Study design: This was a retrospective study.
Objective: This study aimed to ascertain the relationship between preoperative Neck Disability Index (NDI) scores and cervical sagittal alignment in patients with cervical spondylotic myelopathy (CSM).
Summary of background data: Cervical alignment may influence postoperative clinical outcomes. However, the effect of preoperative sagittal balance on the preoperative status in CSM patients remains uncertain.
Materials and methods: From 2010 to 2016, 90 patients who underwent cervical surgery for CSM were enrolled. The inclusion criteria for this study included preoperative standing cervical radiographs and a preoperative NDI score. The following radiographic parameters were measured: (1) C0-C2 lordosis, (2) C2-C7 lordosis, (3) C2-C7 sagittal vertical axis (SVA), (4) neck tilt, (5) thoracic inlet angle, (6) T1 slope, and (7) T1 slope minus cervical lordosis (T1S-CL). The Pearson product-moment correlation coefficients were calculated between all radiographic variables and the NDI scores, and multiple regression analysis was performed to determine the independent predictors of high preoperative NDI scores.
Results: Both C2-C7 SVA and T1S-CL were positively correlated with NDI scores (r=0.732, P<0.001 and r=0.333, P=0.001). Cervical lordosis was negatively correlated with NDI scores (r=-0.267, P=0.011). Significant correlations were found between C2-C7 SVA and the C0-C2 Cobb angle (r=0.244, P=0.020), C2-C7 SVA and the C2-C7 Cobb angle (r=-0.359, P=0.001), the C2-C7 Cobb angle and the C0-C2 Cobb angle (r=-0.457, P<0.001), and the C2-C7 Cobb angle and T1 slope (r=-0.385, P<0.001).
Conclusions: The disability of the neck increased with increasing C2-C7 SVA and T1S-CL and decreasing cervical lordosis before surgical reconstruction. High C2-C7 SVA, low thoracic inlet angle, and high neck tilt values are independent predictors of high preoperative NDI scores.