Certain versions generally provide an improved tibial base member (for example, but not limited to, 10) comprising keel portions (for example, but not limited to, 14a, 14b, 14c) that allow one or both cruciate ligaments to be preserved. Other versions provide improved lateral and/or medial inserts (for example, but not limited to, 110, 210) having a mesial lip (for example, but not limited to, 118, 128) that helps relieve and/or prevent impingement between the femoral component (for example, but not limited to, 400) and the tibial eminence. Other versions provide improved femoral components (for example, but not limited to, 400) having various chamfers (for example, but not limited to, 404, 410, 470) to provide additional clearance with respect to the tibial eminence and posterior cruciate ligament without decreasing bone coverage.
