Clinical measures of static foot posture do not agree

Abstract

Background: The aim of this study was to determine the level of agreement between common clinical foot classification measures. Methods: Static foot assessment was undertaken using the Foot Posture Index (FPI-6), rearfoot angle (RFA), medial longitudinal arch angle (MLAA) and navicular drop (ND) in 30 participants (29 ± 6 years, 1.72 ± 0.08 m, 75 ± 18 kg). The right foot was measured on two occasions by one rater within the same test environment. Agreement between the test sessions was initially determined for each measure using the Weighted Kappa. Agreement between the measures was determined using Fleiss Kappa. Results: Foot classification across the two test occasions was almost perfect for MLAA (Kw = .92) and FPI-6 (Kw = .92), moderate for RFA (Kw = .60) and fair for ND (Kw = .40) for comparison within the measures. Overall agreement between the measures for foot classification was moderate (Kf = .58). Conclusion:The findings reported in this study highlight discrepancies between the chosen foot classification measures. The FPI-6 was a reliable multi-planar measure whereas navicular drop emerged as an unreliable measure with only fair agreement across test sessions. The use of this measure for foot assessment is discouraged. The lack of strong consensus between measures for foot classification underpins the need for a consensus on appropriate clinical measures of foot structure.

Inter- and intraclass correlations for three standard foot radiographic measurements for plantar surface angles. Which measure is most reliable?

“…The LHI may therefore be considered the most useful, reliable, and reproducible variable. Static foot alignment is one of the factors that could increase the risk of injury and is frequently assessed in clinical practice (7). The correlations between the clinical and radiographic measures are at best moderate, and range from 0.24 to 0.74 (7,31).…”

“…Static foot alignment is one of the factors that could increase the risk of injury and is frequently assessed in clinical practice (7). The correlations between the clinical and radiographic measures are at best moderate, and range from 0.24 to 0.74 (7,31). Radiographic assessment requires specialized equipment and exposure to radiation, but remains the current 'gold standard'.…”

“…Plantar loading shows significant differences between flat and normal feet (3), and this could result in injury (4,5,6). Static assessment of the foot is common clinical practice, but the lack of repeatability and reliability are a concern (7,8,9). Numerous anthropometric measures have been suggested over the last three decades ranging from rearfoot angle, medial longitudinal arch angle, navicular drop, and footprint, but the 'gold standard' remains the lateral weight-bearing radiograph (2,7,10).…”

“…Static assessment of the foot is common clinical practice, but the lack of repeatability and reliability are a concern (7,8,9). Numerous anthropometric measures have been suggested over the last three decades ranging from rearfoot angle, medial longitudinal arch angle, navicular drop, and footprint, but the 'gold standard' remains the lateral weight-bearing radiograph (2,7,10). Digital photographic measurements have recently been shown to be highly reliable and valid (11).…”

Application of Zebris dynamometric platform and Arch Index in assessment of the longitudinal arch of the foot

“…Clarke angle Sztriter-Godunow Index KY Arch Index p = 0.0251 p = 0.0012 Clarke angle p = 0.0007 p < 0.05 significant statistical differences in occurrence in the compared groups. to a low reliability and repeatability [21]. Some authors describe inconsistency between various procedures of assessment of the longitudinal foot arch, and point out that these differences occur already in footprints made by means of different measurement techniques.…”