Mechanical lockout for ultrasonic surgical instrument

An ultrasonic surgical instrument, comprising:

• (a) a handle assembly including at least one operator input feature;
• (b) an ultrasonic transducer supported by the handle assembly and operatively connected to the at least one operator input feature;
• (c) a shaft assembly configured to removably couple with the handle assembly, wherein the shaft assembly includes a distal end portion, wherein the shaft assembly further includes:
• (i) an end effector extending distally from the distal end portion;
• and
• (ii) a waveguide acoustically coupled with the ultrasonic transducer;
• and
• (d) a mechanical lockout assembly configured to move between at least an unlocked configuration and a locked configuration,
• wherein in the locked configuration, the handle assembly and the shaft assembly are partially coupled together such that the operator is physically prevented from activating the ultrasonic transducer using the at least one operator input feature, and
• wherein in the unlocked configuration, the handle assembly and shaft assembly are completely coupled together and the operator is able to activate the ultrasonic transducer using the at least one operator input feature.

A method of operating an ultrasonic surgical instrument, wherein the ultrasonic surgical instrument includes:

• (a) a first modular assembly including at least one operator input feature;
• (b) an ultrasonic transducer supported by the first modular assembly;
• (c) a second modular assembly configured to removably couple with the first modular assembly, wherein the second modular assembly further includes at least a portion of an end effector extending distally from a distal end portion of the second modular assembly;
• and (d) a mechanical lockout assembly configured to switch between at least an unlocked configuration and a locked configuration, the method comprising:
• (a) inhibiting the at least one operator input feature from activating the ultrasonic transducer while in the locked configuration when the first modular assembly and the second modular assembly are only partially coupled together which provides instant feedback to an operator;
• (b) coupling the first modular assembly and the second modular assembly completely together to disarm the mechanical lockout assembly;
• and
• (c) activating the ultrasonic transducer using the at least one operator input feature when in the unlocked configuration.