Facet joint violation by pedicle screws under robotic guidance was reduced at some parts of the lumbar spine compared to CT navigation during lumbar spine surgery, according to a study published Aug. 12 in The Spine Journal.
Researchers took cohorts of adult lumbar spinal fusion patients who had CT navigation guidance and robotic navigation and compared data including the number of facet violations and their types. The study found that robotic assistance significantly reduced the rate of rostral facet joint violations at the L2 and L3 levels compared to CT navigation, but not at levels L4 and L5. Facet violations were approaching almost one-third of patients who had screws at the L5 level.
Tiffany Perry, MD, a neurosurgeon at Los Angeles-based Cedars-Sinai and the study's lead author, explained how screw sizes could affect the outcomes.
"The L2 and L3 pedicles are usually smaller," Dr. Perry told Becker's. "They're narrower than the L4 and L5 [pedicles], so we have to pay a lot more attention to the start point and trajectory of the screws at L2 and L3 because you have less of a window that you're working in. You have a narrower pedicle and for L4 and L5, the pedicles tend to be wider. As far as the trajectory of the actual pedicles, they tend to be angled in or medialized a little bit more, which makes it a little easier to have less sky as you're doing robotic approaches."
Another finding from the study showed percuteneous robot-assisted and CT navigated approaches showed fewer facet violations than open approaches.
"With the percutaneous [approach], you've got all of your surrounding tissues that are helping you to maintain your trajectory … and when you're doing open surgery you have all of the soft tissues," Dr. Perry said. "If you have a robotic arm that's coming down through an open incision, you have to have all of the muscle, all the skin and all the soft tissues dissected away. There's nothing that could move your robotic arm or could move your navigation away from that tissue. You have to have a longer incision when you're doing open robotic surgery."
Dr. Perry said another key takeaway from the study is the reminder that no spine robot or spine navigation is perfect without human expertise.
"Ultimately, it goes to show us that no matter how great the technology or how great the robot or how advanced that placement is, there still can be mistakes that are made," she said. "You can have the perfect trajectory and the perfect screw placement, but if that surgeon places that screw in too deeply, you have to fix the violation. No matter how perfect our technology is, there's always human error. So I think this [study] actually does point that out more than anything."