Increased Lateral Waist to Thoracolumbar Height Ratio Correlates With Improved In-brace Correction

Area of Science:

• Orthopedics
• Radiology
• Biomedical Engineering

Background:

• Adolescent idiopathic scoliosis (AIS) treatment relies on bracing, with in-brace correction (IBC) predicting success.
• Body Mass Index (BMI) is a limited predictor of bracing outcomes due to its inability to account for body habitus variations.
• A novel radiographic measure, the lateral waist-to-height (WH) ratio, is proposed to more accurately predict IBC in AIS.

Purpose of the Study:

• To evaluate the lateral waist-to-height (WH) ratio as a predictor of in-brace correction (IBC) in adolescent idiopathic scoliosis (AIS).
• To compare the predictive accuracy of the lateral WH ratio against Body Mass Index (BMI) and other radiographic measures for IBC in AIS patients.

Main Methods:

• Retrospective review of 209 female AIS patients treated with Rigo-style braces (2014-2024).
• Measurement of thoracolumbar (TL) height and waist width from radiographs to calculate lateral WH ratios.
• Linear and multivariate regression analyses to assess associations between IBC and WH ratios, BMI, curve angle, and apex.

Main Results:

• Lateral WH ratio showed a statistically significant positive correlation with IBC (R=0.21, P=0.014).
• BMI and AP ratio did not show significant associations with IBC.
• Multivariate analysis identified major curve angle and lateral WH ratio as independent predictors of IBC.

Conclusions:

• The lateral WH ratio provides a more comprehensive assessment of body habitus than BMI for AIS patients.
• Lateral WH ratio is independently associated with in-brace correction, suggesting its utility in predicting initial brace effectiveness.
• Further research is warranted to explore the role of lateral WH ratio in predicting long-term bracing outcomes for AIS.