Department of Orthopaedic Surgery, BioMedical Research Institute, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea.
Department of Orthopedic Surgery, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, Republic of Korea.
World Neurosurg. 2019 Jul;127:e826-e834. doi: 10.1016/j.wneu.2019.03.274. Epub 2019 Apr 4.
To analyze the correlation between C2 incidence (C2I) and cervical and thoracolumbar sagittal parameters and determine the effectiveness of C2I for evaluating global spinopelvic sagittal alignment.
Whole spine standing lateral radiographs of 226 patients (mean age, 47.8 ± 11.3 years; 63% women) were analyzed. Spinopelvic parameters and incidence angles of inflection point were evaluated. The correlation between each parameter was analyzed using Pearson correlation coefficient and linear regression. Using C2I quartiles, 3 groups were compared to distinguish different alignment patterns by analysis of variance.
C2I correlated significantly with C0-2 lordosis (C02L), C2-7 lordosis (C27L), C0-7 lordosis , C2 slope (C2S), T1 slope-C27L, C2-7 sagittal vertical axis, and chin brow vertical angle (CBVA) in cervical parameters (r = -0.378, r = 0.533, r = 0.251, r = 0.688, r = 0.681, r = 0.278, and r = 0.351, respectively; P < 0.01) and with T1 incidence (T1I), pelvic incidence-lumbar lordosis mismatch, L1 incidence (L1I), pelvic tilt (PT), and pelvic incidence (PI) (r = 0.480, r = 0.516, r = 0.518, r = 0.635, and r = 0.392, respectively; P < 0.01) in thoracolumbar alignment parameters. C2I was estimated by the 2 following equations: C2I = 1.0C2S + 1.0PT and C2I = 0.98PI - 0.99LL + 0.98 thoracic kyphosis - 1.0C27L (R = 0.97, P < 0.001, respectively), with an excellent coefficient of determination. PI, PT, L1I, T1I, and C2S were increased significantly between groups using C2I quartiles. In the high C2I group, C27L and C0-7 lordosis had less lordosis; however, C02L had more lordosis and C2-7 sagittal vertical axis and CBVA showed higher than low C2I group.
C2I was significantly correlated with both cervical and thoracolumbar sagittal parameters, and different sagittal alignment patterns were presented regarding the amount of C2I. As the geometric summation from the pelvis to C2 vertebra, C2I would be a beneficial clue to connect correlation chains of spinal sagittal alignment.
分析 C2 后凸指数（C2I）与颈椎和胸腰椎矢状参数的相关性，并确定 C2I 评估整体脊柱骨盆矢状平衡的有效性。
对 226 例患者（平均年龄 47.8±11.3 岁，63%为女性）的全脊柱站立侧位片进行分析。评估脊柱骨盆参数和拐点发生率。使用 Pearson 相关系数和线性回归分析各参数之间的相关性。使用 C2I 四分位数，通过方差分析比较 3 组之间的差异，以区分不同的排列模式。
C2I 与颈椎参数的 C0-2 前凸（C02L）、C2-7 前凸（C27L）、C0-7 前凸、C2 斜率（C2S）、T1 斜率-C27L、C2-7 矢状垂直轴和颏眉垂直角（CBVA）呈显著相关（r= -0.378、r=0.533、r=0.251、r=0.688、r=0.681、r=0.278 和 r=0.351，均 P<0.01），与 T1 后凸（T1I）、骨盆入射角-腰椎前凸不匹配、L1 后凸（L1I）、骨盆倾斜角（PT）和骨盆入射角（PI）呈显著相关（r=0.480、r=0.516、r=0.518、r=0.635 和 r=0.392，均 P<0.01）。通过以下两个方程估计 C2I：C2I=1.0C2S+1.0PT 和 C2I=0.98PI-0.99LL+0.98 胸曲-1.0C27L（R=0.97，P<0.001），决定系数很高。使用 C2I 四分位数，PI、PT、L1I、T1I 和 C2S 分组间差异有统计学意义。在高 C2I 组中，C27L 和 C0-7 前凸的前凸程度较低；然而，C02L 的前凸程度较高，C2-7 矢状垂直轴和 CBVA 显示高于低 C2I 组。
C2I 与颈椎和胸腰椎矢状参数显著相关，不同的矢状排列模式与 C2I 的量有关。作为从骨盆到 C2 椎体的几何总和，C2I 将是连接脊柱矢状排列关联链的有益线索。
