Differential Effects of Frontal Versus Sagittal Light Touch on Postural Stability in Adolescents with Idiopathic Scoliosis (AIS).

INTRODUCTION

Adolescent Idiopathic Scoliosis (AIS) is a complex three-dimensional spinal deformity that significantly alters postural control strategies and the internal body schema. While the "Light Touch" (LT) phenomenon-defined as non-mechanical haptic feedback (<1N)-is known to reduce postural sway in healthy populations, its efficacy in the context of AIS-specific biomechanical instability remains under-researched. The purpose of this study was to evaluate the differences in postural stability among AIS patients during quiet standing (Eyes Open) compared to Light Touch applied in the frontal plane and the sagittal plane.

METHODS

The study included 29 patients (mean age: 15.6 ± 1.9 years) diagnosed with AIS (Cobb angle: 30.8 ± 15.0). Postural stability was assessed using a force platform under three experimental conditions: 1) Quiet Standing (QS): Baseline free standing with eyes open. 2) Frontal Light Touch (LT-F): Lateral fingertip contact on a stable bar. 3) Sagittal Light Touch (LT-S): Anterior fingertip contact on a stable bar. On the basis of centre of pressure (COP) recordings, the spatial and temporal COP parameters were computed.

RESULTS

The study evaluated the effect of sensory conditions on postural stability in patients with AIS. Repeated measures ANOVA revealed a significant reduction in postural sway under light touch conditions compared to quiet standing (p < 0.05).

DISCUSSION AND

CONCLUSION

Light touch modulated postural control in individuals with AIS in a direction-dependent manner, with mediolateral input inducing global stabilization and anteroposterior input producing more plane-specific effects, particularly in the sagittal plane. These findings indicate that haptic input promotes more stable yet flexible and adaptive postural control, supporting its potential use as a direction-specific strategy in rehabilitation of AIS.