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Table 3 Association rod fracture risk with surgical and instrumentation variables

From: Risk factors for rod fracture after posterior correction of adult spinal deformity with osteotomy: a retrospective case-series

Confounders

Subgroups

Rod(s) fracture

Odds ratio (95 % Cl: min; max)

P(χ2)

Yes

No

Osteotomy by type

Pedicle subtraction

6

31

7.2 (0.8; 62.7)

0.1

Smith-Peterson

1

37

  

Osteotomy by location

Thoracolumbar junction

3

17

2.3 (0.5; 11.1)

0.3

Other

4

51

  

Use of navigation

Yes

7

62

N/A

>0.5

No

0

5

  

Use of cement

Yes

0

16

N/A

0.3

No

7

48

  

Screw/rod manufacturer

Device Company 1

3

29

0.9 (0.2; 4.3)

>0.5

Other

4

34

  

Pre-contoured rods

Yes

1

24

0.3 (0.03; 3.8)

0.4

No

3

14

  

Material of rods

Titanium

5

40

1.2 (0.06; 25.9)

>0.5

Other

0

4

  

Diameter of rods

6 mm

3

29

0.7 (0.1; 3.8)

>0.5

Other

3

20

  

Type of screws

Polyaxial

5

36

N/A

N/A

Monoaxial

0

0

  

Screw density

Incompletea

4

27

2.0 (0.4; 9.8)

0.4

Complete

3

41

  

Connectors

Standard

6

48

2.5 (0.3; 22.1)

0.4

Other

1

20

  

Interbody support

Yes

4

45

0.7 (0.1; 3.2)

>0.5

No

3

22

  

Sagittal rod contour

>60°

5

19

10.0 (1.1; 95.1)

0.04

≤60°

2

49

  

Crosslinks

≥2

3

13

3.2 (0.6; 15.9)

0.2

0–1

4

55

  

Domino and/or parallel connectorsb

Yes

4

8

10.0 (1.9; 53.1)

0.01

No

3

60

  

Number of fused levelsc

≥8

6

41

3.8 (0.4; 33.4)

0.2

8

1

26

  

Number of crossing junctions

2

6

27

9.1 (1.0; 80.0)

0.05

0–1

1

41

  

Fusion to sacrum

Yes

7

38

N/A

0.1

No

0

30

  

Fusion to pelvis

Yes

4

20

3.2 (0.7; 15.6)

0.2

No

3

48

  
  1. aMissing one or more pedicle screws at available locations along construct. bPresence of domino and/or parallel-connectors at date of rod fracture. cIncluding levels when connecting to prior instrumentation