目的: 探讨无症状中国年轻人颈椎矢状位曲度的正常值及其与全脊柱平衡的关系。方法: 2011年11月—2014年12月招募并选择年龄18~30岁的志愿者行全脊柱侧位X线检查，在X线片上测量指标包括C₀-C₂角、从C₂-C₃到C₆-C₇的间盘角、从C₃到C₇的椎体角、T₁倾斜角、胸椎后凸角(thoracic kyphosis, TK)、腰椎前凸角(lumbar lordosis, LL)、骨盆入射角(pelvic incidence, PI)、骶骨倾斜角(sacral slope, SS)、C₂-C₇矢状轴向垂线(C₂-C₇ sagittal vertical axis, C₂-C₇SVA)、头重心至C₇的矢状位轴向垂线(center of gravity of head to C₇SVA, CGH-C₇SVA)、C₇到S₁的矢状位轴向垂线(C₇-S₁SVA)。依据脊柱骨盆矢状位形态进行Roussouly分型，比较不同Roussouly分型下的颈椎曲度及形态。结果: 共纳入126名志愿者参与研究，其中男性67名，女性59名，平均年龄(21.4±2.3)岁。C₀-C₇前凸角平均为26.0°±12.8°，其中C₀-C₂前凸角平均为15.2°±6.7°，C₂-C₃到C₆-C₇间盘前凸角总和平均为9.1°±12.1°，C₃到C₇的椎体前凸角总和平均仅为1.4°±10.2°。C₂-C₇SVA(18.6±7.9) mm和CGH-C₇SVA[(22.9±12.3) mm]由C₇-S₁SVA[(-21.6±31.0) mm]完美代偿。不同的Roussouly分型间颈椎曲度差异有统计学意义(P < 0.01)。颈椎曲度与T₁倾斜角(P < 0.01)、胸椎后凸角(P < 0.01)有显着相关性。从T₁倾斜角到C₀-C₂角，相邻节段间盘角之间存在显著相关性(P < 0.05)。结论: 测量并计算了无症状中国年轻人颈椎椎体角和间盘角的正常值，发现颈椎前凸主要发生在C₀-C₂和椎间盘水平，这些角度受到其他脊柱部位形态(T₁倾斜角、胸椎后凸角和Roussouly分型)的影响，且相邻间盘角之间存在显著的相关性。

Objective: To explore the normal distribution of cervical sagittal alignment and the relationship between cervical alignment and global spine balance in asymptomatic young adults. Methods: A cohort of 272 asymptomatic Chinese adults (including 161 males and 111 females, with an average age of (23.2±4.4) years, ranging from 18 to 45 years) were prospectively recruited from November 2011 to December 2014. The C₀-C₂ angle, disk angles from C₂-C₃ to C₆-C₇, vertebral angles from C₃ to C₇, T₁ slope, thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), C₂-C₇ sagittal vertical axis (C₂-C₇SVA), center of gravity of head to C₇SVA (CGH-C₇SVA), C₇-S₁SVA were measured and statistically analyzed. All the subjects were categorized with the Roussouly classification and the cervical morphologies were evaluated as lordotic, straight, sigmoid or kyphotic. Spinal sagittal alignment parameters were compared between different sexes and Roussouly classifications with independent student t test, analysis of variance (ANOVA) or Chi-square test. Correlations between cervical sagittal alignment and global spine sagittal alignment were calculated using the Pearson and Spearman correlation coefficient. Linear regression analysis was performed. Results: Sixty-seven males and 59 females aged from 18 to 30 years old were included in the study. The mean value of C₀-C₇ was 26.0°±12.8°, composed of 15.2°±6.7° for C₀-C₂, 9.1°±12.1° for sum of disk angles from C₂-C₃ to C₆-C₇, and 1.4°±10.2° for sum of vertebral angles from C₃ to C₇. C₂-C₇SVA [(18.6±7.9) mm] and CGH-C₇SVA [(22.9±12.3) mm]were offset ideally by C₇-S₁SVA [(-21.6±31.0) mm]. Males had a larger T₁ slope (P < 0.05) and accordingly, a larger cervical lordosis C₂-C₇ (P < 0.01) and C₀-C₇ angle (P < 0.01) than females. Males had a smaller C₇-S₁SVA (P < 0.01) and accordingly, a smaller CGH-C₇SVA (P=0.165) than females. Significant difference was found between cervical alignment of different Roussouly types (P < 0.01). In general, a larger LL was consistent with a set of larger TK, C₂-C₇angle, C₀-C₇ angle, and vice versa. There was no significant correlation between cervical morphology and the Roussouly classification (Chi-square=10.548, P=0.308). There was significant correlation between cervical alignment and T₁ slope (P < 0.01), TK (P < 0.01). There was significant correlation between adjacent segmental angles from T₁ slope up to C₀-C₂ angle (P < 0.05). Conclusion: Normative values of each vertebral angle and disk angle were established. The cervical lordosis occurred mainly at C₀-C₂ and disk levels, which was influenced by parameters of other parts of the spine, such as T₁ slope, TK and the Roussouly classification. There was significant correlation between adjacent disk angles.