A Surgeon-Robot Shared Control for Ergonomic Pedicle Screw Fixation

Pedicle screw fixation is a fundamental surgical procedure which requires high accuracy and strength from the surgeon who may be exposed to uncomfortable postures and muscular fatigue. The objective of this paper is to propose a novel approach to robot-aided pedicle screw fixation based on a Surgeon-Robot Shared control that makes the tapping procedure, i.e. threading the patients pedicle, semi-autonomous. The surgeon continues to have a full control over the surgical intervention by i) accurately move the robot end-effector using a hands-on control interface, i.e. the surgical tapper, along a pre-planned axis, ii) continuously controlling the forces exerted onto the patient spine during the tapping phase, iii) modulating the torque about the tapping axis by adequately tuning the tool-bone interaction force along the same axis. Furthermore, the procedure appears to be more comfortable and less tiring for the surgeon. The proposed approach was tested on eight subjects who were asked to perform the tapping procedure onto an anthropomorphic spine phantom. A comparative analysis among the proposed approach and the ones typically adopted in literature to perform pedicle screw placement was carried out. The experimental results demonstrated that proposed approach, with respect to the traditional robot-aided procedure, guarantees comparable accuracy and efficiency in the screw placement and lower fatigue and more comfortable postures for the surgeon.