A Midlay component includes a plastic bearing part and a metal tray part. The upper surface of the bearing part is dished in frontal and sagittal planes, to provide a bearing surface, such that in function, the femoral contact point will remain in the central region of the bearing surface. Hence the load-bearing on the plastic bearing part will be above the thickest portion in the central region. The metal tray part features a tray-bottom that enables retention of strong cortical and cancellous portion of a tibia in the treatment of osteoarthritis of a knee joint, and supports the plastic bearing part, with the rim of the metal tray part maintaining the position of the plastic bearing part and minimizing micromotions.
