Iso-C/3-dimensional neuronavigation versus conventional fluoroscopy for minimally invasive pedicle screw placement in lumbar fusion.

Background: Minimally invasive spinal surgery (MISS) has evolved over the past years due to the combination of microsurgery, minimal access strategies and neuronavigation. Percutaneous or mini-open pedicle screw placement is a challenge, especially for surgeons not experienced in the use of biplanar fluoroscopy or stereotactic imaging techniques. The aim of the study was to compare the precision of pedicle screw fixation for lumbar fusion procedures using Iso-C/stereotactic 3D neuronavigation (3D NAV) vs. standard AP/lateral fluoroscopy (2D NAV).

Methods: Our first 42 patients undergoing MISS for one- or 2-level lumbar or lumbosacral fusion procedures for degenerative lumbar pathology were included in this study. Either 3D NAV (n=29) or standard fluoroscopy (n=13) was used to aid screw placement. Demographics, operative time, blood loss, and screw placement accuracy were evaluated. Screw placement was evaluated postoperatively using lumbar CT scanning. Accuracy of 3D NAV was evaluated by comparing intraoperative planning screenshots to postoperative CT placement of screws.

Results: There were no significant differences between groups for mean age, gender or intraoperative blood loss. 90.9% of 3D NAV screws and 73.7% of fluoroscopy screws had no pedicle perforation (p=0.04). Intraoperative navigation screenshots accurately predicted pedicle screw placement in 90.9% of cases. There was a positive correlation between 3D NAV accuracy and better screw grade (rs 0.45, p=0.036).

Conclusions: Utilization of 3D NAV for percutaneous or mini-open lumbar screw placement during the early learning curve for MISS was associated with higher screw accuracy. This study demonstrates that the use of 3D navigation can facilitate the learning curve for MISS.