(J-398) Laparoscopic Surgical Instrument with Variable Geometry

Laparoscopic surgery is limited to procedures in which a straight path between the entry port and the surgical site can be achieved. Current laparoscopic instruments have rigid linear shafts, with articulation generally limited to the tool tip. Minimally invasive surgery is trending towards the single port method, which alters the surgical landscape from a tool access as well as control standpoint. The traditional straight, non-articulating surgical instruments, which were designed to be used with multiple ports throughout the area of interest, are further limited in their range of motion as entry occurs solely from the navel rather than ports near the site of interest. The single port method also causes crowding of instrument handles outside the body which make single port procedures more technically complicated for surgeons than their traditional multiport counterparts. We have developed a manual laparoscopic instrument which allows static articulation along the entire tool body which allows custom, nonlinear tool configurations to be achieved.

The instrument uses statically articulating joints which are compatible with the soft trocar design used during single port procedures. The design seeks to provide articulation at intervals along the instrument shaft, while otherwise mimicking the style of traditional laparoscopic instruments. The tool is cable driven, and the joints have a concentric, open lumen design with several set increments of rotation. To create articulating joints which could be held rigid with a single cable through the tool body, we devised a system of bending via rotation, in which two slanted cylindrical cross sections mate at the joint. Rotating these slanted faces with respect to each other allows angulation to be achieved while maintaining contact in the same plane within the joint.

The final prototype uses a system of alternating straight and slanted joints to allow directionality and angle of bending to be set using the same incremental rotation design concept. The open lumen design allows for two cables to be routed through the tool body: one to compress the joints into their locked position, and the other to control the open/close motion of the instrument tip (e.g., grasper jaws). The transmission uses a cable agonist, spring antagonist system in which the jaws are held in a default open position, allowing for closing pressure to be modulated using the instrument handle. The tensioning of the two cables is coupled using a ratchet locking lever system within the console which allows incremental tension adjustment to account for cable extension as the geometry is manipulated. The geometry of the tool is adjusted by detensioning the tool and rotating each joint individually.