The margin of stability is bigger in girls with Lenke I adolescent idiopathic scoliosis: A case-control study.

BACKGROUND

The Margin of Stability is used to measure stability in adults with pathologic gait including spinal deformity. The aim was to compare anterior-posterior and mediolateral Margin of Stability in girls with Adolescent Idiopathic Scoliosis to typically-developing girls, and to test the effect of speed and Cobb angle on the Margin of Stability.

METHODS

Eight girls with Lenke 1 Adolescent Idiopathic Scoliosis (Cobb: 53.9±15.2°) were recruited from the Royal National Orthopaedic Hospital between July 2021 and August 2022, and seven propensity-matched typically-developing girls were recruited. Participants walked at three speeds on an instrumented treadmill wearing a full-body plug-in-gait marker set. Mean Margin of Stability at heel strike during 30-seconds of walking was calculated. The Margin of Stability was compared between girls with Adolescent Idiopathic Scoliosis and controls using a Two-way ANOVA with paired analysis and was correlated to Cobb angle in girls with Adolescent Idiopathic Scoliosis using Pearson's r2.

FINDINGS: There was weak evidence for a Group-Speed interaction between for anterior-posterior Margin of Stability at 1.2 m/s. It was higher in Cases than at 1.2 m/s compared to Controls (left: p = 0.05; right: p = 0.06). Anterior-posterior Margin of Stability was not significantly correlated with Cobb angle. Mediolateral Margin of Stability did not differ between Group or Group-Speed interaction but was negatively correlated with increasing Cobb angle (left: p = 0.002; right: p = 0.04).

INTERPRETATION: Girls with moderate-severe Lenke I Adolescent Idiopathic Scoliosis were more anterior-posteriorly stable than Controls at higher speeds. Gait challenges may require compensatory mechanisms for perceived instability caused by their spinal deformity.