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Robotic-assisted navigation (RAN) and augmented reality (AR) showed superior accuracy for pedicle screw placement when compared to conventional freehand techniques during surgeries to treat degenerative spine conditions, according to the findings of a prospective clinical and radiographic analysis performed at the Hospital for Special Surgery (HSS).
The study included 212 adult spine patients who underwent surgery of the lumbar and/or sacral spine between June 2020 and October 2023. Surgeons placed a total of 1,211 pedicle screws using RAN (108 patients received 827 screws) or AR (104 patients received 384 screws). One experienced surgeon performed all the robotic cases, while two other experienced spine surgeons used the AR system.
After surgery, the HHS investigators assessed the position of each pedicle screw based on CT scan or 3D fluoroscopy and the Gertzbein-Robbins classification system, which assigns a grade of A, B, C or D to evaluate accuracy. Screws completely within the pedicle received a Grade A rating. Screws that were 2mm (1/16 inch) or less outside of the desired location received a Grade B. The researchers deemed Grades A and B placements to be acceptable, while screws that received a grade of C or D were found to be unacceptable.
There was no significant difference between RAN and AR screw placement in terms of acceptable ratings, with 99.6% of RAN screws rated as Grade A or B, and 98.7% of AR screws classified as A or B. Overall, 92.6% of the screws achieved a Grade A rating.
The researchers also found no significant difference between RAN and AR in terms of overall accurate (Grade A and B) versus inaccurate (Grade C and D) screw placements. But RAN achieved a significantly higher rate of no-breach Grade A placements (95.2%) compared to AR (89.8%).
The findings were recently published in the journal Spine.
“Our findings suggest that, while both techniques are safe and accurate, RAN may offer superior precision in achieving optimal screw placement,” said study senior author Darren Lebl, M.D., M.B.A., a spine surgeon and Director of Research at HSS.
Dr. Lebl noted that the surgeon who operated with RAN faced an additional obstacle that the AR surgeons did not.
“The AR surgeons used an open technique, meaning they had the advantage of direct visualization, while the robotic cases were done percutaneously,” he explained. “The fact that the robotic cases had much less direct visual data available to the surgeon, yet still performed slightly better, says a lot.”
The HSS study is limited in its scope, but does provide interesting insights. “It’s the first head-to-head comparison of RAN and AR, and I hope and expect larger studies will come later as the technologies become even more widely available,” Dr. Lebl said. “HSS is a specialized environment. Maybe what we’ve done can’t be replicated at every hospital, at least not yet, but there’s still value in looking at our data.”
Making the Move to Navigation
Dr. Lebl grasped the potential of navigation during his first decade of practice when he performed spine procedures freehand. “The concept of navigation in the operating room has since come into play very rapidly to the extent that I’ve converted my entire spinal practice to using it,” he said.
Making the switch to navigation lets Dr. Lebl advance his surgical planning and mapping, allowing the robotic arm to navigate to the surgical site accurately and quickly. This factor contributes to surgical efficiencies and reduces patient time under anesthesia.
The benefits of AR include cost-effectiveness, seamless integration with diverse technologies and user-friendly functionalities. “AR systems are notably more versatile than robots because the headset can be worn or removed as required during the procedure,” Dr. Lebl noted.
This contrasts with RAN technology, which is typically draped adjacent to the surgical field and must remain in place until the surgery’s conclusion. The expense of surgical robots has also likely hampered their widespread adoption. That potential limitation could become less of a factor moving forward. “Significant cost reductions of robotic systems have already occurred and will likely continue as increasing competition enters the market,” Dr. Lebl said.
Increased Attention and Use
Dr. Lebl isn’t the only surgeon at HSS to buy into enabling technology. “Of the 25 spine surgeons we have, the majority use RAN,” he said. “I think that’s part of the broader national and international trend toward using navigation.”
Spine’s major players are taking note and recognizing the increasingly important role that enabling technology plays in the ability to compete at the top of the market. Medtronic is expanding its AiBLE digital ecosystem to drive innovation and growth; Globus Medical launched the ExcelsiusHub navigation system last November; Stryker prioritized maintaining control of the Mako Spine robot during the divestiture of its spine implant business this month; and J&J MedTech is advancing active robotics with the recent introduction of VELYS Spine.
Findings from earlier studies led Dr. Lebl’s research team to consider what might be potential barriers to the adoption of surgical navigation and supported the belief among some experts that AR systems will help drive overall adoption of enabling technologies.
“We’ve noticed that surgeons who have been performing spine surgery freehand for a long time might not feel comfortable going straight to adding a robotic arm to the procedure,” he said. “AR might be an easier stepping-stone so that the surgeon can see the images on the patient, but still have extensive manual involvement.”
The HSS study’s conclusion that RAN and AR are more accurate than freehand techniques can help speed adoption of both technologies, according to Dr. Lebl.
He also believes RAN and AR will eventually blend, giving surgeons access to the best of both technologies. “It won’t be long before there’s no longer a difference between a robotic and an AR system,” he said. “Surgeons will operate with a robotic arm and an AR headset.”
For Dr. Lebl, the most compelling argument in favor of widespread adoption of navigation in spine comes down to improved patient outcomes. “It’s true that a lot of these systems are expensive, but the costs of surgical complications are astronomical,” he said. “We’re on the cusp of seeing the era of the misplaced screw coming to an end.”
