In the surgical replacement of the knee joint, accurate alignment of prosthetic components with respect to the mechanical axis of the leg is essential to the mobility and longevity of the joint. The correct alignment is not obvious during surgery because the long bones are largely obscured by tissue. I participated in the development of an integrated system that allows the surgeon to accurately place implant components during total knee surgery. In the operating room, a robot and specially designed fixturing aid the surgeon in performing the bone resections as determined in the pre-operative plan. Crucial to the accuracy of this system is the rigid immobilization of the involved bones, the robot's ability to determine their exact locations in space and the accuracy of the robot itself. My responsibility in the project was, among other things, to improve the accuracy of the robot. Our project at that time was one of the very few in the world which explore the possibility of automating the surgical procedure in order to enhance the quality and precision of surgery.