Biocompatible screw-based biomechanical alignment technique for improving surgical effect in adolescent flexible flatfoot

The surgical management of adolescent flexible flatfoot with accessory navicular injury remains controversial. We developed a minimally invasive technique combining biocompatible screw–based hindfoot biomechanical alignment correction with Kidner surgery. A biocompatible screw was implanted in the tarsal sinus to stabilize the subtalar joint and maintain normal anatomical relationships of the talocalcaneal and talonavicular joints, thereby correcting hindfoot alignment. Postoperatively, the hindfoot valgus angle improved significantly from 11.3° ± 3.3° to 3.0° ± 1.6° ( P < 0.001), and the Meary angle decreased from 19.8° ± 9.4° to 4.6° ± 4.1° ( P < 0.001), indicating effective reconstruction of hindfoot and midfoot alignment. Functional outcomes also improved markedly: AOFAS scores rose from 71.6 ± 12.8 preoperatively to 93.7 ± 8.1 postoperatively ( P < 0.001), and VAS pain scores dropped from 6.1 ± 3.1 to 2.6 ± 1.1 ( P < 0.001). No serious complications were observed during follow-up, and the biocompatible screws demonstrated excellent stability and biocompatibility. Our findings suggest that this combined approach effectively corrects pathological biomechanics, achieves anatomical realignment, and significantly enhances functional recovery while alleviating pain. It represents a safe, feasible, and promising strategy for treating adolescent flexible flatfoot with accessory navicular injury, offering a novel pathway toward precise, minimally invasive care.