In the Moment: Foot Orthoses
By Emily Delzell
Varying rearfoot post angle levels in foot orthoses designed to correct pronation has dose-response effects at the rearfoot and knee in individuals both with and without pronated feet, according to a study published in May in the Journal of Biomechanics.
Researchers at Glasgow Caledonian University in Scotland recruited 12 individuals with symptomatic pronated feet and 12 matched controls, took weight-bearing foot surface scans, and used CAD-CAM to create nine foot orthoses for each participant.
The orthoses’ external rearfoot posting varied from 6° lateral to 10° medial in 2° increments. After two weeks of daily wear, volunteers underwent 3D gait analysis of rearfoot and knee kinematics and kinetics.
Peak rearfoot eversion decreased by about 2° with neutral posting and by up to 4° at the upper range of medial posting in pronators. The overall range of the dose response for kinematic variables around the neutral posting response was 2°–2.5°. External knee adduction moment (KAM) increased with medial posting and, in the control group, even laterally posted devices tended to increase KAM. The authors noted clinicians should be aware of the potential for this unintended effect.
Telfer S, Abbott M, Steultjens MP, Woodburn J. Dose-response effects of customised foot orthoses on lower limb kinematics and kinetics in pronated foot type. J Biomech 2013;46(9):1489-1495.