An adapter assembly (200) for coupling an end effector (300) to a handle assembly (100), the adapter assembly (200) comprising:an adapter housing (232)a drive coupling assembly (210) rotatably coupled to the adapter housing (232)a drive mechanism (330) disposed within the adapter housing (232) and couplable to a handle assembly and an end effector anda retraction assembly (280) movable relative to the adapter housing between a first configuration, in which the retraction assembly (280) is disengaged from the drive mechanism, and a second configuration, in which the retraction assembly (280) is engaged with the drive mechanism such that rotation of the retraction assembly (280) actuates the drive mechanism (330).
