Foot bone structure and plantar soft tissue deformation behavior in different functional positions

Background: Although the static structure of the foot arch has been extensively investigated, limited information exists on the deformation of arch bones and plantar soft tissue during gait. This study aimed to evaluate the dynamic changes in foot bones and plantar soft tissues at three key gait phases (non-weight-bearing, weight-bearing, and tiptoe positions) and to analyze sagittal plane arch motion. Methods: Sixty-seven participants underwent three-dimensional (3D) plantar scans and X-ray imaging in the three key positions. Radiographic measurements included the talo-first metatarsal angle, calcaneal pitch angle, medial arch angle, lateral arch angle, calcaneus-fifth metatarsal angle, anterior arch angle, and posterior arch angle. The arch index and arch volume were derived from a 3D foot model. Results: Significant differences were observed in radiographic angles and morphological parameters across positions (P