to receive the medial and lateral condyles 114 112 of the femoral component 102 see fig4 the two concave bearing surfaces 160 u2032 162 u2032 are partially separated from one another by a trapezoidal post 164 u2032 upstanding from the tibial tray insert 108 u2032 in this exemplary embodiment the post 164 u2032 is integrally formed with the tibial tray insert 108 u2032 and includes an anterior wall 166 u2032 having a substantially vertical face and a posterior wall 168 u2032 having an inclined face from posterior to anterior the vertical face of the anterior wall 166 u2032 is substantially parallel with the anterior posterior centerline the anterior wall 166 u2032 and posterior wall 168 u2032 are separated from one another by substantially vertical medial and lateral side walls 170 u2032 172 u2032 and a horizontal top wall 174 u2032 referring to fig1 a further alternate exemplary fixed bearing tibial component 104 u2033 includes a tibial tray 106 u2033 and a tibial tray insert 108 u2033 in this exemplary embodiment the tibial tray 106 u2033 includes a stem 141 u2033 that is adapted to be received within the intramedullary canal of the tibia the stem 141 u2033 may be cemented or adapted for bone ingrowth to permanently mount the tibial tray 106 u2033 to the tibia integral with the stem 141 u2033 is a platform 142 u2033 on which the tibial tray insert 108 u2033 is mounted the tibial tray insert 108 u2033 also includes concave bearing surfaces 160 u2033 162 u2033 that are adapted to receive the medial and lateral condyles 114 112 of the femoral component 102 see fig4 the two concave bearing surfaces 160 u2033 162 u2033 are partially separated from one another by a trapezoidal post 164 u2033 upstanding from the tibial tray insert 108 u2033.