Related Experiment Video
Updated: Aug 23, 2026
Clinical Efficacy of Ultrasound-Assisted Scoliosis-Specific Exercise in Mild-Grade Adolescent Idiopathic Scoliosis
Published on: December 2, 2025
Sagittal Alignment Differences Between Normal Subjects and Adolescent Idiopathic Scoliosis Using Vertebral Pelvic
Carlos Aleman1, Thibaut Goetsch2, Jeffrey Hills3
1Service de Chirurgie du Rachis, Hôpitaux Universitaires de Strasbourg, Université de Strasbourg, France.
Study Design:
Retrospective multicenter registry study.
Objective:
To compare sagittal spinopelvic alignment between normal subjects and Adolescent Idiopathic Scoliosis (AIS), to evaluate the relationship between T4 and L1 Pelvic Angles (T4PA-L1PA), including the influence of Thoracolumbar Inflection Point (TIP).
Summary Of Background Data:
Vertebropelvic angles were described as alignment targets for normal adults, but their role remains incompletely defined in younger AIS patients.
Methods:
Full-spine radiographs of 1115 normal subjects and 1779 AIS patients (10-30 y) were analyzed. AIS was classified according to Lenke. Measurements included Pelvic Incidence (PI), Pelvic Tilt (PT), segmental Thoracic Kyphosis (TK) and Lumbar Lordosis (LL), T4PA, L1PA. A Pearson correlation analyzed the relationship between parameters. TIP was categorized as cranial (above T12), junctional (T12-L1), or caudal (below L1), and T4PA-L1PA analyzed according to TIP (ANOVA). Formulae LL=0.5×PI-21 and L1PA=1.4×PI-1.7×L1PA-2 were evaluated using linear regression.
Results:
TK T1-12 was smaller <8° (P<0.001), T10-L1 <5° (P<0.001) in Lenke 1, 2 and 3 compared to normal. LL L1-L4 was larger >3° (P<0.001) in Lenke 1. L1PA differences >3° (P<0.001) existed in Lenke 1 and 2. A correlation existed between L1PA and PI (r>0.7), L1PA and PT (r>0.7), L1PA and T4PA (r>0.9) for normal and each Lenke type. T4PA-L1PA differences increased from negative to positive as the TIP moved from cranial to caudal in normal and AIS (P<0.001). Formulae for L1PA and LL calculation showed good agreement with measured values (R²>0.6).
Conclusion:
Primary thoracic AIS had smaller TK T1-T12, TK T10-L1 and larger LL L1-L4, L1PA, while the T4-L1hip axis remained globally preserved in normal and AIS. The TIP influenced segmental alignment, with larger L1PA and smaller (negative) T4PA-L1PA differences. Vertebropelvic angles provide a reliable target for surgical planning in AIS.
