A surgical device for accurately positioning and cutting a patellar groove in a resected distal femur to receive a patellar track portion of a prosthesis, including a guide element adapted to fit over the distal end of a resected femur, having a central opening which exposes the central, distal an anterior aspects of the femur, each side of the opening being provided with a track, extending the length of the patella track, and, a cutting tool having a cutting surface, perferably convex, adapted to fit into the central opening for the purpose of cutting or abrading a groove into the femur as the tool is moved along the opening. The tool, which is preferably a rotary cutter provided with independently rotatable track-engaging surfaces on each side of the opening is adapted to engage and move along the track.