Abstract
INTRODUCTION
Posterior spinal instrumentation for fusion using intraoperative computed tomography (CT) navigation is gaining traction as an alternative to the conventional two-dimensional fluoroscopic-guided approach to percutaneous pedicle screw placement. However, few studies to date have directly compared outcomes of these 2 minimally invasive instrumentation methods.
METHODS
A consecutive cohort of patients undergoing primary percutaneous posterior lumbar spine instrumentation for spine fusion was retrospectively reviewed. Revision surgeries or cases converted to open were excluded. Accuracy of screw placement was assessed using a postoperative CT scan with blinding to the surgical methods used. The Gertzbein-Robbins classification was used to grade cortical breach: Grade 0 (<0 mm cortical breach), Grade I (<2 mm), Grade II (2-4 mm), Grade III (4-6 mm), and Grade IV (>6 mm).
RESULTS
CT navigation was found to significantly improve accuracy of screw placement (P < .022). There was significantly more facet violation of the unfused level in the fluoroscopy group vs the CT group (9% vs 0.5%; P < .0001). There was also a higher proportion of poor screw placement in the fluoroscopy group (10.1% vs 3.6%). No statistical difference was found in the rate of tip breach, inferomedial breach, or lateral breach. Regression analysis showed that fluoroscopy had twice the odds of incurring poor screw placement as compared to CT navigation.
CONCLUSION
This radiographic study comparing screw placement in minimally invasive fluoroscopy- vs CT navigation-guided lumbar spine instrumentation provides evidence that CT navigation significantly improves accuracy of screw placement, especially in optimizing the screw trajectory so as to avoid facet violation. Long-term follow-up studies should be performed to ascertain whether this difference can contribute to an improvement in clinical outcomes.
Radiographic Accuracy of Percutaneous Pedicle Screw Placement in Fluoroscopic- Versus CT Navigation-Guided Lumbar Spine Instrumentation