Synthesis of CAD/CAM, robotics and biomaterial implant fabrication: single-step reconstruction in computer aided frontotemporal bone resection

The preoperative manufacturing of individual skull implants, developed by a n interdisciplinary research group at Ruhr-University Bochum, is based on t he use of titanium as the most common material for implants at present. Usi ng the existing technology for materials that can be milled or moulded, cus tomized implants may be manufactured as well. The goal of the study was to examine biodegradable materials and to evaluate the practicability of intra operative instrument navigation and robotics. Data acquisition of an adult sheep's head was performed with helical computer tomography (CT). The data were transferred onto a computer aided design/computer aided manufacturing system (CAD/CAM system), and two complex defects in the frontotemporal skul l were designed. Standard individual titanium implants were milled for both of the defects. Additionally, for one of the defects a resection template, as well as a mould for the biodegradable poly(D,L-lactide) (PDLLA) implant , were fabricated by the CAD/CAM system. A surgeon carried out the first bo ne resection (#1) for the prefabricated titanium implant using the resectio n template and an oscillating saw. The robot system Staubli RX90CR, modifie d for clinical use, carried out the other resection (#2). Both titanium imp lants and the PDLLA implant were inserted in their respective defects to co mpare the precision of their fit. A critical comparison of both implant mat erials and both resection types shows that fabrication of a PDLLA implant a nd robot resection are already possible. At present, the titanium implant a nd resection using a template are more convincing due to the higher precisi on and practicability.