• Wen Zhang, Tao Li, Mengmeng Xu, Xiaoyang Liu, Guodong Wang, Bingxiang Wang, Jianmin Sun, Xingang Cui, and Zhensong Jiang.
• Department of Spine Surgery, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Shandong Provincial Hospital Affiliated to Shandong University, No. 9677 in Jingshi Road, Jinan City, China.
• Eur Spine J. 2020 Sep 1; 29 (9): 2384-2391.

PurposeThe aim is to propose a novel spinopelvic parameter C7 sacral tilt (C7ST), of which its sum with global tilt (GT) is equal to pelvic incidence (PI), from a geometrical point of view.MethodsA cohort of 198 patients was recruited and the whole lateral spine and pelvic radiographs were performed. The following sagittal parameters were measured: sagittal vertical axis (SVA), C7 vertical tilt (C7VT), sacral slope (SS), pelvic tilt (PT), PI, GT and C7ST. The correlations between them were analyzed using the Pearson or Spearman correlation coefficient, and simple linear regressions were simultaneously conducted. P < 0.05 was set as the level of significance.ResultsGeometric construction by complementary angles revealed that PI = C7ST + GT, GT = PT + C7VT, and C7ST = SS - C7VT. Both C7ST and GT were moderately correlated with PI (R = 0.52 and 0.596, respectively), strongly correlated with SS and PT, respectively (SS = 0.9 * C7ST + 1.15, R = 0.955; PT = 0.87 * GT + 3.86, R = 0.96). The correlation coefficients of the SVA and C7VT, SVA and SS - C7ST, and SVA and GT - PT were 0.935, 0.925 and 0.863, respectively.ConclusionThe novel proposed spinopelvic parameter C7ST has the advantages of convenient measurement, reduced error, and extrapolation of other parameters. The greatest significance of proposing C7ST is that pelvic parameters (PI, PT and SS) are converted into spinal parameters (C7ST and GT), which is very helpful for a more intuitive understanding of the progression of spinal sagittal imbalance.

12 keywords...

hide…