A Hand-Held Non-Robotic Surgical Tool With a Wrist and an Elbow

Objective: This paper describes a surgical device that provides both wrist and elbow dexterity without motors or electronics. The device provides dexterity advantages in minimally invasive surgery typically associated with robotic systems, but does so with many fewer components. Fully mechanical designs of this type promise to deliver “robot-like dexterity” at a lower financial cost than current surgical robotic systems. Methods: Most non-robotic articulated surgical tools developed to date feature one or two degrees-of-freedom (DOF) close to the tool tip (i.e., a “wrist”). In this paper, we describe a new tool that not only features a two-DOF wrist, but also augments its dexterity with a two-DOF “elbow” consisting of a multi-backbone design seen previously only in robotic systems. Such an elbow offers high stiffness in a thin form factor. This elbow requires static balancing, which we accomplish with springs in the handle, so that the surgeon can benefit from the stiffness without feeling it while using the device. Results: We report the overall tool design and experiments evaluating how well our static balance mechanism compensates for the multi-backbone elbow's intrinsic stiffness. Conclusion: We demonstrate the use of a multi-backbone elbow in a manual tool for the first time and show how to combine the elbow with a pin joint wrist in a fully mechanical (i.e., non-robotic) tool. Significance: This paper is a step toward high dexterity, low-cost surgical instruments that bring some benefits of surgical robotic systems to patients and surgeons at a lower cost.