Forces in minimally invasive surgery: Reliable manipulation of gastric mucosa and the sigmoid colon

Designing a robotic system for surgical procedures is always challenging. Reliability, integration in the operating room and intuitive use even in stressful situations are some major requirements. Our project aims at the improvement of two widespread interventions in minimally invasive surgery (MIS): the endoscopic submucosal dissection (ESD) and the laparoscopic sigmoid resection (LSR). We develop a robotic system for the manufacturing by selective laser sintering (SLS) using the biocompatible polyamide PA2200. The material properties of PA2200 as well as the maximum applicable dimensions of our system, limited by the human anatomy, enforce us to find a suitable balance between the needed flexibility to maneuver through the human body and the needed stiffness to reliably manipulate different kinds of tissue. The tissues we want to manipulate are gastric mucosa in ESD and the sigmoid colon in LSR. To identify the forces needed, we conducted an experiment in a porcine model. In this paper we present the results of our study on expected maximum forces for reliable manipulation of tissue during ESD and LSR. Characteristics and anatomical boundary conditions for both interventions are compared.