Article

Customised foot orthoses (FOs) featuring extrinsic rearfoot posting are commonly
prescribed for individuals with a symptomatic pronated foot type. By altering the
angle of the posting it is purported that a controlled dose-response effect
during the stance phase of gait can be achieved, however these biomechanical
changes have yet to be characterised. Customised FOs were administered to
participant groups with symptomatic pronated foot types and asymptomatic normal
foot types. The electromyographic (EMG) and plantar pressure effects of varying
the dose were measured. Dose was varied by changing the angle of posting from 6
degrees lateral to 10 degrees medial in 2 degrees steps on customised devices
produced using computer aided orthoses design software. No effects due to posting
level were found for EMG variables. Significant group effects were seen with
customised FOs reducing above knee muscle activity in pronated foot types
compared to normal foot types (biceps femoris p=0.022; vastus lateralis p<0.001;
vastus medialis p=0.001). Interaction effects were seen for gastrocnemius
medialis and soleus. Significant linear effects of posting level were seen for
plantar pressure at the lateral rearfoot (p=0.001), midfoot (p<0.001) and lateral
forefoot (p=0.002). A group effect was also seen for plantar pressure at the
medial heel (p=0.009). This study provides evidence that a customised FOs can
provide a dose response effect for selected plantar pressure variables, but no
such effect could be identified for muscle activity. Foot type may play an
important role in the effect of customised orthoses on activity of muscles above
the knee.
CI - Copyright (c) 2013 Elsevier B.V. All rights reserved.

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