The Effect of Medical Insoles on the Kinematics of Lower-Limb Joints in People with Flexible Flatfeet during Walking

Since the height of the medial longitudinal arch decreases in people with flatfeet, thereby resulting in biomechanical changes in the foot-ankle complex, the use of medical insoles as a common treatment has been of interest for therapists. The aim of the present study was to investigate the effect of using medical insoles on the kinematics of lower-limb joints during walking in male athletes with flexible flatfeet. 

A total of 15 male athletes with flexible flatfeet with mean±standard deviation (SD) of age of 21.33±3.39 years, height of 178.72±5.28 cm, and weight of 71.76±8.04 kg participated in the study. The peak angles of ankle, knee, and hip movements in the stance phase of gait in three conditions (bare feet, sandals with insoles, and sandals without insoles) were assessed by eight motion analysis capture cameras (VICON UK). Data analysis was carried out by repeated measures ANOVA and Bonferroni post-hoc test in SPSS software. P-value≤0.05 was considered as the significance level. 

The findings showed that in individuals with flatfeet, the variables of the peak points of the ankle dorsiflexion (P=0.001) in mid-stance and knee flexion (P=0.001) in loading response were significantly different between test conditions. However, there was no significant difference between the peak points for the ankle plantar flexion (P=0.24), knee extension (P=0.92), and hip extension (P=0.87). 

The results showed that controlling the foot motion during walking using sandals and custom medical insoles can make changes in the kinematics of the ankle and knee joints. However, it did not have a significant effect on hip kinematics.