Fig 1.
The pedicle screw and plate system schematic diagram.
Fig 2.
Surgical constructs: unilateral pedicle screw and plate (UP); unilateral pedicle screw and rod (UR); unilateral pedicle screw and rod + transfacet pedicle screw (UR+TFS); unilateral pedicle screw and plate + transfacet pedicle screw (UP+TFS); unilateral pedicle screw and plate + unilateral pedicle screw and rod (UP+UR).
Some part of the facet screw and the plate constructs were ignored in the finite element figures.
Table 1.
The testing order of seven calf spine specimens after intact test.
Fig 3.
Flexion-extension ROM results.
All comparisons related to intact case were significant (p<0.0001).
Table 2.
L4-5 ROM (°) during different loading modes.
Fig 4.
All comparisons related to intact case were significant (p<0.0001).
Fig 5.
Axial rotation ROM results. Except UR fixation, all the other comparisons related to intact case were significant (p<0.012).
Fig 6.
The compressive strains on the surface of the vertebral body for the different fixation modes under flexion motion.
To enable comparisons among the different modes for each strain gauge, each strain was normalized with respect to the average among the fixation modes. The average and standard deviation of the seven specimens were plotted.
Fig 7.
The compressive strains on the surface of the vertebral body for the different fixation modes under lateral bending motion.
To make comparisons among the different modes for each strain gauge, each strain was normalized with respect to the average among the fixation modes. The average and standard deviation of the seven specimens are plotted.
Table 3.
Significance of the difference between left and right strain measurement location in L4 and L5 vertebrae under flexion and lateral bending motion for the different fixation configurations.
Table 4.
Significance of the difference between the different fixation configurations in the four strain measurement locations.