A knee system includes a knee prosthesis having a tibial arrangement including a tibial tray configured for attachment to a surgically-prepared surface of a proximal end of the tibia. The tibial arrangement also includes a tibial insert system including a lateral tibial insert and a medial tibial insert. One of the inserts is configured to move in a generally anterior-posterior direction relative to the tibial tray, and the other insert is configured for fixed attachment to the tibial tray. The knee prosthesis also includes a femoral component configured for attachment to a surgically-prepared surface of a distal end of a femur. The femoral component and tibial inserts each have articular surfaces configured to contact and articulate relative to each other during extension and flexion of the knee.