A Hybrid Position/Force Control for Robot-Aided Pedicle Tapping in Spinal Surgery

Pedicle screw fixation is a widely adopted surgical technique to enhance column stability and promote spinal fusion. Robot-assisted spinal surgery represents a solution to the challenges associated with the tapping phase of this procedure, which requires high precision and can cause surgeon fatigue. Based on the promising results of Authors' previous study, which achieved an improvement in surgeons' overall physical comfort for robot-aided pedicle tapping, this study seeks to improve the intervention effectiveness and efficiency, and enhance at the same time the robotic system usability and acceptability, thereby contributing to increased patient safety and enhanced surgeon's comfort. To accomplish these goals, a new semi-autonomous control strategy based on a hybrid position/force control is proposed. This control strategy offers two operation modes that can be selected according to the surgeon's preference: pushing mode and torquing mode. Eleven subjects were recruited, and an ad hoc experimental setup and protocol were implemented. After a training phase, the subjects performed the tapping procedure on an anthropomorphic spine phantom. The study reveals that both operation modes are equally effective (error from the optimal tapping depth: $0.8 ± 0.4$ [mm]) and efficient, comparable to traditional robot-assisted pedicle tapping, and significantly improve ergonomics (rapid upper limb assessment score: $2.65 ± 0.75$). The torquing mode reduces muscular fatigue more than the pushing mode. Despite subjects' preference for the torquing mode, the possibility to choose between the two maximizes system usability and human-robot interaction acceptability by 18.8%.