Subtalar joint narthroereisis for the treatment of flexible flatfoot in children: a comparative efficacy study based on chronological age and bone age stratification

Objective To investigate subtalar joint arthroereisis efficacy for pediatric flexible flatfoot and analyze how chronological and bone age at surgery influence mid-term outcomes. Methods A retrospective cohort study included 92 children who received subtalar joint arthroereisis at our hospital between January 2012 and December 2020 (surgical age 6–15 years). Eleven children were lost to follow-up, and 81 patients with complete datasets entered final analysis. Patients were stratified by chronological age (Group A: 6–8 years; Group B: 9–12 years; Group C: 13–15 years) and by bone age determined via the Greulich-Pyle method. VAS, AOFAS score, and radiographic parameters (T1MT, T2MT, TCA, Meary's angle, calcaneal pitch, Kite's angle) were compared pre-operatively, 6 months post-operatively, and at final follow-up. Results At 6 months after surgery and the final follow-up, the VAS scores, AOFAS scores, and all imaging angles of the three groups were significantly improved compared with those before surgery ( P < 0.001). At the final follow-up, the scores and imaging angles of Group A and Group C decreased compared with those at 6 months after surgery, with statistically significant differences ( P < 0.0001). Only Group B maintained stable indicators, with no statistically significant difference between the results at 6 months after surgery and the final follow-up ( P > 0.05). Further analysis of bone age stratification confirmed that children aged 9–12 years had a greater reduction in VAS scores, a greater increase in AOFAS scores, and better corrective effects on imaging angles than those in other age groups, with the highest stability of long-term efficacy. Conclusion Within this cohort, children aged 9-12 years had the most stable mid-term outcomes after subtalar arthroereisis. Bone age acts as a valuable complementary reference for individualized surgical-timing decisions. Children aged 6-8 or 13-15 years had acceptable short-term effects but risk mid-term deterioration, requiring intensified long-term follow-up. Further large prospective multicenter studies are needed to validate these findings.