Figure 1: Definition of 3 indices of ankle joint image in anteroposterior view. A: The TAS angle is the angle between the distal 1/3rd of the tibial shaft and its distal joint surface. B: The TMM angle is the angle between the distal 1/3rd of the tibial shaft and the joint surface of the medial malleolar joint surface. C: The TBM angle is the angle between the distal 1/3rd of the tibial shaft and the axis between both malleolar tips.