Custom-made knee endoprosthetics using subtraction data of three-dimensional CT scans. A new approach

A new method is presented which allows the construction and implantation of highly precise custom-made endoprostheses for knee joints. The procedure i s based on a computer-aided subtraction process of three-dimensional CT dat a. Using the differences of the CT scans, the endprosthetic components are modelled by means of a newly developed software package. The implants are m anufactured by CNC machines and stereolithography. The method enables the surgeon to reduce bone resections and ensures an exa ct profile of the bone-implant interface. Incorrect positioning will be avo ided and the implantation process can be performed more easily while the si ze of the operative approach will be minimized. Better postoperative kinematics and reduction of shearing effects will lead to better results in the long run. The procedure offers a series of new po ssibilities to optimize monocondylar and bicondylar knee joint endoprosthes es.