Ultrasonic surgical instrument with a multi-planar articulating shaft assembly

An ultrasonic surgical instrument, comprising:

• (a) an end effector including an ultrasonic blade;
• (b) a body assembly;
• and
• (c) a shaft assembly having a first articulation section and longitudinally extending from the body assembly to the end effector, including:
• (i) a proximal waveguide body portion positioned proximally from the first articulation section and defining a longitudinal axis,
• (ii) a distal waveguide body portion positioned distally from the first articulation section and in acoustic communication with the ultrasonic blade distally projecting therefrom,
• (iii) an articulation body portion extending through the first articulation section between the proximal and distal waveguide body portions,
• wherein the articulation body portion is configured to flex a first direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a first plane,
• wherein the articulation body portion is further configured to flex a second direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a second plane,
• wherein the second direction is different than the first direction such that the second plane is different than the first plane for multiplanar deflection of the ultrasonic blade relative to the longitudinal axis,
• wherein the articulation body portion includes a first flexible member defining a cross-sectional radius, and
• wherein the first articulation section of the shaft assembly is configured to limit the first flexible member to a predetermined maximum bend radius, wherein the predetermined maximum bend radius relates to the cross-sectional radius according to a first condition for uncoupling a longitudinal vibrational component from a transverse vibrational component to communicate an acoustic vibration from the proximal waveguide body portion to the distal waveguide body portion and driving the ultrasonic blade with the acoustic vibration,
• wherein the first condition is the cross-sectional radius divided by the predetermined maximum bend radius is less than 0.1.

A method of deflecting an end effector of an ultrasonic surgical instrument, wherein the ultrasonic surgical instrument has an acoustic waveguide including (a) a proximal waveguide body portion defining a longitudinal axis;

• (b) a distal waveguide body portion having an ultrasonic blade distally projecting therefrom;
• and (c) an articulation body portion with a cross-sectional radius and extending between the proximal and distal waveguide body portions, the method comprising:
• (a) flexing the articulation body portion in a first direction to form a bend radius to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a first plane;
• (b) limiting the bend radius to a predetermined maximum bend radius according to a first condition, wherein the first condition is the cross-sectional radius divided by the predetermined maximum bend radius is less than 0.1;
• and
• (c) uncoupling a longitudinal vibrational component from a transverse vibrational component to communicate an acoustic vibration from the proximal waveguide body portion to the distal waveguide body portion thereby driving the ultrasonic blade with the acoustic vibration.