Fig. 1

Mechanical axis angle is the angle between a line from the center of the femoral head to the mid-condylar point between the cruciate ligaments and a line from the center of the tibial plateau to the center of the tibial plafond (a). The tibia vara angle (black arrow) is formed by the line perpendicular to the epiphysis (white arrowhead) and the anatomical axis of the tibia (white arrow) (b). The posterior tibial slope angle is defined as 90° minus the angle made by the intersection of the line along the longitudinal axis of the tibia and the slope of the medial tibial plateau (c)