The Relationship Between The Navicular Drop And Arch Index As Clinical Measures Of Foot Posture

Background Various different clinical and radiographic measures of foot posture have been reported in the literature. Two of the more widely used clinical measures are the navicular drop and the arch index. Despite their common use, there is little in the way of research assessing the degree of correlation between them. Aim of the Study To determine the degree of correlation between the arch index and the navicular drop. Method A total of 14 school children from a single primary school were recruited for this study. Navicular drop and arch index measures were taken from each participant in one single session. Ten of 14 participants (average age of 10.4 years) were used for statistical analysis. Both the traditional measures of arch index and navicular drop were calculated along with a novel method of calculating the navicular drop as a percentage change. Data Analysis All data was analysed using the statistical package for social sciences (SPSS) software. Pearson's correlation was used to assess the degree of correlation between the arch index and the navicular drop (mm and percentage change) in both feet. Kappa analysis was performed for secondary analysis to see if these two measures agreed once the numerical data was transformed into its categorical form. Results Strong correlation was noted between the right foot navicular drop (percentage change) and arch index (r=0.971) but poor in the left foot (r=0.429). There was poor correlation between the traditional measure of navicular drop and arch index for both feet (left foot, r= 0.496, right foot, r= -0.541). Kappa analysis showed poor agreement between the two measures of navicular drop (mm) and arch index (right foot 0.23, left foot 0.166) Conclusion The results of this study are inconclusive. In the right foot, strong correlation was noted between the arch index and the navicular drop (percentage change). In the left foot, correlation was poor. Kappa analysis demonstrated the 2 measures do not agree. Further research of good methodological quality is needed to assess the degree of correlation between measures of foot posture.msc_podsurunpub1528_ethesesunpu