What question did this study set out to answer?

To identify factors associated with improved postoperative coronal balance in adolescent idiopathic scoliosis patients with left-sided imbalance.

May 28, 2026

Greater Thoracic Deformity Correction is Associated With Improved Coronal Balance in Patients Preoperatively Decompensated to the Left

Key Points

To identify factors associated with improved postoperative coronal balance in adolescent idiopathic scoliosis patients with left-sided imbalance.
Retrospective study analyzing data from a multicenter registry.
Subjects included AIS patients with Lenke one to four curves and significant left-sided preoperative coronal imbalance.
Variables analyzed included preoperative and postoperative radiographic measurements, with at least two years of follow-up.
Forty-seven subjects analyzed; mean preoperative coronal imbalance improved from -3.6 cm to -1.9 cm at two years.
Thirty-two percent (15 subjects) remained imbalanced two years post-operation.
Correlation found between better coronal balance and lower preoperative thoracic curve magnitude (r = -0.34, P = 0.025), with significant relationships to thoracic and lumbar curve corrections.

Abstract

Study Design: Retrospective. Objective: To identify variables associated with improved postoperative coronal balance in patients with adolescent idiopathic scoliosis (AIS) with significant left-sided coronal imbalance (CI) preoperatively. Summary of Background Data: Early postoperative coronal imbalance (CI), particularly to the left, is a well-described challenge in the management of patients with adolescent idiopathic scoliosis (AIS). Materials and Methods: A multicenter registry was queried to identify subjects with Lenke one to four curves with B or C lumbar modifiers who underwent thoracic-only fusion (SF) with a minimum two-year follow-up. Only patients with significant preoperative CI (C7–CSVL ≥−3 cm; negative values represent left-sided deviation) were included. Preoperative and first-erect (FE) postoperative radiographic variables were analyzed to assess correlation with coronal balance. Results: Forty-seven subjects were analyzed. Mean age was 15±2 years. Mean preoperative CI was −3.6±0.7 cm, improving to −2.3±1.4 cm at FE and −1.9±1.3 cm at two years. Fifteen subjects (32%) remained imbalanced at two years. C modifiers demonstrated greater imbalance than B modifiers (−2.1±1 vs . −1.2±1.6, P =0.044) at two years. There was no difference in postoperative coronal balance based on the lowest instrumented vertebra ( P =0.27). Better coronal balance at two years significantly correlated with a lower preoperative thoracic curve magnitude on the bending film ( r =−0.34, P =0.025), and the following variables at FE: upper thoracic curve ( r =−0.39, P =0.007), main thoracic curve ( r =−0.42, P =0.004), lumbar curve ( r =−0.41, P =0.005), percent correction of the thoracic ( r =0.36, P =0.012) and lumbar curves ( r =0.42, P =0.003), and coronal balance ( r =0.42, P =0.003). Conclusions: AIS patients with significant preoperative CI (≥−3 cm) remain challenging to treat with SF, as 1/3 of these patients remained leaning to the left at two years postoperatively. More flexible thoracic curves and greater deformity correction correlated with better coronal balance at two years.

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