From September, 2019 to September, 2020, 42 subjects with AIS were selected and randomly divided into brace group (n = 21) and brace combined with insole group (n = 21). Both groups received two-month routine rehabilitation, including braces for 22 to 23 hours a day and gymnastics for 30 minutes a day. The brace combined with insole group additionally wore insoles, at least eight hours a day for two months. Meanwhile, 32 even-aged adolescents were recruited as healthy controls. Firstly, gait and plantar pressure of 42 patients and 32 healthy adolescents were compared to find out abnormal indicators. Secondly, the scoliosis and above abnormal indicators were compared between the brace group and the brace combined with insole group

The center of pressure excursion index (CPEI) was higher in AIS group than in the healthy group (F = 3.120, P < 0.05), and there was no significant difference in walking speed, gait cycle and phase between two groups (P>0.05). An obvious imbalanced pressure was observed between the medial and lateral heel of the single foot and the bilateral foot in AIS patients (P < 0.05). After treatment, the Cobb's angle decreased in AIS patients (t > 7.552, P < 0.001), however, no difference was found between the brace group and the brace combined with insole group (t = 0.459, P > 0.05); the CPEI decreased (t = 2.209, P < 0.05), and the pressure in medial and lateral heel as well as the left and right foot tended to be balanced (t > 2.306, P < 0.05) in the brace combined with insole group, and were better than that of the brace group (|t| > 2.319, P < 0.05).

Plantar pressure distribution shows obvious local and global asymmetric changes in AIS patients. The efficacy of insoles on the scoliosis is limited, but the insole can effectively improve the abnormal biomechanics and balance the force.