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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)