P 170- Effect of sensorimotor foot orthoses on kinematics of knee

Abstract

1. Introduction
Sensorimotor foot orthoses (FO) is concept that is reported to deliver both mechanical effect and influence muscle function [1]. This concept has not yet been fully scientifically explored. In this study we focused on the effect of two types of FO on knee kinematics.

2. Research question
What are the effects of sensorimotor FO on knee kinematics?

3. Methods
Eleven healthy subjects (7 males, 4 females, mean age 23.0 ± 3.3) were tested under three conditions: a) no FO, b) FO with retrocapital pad attached behind second to fifth metatarsal with elevation to medial side (RM), c) FO with an elevation to lateral side (RL). All measurements were conducted whilst wearing the same type of shoes (ProTouch Drop Shot). Eight trials were recorded for each condition using a Vicon MX system (200 Hz), with a 5 min initial familiarization and “wash out” period between conditions. A Repeated Measures ANOVA with post hoc pairwise comparison using the least significance difference method was used to explore the differences between conditions, with the significance level 0.05. The dependent variables were knee flexion at heel strike (HS), the first peak of knee flexion and sagittal plane range of motion (ROM), transverse plane knee rotation at (HS), peak knee internal rotation during midstance and ROM in transverse plane.

4. Results
In sagittal plane, there was a significant difference at the first peak knee flexion (p = 0.03; ηp² = 0.297). Further pairwise comparisons revealed that both RM and RL increased flexion, RL significantly (p = 0.11) by 0.936 degrees (std. error = 0.302). In the transverse plane there were significant differences in peak knee internal rotation (p = 0.037; ηp² = 0.280) and ROM between HS and peak knee internal rotation during midstance (p = 0.004; ηp² = 0.427). Further pairwise comparisons revealed that both RL and RM increased the peak internal rotation, RL significantly by 3.1 degrees (p = 0.041), and both RL and RM significantly increased transverse plane ROM, with RM increasing ROM by 1.7 degrees and RL increasing ROM by 2.57 degrees (p = 0.01).

5. Discussion
The results of this study correspond with current knowledge that links knee flexion and internal rotation, as flexion increases so does internal rotation. Our findings show that both FO affected knee rotation in the same way albeit by different amounts. This is not in agreement with their perceive function, with RL theoretically promoting external rotation and RM theoretically promoting internal rotation.