BackgroundPediatric flexible flatfoot is sometimes asymptomatic but it can rarely cause physical impairment, pain, and difficulty walking. We evaluated the radiographic effectiveness of intervention of subtalar arthroereisis with endorthesis for pediatric flexible flatfoot with final follow-up at skeletal maturity. MethodsThis is a retrospective cross-sectional study. 56 consecutive patients (112 feet) who underwent surgical treatment with subtalar arthroereisis for pediatric flexible flatfoot (mean age at final follow-up 15.5±1.2 years, 39.3% female) were enrolled. All the radiographic studies were performed in the hospital. Radiographs (standard weight-bearing radiographs of the foot with anteroposterior and lateral view) were used to measure lateral talocalcaneal angle (LTC), calcaneal pitch angle (CP), Meary’s angle (MA), anteroposterior talonavicular angle (APTN), talonavicular uncoverage percent (TNU). Minimum follow-up was 18 months. Measures were assessed pre-operatively and at the final follow-up. Clinical and functional parameters were assessed at the final follow-up. ResultsChildren who underwent surgical treatment with subtalar arthroereisis for pediatric flexible flatfoot exhibited a statistically significant improvement in all radiographic measurement parameters at the last follow-up at skeletal maturity (all, p<0.004). Mean follow-up was 40.1±23.6months. Clinical parameters were not correlated with the foot radiographic parameters at follow up period. ConclusionsOur results suggest that endorthesis in pediatric flexible flatfoot was effective for improving radiographic parameters at skeletal maturity. The amount of the morphologic correction at the end of the skeletal growth should be expected mainly for lateral tarso-metatarsal alignment and talo-navicular congruency (MA, APTN, TNU). Level of evidenceLevel III, retrospective study.