An apparatus for modifying a patient's femur for receiving a patellofemoral prosthesis, comprising: a guide operating to engage a distal end of the femur, the guide including: (i) a mounting element disposed at a first end of the guide, having an engagement surface defining an anterior resection plane, and operating to rigidly couple the guide to an anterior resection surface of the femur, (ii) a distal slot extending through the guide substantially parallel to the anterior resection plane, toward the patellar groove in a distal-proximal direction when the guide is coupled to the femur, and (iii) an anterior slot extending through the guide, substantially transverse to the anterior resection plane, toward the patellar groove in an anterior-posterior direction when the guide is coupled to the femur; a distal punch having a cutting edge and being sized and shaped to slidingly pass through the distal slot such that the cutting edge penetrates into the patellar groove of the femur, in the distal-proximal (D - P) direction, producing a distal cut; and an anterior punch having a cutting edge and being sized and shaped to slidingly pass through the anterior slot such that the cutting edge penetrates into the patellar groove of the femur, in the anterior-posterior (A - P) direction producing an anterior cut,wherein the respective cutting edges of the distal punch and the anterior punch, as well as the orientations of the respective distal and anterior slots, are sized and shaped such that the anterior cut meets the distal cut and a portion of the patient's femur is removed to receive a portion of the patellofemoral prosthesis; and wherein the distal punch and the anterior punch are separate punches. a guide operating to engage a distal end of the femur, the guide including: (i) a mounting element disposed at a first end of the guide, having an engagement surface defining an anterior resection plane, and operating to rigidly couple the guide to an anterior resection surface of the femur, (ii) a distal slot extending through the guide substantially parallel to the anterior resection plane, toward the patellar groove in a distal-proximal direction when the guide is coupled to the femur, and (iii) an anterior slot extending through the guide, substantially transverse to the anterior resection plane, toward the patellar groove in an anterior-posterior direction when the guide is coupled to the femur; (i) a mounting element disposed at a first end of the guide, having an engagement surface defining an anterior resection plane, and operating to rigidly couple the guide to an anterior resection surface of the femur, (ii) a distal slot extending through the guide substantially parallel to the anterior resection plane, toward the patellar groove in a distal-proximal direction when the guide is coupled to the femur, and (iii) an anterior slot extending through the guide, substantially transverse to the anterior resection plane, toward the patellar groove in an anterior-posterior direction when the guide is coupled to the femur; a distal punch having a cutting edge and being sized and shaped to slidingly pass through the distal slot such that the cutting edge penetrates into the patellar groove of the femur, in the distal-proximal (D - P) direction, producing a distal cut; and an anterior punch having a cutting edge and being sized and shaped to slidingly pass through the anterior slot such that the cutting edge penetrates into the patellar groove of the femur, in the anterior-posterior (A - P) direction producing an anterior cut,wherein the respective cutting edges of the distal punch and the anterior punch, as well as the orientations of the respective distal and anterior slots, are sized and shaped such that the anterior cut meets the distal cut and a portion of the patient's femur is removed to receive a portion of the patellofemoral prosthesis; and wherein the distal punch and the anterior punch are separate punches.