A surgical instrument includes an end effector, a shaft assembly, and a torque wrench integrally connected with the shaft assembly. The shaft assembly has an acoustic waveguide extending therethrough and the end effector projects distally from the shaft assembly. The acoustic waveguide has a proximal end portion configured to rotatably couple with an ultrasonic transducer assembly. The torque wrench is configured to transmit torque applied to the acoustic waveguide up to a predetermined torque. A portion of the torque wrench is configured to deflect upon receipt of torque greater than the predetermined torque. Accordingly, the portion of the torque wrench slips relative to the acoustic waveguide for limiting coupling of the acoustic waveguide to the ultrasonic transducer assembly to the predetermined torque.