Neurological events due to pedicle screw malpositioning with lateral fluoroscopy-guided pedicle screw insertion

The risk of novel postoperative neurological events due to pedicle screw malpositioning in lumbar fusion surgery is minimized by using one of the several image-guided techniques for pedicle screw insertion. These techniques for guided screw insertion range from intraoperative fluoroscopy to intraoperative navigation. A practical technique consists of anatomical identification of the screw entry point followed by lateral fluoroscopy used for guidance during insertion of the screw. This technique is available in most clinics and is less expensive than intraoperative navigation. However, the safety of lateral fluoroscopy-guided pedicle screw placement with regard to novel postoperative neurological events due to screw malposition has been addressed only rarely in the literature. In this study the authors aimed to determine the rate of novel postoperative neurological events due to intraoperative and postoperatively established screw malpositioning during lateral fluoroscopy-assisted screw insertion.

Included patients underwent lateral fluoroscopy-assisted lumbosacral screw insertion between January 2012 and August 2017. The occurrence of novel postoperative neurological events was analyzed from patient files. In case of an event, surgical reports were screened for the occurrence of intraoperative screw malposition. Furthermore, postoperative CT scans were analyzed to identify and describe possible screw malposition.

In total, 246 patients with 1079 screws were included. Novel postoperative neurological events were present in 36 patients (14.6%). In 8 of these 36 patients (3.25% of the total study population), the neurological events could be directly attributed to screw malposition. Screw malpositioning was caused either by problematic screw insertion with immediate screw correction (4 patients) or by malpositioned screws for which the malposition was established postoperatively using CT scans (4 patients). Three patients with screw malposition underwent revision surgery without subsequent symptom relief.

Lateral fluoroscopy-assisted lumbosacral screw placement results in low rates of novel postoperative neurological events caused by screw malposition. In the majority of patients suffering from novel postoperative neurological events, these events could not be attributed to screw malpositioning, but rather were due to postoperative neurapraxia of peripheral nerves, neuropathy, or intraoperative traction of nerve roots.