A comparison of foot posture and walking performance in patients with mild, moderate, and severe adolescent idiopathic scoliosis

Background Adolescent idiopathic scoliosis (AIS) is the most common form of scoliosis. However, the underlying mechanisms linking spinal curvature in AIS to foot characteristics and walking performance remain unclear. Objective This study aimed to compare walking performance between adolescents with mild, moderate, and severe scoliosis and matched healthy peers with foot posture as covariates. Methods This cross-sectional study of 96 adolescents was conducted between April 2020 to October 2020 in China, with 32 healthy peers in the control group and 64 patients in the AIS group. Foot posture and morphology, plantar pressure distribution, and gait characteristics were analyzed. One-way analysis of variance with Bonferroni correction and a post hoc comparison of the mean differences between the different groups was performed. Multiple analyses of covariance adjusted for age, sex, body mass index, foot posture index (FPI), arch index (AI), and walking speed were performed. Results Of the 64 adolescents with scoliosis, 18 had mild AIS, 32 had moderate AIS, and 14 had severe AIS. The AI and FPI were much higher in the moderate and severe AIS groups (p = 0.018) and the severe AIS group (p<0.001), respectively, than in the control group. The severe AIS group had advanced and longer midstance (p = 0.014) and delayed propulsion phase (p = 0.013) than the control group. Patients with moderate and severe AIS had asymmetrical gait periods in the left and right limbs (p<0.05). Significant differences in the center-of-pressure excursion index (CPEI) were found between the moderate and severe AIS and control groups (p = 0.003). Conclusion Moderate and severe AIS significantly influenced walking performance; however, no significant differences were observed between adolescents with mild AIS and healthy controls. Thus, early intervention could target the prevention of specific functional deficits and prevent it from progressing to a severe state.