Factors influencing the flexible flatfoot in preschool children and analysis of the effects of orthopedic insoles

Abstract Purpose: To explore the influencing factors of flexible flatfoot in preschool children and effects of orthopedic insoles. Methods: 171 preschool children fitted with orthopedic insoles and revisited after 1 year, were selected as the experimental group, while 805 children matched as the control group. All included children were assessed for biomechanical parameters. Results: At follow-up, degree of flatfoot, calcaneal valgus angle, knee valgus angle, foot posture index, and joint flexibility were lower than at the initial visit in the experimental group (p<0.05). Calcaneal valgus angle, knee valgus angle, and foot posture index were lower than the control group(p<0.05). Age, and tibial torsion angle were negatively correlated (r=-0.19, -0.07, p<0.001) with degree of flatfoot, while hallux valgus angle, calcaneal valgus angle, knee valgus angle, navicular drop height, foot posture index, and body mass index were positively correlated (r=0.06, 0.39, 0.05, 0.38, 0.51, 0.16, p<0.05). Significant difference was found in degree of flatfoot between genders (χ²=99.76, p<0.001).Navicular drop height [OR:3.29 (95% CI: 2.55-4.23)], male gender [OR:1.77 (95% CI: 1.48-2.13)], foot posture index [OR:1.42 (95% CI: 1.33-1.48)], body mass index [OR:1.09 (95% CI: 1.06-1.12)], heel valgus angle [OR:1.10 (95% CI: 1.06-1.15)], and age [OR:0.78(95% CI: 0.73-0.83)] were factors influencing degree of flatfoot (p<0.05). Conclusion: Degree of flatfoot in preschool children is influenced by navicular drop height, gender, foot posture index, body mass index, heel valgus angle, and age. With growth, there may be some relief. Orthopedic insoles can to some extent correct heel and knee valgus, but it cannot reduce degree of flatfoot.