Fig. 1

The method of angular measurement was shown. a The anteroposterior axis of the distal femur (AP axis), which projects perpendicular to the surgical transepicondylar axis (sTEA) that connects the most prominent points of the lateral epicondyle and sulcus of the medial epicondyle, was used as the reference axis. b The center of the posterior cruciate ligament was defined as cPCL. The angle PCL-PT was made by the AP axis and a line from cPCL to the medial border of the patellar tendon (a). c The angle PCL-TT1 was made by the AP axis and a line from cPCL to the medial border of the tibial tuberosity (b). d The angle PCL-TT2 was made by the AP axis and a line from cPCL to the medial one-third of the tibial tuberosity (c). e The angle PCL-TT3 was made by the AP axis and a line from cPCL to the apex of the tibial tuberosity (d). f The angle ATCC was made by the AP axis and the anteroposterior axis of the tibial prosthesis (e) (using tibial prosthesis template) along the anterior tibial curved cortex (asterisk)