Study finds both AR and robot-assisted surgeries enable high precision

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Three surgical robotic arms with long needles on each end.

An HSS study tested the effectiveness of robot-assisted and augmented reality surgeries. | Source: Adobe Stock

A study at the Hospital for Special Surgery, or HSS, comparing robot-assisted navigation to the use of augmented reality in spinal surgery found that both techniques demonstrate excellent accuracy and safety for pedicle screw placement.

More than 1.2 million spinal surgeries are performed in the U.S. each year, according to the National Center for Health Statistics. Many of these procedures involve 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 [RAN] and the use of augmented reality [AR] have demonstrated superior accuracy,” said Darren R. Lebl, M.D., MBA. “Our study is the first to directly compare RAN to AR with respect to screw placement precision.”

Lebl is a spine surgeon and director of research at HSS, plus principal investigator of the study. The research was published online in the journal Spine.

HSS is a leading academic medical center focused on musculoskeletal health. Founded in 1863, the New York-based healthcare provider claimed it has the lowest readmission rates in the nation for orthopedics, as well as some of the lowest infection and complication rates.

In addition to patient care, HSS said it supports research, innovation, and education. The HSS Research Institute includes 20 laboratories and 300 staff members focused on advancing musculoskeletal health through the prevention of degeneration, tissue repair, and tissue regeneration.

Head shot of Darren R. Lebl, MD, MBA, a spine surgeon and director of research at HSS, and principal investigator of the study.

Darren R. Lebl is a spine surgeon and director of research at HSS. | Source: Hospital for Special Surgery

Robot-assisted surgery and AR offer aid

Over the past decade, numerous robot-assisted navigation and augmented reality systems have emerged for spine surgery.

“In addition to enhanced accuracy, the potential advantages of both technologies include reduced radiation exposure and provide for improved safety in spine surgery,” noted Dr. Lebl. “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 a headset. A preoperative CT scan of the patient’s spine is used to plan and perform the surgery.

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Study analyzes spinal surgeries

The HSS study included 212 adult spine surgery patients who had a total of 1,211 pedicle screws placed between June 2020 and October 2023. It followed 108 people who received 827 screws using robots and 104 patients who received 384 screws with augmented reality.

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. The study found no significant difference between robot-assisted 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.”