A study comparing robotic-assisted navigation (RAN) with augmented reality (AR) in spine surgery reveals that both technologies demonstrate excellent accuracy and safety for pedicle screw placement.
The study, conducted at the Hospital for Special Surgery (HSS) in the US, recently published its findings online in the journal Spine.
Spine surgery frequently requires the use of pedicle screws to stabilise the spine, and precise placement of these implants is crucial for surgical success.
Darren R Lebl is an associate professor of spinal surgery, specialising in minimally invasive surgery, the cervical spine, motion-preserving spine procedures, and robotic computer navigation surgery.
As director of research at HSS and the study’s principal investigator, he explained: ‘Compared to conventional free-hand techniques, both robotic-assisted navigation and augmented reality have demonstrated superior accuracy. Our study is the first to directly compare RAN to AR concerning screw placement precision.’
Both systems have become increasingly sophisticated and widely adopted in the past decade.
Dr Lebl added: ‘In addition to enhanced accuracy, the potential advantages of both technologies include reduced radiation exposure and improved safety in spine surgery. A growing number of major medical centres nationwide are now utilising at least one of these technologies.’
RAN uses robotic guidance to assist with surgeon-operated instruments. Using a robotic arm, 3D imaging of the patient’s anatomy, and GPS-like navigation technology, the surgeon can perform a minimally invasive procedure planned using advanced software.
Conversely, AR-assisted spine surgery overlays 3D images of the patient’s anatomy onto the surgeon’s visual field via an augmented reality headset. Preoperative CT scans of the patient’s spine are used to plan and execute the surgery.
The study evaluated 212 adult patients who underwent lumbar and/or sacral spine surgery for degenerative conditions between June 2020 and October 2023. A total of 1,211 pedicle screws were placed: 827 screws in 108 patients using RAN and 384 screws in 104 patients using AR.
One experienced surgeon performed all robotic cases, while two experienced spine surgeons performed the AR-assisted surgeries.
To assess screw placement accuracy, the Gertzbein-Robbins classification system was used, which assigns a grade of A, B, C, or D. Grades A and B were considered acceptable. Grade A indicates a screw is entirely within the pedicle, while Grade B allows for up to 2mm (1/16 inch) deviation from the ideal position. Screws graded C or D were deemed unacceptable.
Postoperative imaging, including CT scans or 3D fluoroscopy, was reviewed by two independent spine surgeons who evaluated each screw. The study found no significant difference in accuracy between the two techniques:
• 99.6% of RAN screws were graded A or B.
• 98.7% of AR screws achieved the same grades.
• Overall, 92.6% of screws across both groups earned the highest Grade A rating.
Dr Lebl said: ‘Our results confirmed excellent accuracy for both techniques, making both robotics and AR safe tools for accurate positioning of lumbosacral pedicle screws. However, a higher rate of Grade A screws was observed in the RAN group, potentially highlighting superior precision for robotics.’
He views this study as a window into the future of spine surgery.
‘At HSS, we are advancing spine surgery to make it safer, less invasive, and more precise, with reduced radiation exposure. Our team has already implemented real-time confirmation of implant accuracy in the operating room, ensuring optimal placement before the patient enters recovery.’
Looking ahead, he envisions a growing focus on automating the surgical process. ‘Future developments will likely centre on optimising the timing and type of surgery, with the actual execution becoming increasingly automated.’
