BACKGROUND T1s, C2-7 lordosis, and C2-7 sagittal vertical axis (SVA) are the three most important sagittal parameters in the cervical spine. This study was conducted to investigate the relationships between classical sagittal alignment parameters and a new parameter, K-line tilt, and to study the impact of K-line tilt. MATERIAL AND METHODS A total of 72 patients who underwent adjacent two-level anterior cervical discectomy and fusion (ACDF) were retrospectively analyzed. Radiographic measurements included T1 slope (T1s), C2-7 lordosis, segment angle (SA), C2-7 SVA, and K-line tilt. The Neck Disability Index (NDI) scores were used to evaluate the clinical prognosis. Pearson correlation coefficients were calculated between radiographic measures. Linear regression analysis was used to analyze the relationship between follow-up K-line tilt and NDI. RESULTS ΔNDI was positively correlated with ΔT1s (r = 0.620, p < 0.05), ΔC2-7 SVA (r = 0.645, p < 0.05), and ΔK-line tilt (r = 0.702, p < 0.01); ΔK-line tilt was positively correlated with ΔT1s (r = 0.650, p < 0.05), ΔSA (r = 0.269, p < 0.05), and ΔC2-7 SVA (r = 0.293, p < 0.05); ΔT1s was positively correlated with ΔC2-7 lordosis (r = 0.428, p < 0.05), ΔSA (r = 0.631, p < 0.01), and ΔC2-7 SVA (r = 0.235, p < 0.05); ΔC2-7 lordosis was positively correlated with ΔSA (r = 0.666, p < 0.05) and negatively correlated with ΔC2-7 SVA (r = - 0.467, p < 0.01). The preoperative and postoperative K-line tilt values were statistically significant (p < 0.01), increasing from (7.50 ± 6.48)° to (9.95 ± 5.09)°. Preoperative NDI was positively correlated with preoperative C2-7 SVA (r = 0.639, p = 0.011) and K-line tilt (r = 0.516, p = 0.026); follow-up NDI was positively correlated with follow-up T1s (r = 0.664, p = 0.038), C2-7 SVA (r = 0.756, p = 0.004), and K-line tilt (r = 0.832, p = 0.006). The linear regression model showed that when the follow-up K-lint tilt was > 23.75°, NDI scores were > 25 (R2 = 0.737, p = 0.000). CONCLUSION This study showed that the K-line tilt was strongly correlated with the C2-C7 SVA, indicating that the K-line tilt can be used as another cervical parameter to evaluate cervical alignment in adjacent two-level ACDF. K-line tilt is an important parameter similar to the classical parameter C2-C7 SVA. In particular, a K-line tilt greater than 23.75 corresponded to a worse clinical prognosis, which was defined as an NDI score greater than 25.

中文翻译：

---

相邻两级颈椎前路椎间盘切除术和融合术后的影像学参数K线倾斜分析：一项回顾性研究。

背景技术T1，C2-7脊柱前凸和C2-7矢状垂直轴（SVA）是颈椎中三个最重要的矢状参数。进行这项研究以研究经典矢状面对准参数与新参数K线倾斜之间的关系，并研究K线倾斜的影响。材料与方法回顾性分析了72例行相邻两级颈椎前路椎间盘摘除术和融合术（ACDF）的患者。射线照相测量包括T1斜率（T1s），C2-7脊柱前弯，节段角（SA），C2-7 SVA和K线倾斜。颈部残疾指数（NDI）评分用于评估临床预后。在射线照相测量之间计算皮尔逊相关系数。线性回归分析用于分析随访K线倾斜与NDI之间的关系。结果ΔNDI与ΔT1s（r = 0.620，p <0.05），ΔC2-7SVA（r = 0.645，p <0.05）和ΔK线倾斜（r = 0.702，p <0.01）正相关; ΔK线倾斜与ΔT1s（r = 0.650，p <0.05），ΔSA（r = 0.269，p <0.05）和ΔC2-7SVA（r = 0.293，p <0.05）正相关; ΔT1s与ΔC2-7脊柱前凸正相关（r = 0.428，p <0.05），ΔSA（r = 0.631，p <0.01）和ΔC2-7SVA（r = 0.235，p <0.05）; ΔC2-7脊柱前凸与ΔSA正相关（r = 0.666，p <0.05），与ΔC2-7SVA负相关（r =-0.467，p <0.01）。术前和术后K线倾斜值具有统计学意义（p <0.01），从（7.50±6.48）°增加到（9.95±5.09）°。术前NDI与术前C2-7 SVA（r = 0.639，p = 0.011）和K线倾斜（r = 0）正相关。516，p ＝ 0.026）；随访NDI与随访T1s（r = 0.664，p = 0.038），C2-7 SVA（r = 0.756，p = 0.004）和K线倾斜（r = 0.832，p = 0.006）正相关。 。线性回归模型显示，当随访的K-lint倾斜度> 23.75°时，NDI得分> 25（R2 = 0.737，p = 0.000）。结论这项研究表明，K线倾斜度与C2-C7 SVA密切相关，表明K线倾斜度可以用作评估相邻两级ACDF的颈椎排列的另一个颈椎参数。K线倾斜是一个重要参数，类似于经典参数C2-C7 SVA。特别是，K线倾斜度大于23.75对应于较差的临床预后，其定义为NDI评分大于25。038），C2-7 SVA（r = 0.756，p = 0.004）和K线倾斜度（r = 0.832，p = 0.006）。线性回归模型显示，当随访的K-lint倾斜度> 23.75°时，NDI得分> 25（R2 = 0.737，p = 0.000）。结论这项研究表明，K线倾斜度与C2-C7 SVA密切相关，表明K线倾斜度可以用作评估相邻两级ACDF的颈椎排列的另一个颈椎参数。K线倾斜是一个重要参数，类似于经典参数C2-C7 SVA。特别是，K线倾斜度大于23.75对应于较差的临床预后，其定义为NDI评分大于25。038），C2-7 SVA（r = 0.756，p = 0.004）和K线倾斜度（r = 0.832，p = 0.006）。线性回归模型显示，当随访的K-lint倾斜度> 23.75°时，NDI得分> 25（R2 = 0.737，p = 0.000）。结论这项研究表明，K线倾斜度与C2-C7 SVA密切相关，表明K线倾斜度可以用作评估相邻两级ACDF的颈椎排列的另一个颈椎参数。K线倾斜是一个重要参数，类似于经典参数C2-C7 SVA。特别是，K线倾斜度大于23.75对应于较差的临床预后，其定义为NDI评分大于25。25（R2 = 0.737，p = 0.000）。结论这项研究表明，K线倾斜度与C2-C7 SVA密切相关，表明K线倾斜度可以用作评估相邻两级ACDF的颈椎排列的另一个颈椎参数。K线倾斜是一个重要参数，类似于经典参数C2-C7 SVA。特别是，K线倾斜度大于23.75对应于较差的临床预后，其定义为NDI评分大于25。25（R2 = 0.737，p = 0.000）。结论这项研究表明，K线倾斜度与C2-C7 SVA密切相关，表明K线倾斜度可以用作评估相邻两级ACDF的颈椎排列的另一个颈椎参数。K线倾斜是一个重要参数，类似于经典参数C2-C7 SVA。特别是，K线倾斜度大于23.75对应于较差的临床预后，其定义为NDI评分大于25。