Impact of a novel spine stabilization technique on intervertebral movement in cervical spine surgery using a humanoid...

Navigation and robotic systems in spine surgery rely on the assumption that the spine behaves as a rigid body during surgery; however, intervertebral motion persists under typical intraoperative conditions. For robotic execution of hard-tissue procedures to be effective, the system must be capable of autonomously securing and stabilizing the target vertebra throughout the intervention.

A cadaveric study was performed using 6 human cervical spine specimens. In part 1, C2-C7 vertebrae were instrumented with markers and subjected to robotically applied 30 N forces along planned pedicle screw trajectories, with and without robotic stabilization. Intervertebral motion was quantified using a 3D optical tracking system. In part 2, surgeons placed 30 cervical pedicle screws (C1-T1) using standard robot-assisted navigation and 36 screws using a novel FDA-cleared bi-manual 2-armed surgical robotic system incorporating autonomous vertebral stabilization and individual vertebra tracking. Screw accuracy was assessed by comparing planned and actual trajectories on postoperative 3D imaging.

Robotic stabilization reduced translational motion by up to 57.8% and rotational motion by up to 57.4% at the targeted level, with meaningful reductions at adjacent levels and diminishing effects with increasing distance. No major pedicle screw placement errors (>2 mm or >2°) were observed with stabilization. Mean angular error decreased by 31.7% (1.5 ± 1.2° vs. 1.0 ± 0.5°).

Bi-manual robotic stabilization significantly reduced intervertebral motion and improved pedicle screw placement accuracy. Targeted intraoperative stabilization may mitigate limitations associated with spinal nonrigidity in robotic-assisted navigation.