Pedicle screws are used in many spine procedures to stabilize the spine. Precise positioning of these screws is critical for a successful outcome, with positioning usually confirmed with 2-dimensional radiographs.
Now, a study from Hospital for Special Surgery (HSS), presented at the 2023 annual meeting of the American Academy of Orthopaedic Surgeons, demonstrates the superiority of intraoperative 3-dimensional (3D) imaging in confirming the accuracy of pedicle screw placement during spine surgery when compared with 2-dimensional radiographs.
“Two-dimensional biplanar radiographs have been the gold standard to confirm pedicle screw placement in spine fusion surgery for many years,” said Darren Lebl, MD, a spine surgeon at HSS and principal investigator of the study.
“Our study is the first to compare the differences in intraoperative biplanar radiography and 3D imaging for pedicle screw accuracy in thoracic and lumbar cases using robotic technology.”
False Positives, False Negatives
For this study, Dr. Lebl and colleagues analyzed data from 103 patients who underwent spinal fusion by a single surgeon between 2019 and 2022. Pedicle screw placement was assessed with both intraoperative biplanar radiography and 3D imaging in each case.
“CT scans taken after surgery were compared to the findings of intraoperative biplanar radiography and 3D imaging to detect either false-positive or false-negative readings,” said Fedan Avrumova, BS, an HSS clinical research coordinator who presented the study at the AAOS meeting.
“False positive findings are instances when biplanar radiography imaging suggests the screw was not in an acceptable position, while in fact a more advanced 3D image – intraoperative 3D scan or postoperative CT scan – showed the screw to be in an acceptable position.
“Conversely, a false negative instance was when a biplanar radiography image led one to believe or looked as though the screw was in an acceptable position, when in fact a more advanced 3D image or post-operative CT scan showed that it was in fact not acceptable.”
Postoperative CT imaging revealed a clinically significant number of patients who had false-negative and false-positive screw placement readings on biplanar radiography. However, screw position shown on intraoperative 3D imaging was found to be much more accurate.
New Standard of Care?
“Based on our study, biplanar radiography imaging may … miss many screws that are not in fact acceptable,” Dr. Lebl said. “In our study, it was approximately 1% of cases where this occurred.
“However, for surgeons and centers that implant hundreds or thousands of screws per year, this is going to result in a significant clinical impact for many people. Even 1 misplaced screw can have a significant impact for a patient, a surgeon, and a hospital system.
“Therefore, based on these findings, we suggest that for intraoperative confirmation of screw position 3D imaging may soon represent a new standard of care.”