Intra- and interday reliability of the dynamic navicular rise, a new measure for dynamic foot function : A descriptive, cross-sectional laboratory study

Background

The lack of reliable parameters to evaluate dynamic foot function, emphasizes the need for a deeper insight in foot biomechanics. The aims were to investigate the reliability of a new parameter (dynamic navicular rise dNR), and its relationship with the dynamic navicular drop (dND).
Methods

Twenty healthy participants (mean age 30.2 ± 8.1 years) had to walk on even ground and downstairs. Data of ten trials per task on two measurement days were recorded. The dNR was defined as the difference in millimetres (mm) between the minimum navicular height (NH) during stance and the NH at toe off. To test intra- and interday reliability, Intraclass Correlation Coefficients (ICC2.1) and repeatability were calculated. To obtain the absolute repeatability (RP) in mm, the equation RP = 1.96 × SDdifferences was used. Furthermore, the relationship between the dNR and the dND was examined by calculating Pearson (r) or Spearman (rs) correlation coefficients.
Results

Included participants showed a mean dNR of (12.2 ± 3.7) mm for level walking and (14.8 ± 3.4) mm for stair descent. The ICC2.1 for the dNR were 0.98 (intraday), 0.91 (interday) for level walking and 0.97 (intraday), 0.94 (interday) for stair descent. The interday repeatability was 3.2 mm (level walking), 2.7 mm (stair descent) respectively. For level walking, r was 0.31 (p = 0.049), and rs = 0.88 (p < 0.001) for stair descent.
Conclusions

The dNR seems to be highly reliable (ICCs), however, repeatability is unacceptable. For level walking, the dNR might be an independent measure, but not for stair climbing.

Keywords

Gait analysis ; Motion analysis ; Foot function ; Navicular bone ; Dynamic navicular drop