Ultrasonic surgical instrument with transducer locking feature

A surgical instrument includes a body, an ultrasonic transducer assembly, and a transducer lock having a lock member configured to move between unlocked and locked positions. The transducer assembly is rotatably mounted along a longitudinal axis within the body such that the transducer assembly is configured to selectively rotate about the longitudinal axis. With the lock member in the unlocked position, the transducer assembly is configured to be selectively rotated about the longitudinal axis relative to the body. With the lock member in the locked position, the transducer lock is configured to seize the transducer assembly and inhibit rotation relative to the housing for coupling with an acoustic waveguide. The surgical instrument may also include an integral torque wrench for coupling the acoustic waveguide with a predetermined torque and an integral torque indictor for signaling to a user that the acoustic waveguide is coupled with the predetermined torque.