There is provided a tracing platform configured to rigidly attach to an anatomy of a patient that has at least one surface configured to provide a defined path (represented by path definition data) for tracing by a surgical instrument. An intra-operative computing unit receives pose data for the instrument when tracing the path and calculates a location of the defined path using the pose data and the path definition data. A change in location may be determined from pose data of different traces. Tracing the defined path generates a plurality of pose data which may increase accuracy of the location calculations. Redundant trace data may be received to eliminate bias. A geometric feature (e.g. V-groove), shape and/or magnetic properties of the platform may assist with tracing. The platform may rigidly attach to a bone using at least one of spikes, a bone screw, a cerclage wire, and a bone clamp.