Reference values for foot morphological characteristics: a cross-sectional study of urban Chinese children aged 9–36 months

BACKGROUND: The first three years are critical for foot development, yet standardised assessments are lacking. AIM: This study aimed to establish sex-specific reference percentiles for key foot dimensions in Chinese children under three years of age. SUBJECTS AND METHODS: We recruited 6,284 children aged 9-36 months from a child health clinic in Xi'an, China. Foot length, width, calcaneal eversion angle, and the arch index were measured from static, weight-bearing images. Sex-specific percentile curves were constructed using the Generalised Additive Model for Location, Scale, and Shape (GAMLSS). RESULTS: Foot length, width, and arch index increased with age, whereas the foot width/length ratio and calcaneal eversion angle decreased. Median (P50) foot length increased from 11.29 cm to 15.07 cm in boys and from 10.95 cm to 14.76 cm in girls. Corresponding values for foot width were 5.37-6.50 cm (boys) and 5.15-6.30 cm (girls). The arch index rose from 0.04 to 0.18 (boys) and 0.06 to 0.23 (girls), while the foot width/length ratio declined from 47.45% to 43.04% (boys) and 47.03% to 42.51% (girls). CONCLUSION: This study provides the first foot morphology reference standards for urban Chinese children under three years of age, offering essential data for early foot structure assessment in this population.