An ultrasonic surgical instrument (10) includes a transducer assembly having a distal engagement member (266) and configured to supply ultrasonic energy. A waveguide (30) defines a longitudinal axis and has a proximal engagement member (34) configured to threadingly engage the distal engagement member. The waveguide is configured to transmit the ultrasonic energy therealong to a distal end thereof for treating tissue. A torque member (300) is coupled to the transducer assembly and is disposed about the longitudinal axis. The torque member is selectively rotatable about the longitudinal axis and relative to the waveguide to threadingly engage the transducer assembly and the waveguide to one another. The torque member includes a plurality of fingers (322) pivotably coupled thereto and movable between a closed position and an open position. In the open position, each finger extends substantially perpendicularly from the longitudinal axis to define a moment arm that facilitates the engagement of the transducer assembly and the waveguide.