A surgical instrument includes an end effector, a handle assembly, a trigger assembly, an input driving body, and a coupling body. The end effector includes a pair of jaws, a knife, and an RF electrode assembly. The input driving body drives the knife between the pre-fired position and the fired position when traveling between the first position and the second position. The engagement body of the trigger assembly drives the input driving body from the first position to the second position when the coupling body is in the engaged position. The input driving body returns to the first position when the coupling body is in the disengaged position. The coupling body moves from the engaged position to the disengaged position is response to the input driving body traveling from the second position to the third position such that the input driving body returns to the first position.
