Table 3 Correlation between sagittal parameters on lateral X-ray radiographs and the ideal S2AI screw trajectory parameters on CT imaging in deformity patients with AS

Sag angle

r

−0.227^a

− 0.618^b

0.232^a

− 0.220^a

− 0.607^b

0.284^b

Tsv angle

r

0.080

−0.243^a

0.052

0.004

−0.239^a

0.131

Max-length

r

−0.192

− 0.137

− 0.002

−0.304^b

− 0.176

−0.14

Sacral distance

r

−0.023

0.133

−0.084

0.026

0.103

−0.089

Iliac width

r

0.043

0.458^b

−0.103

0.062

0.324^b

−0.096

S2 midline

r

0.169

0.039

−0.079

0.133

0.445^b

−0.098

Skin distance

r

0.148

−0.038

−0.238^a

0.113

−0.053

− 0.250^a

Iliac wing

r

0.018

0.162

−0.139

−0.007

0.178

−0.052

PSIS distance

r

0.062

−0.135

−0.201

0.063

−0.109

− 0.166