Lateral radiological evaluation of transarticular screw placement in the lower cervical spine

Abstract

This study assessed the ideal district of lateral radiograph in evaluation of transarticular screw placement in the lower cervical spine. To assess the ideal zone of lateral radiographs in determining the safe or hazardous locations of the screw tips during transarticular screw implantation in the lower cervical spine. Transarticular screw in the lower cervical spine had been used as an alternative technique to achieve posterior cervical spine stability. Injury to the spinal nerves caused by transarticular screws which are too long must be identified quickly to minimize the neurologic complication. No previous radiological study regarding evaluation of the transarticular screw placement using lateral radiographs has been reported. Twelve cervical spines were removed from embalmed cadavers. Four transarticular screw placements with Dalcanto's technique under direct visualization, including placement of the screw tip staying the ventral cortex, 2, 4 and 6 mm over-penetration of the ventral cortex, were performed on each specimen. Following each placement, a lateral radiograph was taken. Each vertebral body was divided vertically into four equal zones, and another equal zone posterior to the posterior border of the vertebral body was defined as Zone pre-1. The numbers of screw tips seen in each zone were quantified for each placement. Partitions of v 2 method was used to evaluate the ideal zone on lateral radiograph for transarticular screw insertion. At C34 and C45, no significant difference was found between Zone pre-1 and Zone 1 (v 2 = 0.18, P [ 0.50), while there was significant difference between Zones 1 and 2 (v 2 = 73.6, P \ 0.005), as well as Zones 2 and 3 (v 2 = 13.2, P \ 0.005). At C56 and C67, No significant difference was found between Zones 2 and 3 (v 2 = 0.25, P [ 0.50), while there was significant difference between Zone pre-1 and Zone 1 (v 2 = 66.2, P \ 0.005), as well as Zones 1 and 2 (v 2 = 10.5, P \ 0.005). Ideal screw tip positions on lateral radiograph for transarticular screw by Dalcanto's technique should be in Zone 1 at C34 and C45, in Zone pre-1 at C56 and C67. If the screw tip was in Zones 3 and 4, the safe rate will be decreased significantly and it might be too deep and be dangerous.

Pedicle screw insertion accuracy with different assisted methods: a systematic review and meta-analysis of comparative studies

“…To be included in the study, the following criteria were used: (1) the paper must include a navigated pedicle screw insertion comparative design; (2) pedicle screw placement accuracy was to be analyzed. Exclusion criteria were: (1) pedicle screw inserted but no navigation employed or applied, and no postoperative accuracy assessment conducted; (2) repetitive studies.…”

“…However, pedicle violation resulted from malpositioned screw leading to potential harm to nearby vital structures, which prompted surgeons to search for the perfect strategy. Though alternative methods (e.g., transarticular screw [2], lateral mass [3], extrapedicular screw fixation [4,5]) were developed for better surgical outcome, surgeons were more prone to improve the pedicle screw insertion accuracy by trying various supporting methods (e.g., intraoperative monitoring [6,7], anatomical markers [13,24,26,47]). Nevertheless, none of the conventional methods was considered as the perfect intraoperative assisting method.…”

Computed tomography–based determination of a safe trajectory for placement of transarticular facet screws in the subaxial cervical spine

“…Alternatively, fluoroscopic imaging of the facet joint space shows the reference plane for the sagittal angle, but the lower part of the cervical spine is often obscured by the shoulders. 16 Also, fluoroscopy offers limited information to tailor the axial trajectory for a given transarticular screw. Again, knowledge of the axial trajectory angle in combination with an exposure of the lateral edge of the facet joints directs the freehand technique: from C2-3 to C5-6, the mediolateral angle ranges from 23° to 25°, and it is noticeably more lateral (33°) at C6-7 (Table 1).…”

The Study on Comparison of 3 Techniques for Transarticular Screw Placement in the Lower Cervical Spine

“…However, in clinical practice, avoiding impingement of the vertebral artery and other neurovascular structures can be limited by measurements from the fl uoroscopic images. According to the report of Xu et al , 11 if the tip of transarticular screw was in zones 3 and 4 (anterior half part of the vertebral body) on the lateral view, the safe rate will be decreased signifi cantly and it might be too deep and be dangerous.…”