Background: Many indirect clinical techniques have been developed to assess foot posture; however, there is relatively little research investigating the relationships among these techniques. We investigated the relationships among the most commonly used clinical measures of foot posture-Foot Posture Index-6 (FPI-6), navicular drop (NDP), navicular drift (NDT), and static and dynamic arch indices (SAI and DAI)-in individuals with normal foot posture and those with pronated foot.
Methods: Sixty-three individuals with FPI-6 scores of 0 to 12 were included. A digital caliper was used to measure NDP and NDT; SAI and DAI were measured by electronic pedobarography. Assessments were applied on the dominant foot. Pearson correlation coefficients were calculated to determine the relationships among measures. Participants were classified into two groups, pronated foot (n = 33) and normal foot posture (n = 30), based on FPI-6 scores, providing a multisegmental and multiplanar assessment. The independent-samples t test was used to compare groups regarding NDP, NDT, SAI, and DAI.
Results: We found a high correlation between NDP and FPI-6 (r = 0.754) and between NDP and NDT (r = 0.778) (all P < .001). A moderate correlation was found between NDT and FPI-6 (r = 0.599) and between DAI and SAI (r = 0.519) (all P < .001). A negligible correlation was found between NDP and DAI (r = 0.268; P = .033). Furthermore, NDP, NDT, and DAI values were higher in individuals with pronated foot compared with those with normal posture (P < .001 for NDP and NDT; P = .022 for DAI), whereas SAI values were not (P = .837).
Conclusions: These results suggest that there are moderate-to-strong relationships among FPI-6, NDP, and NDT and between SAI and DAI. The NDP, NDT, and DAI are suitable for the classification of foot posture based on FPI-6 scores. This study can guide clinicians and researchers to associate the foot posture measures with each other.