Impacts of Different Arch Stiffness on Lower Extremity Joint Kinematics during Unexpected Gait Termination

Abstract

The purpose of this study was to compare the lower limb kinematic characteristics of individuals with different arch stiffness during unexpected gait termination (UGT) and to investigate the functional biomechanical adjustment and human compensation mechanism of gait termination related to the morphological characteristics of the foot arch. Sixty-five healthy male subjects were recruited to complete this biomechanical test. An Easy-Foot-Scan scanner was used to acquire the morphological parameters of the foot arch in standing and sitting positions, and the subjects were divided into stiff and flexible arch groups according to the calculated arch stiffness index (ASI). A Vicon motion capture system was used to capture hip, knee, ankle, and metatarsophalangeal joint (MPJ) kinematic data during the UGT task. It was found that the flexible arch had a significantly greater range of motion (ROM) in the frontal plane of the knee compared to the stiff arch. The stiff arch group showed a greater ROM in the sagittal plane of the ankle joint. The ROM was greater in the flexible arch group in the frontal plane. For the MPJ, the joint angle in the frontal plane was significantly greater in the stiff arch group than in the flexible arch group. The differences in biomechanical characteristics due to different arch stiffnesses were mainly concentrated in the distal joints. During UGT, the arch must bear and distribute the impact load transmitted to the foot. The flexible arch is more easily compressed, thus reducing the medial longitudinal arch height and leading to a limited windlass mechanism.