Influence of curve location and type of adolescent idiopathic scoliosis on static and dynamic plantar pressure

This study aimed to investigate the characteristics of various plantar pressure parameters of patients with different curve locations (thoracic/lumbar) and types (single/double) of adolescent idiopathic scoliosis (AIS). Seventy-eight moderate AIS patients were included from Nanjing Drum Tower hospital, who were then classified into 4 groups by curve location and type, single thoracic scoliosis (S-T, n = 20), single lumbar scoliosis (S-L, n = 16), double curves with major curve at thoracic region (D-T, n = 22), double curves with major curve at lumbar region (D-L, n = 20). Another 22 healthy subjects were included as the control group. Multiple static and dynamic features, such as medial-lateral (M-L) area ratio and loading pattern were compared across groups. For static plantar pressure, on the major curve side, the medial-lateral (M-L) area ratio was significantly different among five groups on both feet (P < 0.01). The ratio of S-T group was significantly lower than lumbar scoliosis groups on major curve side (P < 0.01). In midfoot, ratios of thoracic scoliosis groups were significantly lower than S-L group P < 0.01). On the compensatory side, D-L group had markedly lower ratio than thoracic groups in M-L area ratio and midfoot M-L area ratio (P < 0.01). For dynamic plantar pressure, the maximum pressure of medial rearfoot of thoracic scoliosis was significantly lower than lumbar scoliosis and control group on major curve side(P < 0.01). Meanwhile, the lateral rearfoot of thoracic had greater pressure than lumbar scoliosis groups (P < 0.01). The load distribution of metatarsal head (MH) had marked differences among groups on the compensated side, especially at MH1, MH4 and MH5 P < 0.01). Moreover, the loads of thoracic scoliosis were significantly larger than lumbar scoliosis at MH5 (P < 0.01). In moderate AIS patients, scoliosis curve location significantly affected static and dynamic plantar pressure while single or double curves had limited impact. • In moderate AIS, plantar pressure is mainly affected by curve location (thoracic/lumbar); curve type has minor effect. • In AIS, thoracic curves show lower M-L area (supinated foot) while lumbar curves show higher M-L area (pronated foot). • Walking: thoracic curves drop medial heel pressure; lumbar curves drop lateral pressure; high arches raise lateral pressure. • CoP deviation differs in the coronal plane on the major curve side; single thoracic curves show abnormal shift toward side.