Abstract: The present invention relates to a scissor-action hand surgical instrument having first and second limbs pivotally connected together by a box-joint comprising a tenon portion and a mortice portion through which the tenon portion extends. The second limb has at the mortice portion a pivot pin comprising a neck portion and an enlarged head portion. The tenon portion has a keyhole aperture with a first reduced diameter portion and a second enlarged diameter portion spaced apart from and connected to the first portion and through which the pivot pin head portion is passable for assembly and disassembly of the limbs. The pivot pin neck portion is translatable between the first and second aperture portions. The mortice portion has a central opening at one side around the pivot pin head portion.