Li Wenpeng, Wang Qiwei, Zhao Qiancheng, Zeng Ziliang, Hu Xumin, Lv Xin, Gao Liangbin
Department of Neurosurgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
Department of Orthopedics, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
Clin Orthop Surg. 2025 Feb;17(1):130-137. doi: 10.4055/cios24186. Epub 2025 Jan 14.
Developing and validating a modified parameter, the SYS-G angle (the angle between the lower endplate of the C2 and the upper endplate of C7 vertebrae), as a feasible substitute for the C2-C7 Cobb method in assessing cervical sagittal alignment and exploring its reference range through a large-scale retrospective study.
The visibility of the C6, C7 upper, and C7 lower endplates was graded and compared. Baseline data such as height, weight, body mass index (BMI), age, and sex were analyzed for their impact on the visibility of the C7 lower endplate. Values of C2-6 Cobb angle, SYS-G angle, and C2-7 Cobb angle were measured. The intra- and interobserver reliability, differences, and efficacy of evaluation on cervical lordosis of the parameters were compared, and the correlations among the parameters were analyzed. Furthermore, reference ranges for the SYS-G angle were established based on lateral cervical spine x-rays of 825 asymptomatic Chinese adults across different age groups and sexes.
The visibility of the C7 lower endplates was significantly reduced compared to the C6 lower and C7 upper endplates. Age, weight, BMI, and male sex were identified as factors negatively influencing the visibility of the C7 lower endplate. Both intraobserver and interobserver reliability demonstrated excellence for all tested parameters. The linear regression model unveiled a stronger association of the SYS-G angle with the C2-7 Cobb angle compared to the C2-6 Cobb angle. Furthermore, the SYS-G angle exhibited excellent efficacy in evaluating cervical lordosis. Age displayed a positive correlation with the SYS-G angle, and across every age bracket from 20 to 69 years, men exhibited a higher mean SYS-G angle compared to women.
The visibility of the C7 lower endplate diminishes with increasing age, weight, BMI, and male sex. In cases where the C7 lower endplate is unclear, the SYS-G angle emerges as a reliable method for estimating cervical sagittal morphology. Reference ranges for the SYS-G angle were established across various age groups and sexes among asymptomatic Chinese adults, offering a valuable resource to guide therapeutic interventions for cervical spine disorders and deformities.
通过大规模回顾性研究，开发并验证一种改良参数——SYS-G角（C2椎体下端板与C7椎体上端板之间的夹角），作为评估颈椎矢状位排列时C2-C7 Cobb法的可行替代方法，并探索其参考范围。
对C6、C7上终板和C7下终板的可视性进行分级和比较。分析身高、体重、体重指数（BMI）、年龄和性别等基线数据对C7下终板可视性的影响。测量C2-6 Cobb角、SYS-G角和C2-7 Cobb角的值。比较各参数在颈椎前凸评估中的观察者内和观察者间可靠性、差异及评估效能，并分析各参数之间的相关性。此外，基于825名不同年龄组和性别的无症状中国成年人的颈椎侧位X线片，建立SYS-G角的参考范围。
与C6下终板和C7上终板相比，C7下终板的可视性显著降低。年龄、体重、BMI和男性被确定为对C7下终板可视性有负面影响的因素。所有测试参数的观察者内和观察者间可靠性均表现出色。线性回归模型显示，与C2-6 Cobb角相比，SYS-G角与C2-7 Cobb角的相关性更强。此外，SYS-G角在评估颈椎前凸方面表现出优异的效能。年龄与SYS-G角呈正相关，在20至69岁的每个年龄组中，男性的平均SYS-G角均高于女性。
C7下终板的可视性随着年龄、体重、BMI的增加以及男性性别而降低。在C7下终板不清楚的情况下，SYS-G角是估计颈椎矢状形态的可靠方法。在无症状中国成年人的不同年龄组和性别中建立了SYS-G角的参考范围，为指导颈椎病和畸形的治疗干预提供了有价值的资源。
