Ultrasonic surgical instrument with integral shaft assembly torque wrench

A surgical instrument, comprising:

• (a) an end effector;
• (b) a shaft assembly having the end effector projecting distally therefrom, wherein the shaft assembly includes an acoustic waveguide extending therethrough and a proximal end portion configured to rotatably couple with an ultrasonic transducer assembly;
• and
• (c) a torque wrench integrally connected with the shaft assembly, the torque wrench including a drive feature configured to engage with a driven feature to transmit torque from the shaft assembly to the acoustic waveguide up to a predetermined torque, wherein the drive feature is configured to slip relative to the driven feature upon receiving torque greater than the predetermined torque for limiting coupling of the acoustic waveguide to the ultrasonic transducer assembly to the predetermined torque.

A surgical instrument, comprising:

• (a) an instrument body;
• (b) an ultrasonic transducer assembly positioned at least partially within the instrument body and configured to rotate about an axis, wherein the ultrasonic transducer assembly is configured to connect to an acoustic waveguide of a shaft assembly;
• and
• (c) an engagement feature connected to the ultrasonic transducer assembly, wherein the engagement feature is configured to be engaged by an arrester to selectively inhibit rotation of the ultrasonic transducer assembly about the axis for rotatably securing the ultrasonic transducer assembly relative to the instrument body.

A method of coupling an acoustic waveguide to an ultrasonic transducer assembly with a predetermined torque for a surgical instrument, the surgical instrument including an end effector;

• a shaft assembly having the end effector projecting distally therefrom, wherein the shaft assembly includes an acoustic waveguide extending therethrough and a proximal end portion configured to rotatably couple with an ultrasonic transducer assembly;
• and a torque wrench integrally connected with the shaft assembly, the torque wrench including a drive feature configured to engage with a driven feature to transmit torque from the shaft assembly to the acoustic waveguide up to a predetermined torque, wherein the drive feature is configured to slip relative to the driven feature upon receiving torque greater than the predetermined torque for limiting coupling of the acoustic waveguide to the ultrasonic transducer assembly to the predetermined torque, the method comprising:
• (a) inhibiting rotation of the ultrasonic transducer assembly about an axis;
• (b) rotating the acoustic waveguide into the ultrasonic transducer assembly threadably coupling the acoustic waveguide with the ultrasonic transducer assembly;
• (c) tightening the acoustic waveguide into the ultrasonic transducer assembly up to the predetermined torque thereby coupling the acoustic waveguide with the ultrasonic transducer assembly;
• and
• (d) slipping the drive feature relative to the driven feature upon reaching the predetermined torque to inhibit overtightening the acoustic waveguide into the ultrasonic transducer assembly.