Ultrasonic surgical instrument and ultrasonic surgical system

An ultrasonic surgical system, comprising an ultrasonic surgical instrument, wherein the ultrasonic surgical instrument comprising, a waveguide rotatable around an axis and in threaded connection with a transducer, wherein said ultrasonic surgical instrument further comprises a force transmission mechanism and a rotatable mechanism;

• said force transmission mechanism is in fixed connection with said waveguide, provided with at least one stress surface thereon;
• said rotatable mechanism comprises a pushing mechanism and a rotatable driving mechanism having at least one applying surface thereon;
• said stress surface and said applying surface are not perpendicular to said axis and can be engaged with each other;
• said pushing mechanism provides a pushing force to press said rotatable driving mechanism towards said force transmission mechanism so as to force said stress surface being engaged with said applying surface;
• said pushing force is configured such that when a force between said stress surface and said applying surface is in excess of a predetermined value, said rotatable driving mechanism can overcome said pushing force so as to make said stress surface disengage with said applying surface, the ultrasonic surgical system further comprising a generator, and a transducer and a controlling switch, both of which are wired to said generator, wherein said ultrasonic surgical instrument is in threaded connection with said transducer.