Clinical and radiographic outcomes of the calcaneo-stop procedure for symptomatic flexible flatfoot in adolescents : A retrospective cohort study of 160 feet.

Abstract

Background: Symptomatic flexible flatfoot is a common musculoskeletal disorder among children and adolescents, characterized by hindfoot valgus, medial arch collapse and forefoot abduction under weight-bearing conditions. When conservative treatment fails, the calcaneo-stop procedure offers a minimally invasive, joint-preserving surgical option.

Objective: To evaluate the clinical and radiological outcomes of the calcaneo-stop procedure in adolescents with symptomatic flexible flatfoot refractory to conservative care, with emphasis on postoperative complications and their management.

Patients and methods: A retrospective cohort analysis was conducted on 160 feet in 90 patients (45 males, 45 females) aged 12-17 years. Clinical outcomes were assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and hindfoot valgus angle. Radiological parameters included calcaneal pitch angle, Kite's angle, talar declination angle, Meary's angle and talonavicular coverage angle, evaluated preoperatively, immediately postoperatively and at final follow-up (mean 24.3 ± 1.8 months). A linear mixed-effects model was employed to account for bilateral clustering (70 patients with bilateral procedures).

Results: All radiological parameters and functional outcome scores demonstrated statistically significant improvement (all p < 0.001) with large effect sizes (η² = 0.415-0.678). Hindfoot valgus angle decreased from 10.12° ± 1.83° preoperatively to 3.03° ± 1.15° at final follow-up (total reduction 7.07°). Calcaneal pitch increased by 5.51° (12.58° ± 2.11° to 18.09° ± 1.71°). Kite's angle declined by 7.34° (32.44° ± 3.20° to 25.10° ± 2.53°), talar declination by 10.02° (40.88° ± 4.17° to 30.93° ± 3.28°), Meary's angle by 6.97° (21.04° ± 3.45° to 14.18° ± 2.54°) and talonavicular coverage angle by 8.33° (28.71 ± 3.38° to 20.39 ± 2.61°). The AOFAS score improved from 72.17 ± 7.34 to 92.08 ± 5.91 (total gain + 19.92 points). Mixed-effects modelling confirmed these findings after accounting for within-patient clustering (intraclass correlation coefficient, ICC = 0.21-0.27). Postoperative complications occurred in 15 feet (9.375%), including surgical site pain (3.75%), local wound swelling (2.50%), superficial infection (1.25%), asymptomatic screw loosening (1.25%) and overcorrection requiring screw revision (0.625%). All complications resolved without implant removal.

Conclusion: The calcaneo-stop procedure was associated with statistically significant and clinically meaningful improvements in functional scores and multiplanar radiological parameters at a mean follow-up of 24.3 months in skeletally immature patients. The observed complication rate of 9.375% appears comparable with previously published series. Longer follow-up beyond skeletal maturity and implant removal is required to establish the durability of correction.

Level of evidence: IV.