[Risk factor of coronal imbalance after posterior hemivertebra resection with short segment fixation for congenital...

Objective: To evaluate the clinical efficacy of posterior hemivertebra resection with short-segment fixation in the treatment of lumbosacral hemivertebra (LSHV) and to investigate the incidence and risk factors of postoperative coronal imbalance (CIB). Methods: The clinical data of children with LSHV who underwent posterior lumbosacral hemivertebra resection with short-segment fixation at Nanjing Drum Tower Hospital from August 2005 to April 2023 were retrospectively analyzed. Based on coronal balance status at the final follow-up, the children were divided into the balanced group and the imbalanced group. The radiographic parameters before and after the operation were recorded, included the Cobb angle, coronal balance distance (CBD), pelvic obliquity (PO), sacral obliquity (SO), upper instrumented vertebra tilt (UIV tilt), sagittal vertical axis (SVA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). The differences in imaging indices between the two groups of children with LSHV were compared, variables associated with postoperative coronal imbalance were screened by the Least Absolute Shrinkage and Selection Operator (LASSO) regression model, and variables were included in multivariate logistic regression to analyze the risk factors for coronal plane imbalance after posterior lumbosacral hemivertebra resection with short-segment fixation for congenital lumbosacral deformity. Results: This study included 63 children with LSHV deformity, 32 males and 31 females, with a mean age of (7.2±3.8) years. The balanced group consisted of 49 patients, 24 males and 25 females, with a mean age of (7.3±4.1) years, and the imbalanced group consisted of 14 patients, 8 males and 6 females, with a mean age of (7.1±2.8) years. There was no statistically significant differences between the two groups in age, gender, follow-up time, hemivertebra location, or segmentation type (all P>0.05). Postoperatively, the Cobb angle and CBD improved significantly in both groups compared to the preoperative values (all P<0.05). At the final follow-up, the balanced group maintained good correction. However, the CBD in the imbalanced group worsened significantly at the final follow-up compared to the immediate postoperative value [(28.6±7.4) vs (16.5±8.8) mm, P<0.001]. Preoperatively, the CBD was greater in the imbalanced group than in the balanced group [(21.5±9.3) vs (12.2±10.0) mm, P=0.003], and this difference increased further at the final follow-up [(28.6±7.4) vs (12.8±7.1) mm, P<0.001]. Postoperatively, the UIV tilt was significantly greater in the imbalanced group than that in the balanced group (9.2°±5.5° vs 4.6°±3.3°, P<0.001). There was no statistically significant differences in other postoperative radiographic parameters between the two groups (all P>0.05). Multivariate logistic regression analysis showed that preoperative coronal classification type C [OR (95%CI)=5.691(1.161-27.909),P=0.032] and a larger postoperative UIV tilt [OR(95%CI)=1.204(1.001-1.449),P=0.048] were risk factors for CIB after surgery in LSHV children. Conclusion: Preoperative coronal classification type C and a larger postoperative upper instrumented vertebra tilt angle are risk factors for coronal imbalance following posterior surgery for LSHV deformity.