INTRODUCTION
Accurate placement of pedicle screws is essential in spinal instrument surgery to ensure postoperative stability and prevent vascular injury and neurological complications. However, in MISS (Minimally Invasive Spine Surgery), accurate and safe placement of pedicle screws traditionally requires the use of a C-arm, making radiation exposure for the medical staff unavoidable. MISS techniques, combined with advanced technologies like intraoperative 3D-CT imaging and the novel navigation system, have been introduced to enhance accuracy and reduce radiation exposure. The aim of this study was to investigate the accuracy of pedicle screw insertion using the Novel Navigation System and Intraoperative 3D-CT imaging system in posterior lumbar spinal instrumentation surgery without occupational radiation exposure.
METHODS
From June 2023 to October 2024, a total of 53 consecutive patients (26 men and 27 women, mean age 69.3 years) who underwent posterior thoracolumbar spinal fusion or fixation surgery under the use of the novel navigation system (NextAR, Medacta International SA, Castel San Pietro, Switzerland) and Intraoperative 3D-CT imaging system (COREVISION 3D, Fuji Film, Tokyo, Japan) at our institute were included in this study. All patients underwent thoracolumbar spinal instrumentation surgery using pedicle screws, with the novel navigation system involved the use of intraoperative 3D-CT imaging to provide real-time navigation. All screws were inserted under conditions without radiation exposure. To evaluate the accuracy of pedicle screw placement, postoperative CT scans (within 3 days after surgery) were analyzed using the Gertzbein and Robbins classification, which categorizes screw placement accuracy based on pedicle wall breaches (Grade 0: no breach, Grade 1: <2-mm breach, Grade 2: 2-4-mm breach, Grade 3: 4-6mm breach, Grade 4: >6-mm breach).
RESULTS
A total of 259 screws were placed using the Novel Intraoperative CT Navigation System, with the following accuracy rates: Grade 0: 96.5% (250 screws), Grade 1: 1.5% (4 screws), Grade 2: 1.9% (5 screws), Grade 3 and 4: 0% (0 screw). Revision surgery was performed in two cases due to insufficient fixation stability, in which bilateral Grade 2 screw deviations were observed. No neurovascular injury due to screw deviation was observed.
DISCUSSION
Our data revealed a 96.5% accuracy rate, with 240 out of 259 screws accurately placed. These results indicate that Novel Intraoperative CT Navigation System with intraoperative 3D-CT imaging system are promising tools for achieving precise pedicle screw positioning in posterior lumbar spinal fusion surgeries. Despite the high accuracy rate, 9 screws in our study did not meet the defined accuracy criteria. Possible factors contributing to these discrepancies include patient-specific anatomical variations, minor registration errors, or technical limitations inherent to the navigation system. In addition to the high accuracy of screw insertion, these systems are highly beneficial because the intraoperative 3D imaging system used in this study minimizes patient radiation exposure and can reduce occupational exposure to zero for operating room staff.