Devices and method for performing replacement prosthetic knee surgery are disclosed in which a spacing means is introduced between the femur (1) and tibia (2) while the patella (9) is in place. The spacing means separates the femur (1) from the tibia (2) by an amount essentially equal to or greater than the required flexion gap (4). An alignment device (26) is used for performing femoral bone cuts, which device attaches temporarily to a fitted tibial plate.
