Is standing balance control in adolescent idiopathic scoliotic girls associated to the horizontal body and trunk center of mass offset?

Introduction Though adolescent idiopathic scoliosis (AIS) is characterized by a lateral deviation of the spine with resulting geometric changes in the trunk and rib cage standing imbalance was reported. The type and location of the spinal deformity was shown to perturb balance control while the interaction between standing posture and balance in AIS suggest a dysfunction in the postural regulation system of scoliotic subjects. Postural responses appear to be dependent on body somatotypes and in particular that ectomorphic girls have a tendency to lean further back favoring a hypokyphotic trunk attitude and increasing the risk of spinal deformity progression. These observations on spinal deformity and body shape alterations that modify trunk COM position imply a change in the body center of mass position as well that could perturb standing balance. In scoliotic girls, postural imbalance was attributed to a sensory rearrangement of the motor system on the representation of the body in space. The objectives of this study were to test if the antero-posterior (AP), medio-lateral (ML) and resultant body-head and trunk center of mass (COM) horizontal offsets were similar in able-bodied and scoliotic girls and if these offsets were related to the center of pressure displacements.