Abstract
PurposePedicle screw fixation in the upper cervical spine is a difficult and high-risk procedure. The screw is difficult to place rapidly and accurately, and can lead to serious injury of spinal cord or vertebral artery. The aim of this study was to design an individualized 3D printing navigation template for pedicle screw fixation in the upper cervical spine.MethodsUsing CT thin slices data, we employed computer software to design the navigation template for pedicle screw fixation in the upper cervical spine (atlas and axis). The upper cervical spine models and navigation templates were produced by 3D printer with equal proportion, two sets for each case. In one set (Test group), pedicle screws fixation were guided by the navigation template; in the second set (Control group), the screws were fixed under fluoroscopy. According to the degree of pedicle cortex perforation and whether the screw needed to be refitted, the fixation effects were divided into 3 types: Type I, screw is fully located within the vertebral pedicle; Type II, degree of pedicle cortex perforation is <1 mm, but with good internal fixation stability and no need to renovate; Type III, degree of pedicle cortex perforation is >1 mm or with the poor internal fixation stability and in need of renovation. Type I and Type II were acceptable placements; Type III placements were unacceptable.ResultsA total of 19 upper cervical spine and 19 navigation templates were printed, and 37 pedicle screws were fixed in each group. Type I screw-placements in the test group totaled 32; Type II totaled 3; and Type III totaled 2; with an acceptable rate of 94.60%. Type I screw placements in the control group totaled 23; Type II totaled 3; and Type III totaled 11, with an acceptable rate of 70.27%. The acceptability rate in test group was higher than the rate in control group. The operation time and fluoroscopic frequency for each screw were decreased, compared with control group.ConclusionThe individualized 3D printing navigation template for pedicle screw fixation is easy and safe, with a high success rate in the upper cervical spine surgery.
Highlights
The difficult of posterior cervical spinal surgery is the focal point of this study
The upper cervical spine models and navigation templates were produced by 3D printer with equal proportion, two sets for each case
In one set (Test group), pedicle screws fixation were guided by the navigation template; in the second set (Control group), the screws were fixed under fluoroscopy
Summary
The difficult of posterior cervical spinal surgery is the focal point of this study. Nowadays, the primary system of internal screw placement in posterior cervical surgery is the screw-rod system[1], which includes pedicle screws system, lateral mass screws system, transarticular screws system, spinous screws system, and laminar screws system. The cervical pedicle screw internal fixation system is the product of spinal biomechanics, an area of study that is of milestone significance, laying the foundation for a greater understanding of the functional behavior and development of the spine. The pedicle screw system has become the strongest and the most common internal fixation method for posterior cervical surgery because of its excellent biomechanical property [2]. Cervical pedicle screw internal fixation system can correct cervical deformity and instability, and can restore and maintain normal intervertebral height and physiological curvature. As well, it provides obvious advantages for maintaining axial rotation of the cervical spine and flexion and extension stability [4, 5]
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