Authors defined various anteroposterior axes of the tibial component as references and evaluated their accuracy and variability using virtual surgery. They presumed that Akagi’s Line could result in high accuracy and low variability in varus osteoarthritic knees; anteroposterior axes defined by using the tibial bony cutting surface as a landmark might be good substitutes for Akagi’s Line; extra-articular bony landmarks might influence the variability of the anteroposterior axis. In varus osteoarthritic knees, the best accuracy and least variability were provided by Akagi’s Line. Due to the difficulty of identifying the attachment site of the posterior cruciate ligament after the proximal tibia has been cut, good substitutes for Akagi’s Line were Axis 1/6MED and Axis MED. Findings did not suggest the use of extra-articular bony landmarks for alignment due to their high variability. Surgeons will be aided by this study to choose the proper anteroposterior axis of the tibial component to reduce rotational mismatch and thus achieve good clinical knee outcomes.