Changes in Gait and Radiographic and Clinical Results of Calcaneal Lengthening Osteotomy in Children with Idiopathic Flexible Flatfoot

BACKGROUD: In this study, we aimed to analyze kinematic and kinetic changes in gait and to assess radiographic and clinical improvement after calcaneal lengthening osteotomy (CLO) in children with idiopathic symptomatic flexible flatfoot deformities. METHODS: The study group consisted of 22 children (28 feet) with idiopathic symptomatic flexible flatfoot, which was treated by CLO as an index operation. We excluded patients with flatfoot that developed secondary to neuromuscular diseases. There were 18 boys (22 feet) and 4 girls (6 feet). The average age of the patients was 10.8 ± 1.51 years. Surgical results were assessed by radiologic imaging, clinical evaluation, and gait analysis, which were performed before surgery and 1 year after surgery. Medical records were reviewed to check postoperative complications. RESULTS: Talonavicular coverage was recovered to 16.7° from 32.7° (p < 0.01). Lateral talo-first metatarsal angle and calcaneal pitch angle increased by 20.1° and 9.9°, respectively (p < 0.01). Weight-bearing radiographs demonstrated a decrease in the anteroposterior angle and lateral talocalcaneal angle by 6.9° and 10°, respectively (p < 0.01). Hindfoot valgus was corrected to near neutral position after CLO. Kinematic results showed that the ankle valgus angle in the coronal plane was reduced from 35.48° preoperatively to 16.64° postoperatively during gait (p < 0.05). The preoperative out-toeing gait (preoperative foot progression angle, 20.31°) was also normalized to 14.21° postoperatively. The kinetics results showed that the push-off moment (maximum ankle plantar flexion) on the sagittal plane increased from 0.66 Nm/kg preoperatively to 0.83 Nm/kg postoperatively (p < 0.01). The mean Yoo score was 9.2 ± 1.05 postoperatively: satisfactory in 24 cases (86%) and unsatisfactory in 4 cases. Of the 4 unsatisfactory cases, 2 cases were overcorrection and 2 cases were undercorrection, and 3 of them were well managed by wedge foot insoles. CONCLUSIONS: The 3-dimensional deformities of the flexible flatfoot were effectively corrected by CLO, based on the morphological assessment using radiologic imaging. The correction was well maintained during gait at 1 year after the operation.