Carl Nelson, PhD1, Tao Shen, BS1, Tammy Kindel, MD, PhD2, Dmitry Oleynikov, MD2. 1University of Nebraska-Lincoln, 2University of Nebraska Medical Center (UNMC)
INTRODUCTION: The clinical integration of natural orifice transluminal endoscopic surgery (NOTES) has been delayed due to the lack of technologic development of novel instruments and endoscopes as well as multi-tasking platforms. Robotic NOTES (R-NOTES) has been recently introduced as a technology to overcome the limitations of traditional NOTES. However, case reports of R-NOTES application using external robotic systems are also limited by small robotic workspaces and prolonged instrumentation docking times, often requiring a hybrid of R-NOTES and laparoscopy for completion of a successful procedure. This study describes the development of a novel R-NOTES transvaginal system with improved robotic functionality and enhanced surgeon-robotic interactions.
METHODS AND PROCEDURES: A robot for transvaginal NOTES was designed, prototyped, and tested. The robot consists of a bimanual manipulator with interchanging tool tips, a cable-driven serpentine linkage for insertion and stabilization of the manipulator, and an external drive system housing motors and cable-pulley hardware. The two manipulator arms each contain four small motors, for a total of eight local degrees of freedom. The serpentine linkage provides four additional active degrees of freedom for global gross positioning of the manipulator, allowing retroflexed access to the surgical site. The control system was designed to allow for toggling between control of the gross positioning (primarily during insertion/removal) and fine manipulator control. Robot workspace, speed, and force capabilities were tested, as was manipulator connection/disconnection (necessary for insertion/removal of the robot).
RESULTS: The serpentine linkage showed capacity of achieving a retroflected “S” shape with 90-degree rotation in two independent curvature sections. This serpentine linkage demonstrated a workspace with a volume of approximately 2.4 L. Adding the workspaces of each of the manipulator arms (0.4 L each), the robot can properly locate the end effector for typical surgical tasks in the abdomen, such as stretch-and-dissect maneuvers. A novel connector provided convenient modularity to assemble and disassemble the system for insertion/removal and provided supporting force in excess of 20 N for loads applied on the robot arms during surgery. The multifunctional manipulator successfully achieved the tool-changing function, requiring 20 seconds to switch from one surgical tool to another.
CONCLUSIONS: This report describes the successful development of a new robotic system for transvaginal NOTES that circumvents the limited dexterity, power, and general usability of previous hardware designs. In particular, better tool multifunctionality and a simplified setup procedure can decrease operative times and improve ease of operation in transvaginal R-NOTES, potentially limiting the need for hybrid R-NOTES techniques.
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