Abstract: A system for resecting a tibia and femur during arthroplasty includes anchoring devices, a three-way alignnment guide attachable to an anchoring device. The alignment guide provides for locating a resection guide in three degrees of freedom, including one translation and two rotations. The resection guide is coupled to a computer navigation system.

Abstract: Tools for resecting tibia and femur include anchoring devices, a three-way alignment guide attachable to the anchoring devices, two embodiments of a resection guide attachable to the alignment guide and equipped with couplings for trackers, a plane probe for examining the resected plane, and apparatus for EM alignment of the resection guide in the event of a computer failure. The methods of the invention include operating a computer aided navigation apparatus in the conventional manner including attaching one or more trackers to the bone to be resected; choosing a location for the anchoring device with or without guidance from the computer and installing the anchoring device; attaching the three-way alignment guide to the anchoring device; attaching a resection guide to the alignment guide; attaching one or two trackers to the resection guide; locating the resection guide with the aid of the alignment guide and the computer; fixing the resection guide to the bone with pins.