International normative data for paediatric foot posture assessment: a cross-sectional investigation

OBJECTIVES: The foot posture index (FPI) is an observational tool designed to measure the position of the foot. The objective of this study was to establish international reference data for foot posture across childhood, and influence of body mass index (BMI) on paediatric foot posture. DESIGN: Cross-sectional study. SETTING AND PARTICIPANTS: The dataset comprised 3217 healthy children, aged from 3 to 15 years. Contributing data were acquired from Spain, UK and Australia. INTERVENTIONS: Foot posture was described by means and z-score of the FPI and the height and weight of each subject was measured and the BMI was calculated. RESULTS: The foot posture of 3217 children were reviewed. A pronated (FPI ≥+6) foot posture was found in 960 (29.8%) children, a normal (FPI 0 to +6) foot posture in 1776 (55.2%) and a highly pronated (FPI +10) foot posture was found in 127 children (3.9%) (range −4 to +12 FPI). Less than 11% were found to have a supinated foot type (n=354). Approximately 20% of children were overweight/obese, but correlation between BMI and FPI was weak and inverse (r=−0.066, p<0.01), refuting the relationship between increased body mass and flatfeet. CONCLUSIONS: This study confirms that the ‘flat’ or pronated foot is the common foot posture of childhood, with FPI score of +4 (3) the average finding. Trend indicated a less flatfoot with age, although non-linear. A wide normal range of foot posture across childhood is confirmed.