Ultrasound and optically controlled robotic instrument for resternotomy in cardiothoracic surgery

A surgical robotic instrument is introduced, which synergistically supports the surgeon in the application of resternotomy, an important part of many reoperations in heart- and thoracic surgery. A frequent complication occurring during this operation is injury of underlying soft tissue structures, which can even result in death of the patient. To improve safety, the proposed robotic instrument automatically adjusts the cutting depth on the basis of the related local bone thickness. To obtain anatomical information, most systems available are based on optical tracking and computed tomography. However, a combination of these modalities is not yet common in heart- and thoracic surgery. In this context, two different concepts for acquiring anatomical information and realizing real-time cutting depth adjustment are presented, using ultrasound and optical bone surface characteristics. Both approaches were evaluated in an experimental setup with phantom sternums demonstrating feasibility of the approach. Future work will include a combination of different sensors to improve robustness of the system and cadaver trials.