A study demonstrated a high accuracy (90.2%) for 2-D fluoroscopy-guided pedicle screw using electromonitoring. Only 0.71% of the 470 screws had a major breach. Knowing the radiological spine pedicle anatomy and the correct interpretation of EMG are the key factors for this technique 1).
Nevzati et al., retrospectively reviewed consecutive patients who underwent fluoroscopy-guided transpedicular screw fixation from January 2007 to May 2011 in the Department of Neurosurgery, Kantonsspital Aarau, a certified Swiss National Neurosurgical Education and Training Center. The accuracy of the pedicle screw trajectory was assessed using reconstructed postoperative axial, sagittal, and coronal computed tomography images. The displacement was classified as minor (≤ 2 mm), moderate (2.1-4 mm), and severe (>4 mm).
A total of 1236 pedicle screws were placed in 273 consecutive patients in the thoracic and lumbosacral spine. All surgeries were performed under the supervision of 7 board-certified neurosurgeons and faculty members. A total of 17 surgeons, including trainees, participated in all procedures. A total of 247 (20%) screws breaching the pedicle were identified, with 135 (10.9%) minor violations, 65 (5.3%) moderate violations, and 47 (3.8%) severe violations. Sixteen (5.9%) patients developed postoperative radiculopathy. All of these patients belonged to the subgroup of severe screw displacement.
The data presented confirm that for a training and education center, transpedicular fluoroscopy-guided screw fixation remains a technically demanding procedure. As defined in this study, neurological symptoms are likely associated only with severe screw misplacement 2).
198 consecutive patients who underwent transpedicular screw fixation.
Accuracy of screw placement was evaluated by postoperative CT scan. Misplacement was defined in cases where more than 25% of the screw size was residing outside the pedicle.
The indications for hardware placement, radiologic studies, patient demographics, and reoperation rates were recorded. Five hundred twenty-eight screws (Group A, n=81) were inserted into the vertebral body with the assistance of lateral fluoroscopy only, whereas 690 screws (Group B, n=117) were inserted with the assistance of lateral fluoroscopy, and the final positions of the screws were checked with AP fluoroscopy.
A total of 1,218 screws were analyzed, with 962 screws placed at the lumbosacral region and 256 screws at the thoracic region. According to the postoperative CT scan, 27 screws (2.2%) were identified as breaching the pedicle. Nineteen of them (3.6%) were in Group A, whereas 8 (1.16%) were in Group B. The rate of pedicle breaches was significantly different between Group A and B (p=.0052). In Group A, the lateral violation of the pedicle was seen in 10 screws (1.9%), whereas medial violation was seen in 9 screws (1.7%). In Group B, the lateral violation of the pedicle was seen in six screws (0.87%), whereas medial violation was seen in two screws (0.29%). The medial and lateral penetration of screws were significantly different between Groups A and B (p<.05). A pedicle breach occurred in 21 patients, and 15 of them underwent a revision surgery to correct the misplaced screw. Of these patients, 11 (13.6%) were in Group A, and 4 (3.4%) were in Group B (p=.0335).
In this study, Koktekir et al., evaluated and clarified the diagnostic value of intraoperative fluoroscopy in both the lateral and AP imaging that have not yet been evaluated in any comparative study. They concluded that the intraoperative use of fluoroscopy, especially in the AP position, significantly decreases the risk of screw misplacement and the results are comparable with other advanced techniques 3).