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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