Effectiveness of 2 Types of Drill Templates for Cervical Anterior Transpedicular Screw Placements: A Comparative Study.
OBJECTIVE
To evaluate effectiveness of regular and modified drill templates used to guide cervical anterior transpedicular screw (ATPS) placement.


METHODS
This study included 15 adult cadaveric specimens. Computed tomography images were imported into Mimics software. Three-dimensional modeling of all cervical vertebrae was done, and the ideal trajectories were designed for ATPSs. Models of regular and modified templates were designed for every level on the left or right side randomly. After three-dimensional printing, 2 types of templates were used to guide the insertion. Postoperative computed tomography scans were used to measure deviations between real and ideal trajectories in the direction and positioning of entry points. The deviations in the 2 groups were compared using paired t test.


RESULTS
There were 120 templates and ATPSs fabricated and placed. Postoperative images showed that 7 screws perforated pedicles in the regular group, with an accuracy rate of 88.3%. Deviations between real and ideal trajectories in cranially inclined angles and extroversive angles were 1.13° ± 0.61° and 0.97° ± 0.60°, respectively, and deviations of entry point position in the x-axis and y-axis were 0.72 ± 0.38 mm and 0.95 ± 0.47 mm, respectively. In the modified group, there were 2 malposition screws with accuracy rate of 96.7%. Deviations in cranially inclined angles were 0.66° ± 0.53° and 0.66° ± 0.55° in extroversive angles, respectively, and deviations in entry point positions in the x-axis and y-axis were 0.45 ± 0.37 mm and 0.51 ± 0.34 mm, respectively. The differences in deviations between groups were statistically significant.


CONCLUSIONS
Compared with regular drill templates, modified drill templates can provide higher accuracy and stronger trajectory control in ATPS insertions.
['Wang|Liran|L|', 'Zhao|Liujun|L|', 'Gu|Yongjie|Y|', 'Yu|Liang|L|', 'Ma|Weihu|W|', 'Xu|Rongming|R|']
D000328:Adult D000368:Aged D000369:Aged, 80 and over D001863:Bone Screws D002102:Cadaver D002574:Cervical Vertebrae D005260:Female D006801:Humans D021621:Imaging, Three-Dimensional D016268:Internal Fixators D008297:Male D008875:Middle Aged D009333:Neck D025321:Surgery, Computer-Assisted D014057:Tomography, X-Ray Computed
Drill templates Cervical anterior transpedicular screw 3D printing