Risk factors of postoperative shoulder imbalance after major thoracic curve correction in patients with adolescent idiopathic scoliosis

Objectives: To investigate the prevalence and risk factors of postoperative shoulder imbalance after posterior correction of major thoracic curve in patients with adolescent idiopathic scoliosis. Methods: A retrospective review of 96 consecutive patients undergoing posterior segmental pedicle screw correction and fusion was carried out, the pathogenisis included Lenke 1, 2, 3, 4 types with right thoracic curve of less than80°. There were 15 males and 81 females with a mean age of 14.5 years(10-18 year). The average follow-up was 42.2 months(range, 22-68 months). According to postoperative shoulder height difference, all patients were divided into balance group and imbalance group. Demographics and radiographic data were studied to determine risk factors for postoperative shoulder imbalance. Results: Among the 96 patients, 17 cases(17.7%) presented with postoperative shoulder imbalance. Univariate and multivariate logistic regression analysis between two groups identified clavicle angle(OR=1.873, P=0.018), preoperative main thoracic Cobb angle(OR=2.222, P=0.028) and postoperative main thoracic Cobb angle(OR=0.483, P=0.039), as independent factors correlated with postoperative shoulder imbalance. Great clavicle angle and preoperative main thoracic Cobb angle were risk factors, while great postoperative main thoracic Cobb angle was a protective factor for postoperative shoulder imbalance. Conclusions: Positive tilt of clavicle angle, great preoperative main thoracic Cobb angle and small postoperative main thoracic Cobb angle are independent factors for postoperative shoulder imbalance in patients with major thoracic curve undergoing posterior surgery.