The predictor for Preoperative Coronal Imbalance in patients with Degenerative Lumbar Scoliosis--A related analysis on spinopelvic parameters

Abstract

Background: The mechanism of coronal imbalance is still unclear. The relationships among CBD and major curve, L4 and L5 tilt have been reported, which were not explicit although. The aim of this retrospective study was to explore and examine the association between spinopelvic parameters and coronal balance distance (CBD) in degenerative lumbar scoliosis (DLS) patients.Methods Following institutional ethics approval, the radiographs of 161 DLS patients were retrospectively reviewed. The coronal measurements involving CBD, L4 coronal tilt, L5 coronal tilt, fractional curve, pelvic coronal tilt, the Cobb angle and included vertebras of major curve were documented. All of those participants were divided into group A (CBD≥30mm) and group B (CBD < 30mm). Statistical analysis was performed to compare the difference of continuous and categorical variables. Pearson-Correlation, and Multiple-Regression Analysis were performed to explore the related parameter with CBD.Results The CBD in 31 (19.25%) DLS patients at pre-operation was over 30mm. With similar major Cobb angle, main curve of patients in the group A had less involving vertebras (P=0.009), but more rotation of the apical vertebra (P<0.001) compared with that in the group B respectively. Additionally, the L4 coronal tilt in group A was much larger (P=0.02). Pearson-correlation analysis showed that CBD had significant relationship with L4/L5 coronal tilt(P<0.001), weak relationship with fractional curve (P=0.027), but linearly independent with pelvic tilt and major Cobb. Stepwise Multiple- regression analysis revealed that only L4 tilt was the independent predictor for major Cobb and CBD.Conclusions The prevalence of coronal imbalance at pre-operation in DLS patients is about 20%. With similar major Cobb, the less the number of involving vertebra, the higher the incidence of coronal imbalance in DLS patients. L4 coronal tilt would be the predictive variable for progression of scoliosis and global coronal malalignment. Pelvis, the foundation of spine, had less effect on full-spine coronal balance.