Design of a Non-Assembly Articulating Neuroendoscopic Forceps

Abstract

Minimally invasive surgery has some major benefits over traditional open surgery for the patient, but makes surgery more complex for the surgeon. Articulating instruments can regain some of the manoeuvrability that is lost by using a small incision. However, in endoscopic neurosurgery such articulating devices do currently not exist, due to scale dependent assembling and manufacturing challenges. We explored the use non-assembly additive manufacturing to circumvent the infeasible assembly and enable production of a 2 mm articulating forceps. Four different designs were made to explore different levels of articulation intricacy, with a distinction in planar or spatial, and concentrated or distributed bending. Eligible 3D printers capable of printing surgical instrument-sized parts including sub 2 mm mechanisms need relatively large clearances between moving parts. This poses a serious challenge that we solved by using compliant grasping and bending mechanisms. Three out of four designs were successfully 3D printed on a 5 mm and 2 mm scale, and their geometrical requirements were validated. The designs fitted through a 2.2 mm dummy trocar, reached bending angles up to 70°, and an forceps opening angle of 40°. The distributed planar and distributed spatial bending design were deemed infeasible due to their lack of bending stiffness upon external forces. The two remaining designs proof that 3D printed non-assembly forceps for neuroendoscopy are possible, with planar and spatial articulation. With these articulating devices, many more neurosurgeries could be executed in a minimally invasive manner. However, simulated surgical tasks should be performed to further test the designs, before they could be commercialised.