Risk of coronal imbalance after posterior surgery for adolescent idiopathic scoliosis of type Lenke5C.

Purpose: To investigate the incidence, risk factors, and clinical impact of persistent coronal imbalance (PCI) in Lenke5C adolescent idiopathic scoliosis (AIS) undergoing posterior spinal fusion (PSF).

Methods: We analyzed the medical records of 112 Lenke5C AIS patients. They were grouped into PCI (+) group and PCI (-) group according to the occurrence of PCI at 2 years after surgery. Coronal and sagittal parameters were measured and compared between both groups preoperatively, immediately postoperatively, and 2 years postoperatively. Scoliosis Research Society-22 (SRS-22) score was used to evaluate clinical outcomes.

Results: Of the 112 patients, 12 had coronal imbalance persisting 2 years after surgery. Logistic regression analysis indicated risk factors including older age [odds ratio (OR) = 1.841, 95% confidence interval (CI) = 1.147-2.132, p = .001], lower preoperative flexibility main thoracic (MT) curve (OR = 1.308, 95% CI = 1.041-2.015, p = .016), greater preoperative apical vertebral translation (AVT) of the thoracolumbar/lumbar (TL/L) curve (AVT-TL/L) (OR = 2.291, 95% CI = 1.120-4.719, p = .001), larger preoperative lowest instrumented vertebra tilt (LIV lilt) (OR = 2.141, 95% CI = 1.491-3.651, p = .011), and postoperative immediate coronal imbalance (OR = 5.512, 95% CI = 4.531-6.891, p = .001). The satisfaction and total score of the SRS-22 scale in the PCI (+) group were lower than those in the PCI (-) group at 2 years after surgery (p <.05).

Conclusions: We found a 10.7% incidence of PCI in patients with Lenke5C AIS undergoing PSF. PCI adversely affects clinical outcomes. Risk factors of PCI included older age, reduced preoperative MT curve flexibility, increased preoperative AVT in the TL/L curve, greater preoperative LIV tilt, and immediate postoperative coronal imbalance.