An ultrasonic surgical instrument includes a housing, an ultrasonic transducerassembly, and a waveguide. The ultrasonic transducer assembly extends througha proximalopening into the housing and includes a horn disposed within the housingdefining a firstengagement member. The ultrasonic transducer assembly further includes aninner housingextending through the proximal opening and an outer knob disposed externallyof the housingand slidably positioned about the inner housing in fixed rotationalorientation relative thereto.The outer knob is selectively translatable relative to the inner housing froma proximal,unlocked position and a distal, locked position to rotationally lock theultrasonic transducerrelative to the housing. The waveguide defines a blade at a distal end and asecondengagement member at a proximal end. The second engagement member isconfigured toreleasably engage the first engagement member to thereby engage the waveguidewith theultrasonic transducer assembly.
