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Introduction| Despite its success, eg in prostatectomy, da Vinci’s steerable grasper EndoWrist from Intuitive Surgical has a complex design prone to steel cable fatigue, potential sterilisation issues and high associated costs, all of which insinuate a need for an alternative. The aim of this paper is to demonstrate a design of a structurally simple handheld steerable laparoscopic grasping forceps free from cable fatigue, while attaining sufficient bending stiffness for surgery and improving on EndoWrist’s manoeuvrability and dimensions.

Methods| Having equal joint functionality to EndoWrist, DragonFlex’s instrument tip contains only four parts, driven and bound by two cables mechanically fixed in the handle. Two orthogonal planar joints feature an innovative rolling link mechanism allowing the cables to follow circular arc profiles of a diameter 1.5 times larger than the width of the instrument shaft. Besides maximising the cable lifespan, the rolling link was designed to equalise the force requirements on both cables throughout joint rotation, making the handling fluid and effortless. The smart joint design and stacked instrument construction enable control of seven degrees of freedom by only two cables and seven instrument components in tip, shaft and handgrip altogether.