A process for creating a curved contour on or within a bone is provided, where the process includes positioning a bone of a patient in a fixed position in a coordinate system, generating scan data of the bone, creating a three-dimensional surface model of the bone based on the scan data, generating a cutting program to modify a surface of the bone based on the three-dimensional surface model and a prosthesis having a bone interface shape that is complementary to the curved contour, and modifying the bone with one or more curved blades or a curved drill bit that is robotically driven and positioned with the cutting program to form the curved contour. A system for creating a curved congruent contour on or within a bone for mounting a prosthesis is also described.