Surgical cutting instrument for robotic surgery and method

A surgical cutting instrument comprising a rod having a distal end and an articulated end-effector connected to the distal end of the rod, wherein said articulated end-effector comprises:

• a connection link connected to the distal end of the rod having a body comprising in a single piece:
• one or more convex ruled surfaces of connection links with parallel generator lines,
• a first distal connecting portion;
• a support link articulated to the connection link and having a body comprising in a single piece:
• one or more convex ruled surfaces of support links with parallel generator lines;
• a proximal connecting portion articulated to the first distal connecting portion of the first connection link, defining a proximal rotational joint for the connection link and the support link so that the connection link and the support link are rotatable relatively about a common proximal rotation axis;
• a second distal connecting portion;
• a blade holder link articulated to the support link having a body comprising in a single piece:
• a blade holder link attachment root having a pulley portion formed by one or more convex ruled surfaces of blade holder root with parallel generator lines,
• a drag portion
• a blade link, integral in rotation with said blade holder link, having a body comprising in a single piece a cutting edge and a drag counter-portion engaged with said drag portion of the blade holder link;
• a reaction link articulated to the support link and to the group formed by the blade link and the blade holder link, having a body comprising in a single piece an attachment root having a pulley portion formed by one or more convex ruled surfaces of reaction link root, with parallel generator lines;
• wherein:
• the blade holder link attachment root and the attachment root of the reaction link define with the second distal connecting portion of the support link a distal rotational joint for the blade holder link, the reaction link and the support link, so that the blade holder link, the reaction link and the support link are relatively rotatable about a common distal rotation axis, orthogonal to said common proximal rotation axis;
• a counter-blade portion which is integral in rotation with said attachment root of the reaction link;
• and wherein said surgical cutting instrument further comprises:
• a first pair of antagonistic tendons extending along the rod and connected to the blade holder link to move the blade link about said common distal rotation axis,
• a second pair of antagonistic tendons extending along the rod and connected to said reaction link to move the counter-blade portion about said common distal rotation axis,
• each tendon having a longitudinal extension;
• and wherein:
• the attachment root of the blade holder link comprises in a single piece at least a first termination seat which receives said first pair of antagonistic tendons;
• the attachment root of the reaction link comprises in a single piece at least a second termination seat which receives said second pair of antagonistic tendons;
• and wherein:
• said one or more convex ruled surfaces with parallel generator lines of the connection link are parallel to said common proximal rotation axis;
• at least one of said one or more convex ruled surfaces with parallel generator lines of the support link is parallel to said common proximal rotation axis;
• said one or more convex ruled surfaces of blade holder root with parallel generator lines of the blade holder link and said one or more convex ruled surfaces of further root with parallel generator lines of the reaction link are parallel to the common distal rotation axis;
• the first pair of antagonistic tendons and the second pair of antagonistic tendons are adapted to slide longitudinally on said one or more convex ruled surfaces of the connection link and on said one or more convex ruled surfaces of the support link and are adapted to wind/unwind without sliding on the respective convex ruled surface of the root of the blade holder link or of the reaction link, to move the blade link and the counter-blade portion respectively in opening/closing;
• and wherein
• the cutting edge of the blade link is adapted to abut against said counter-blade portion during the movement of the degree of freedom of opening/closing in a mechanical interference contact condition to exert a cutting action;
• the cutting edge of the blade link is elastically bendable in a direction parallel to the common distal rotation axis;
• a first distance in a direction parallel to the common distal rotation axis between the first termination seat of the root of the blade holder link and a surface of said one or more convex ruled surfaces of the support link is constant for any cutting condition;
• a second distance in a direction parallel to the common distal rotation axis between the second termination seat of the root of the reaction link and a surface of said one or more convex ruled surfaces of the support link is constant for any cutting condition.