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Table 2 Bilateral S2AI screw trajectory parameters on CT imaging

From: Does the thoracolumbar kyphosis secondary to ankylosing spondylitis affect the iliac trajectory of S2AI screw?

Parameters Left Right
AS deformity AS non-deformity non-AS deformity AS deformity AS non-deformity non-AS deformity
Sag angle (°) 8.2 ± 11.7 26.6 ± 6.2* 26.9 ± 10.2* 8.0 ± 13.3 27.6 ± 6.9* 27.0 ± 10.5*
Tsv angle (°) 42.6 ± 6.7 43.1 ± 6.1 36.8 ± 7.3* 43.1 ± 7.7 42.5 ± 6.3 36.9 ± 7.5*
Max-length (mm) 111.6 ± 13.8 111.8 ± 11.3 114.4 ± 7.5 112.3 ± 14.7 112.9 ± 9.7 114.1 ± 7.8
Sacral distance (mm) 36.4 ± 6.1 34.9 ± 7.6 30.6 ± 6.6* 38.7 ± 5.8 38.2 ± 4.8 30.6 ± 5.8*
Iliac width (mm) 14.4 ± 4.0 12.3 ± 4.0 13.4 ± 2.0 14.3 ± 4.2 12.0 ± 1.9 13.6 ± 1.7
S2 midline (mm) 26.3 ± 3.6 25.4 ± 4.1 25.8 ± 6.4 26.4 ± 4.1 25.4 ± 2.6 25.7 ± 6.3
Skin distance (mm) 41.4 ± 14.8 36.8 ± 8.1 37.6 ± 9.9 41.0 ± 14.1 37.8 ± 5.7 37.2 ± 9.4
Iliac wing (mm) 12.7 ± 3.8 13.4 ± 4.1 12.5 ± 2.4 13.0 ± 4.5 13.2 ± 2.6 12.9 ± 2.0
PSIS distance (mm) 20.6 ± 12.3 20.1 ± 6.4 21.9 ± 9.1 20.1 ± 12.6 21.0 ± 6.3 21.3 ± 8.5
  1. PSIS Posterior superior iliac spine
  2. * data was statistically different from that of AS deformity (P < 0.05)