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. 2018 Dec;4(4):736-743.
doi: 10.21037/jss.2018.10.03.

Three-dimensional fluoroscopic navigation versus fluoroscopy-guided placement of pedicle screws in L4-L5-S1 fixation: single-centre experience of pedicular accuracy and S1 cortical fixation of 810 screws

Manuel García-Fantini  1 , Ricardo De Casas  2
Affiliations

Three-dimensional fluoroscopic navigation versus fluoroscopy-guided placement of pedicle screws in L4-L5-S1 fixation: single-centre experience of pedicular accuracy and S1 cortical fixation of 810 screws

Manuel García-Fantini et al. J Spine Surg. 2018 Dec.

Abstract

Background: Three-dimensional (3D) navigation techniques can theoretically provide higher accuracy rates and increased safety for pedicle screw (PS) placement than traditional fluoroscopy (FL) guided methods. In this study, we compare the pedicular accuracy of 3D isocentric fluoroscopic navigation (3DFL) versus FL guidance in PS L4-L5-S1 fixation and evaluate the differential cortical purchase and safety of fixation of the S1 PS.

Methods: This is a single-centre retrospective study of 810 PSs placed in open L4-L5-S1 fixation between 2012 and 2017 in 39 patients using standard FL and in 96 patients under 3DFL. Pedicular screw accuracy was determined by postoperative computed tomography (CT) and graded on a 4-tiered classification system according to Gertzbein and Robbins. In addition, sacral screws were evaluated depending on the degree of cortical fixation: monocortical, bicortical or tricortical, and the degree of safety with respect to retroperitoneal structures.

Results: Grade 0 perfect pedicular screw placement was 95% for 3DFL screws compared to 85% for screws placed under fluoroscopy (P<0.05). The number of grade 0 versus grade 1 and higher (breached screws) was statistically significant (P<0.05). Higher S1 cortical screw accuracy [77% versus 51% (P<0.05)] for bi- and tricortical fixation and a lower percentage of "at risk" PSs (P<0.05) were achieved with placement under 3DFL versus FL.

Conclusions: 3DFL enhances the accuracy and safety of PS placement in L4-L5-S1 fixation, reducing the rate of misplaced screws and improving S1 cortical fixation.

Keywords: Navigated spine surgery; lumbosacral spine; pedicle screw accuracy; sacrum cortical fixation; three-dimensional fluoroscopy.

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Conflict of interest statement

Conflicts of Interest: The authors have no conflicts of interest to declare.

Figures

Figure 1
Figure 1
Representative CT images in the axial and coronal planes of grade 0 (A,B), grade 1 (C,D), grade 2 medial and grade 3 lateral (E,F) and grade 3 medial (G,H) pedicle screw placements. CT, computed tomography.
Figure 2
Figure 2
Representative images of different cortical fixations of an S1 pedicular screw: monocortical (A), bicortical (B) and tricortical (C,D) purchase.
Figure 3
Figure 3
S1 pedicular screw “at risk”: protrusion >4 mm close to the common iliac artery (CIA) and vein (CIV).
See this image and copyright information in PMC

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