Purpose This study investigated side-to-side gait asymmetry in subjects with adolescent idiopathic scoliosis. Methods There were 20 adolescents with idiopathic scoliosis and 20 age-matched control subjects, who participated in the study. To minimize confounding effects, we recruited patients with similar spinal curvature for the scoliosis group, and all participants are right hand dominant. The participants were instructed to ambulate on a 10 m walkway while barefoot. There were two force plates in the middle of the walkway. The ground reaction force (GRF) and angular displacements of six segments (foot, shank, thigh, pelvis, trunk, and head) were measured during one gait cycle based on the right and left lower extremities. To remove the positional information in the kinematic data, the derivative of angular displacement in each segment was calculated. To evaluate the side-to-side gait symmetry, we calculated the cross-correlation of each bilateral gait parameter. Results In the kinematics, the scoliosis group demonstrated asymmetrical gait in the frontal and transverse planes compared to the control group. In the GRF data, the scoliosis group demonstrated asymmetrical gait in the medial-lateral (M/L) direction compared to the control group.Conclusions These results indicated that the scoliosis group produced an asymmetrical rotation pattern of the segments bilaterally in the frontal and transverse planes, resulting in asymmetrical GRF patterns in the M/L direction. This asymmetrical gait may be produced by changes in global postural control during gait and not simply by changes in control of only one or two specific segments.

These results suggest that FDS and EDC are controlled by different neural mechanisms, most likely attributable to their different functional roles in daily activities.