the effect of AFO
design characteristics generally excludes higher impact activities such as
running, providing clinicians and researchers limited information to guide the
development of objective prescription guidelines.
The proximal location of the
bending axis may directly influence energy storage and return and resulting
running mechanics. The purpose of this study was to determine if the location of
an AFO's bending axis influences running mechanics. Marker and force data were
recorded as 12 participants with lower extremity weakness ran overground while
wearing a passive-dynamic AFO with posterior struts manufactured with central
(middle) and off-centered (high and low) bending axes. Lower extremity joint
angles, moments, powers, and ground reaction forces were calculated and compared
between limbs and across bending axis conditions. Bending axis produced
relatively small but significant changes. Ankle range of motion increased as the
bending axis shifted distally (p<0.003). Peak ankle power absorption was greater
in the low axis than high (p=0.013), and peak power generation was greater in the
low condition than middle or high conditions (p<0.009). Half of the participants
preferred the middle bending axis, four preferred low and two preferred high.
Overall, if greater ankle range of motion is tolerated, a low bending axis
provides power and propulsive benefits during running, although individual
preference and physical ability should also be considered.
CI - Published by Elsevier B.V.

Langue : ANGLAIS