The purpose of this study was to investigate whether any relationships exist between the presence of flatfoot and ultrasonographic morphometric findings of Achilles tendon in children.

The study included 30 pediatric patients with a mean age of 11.96±2.44 (SD) years (range: 9–16 years) with flexible flatfoot and 29 healthy pediatric controls who were matched for age and served as a control group. Demographic data of both groups such as age, height and weight, and anthropometric measurements including leg length and, length and cross-sectional area of the Achilles tendon on ultrasonography were tabulated. Relationships between the cross-sectional area of Achilles tendon and flatfoot and the other parameters were searched for using backward multiple regression analysis.

No associations between flatfoot and length and cross-sectional area of the Achilles tendon, age, height, leg and foot length were found. A negative correlation was found between the cross-sectional area of Achilles tendon and presence of flatfoot (Beta=−4.93, P=0.01) and age (Beta=−1.96, P=0.04). A positive correlation was found between the cross-sectional area of Achilles tendon and shoe size (Beta=2.13, P=0.007).

Flatfoot, shoe size, age and weight must be kept in mind as a clue for a thinner Achilles tendon morphometry which can be a risk factor in lower limb pathologies.