Certain embodiments generally provide an improved tibial base member comprising keel portions that allow one or both cruciate ligaments to be preserved. Other embodiments provide improved lateral and/or medial inserts having a mesial lip that helps relieve and/or prevent impingement between the femoral component and the tibial eminence. Other embodiments provide improved femoral components having various chamfers to provide additional clearance with respect to the tibial eminence and posterior cruciate ligament without decreasing bone coverage.