Analysis of Foot Kinematics with Unstable Sole Structure Using Oxford Foot Model

To determine the influence of the unstable sole structure on foot kinematics. 12 healthy female subjects walked through a 10-meter experimental channel with normal speed wearing experimental shoes and control shoes respectively. Differences between the groups in triplanar motion of the forefoot, rearfoot and hallux during walking were evaluated using a three-dimensional motion analysis system incorporating with Oxford Foot Model (OFM). Compare to the control group, subjects wearing unstable shoes demonstrated greater peak forefoot dorsiflexion, forefoot supination and longer time of hallux plantar-flexion in support phase. Additionally, subjects with unstable sole structure also demonstrated smaller peak forefoot plantar flexion, rearfoot dorsiflexion and range of rearfoot motion in sagittal and frontal plane. There is no significant difference between the groups in transverse plane. The unstable shoes with unstable structural elements leading to instability on foot motions. The difference mainly appeared in sagittal and frontal plane. A stimulation of unstable lead to the reinforcement of different flexion between middle and two ends of the foot model. The greater forefoot supination is inferred that unstable structure elements may has a control effect to strephexopodia people. The stimulation also reduce the range of rearfoot motion in sagittal and frontal planes to control the gravity center of the body and keep a steady state during walking.