A computer-assisted surgery system for performing a surgical procedure on a patient's anatomy includes a robotic device, a guide coupled to the robotic device, and a computer in communication with the robotic device. The computer is configured to command the robotic device to selectively operate in one of a first mode in which the guide is manually moved by a user or a second mode in which the robotic device autonomously moves the guide. In the first mode, the robotic device is controlled by the computer to constrain motion of the guide to a predefined plane while allowing the guide to be manually moved along the pre-defined plane.
