Changes in Resting Calcaneal Stance Position Angle Following Insole Fitting in Children With Flexible Flatfoot

OBJECTIVE To clarify the relationship of the initial radiologic and a biomechanical parameter at first clinical visit, and define the effectiveness of modified insole, following insole fitting in children with flexible flatfoot. METHODS Children aged less than 13 years with flexible flatfoot were enrolled. The total number of subjects was 66 (33 boys, 33 girls). The subjects were divided into 5 subgroups, based on age: 1-2, 3-4, 5-6, 7-9, and 10-12 years. The mean time period between the initial & final examination for their resting calcaneal stance position angle (RCSPA) was 24 months. Radiography quantified the deformity by measuring angles, including the talometatarsal angle, the metatarsal angle, and the calcaneal pitch angle. RESULTS From the angles measured on radiographs, only the talometatarsal angle showed a statistically significant correlation to the initial RCSPA (r=-0.578 for right side, r=-0.524 for left side; p<0.01). The mean RCSPA improved in all subgroups of subjects following insole fitting. Moreover, in children younger than 7 years, the improvement in RCSPA from the insole fitting was greater compared to children aged 7 years and older. CONCLUSION The insole has additionally beneficial effects in all populations younger than 13 years. However, there might exist a hidden effect of normal structural pedal alignment during growth accompanied with bony maturation and developmental process. To date, it is controversial whether the treatment of flexible flatfoot is necessary in the vast majority of cases, or simple observation and advice to parents would suffice.