Bending Radiograph as Predictive Factor of In-Brace Correction (IBC) in Adolescent Idiopathic Scoliosis (AIS)

Abstract

Introductions: In-brace correction (IBC) is one of the most important factors in bracing treatment for Adolescent Idiopathic Scoliosis (AIS). Several factors influenced IBC achievement. The curve flexibility found to be associated with the IBC. One of the most common methods for assessing curve flexibility is to take a side bending radiograph. It has been widely used as a predictor of surgical correction in AIS. However, bending radiograph to predict the amount of fulltime IBC is not cleared in orthotics practice. The purpose of this study was to evaluate flexibility as measured by a side bending radiograph as a predictive factor of in-brace correction in AIS.

Methods: A retrospective cohort study. This study included 82 consecutive patients with AIS who received full-time bracing treatment at King Chulalongkorn Memorial Hospital (KCMH) from January 2017 to December 2021. Data collection was based on the medical record of AIS patients. Demographic data and radiographic imaging (standing posteroanterior before brace, side bending, and in-brace) were reviewed. The association between IBC and its associated predictive factors was determined using correlation analysis and simple linear regression. A multivariable linear regression was performed to establish the IBC prediction model.

Results: The mean Cobb angle was 32.9±8.7º. The mean Cobb angle in a side bending radiograph and in-brace were 17.9±12.7º and 22.5±11.8º, respectively. Curve flexibility had a strong positive linear relationship with IBC (r=0.732, P<0.001). Univariate analysis revealed no relationship between IBC with age, sex, height, weight, Risser sign, and curve types. The established regression model to predict IBC was ((IBC=60.42 + 0.51(flexibility) – 0.42 (initial cobb angle) -1.96 (BMI)).

Conclusions: The amount of IBC in a full-time brace could be estimated using the flexibility of the spine measured by a side bending radiograph. The most influential factor in IBC was found to be spine flexibility, followed by BMI and initial cobb angle.