Differential Impact of C2-7 Sagittal Vertical Axis on Postoperative Axial Symptoms in Laminoplasty vs Laminectomy With Fusion: A Propensity Score-Trimmed Retrospective Cohort Study.

BACKGROUND This study investigated the association between postoperative C2-7 sagittal vertical axis (SVA) and axial symptoms after posterior cervical surgery, and explored whether this association differed between open-door expansive laminoplasty (LP) and total laminectomy with fusion (LF). MATERIAL AND METHODS This single-center retrospective cohort study included 64 patients with MCSM, including 33 in the LP group and 31 in the LF group, after propensity score-based trimming and covariate balance assessment. Cervical sagittal parameters, range of motion (ROM), and clinical outcomes were evaluated preoperatively and during 2 to 3 years of follow-up. Logistic regression and receiver operating characteristic (ROC) analyses were performed as exploratory analyses. RESULTS The incidence of axial symptoms did not differ significantly between the LP and LF groups (21.2% vs 32.3%, P=0.40). Both groups showed significant improvements in visual analog scale, Japanese Orthopaedic Association, and Neck Disability Index scores. Compared with LP, LF was associated with greater postoperative changes in C2-7 SVA, C2-7 Cobb angle, C7 slope, and ROM reduction. Postoperative C2-7 SVA was associated with AS. Exploratory ROC analyses suggested optimal C2-7 SVA cutoffs of 3.46 cm in the LP group and 3.10 cm in the LF group. The group × C2-7 SVA interaction was statistically significant but based on a small number of axial symptom events. CONCLUSIONS Postoperative C2-7 SVA may be associated with axial symptoms, and this association appeared stronger after LF in this small cohort. All ROC-derived thresholds and interaction findings are exploratory, hypothesis-generating, and not clinically actionable, pending validation in larger prospective studies.