Concentric Tube Robots for Minimally Invasive Surgery: Current Applications and Future Opportunities

Minimally Invasive Surgery (MIS) evolved as an alternative to open surgical approaches, and resulted in reduced surgical trauma and faster recovery. However, the confined workspace, loss of depth perception, compromised hand-eye coordination, as well as extended learning curves precluded the surgeons from adapting this approach in all cases. Unlike rigid robots that are characterized with mechanical rigidity and limited degrees-of-freedom (DOFs), continuum robots were developed mainly for interventional medicine. A special class of continuum robots are Concentric Tube Robots (CTRs), that have diameters comparable to those of catheters and steerable needles. Since their introduction, huge effort has been dedicated to the kinematic modelling and real-time control. Due to their intrinsic actuation capability, miniaturization potential and controllable mechanical properties, they have been adopted for different surgical applications. Experimental tests based on phantom and cadaveric studies were performed to prove their feasibility. This review encompasses the generic design, modelling and control methods of CTRs. It also addresses, in detail, their different surgical applications. Finally, related main research limitations and future opportunities are briefly discussed.