VARIABLES TO BE COLLECTED AND SOURCE The primary efficacy endpoint will be the maintenance of flatfoot correction over time, assessed both clinically (tip-toe test, Jack test, tip-toe walking test) and radiologically (evaluation of Meary's angle on the lateral foot view and the talocalcaneal angle).

The secondary efficacy endpoint will be the absence of pain at follow-up, assessed using the VAS scale, and evaluation of the footprint using a podoscope.

TIP-TOE TEST:

The patient is observed under weight-bearing conditions and then while rising onto the toes. If the foot is flexible, the plantar arch-previously absent-reappears when standing on tip-toe.

JACK TEST:

This consists of passive dorsiflexion of the hallux under weight-bearing conditions. If the previously absent arch reappears, the flatfoot is considered flexible.

TIP-TOE WALKING TEST:

The patient walks for about ten steps on tip-toe. The examiner observes any varus alignment of the hindfoot and reconstruction of the plantar arch.

MEARY'S ANGLE:

Measured between the longitudinal axis of the talus and that of the first metatarsal on a weight-bearing lateral foot radiograph.

TALOCALCANEAL ANGLE:

Measured between the longitudinal axis of the talus and that of the calcaneus on a weight-bearing dorsoplantar foot radiograph.

VAS:

The Visual Analog Scale for pain is a tool used to measure the subjective characteristics of pain experienced by the patient, ranging from 0 (no pain) to 10 (worst imaginable pain).

PODOSCOPE FOOTPRINT ASSESSMENT:

Evaluation of the isthmus (the narrow portion of the footprint connecting the heel to the forefoot). The foot is considered normal when the width of the isthmus is between one-third and one-half of the maximum width of the forefoot.

SAMPLE SIZE AND STATISTICS In Prof. Giannini's study, 30 patients were enrolled; approximately 30% were lost to follow-up over 12 years. Barring further losses, about 20 patients currently followed at Clinic I are expected to be available.

ENROLLMENT PROCEDURE Eligible patients will be enrolled in the study only after providing written informed consent. No data collection, procedures, or analyses will be performed prior to obtaining consent.

DATA COLLECTION Clinical data required for the study will be extracted from patients' medical records and source documents.

A dedicated data collection form will be used to record clinical information and the results of the analyses by the study.

For each enrolled patient, a Case Report Form (CRF) will be completed.

INCLUSION CRITERIA:

Patients already in follow-up after undergoing subtalar arthroereisis with calcaneostop and endorthosis, enrolled in the study "Flatfoot treatment: comparison between resorbable endorthosis and resorbable calcaneal stop" by Prof. Giannini, still in follow-up at IOR.

EXCLUSION CRITERIA:

Patients who have undergone subsequent surgical procedures on the foot and ankle

Primary objective:

To evaluate, at more than ten years' follow-up, the clinical and radiological outcomes of patients who underwent subtalar arthroereisis with calcaneostop and endorthosis for the correction of pediatric flatfoot.

Secondary objectives:

To compare, within the same patient, the clinical and radiological outcomes of feet treated with subtalar arthroereisis using calcaneostop versus endorthosis.