Between October 2011 and October 2012 , 60 cases undergoing unilateral TKA and meeting the selection criteria were randomly divided into 2 groups : in group A ( 30 cases ) , the tibial plateau center as the entry point of tibial intramedullary positioning was used ; in group B ( 30 cases ) , Mimics 10.01 software to simulate the guide rod point of tibial intramedullary positioning was used .