A computer assisted surgery (CAS) system and method for preparing an anatomical structure to receive an orthopaedic implant. The method generally involves the steps of determining a contour of the anatomical structure by using the CAS system to acquire a plurality of points on the anatomical structure and provide a best fit approximation of the anatomical structure based on the plurality of points, selecting an implant to replicate the anatomical structure, and preparing the anatomical structure to receive the implant.