A comparison of CT-based navigation techniques for minimally invasive lumbar pedicle screw placement.
METHODS
A comparison of 2 surgical techniques.


OBJECTIVE
To determine the relative accuracy of minimally invasive lumbar pedicle screw placement using 2 different CT-based image-guided techniques.


BACKGROUND
Three-dimensional intraoperative fluoroscopy systems have recently become available that provide the ability to use CT-quality images for navigation during image-guided minimally invasive spinal surgery. However, the cost of this equipment may negate any potential benefit in navigational accuracy. We therefore assess the accuracy of pedicle screw placement using an intraoperative 3-dimensional fluoroscope for guidance compared with a technique using preoperative CT images merged to intraoperative 2-dimensional fluoroscopy.


METHODS
Sixty-seven patients undergoing minimally invasive placement of lumbar pedicle screws (296 screws) using a navigated, image-guided technique were studied and the accuracy of pedicle screw placement assessed. Electromyography (EMG) monitoring of lumbar nerve roots was used in all. Group 1: 24 patients in whom a preoperative CT scan was merged with intraoperative 2-dimensional fluoroscopy images on the image-guidance system. Group 2: 43 patients using intraoperative 3-dimensional fluoroscopy images as the source for the image guidance system. The frequencies of pedicle breach and EMG warnings (indicating potentially unsafe screw placement) in each group were recorded.


RESULTS
The rate of pedicle screw misplacement was 6.4% in group 1 vs 1.6% in group 2 (P=0.03). There were no cases of neurologic injury from suboptimal placement of screws. Additionally, the incidence of EMG warnings was significantly lower in group 2 (3.7% vs. 10% (P=0.03).


CONCLUSIONS
The use of an intraoperative 3-dimensional fluoroscopy system with an image-guidance system results in greater accuracy of pedicle screw placement than the use of preoperative CT scans, although potentially dangerous placement of pedicle screws can be prevented by the use of EMG monitoring of lumbar nerve roots.
Wood
Martin
M
The Mater Private Hospital Brisbane, Queensland, Australia. mwood@mc.mater.org.au
Mannion
Richard
R
D000328:Adult; D000368:Aged; D001863:Bone Screws; D004576:Electromyography; D005260:Female; D005471:Fluoroscopy / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods; D016896:Treatment Outcome