Introduction: Pedicle screw stabilization is perhaps the most common way surgeons fixate the unstable spine. Accuracy of screw placement is crucial to prevent neurovascular injury, pain, or biomechanical failure. Electromyography (EMG) is commonly used to analyze the accuracy of screw placement, but recent literature has questioned the value of EMG in detecting bony breaches caused by screw placement. CT is an accepted method to evaluate a bony breach from a malpositioned screw. In this study, the authors evaluated the accuracy of EMG monitoring in predicting bony breaches when utilizing intraoperative CT guided neuronavigation in conjunction with a navigated high speed drill for screw placement.

Methods: 100 consecutive patients who underwent this procedure at Florida Hospital Orlando between 2011 and 2014 were evaluated. Of these, 89 patients had postoperative CT imaging for analysis. The data analyzed includes the total number of screws placed, the total number of screw breaches based on post-op CT, and the EMG results of each screw placed. The number of screw breaches based on post-op CT was compared to EMG results to determine whether a correlation exists.

Results: A total of 728 screws were inserted for the 89 patients. The accuracy of screw placement was 98.8% with only 9 screws (1.2%) showing a bony breach on CT. Meanwhile out of the 728 screws inserted only 5 screws (0.69%) demonstrated an EMG positive result, yet none showed breach by CT. The 9 screws that showed pedicle breach showed normal EMG values.

Conclusions: Intraoperative CT guided power drill neuronavigation demonstrates an accuracy of 98.8% and a lack correlation between post-op CT and EMG results. Post-op CT is a more accurate measure for the accuracy of pedicle screw placement, and an alternative for EMG needs to be established as a standard of care for spinal fusion surgery.

Patient Care: Improved method for pedicle screw placement

Learning Objectives: 1. Assess the correlation between EMG and post-operative CT in detecting pedicle screw perforation. 2. Suggest alternatives for assessing screw accuracy in surgical management. 3. Introduce a novel approach for pedicle screw placement in spinal fusion surgery.

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