Can Preoperative C2 Slope Predict Postoperative Cervical Sagittal Imbalance After Laminoplasty?

Study Design Retrospective study. Objective To investigate the impact of preoperative C2 slope (C2S) on change in sagittal vertical axis (SVA) and postoperative cervical sagittal imbalance (CSI) after laminoplasty (LP). Methods Consecutive patients who underwent LP between January 2015 and January 2022 with a minimum of 12-month follow-up were reviewed. The clinical variables and radiographic measurements were assessed. Patients were divided into improvement (ΔcSVA ≤ −10 mm), stable (−10 mm ≤ ΔcSVA <10 mm), and CSI groups (ΔcSVA≥10 mm). Correlation analysis was performed to explore the associations between ΔcSVA and preoperative factors, postoperative change and outcome variables. Multivariable logistics regression was conducted to determine the factors predicting CSI. Results Over the 186 enrolled patients, 23 developed CSI. The CSI group presented with significantly lower preoperative cSVA, greater cervical lordosis (CL) and C2S. At the final follow-up, the CSI group presented significantly higher increase in neck pain, C2S and C7S, and greater loss in CL and range of motion at flexion position. Correlation analysis revealed that ΔcSVA is correlated positively to preoperative CL and surgical segments and negatively to preoperative C2S and cSVA. Multivariable regression revealed that lower preoperative C2S ( P = 0.026) was risk factor for postoperative CSI, with 8.9 as a potential cut-off value for C2S. Conclusions Lower preoperative C2S slope was risk factor for post-laminoplasty CSI. The cut-off value of C2S was 8.9. Laminoplasty should be carefully considered for patients with low C2S due to risk of postoperative CSI.