Interactive pre-operative selection of cutting constraints, and interactive force controlled knee surgery by a surgical robot

Abstract

This paper describes a low-cost computer system that takes CT images of the knee, and with three-dimensional models of knee prostheses allows a surgeon to position the prosthesis correctly pre-operatively in an interactive manner. Once in position the computer can process bone and prosthesis geometry to derive a set of constraint boundaries that constitute a safe cutting area for a force controlled robot (i. e. that avoids soft tissue such as ligaments), and provides the correct cutting planes for good prosthesis/bone alignment. This boundary information is used to program the robot, allowing a surgeon to move the robot within predefined regions to machine away bone accurately whilst preventing damage to soft tissue.