Effects of orthotic insole on peak plantar pressure, center of pressure trajectory, and muscle activity of lower limb during one leg standing in adults with flexible flat foot

Dept. of Rehabilitation Therapy/석사A flat foot is a commonly observed abnormal foot posture. Flexible flat foot, is characterized by a dropped medial longitudinal arch when loaded. The purpose of this study was to identify differences in peak plantar pressure (PP), center of pressure trajectory (COPT), and the muscle activity pattern of the hip and knee joint with and without orthotic insole during one leg standing (OLS) in people with flexible flat foot. The research hypothesis was that, in subjects with flexible flat foot, use of an orthotic insole would reduce PP, and COPT and would alter the muscle activity pattern of the lower extremity during OLS. Fifteen subjects with flexible flat foot (six males, nine females) participated. Two screening testing (the navicular drop test and the OLS test) were administered. PP, COPT, and ratio of lateral/medial PP were measured using a flexible F-Scan insole sensing system, and the muscle activity ratio was determined using surface electromyography. A paired t-test was used to test statistical differences, with a significance level of 0.05. PP, ratio of lateral/medial PP, and COPT measurements demonstrated a significant difference between the two conditions (with and without orthotic insole) during OLS (p<0.05). The VMO/VL activity ratio was significantly greater with an orthotic insole during OLS (p<0.05). The findings of this study suggest that PP, COPT, and the VMO/VM muscle activity ratio were changed by using an orthotic insole at the plantar surface. Thus, the use of orthotic insole for subjects with flexible flat foot is recommended for reducing plantar pressure, decreasing COPT, and increasing ratio of lateral/medial PP and muscle activity ratio of VMO/VL.restrictio