Table 1.
Parameters of screws.
Fig 1.
A novel cervical pedicle screw design (right) involving a tapering core and thread diameter would lessen the chance of pedicle wall penetration when compared with the conventional cervical pedicle screw (left).
Fig 2.
The 3D model of C3-C7 cervical spine with subtraction of lamina and spinous processes with screw aiming tract (blue arrow) in an image processing software before 3D printing.
Fig 3.
The 3D printed model (white) was loaded into the specially designed immobilizers to secure their positions throughout the screw insertion experiment.
Fig 4.
The Tri-layers foam (left) and the mono-layer foam (right) were prepared into 30 mm × 15 mm × 30 mm dimensions.
Fig 5.
A screw placement in a foam model, the new CPS screw (a), the stand CPS screw (c), and the lateral mass screw (c) were loaded in a special jig prepared for the actual pullout test.
Table 2.
Proportion of pedicle wall perforation between the 2 types of screws.
Fig 6.
The pedicle wall perforation was observed from the model after the safety insertion test.
The perforation grade 1 (yellow star) and grade 2 (red star) were observed in standard CPS insertion.
Table 3.
Mean difference and P-value compared in each group.
Fig 7.
Pullout strength comparison of three posterior cervical fixation methods.