Fig. 4
Box plots for the VS comparison. a: VS-U distribution among three VD angles. Kruskal–Wallis H test was used to test the difference, and then Mann–Whitney U test for pairwise comparison, and statistical test criteria for pairwise comparison was calibrated as α’ = α/3, that was 0.05/3. b: VS-L distribution among three VD angles. Kruskal–Wallis H test was used to test the difference, and then Mann–Whitney U test for pairwise comparison, and statistical test criteria for pairwise comparison was calibrated as α’ = α/3, that was 0.05/3. c: Two independent Mann–Whitney U test was used to test the difference between VS-U and VS-L of the same VD angle and statistical test criteria was α, that was 0.05. VS: vertebral stiffness. VS-U: VS when the load perpendicular to the upper edge of L1. VD angle: vertebral deformity angle. L1: 1st lumbar vertebral body. QCT-FEA: quantitative computed tomography-based finite element analysis. VS-L: VS when the load perpendicular to the lower edge of L1