Total mesorectal excision using a soft and flexible robotic arm: a feasibility study in cadaver models.

Background: Sponsored by the European Commission, the FP7 STIFF-FLOP project aimed at developing a STIFFness controllable Flexible and Learn-able manipulator for surgical operations, in order to overcome the current limitations of rigid-link robotic technology. Herein, we describe the first cadaveric series of total mesorectal excision (TME) using a soft and flexible robotic arm for optic vision in a cadaver model.

Methods: TME assisted by the STIFF-FLOP robotic optics was successfully performed in two embalmed male human cadavers. The soft and flexible optic prototype consisted of two modules, each measuring 60 mm in length and 14.3 mm in maximum outer diameter. The robot was attached to a rigid shaft connected to an anthropomorphic manipulator robot arm with six degrees of freedom. The controller device was equipped with two joysticks. The cadavers (BMI 25 and 28 kg/m) were prepared according to the Thiel embalming method. The procedure was performed using three standard laparoscopic instruments for traction and dissection, with the aid of a 30° rigid optics in the rear for documentation.

Results: Following mobilization of the left colonic flexure and division of the inferior mesenteric vessels, TME was completed down to the pelvic floor. The STIFF-FLOP robotic optic arm seemed to acquire superior angles of vision of the surgical field in the pelvis, resulting in an intact mesorectum in both cases. Completion times of the procedures were 165 and 145 min, respectively. No intraoperative complications occurred. No technical failures were registered.

Conclusions: The STIFF-FLOP soft and flexible robotic optic arm proved effective in assisting a laparoscopic TME in human cadavers, with a superior field of vision compared to the standard laparoscopic vision, especially low in the pelvis. The introduction of soft and flexible robotic devices may aid in overcoming the technical challenges of difficult laparoscopic procedures based on standard rigid instruments.