Background: The purpose of this study was to establish the effect of simple non moulded flat based insoles on three-dimensional foot motion during normal walking. Excessive foot pronation is considered a major contributing factor to lower limb injuries. Moulded foot orthoses have been shown to decrease maximum foot eversion. Simple insoles are widely used in clinical practice as an alternative to moulded orthoses. However, there has been little research into the kinematic effects of simple insoles.
Methods: All subjects had an inverted rearfoot and forefoot position when the subtalar joint was placed in neutral, which was assessed by a weight bearing goniometer. Rotations of the whole foot about three orthogonal axes relative to the shank were estimated using a five camera motion analysis system.
Findings: Biplanar insoles significantly (P < 0.05) reduced maximum eversion by an average of 3.1 degrees when compared to the no insole condition. The cobra insole reduced maximum eversion by an average of 2.1 degrees when compared to the no insole condition. This difference approached statistical significance (P = 0.058).
Interpretation: Biplanar and cobra insoles had no significant effect on maximum dorsiflexion, abduction or rate of eversion, when compared to the no insole condition. These results provide some limited support for the use of simple insoles to control for excessive foot pronation during walking.