An Articulating Tool for Endoscopic Screw Delivery

This paper describes the development of an articulating endoscopic screw driver that can be used to place screws in osteosynthetic plates during thoracoscopic surgery. The device is small enough to be used with a 12 mm trocar sleeve and transmits sufficient torque to fully secure bone screws. The articulating joint enables correct screw alignment at obtuse angles of up to 60 deg from the tool axis. A novel articulating joint is presented, wherein a flexible shaft both transmits torque and actuates the joint; antagonist force is provided by a superelastic spring. Screws are secured against the driver blade during insertion and with a retention mechanism that can passively release the screw when it has been securely placed in the bone. The prototype has been fitted with a blade compatible with 2.0 mm and 2.3 mm self-drilling screws although a different driver blade or drill bit can easily be attached. Efficacy of the tool is demonstrated by securing an osteosynthetic plate to a rib in a mock surgical setup. This tool enables minimally invasive, thoracoscopic rib fixation.