Increased safety in robotic paranasal sinus and skull base surgery with redundant navigation and automated registration.

We present an advanced version of our robotic setup for paranasal sinus surgery that was developed at the Department of Otorhinolaryngology, Head and Neck Surgery in Erlangen, Germany. The system was interconnected with a redundant navigation system for increasing intraoperative safety while performing telemanipulatory as well as fully automated maneuvers.In contrast to the previous "all in one" version, we built a modular three component setup. The basic feature of the computer navigation system is the "CAPPA ENT" station. The system references by automatically detecting a referencing frame mounted on a non-invasive upper jaw mouthpiece. Software components of both systems, navigation and robotics were combined on one user interface. Accuracy as well as clinical applicability studies were carried out. For better surveillance and increased safety, we decided to evaluate the robots reproducibility errors and overall stereotactic accuracy by means of redundant navigational control on a phantom model for paranasal sinus and skull base surgery. Multiple measurements from 14 CT-markers were taken representing different surgical approaches.A modular setup was designed and was deemed feasible in its size and weight dimensions as well as its maneuvrability for application in a routine operating room environment. The navigational feedback is integrated in real time in the robots user interface. In case of blocked visibility to the Dynamic Referencing Frame the robot powers down and activates the force torque sensor, thus softening all articulating joints. We found only adequate accuracies in pinpointing a specific CT-marker both in telemanipulatory and fully automated maneuvers. No significant offsets were observed evaluating accuracies for different surgical approaches.By using redundant navigation feedback, we were able to add another safety feature, the "loss of control" function, which shuts down any robotic action. However, no increase of the absolute accuracy was observed by adding this feature. We conclude that redundant navigational control does not make the robot more accurate, but it adds a potent safety feature to the system.