Femoral and tibial cutting block mounted on the distal femur and on the proximal tibia respectively. These are company manufactured patient specific femoral cutting blocks based on CT scan created virtual bone models. Multiple contact points on the femoral cutting block and the tibial cutting block, along with markings allow accurate positioning and rotational alignment improving accuracy of the cuts and femoral and tibial rotation respectively. There are slots for external jigs to double check slope and tibial base plate rotation.