An implant is provided for which has an outer bearing surface and an inner attachment surface. The outer bearing surface functions as ajoint contact surface for a reconstructed bone joint. The inner attachment surface contacts a bone and is attached thereto. The inner attachment surface of the implant is curvilinear from the anterior to the posterior area of the femur, and is also curvilinear from the medial to the lateral areas of the femur to approximates the shape of natural femur. The resection of the femur for accommodating the implant can be properly performed by a milling device employing one or more curvilinear milling bits.