Fig. 1. (A) Schematic drawing of the standard method. (B) The transepicondylar axis is defined as a line between the most medial and most lateral extension of the distal humerus. (C) The angle between the central axis of the humeral head and the elbow transepicondylar axis (asterisk) is shown. The central axis is a perpendicular axis of the boundaries of the articular surface determined by using the limits of the subchondral bone in the largest circle of the humeral head.