Risk Factors for Postoperative Loss of Lordosis, Cervical Kyphosis, and Sagittal Imbalance After Cervical Laminoplasty

Objective: A retrospective cohort study was undertaken to elucidate the risk factors of loss of cervical lordosis (LCL), kyphotic deformity, and sagittal imbalance after cervical laminoplasty. Methods: A total of 108 patients who underwent laminoplasty to treat cervical myelopathy and were followed for ≥2 years were included. Logistic regression analysis and multiple regression analysis were performed to identify preoperative risk factors of LCL, kyphotic deformity (cervical lordosis <0°), and sagittal imbalance (sagittal vertical axis >40 mm) at postoperative 2 years. Results: Within multivariate multiple regression analysis, C2-C7 lordosis (P = 0.002), and C2-C7 extension capacity (P<0.001) showed significant association with LCL. Furthermore, age (P = 0.043) and C2-C7 lordosis (P = 0.038) were significantly associated with postoperative kyphosis. Receiver operating characteristic curve analysis for postoperative kyphosis showed that preoperative C2-C7 lordosis of 10.5° had a sensitivity and specificity of 81.3% and 82.4%, respectively. Preoperative K-line tilt (P = 0.034) showed a significant association with postoperative cervical sagittal imbalance at postoperative 2 years. Receiver operating characteristic curve analysis showed that a K-line tilt cutoff value of 12.5° had a sensitivity and specificity of 78.6% and 77.7%, respectively, for predicting postoperative sagittal imbalance. Conclusions: Higher preoperative C2-C7 lordosis and less preoperative cervical extension capacity were risk factors of LCL. Small preoperative C2-C7 lordosis <10.5° and younger age were risk factors of postoperative kyphosis. Furthermore, a greater K-line tilt would increase the risk of postoperative sagittal imbalance, with a cutoff value of 12.5°.