An Automated Extracorporeal Knot-tying System Using Two Concentric Tube Robotic Arms for Deployment through a 3-mm Port

Ligation is a process of closing or blocking a blood vessel or duct intracorporeally to obstruct the flow of fluid before cutting it. Ligation through knot tying using a suture is a quite complex procedure and needs the use of dexterous tools to properly secure the knot. In case of natural orifice transluminal endoscopic surgery (NOTES) and single-incision laparoscopic surgery (SILS), ligation through suture knot tying is even more difficult because of the small diameters of the accessible ports. In this study, a robotic solution for suture ligation has been proposed for possible use in SILS and NOTES. The developed device can operate through a 3-mm laparoscopic port and has a workspace of 35 x 10x5 mm (length x width x height) around the duct. The device uses a pre-tied Roeder's knot, which is pushed down onto the duct by the operation of two concentric tube-based manipulator arms. Preliminary evaluation validates that the device can work around a phantom duct with 7 mm outer diameter without any collisions. The operation takes an average of 128.10 s with a standard deviation of 15.72 s. The knot tied is secure enough to abduct the fluid flow inside the duct, which is validated by testing on a water-filled rubber tube. The proposed device assists surgeons for suture ligation in SILS and NOTES without the requirement for any other tools and with a possibility of decreasing the operating time.