New sagittal classification of AIS: validation by 3D characterization

Area of Science:

• Orthopedics
• Radiology
• Spine Surgery

Background:

• Adolescent idiopathic scoliosis (AIS) surgical planning relies on accurate sagittal deformity assessment.
• Existing 2D imaging may not fully represent 3D spinal deformities.
• A novel sagittal classification was proposed to address these limitations.

Purpose of the Study:

• To evaluate the reliability of a new sagittal classification system for AIS.
• To compare 2D and 3D imaging analyses of spinal and spinopelvic parameters in AIS patients.
• To determine the concordance between 2D and 3D classifications.

Main Methods:

• Retrospective analysis of 93 AIS patients using EOS imaging system.
• 2D (Keops) and 3D (sterEOS) analyses of spinal and spinopelvic parameters.
• Assessment of apical vertebra rotation (AVR) in 3D.

Main Results:

• Excellent correlation between 2D and 3D measurements for most parameters, except T10L2 and L1S1 angles.
• Increased variability in T10L2 measurements with larger Cobb angles.
• 82% of patients were classified similarly in both 2D and 3D; misclassified cases involved underestimation of thoracolumbar junction lordosis in 2D.

Conclusions:

• 2D analysis is sufficient for surgical decision-making in the majority of AIS cases (82%).
• 3D analysis is recommended for severe AIS cases (Cobb angle >55°) for precise thoracolumbar junction evaluation.
• The new sagittal classification demonstrates reliability in both 2D and 3D assessments.