Background: A few studies have investigated the relationship between foot posture measures and plantar pressure parameters, but no study has investigated the correlation of foot posture measures with all primary parameters consisting of contact area (CA), maximum force (MF), and peak pressure (PP). We aimed to determine the relationship of Foot Posture Index-6 (FPI-6) and navicular drop (ND) with plantar pressure parameters during static standing and preferred walking.
Methods: Seventy people were included. ND and FPI-6 were used to assess foot posture. Plantar pressure parameters including CA, MF, and PP were recorded by a pressure-sensitive mat during barefoot standing and barefoot walking at preferred speed. All assessments were repeated three times and averaged. Pearson correlation coefficients below 0.300 were accepted as negligible and higher ones were interpreted.
Results: ND was moderately correlated with dynamic CA under the midfoot and second metatarsal (M2), also FPI-6 was moderately correlated with dynamic CA under the midfoot (0.500<r<0.700). The other interpreted correlations were poor (0.300<r<0.500). Both measures were correlated with dynamic CA under the M2 and M3, dynamic CA and MF under the midfoot, and static CA, MF, and PP under the M1 and hallux (p<0.01). ND was also correlated with dynamic MF under the M1 and dynamic CA under the M4 (p<0.01). Further, ND was correlated with static CA and PP under the M2 also static PP under the M5 (p<0.01). FPI-6 was also correlated with dynamic MF and PP under the hallux (p<0.01).
Conclusions: The correlations between foot posture measures and plantar pressure variables are poor to moderate. The measures may be useful in the clinical assessment of medial forefoot problems related to prolonged standing and midfoot complaints related to high force during walking. Further, FPI-6 may provide valuable data regarding hallux complaints related to the high loads during walking.
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.
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.
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).
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.