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UrduMany spinal surgeries require the use of implants called pedicle screws to stabilize the spine, and precise positioning is critical for a successful surgery. “Compared to conventional free-hand techniques, both robotic-assisted navigation and the use of augmented reality have demonstrated superior accuracy,” said Darren R. Lebl, MD, MBA, a spine surgeon and director of research at HSS, and principal investigator of the study. “Our study is the first to directly compare RAN to AR with respect to screw placement precision.”
Over the last decade, numerous robotic-assisted navigation and augmented reality systems designed for spine surgery have emerged. “In addition to enhanced accuracy, the potential advantages of both technologies include reduced radiation exposure and provide for improved safety in spine surgery,” Dr. Lebl notes. “A growing number of major medical centers nationwide are using at least one of these technologies.”
RAN involves robotic guidance of surgeon-operated instruments. A robotic arm, along with 3D images of the patient’s anatomy and navigation technology similar to GPS, enables the surgeon to perform a minimally invasive procedure that is planned ahead of time on advanced software. AR-assisted spine surgery superimposes 3D images of a patient’s anatomy onto the surgeon’s visual field during surgery via an augmented reality headset. A preoperative CT scan of the patient’s spine is used to plan and perform the surgery.
The HSS study included 212 adult spine surgery patients who had a total of 1,211 pedicle screws placed using either robotics (108 individuals received 827 screws) or augmented reality (104 patients received 384 screws) between June 2020 and October 2023. They underwent surgery in the lumbar and/or sacral spine for degenerative spinal conditions. One experienced surgeon performed all of the robotic cases, while two other experienced spine surgeons used the AR system.
The position of each pedicle screw was assessed after surgery based on either CT scan or 3D fluoroscopy using the Gertzbein-Robbins classification system, which assigns a grade of A, B, C or D to evaluate accuracy. The HSS researchers considered Grades A and B to be acceptable. The A rating is assigned to screw placement completely within the pedicle, a bony structure on the vertebra that protects the spinal cord. Grade B, still acceptable, is assigned to a screw that is 2mm (1/16 inch) outside of the desired location. In the study, any screw with a Grade C or D would be deemed unacceptable.
After surgery, two independent spine surgeons assigned a grade to all the pedicle screws. No significant difference was found between RAN and AR screw placement in terms of accuracy, 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 the top Grade A rating.
“Our results confirmed excellent accuracy for both techniques, making both robotics and AR safe tools for accurate positioning of lumbosacral pedicle screws,” Dr. Lebl said. “However, a higher rate of Grade A screws was seen in the RAN group, potentially highlighting superior precision for robotics.”
Dr. Lebl believes the study represents the future of spine surgery. “Our team at HSS is working to advance spine surgery to make it safer, less invasive and more precise, with less radiation exposure,” he explains. “Our team has already implemented spine surgery with real-time confirmation of implant accuracy in the operating room so that everything is optimally positioned before the patient goes to the recovery room. In the future, more focus will be on decisions regarding the timing and type of surgery, and the actual execution of the surgery will become much more automated.”
About HSS
HSS is the world’s leading academic medical center focused on musculoskeletal health. At its core is Hospital for Special Surgery, nationally ranked No. 1 in orthopedics (for the 15th consecutive year), No. 3 in rheumatology by U.S. News & World Report (2024-2025), and the best pediatric orthopedic hospital in NY, NJ and CT by U.S. News & World Report “Best Children’s Hospitals” list (2024-2025). In a survey of medical professionals in more than 20 countries by Newsweek, HSS is ranked world #1 in orthopedics for a fifth consecutive year (2025). Founded in 1863, the Hospital has the lowest readmission rates in the nation for orthopedics, and among the lowest infection and complication rates. HSS was the first in New York State to receive Magnet Recognition for Excellence in Nursing Service from the American Nurses Credentialing Center five consecutive times. An affiliate of Weill Cornell Medical College, HSS has a main campus in New York City and facilities in New Jersey, Connecticut and in the Long Island and Westchester County regions of New York State, as well as in Florida. In addition to patient care, HSS leads the field in research, innovation and education. The HSS Research Institute comprises 20 laboratories and 300 staff members focused on leading the advancement of musculoskeletal health through prevention of degeneration, tissue repair and tissue regeneration. In addition, more than 200 HSS clinical investigators are working to improve patient outcomes through better ways to prevent, diagnose, and treat orthopedic, rheumatic and musculoskeletal diseases. The HSS Innovation Institute works to realize the potential of new drugs, therapeutics and devices. The HSS Education Institute is a trusted leader in advancing musculoskeletal knowledge and research for physicians, nurses, allied health professionals, academic trainees, and consumers in more than 165 countries. The institution is collaborating with medical centers and other organizations to advance the quality and value of musculoskeletal care and to make world-class HSS care more widely accessible nationally and internationally. www.hss.edu.
