A total knee prosthesis (100) including a tibial component (110) having a baseplate portion (112) and a protruding portion (114) extending from the baseplate portion (112) is disclosed. An axle (160) is connectable to the tibial component (110) directly or indirectly. A femoral component (180) has an articular surface (190) and an opening (184) for receipt of the axle (160). The opening (184) defines a pivot center (192) about which the femoral component (180) rotates. The articular surface (190) has a posterior portion (193) that defines a first flexion radius and a first flexion center (194). The first flexion center (194) is offset from the pivot center (192) a distance substantially equal to a product of a constant and the first flexion radius.
