The asymmetry spinal kinematics in C-shaped adolescent idiopathic scoliosis during level walking

Adolescent idiopathic scoliosis (AIS) patients exhibit trunk movement asymmetry during gait, reflecting altered motion patterns and postural control strategies. To study movement asymmetry at specific spinal joints, it is necessary to develop gait models precise to these joints and avoid mixed AIS classification. Based on an articulated thoracolumbar spine model and a refined marker placement protocol, we achieved a detailed analysis of spinal kinematics in patients with mild AIS. Gait data were collected from 10 PUMC type IA AIS patients, 13 PUMC type IB AIS patients, and 13 healthy controls. Joint angles at each spinal joint were compared between convex-side and concave-side stance phases, with cross-correlation coefficients computed to quantify angular velocity curve asymmetries. The control group showed no significant joint angle asymmetry. In contrast, both PUMC type IA and IB patients demonstrated persistent joint angle asymmetry at specific joints throughout stance (p < 0.05). Compared to controls, both AIS subtypes exhibited decreased cross-correlation coefficients (CC) of angular velocity curves, primarily in coronal plane movement at upper thoracic and thoracolumbar joints (p < 0.05), with distinct CC reduction patterns between subtypes. These joint angle asymmetry results provide detailed characteristics of postural adjustment during gait in AIS, while angular velocity curve asymmetries reveal movement impairments from a novel perspective.