COMBINATION ULTRASONIC AND ELECTROSURGICAL INSTRUMENT HAVING ULTRASONIC WAVEGUIDE WITH DISTAL OVERMOLD MEMBER

A surgical instrument includes an ultrasonic transducer, a shaft extending distally along a shaft axis, a waveguide acoustically coupled with the ultrasonic transducer and extending distally through the shaft, and an end effector at a distal end of the shaft. The end effector includes an ultrasonic blade acoustically coupled with the waveguide. A nodal support element is arranged within a distal portion of the shaft and encircles the waveguide at a distal-most acoustic node of the waveguide. The nodal support element includes a support portion aligned with the distal-most acoustic node, and a sealing portion extending axially from the support portion. The support portion engages an inner surface of the shaft and is configured to support the waveguide in coaxial alignment with the shaft axis. The sealing portion sealingly engages the inner surface of the shaft and is configured to prevent proximal ingress of fluid through the shaft.