Fig. 1. Measurement of cortical thickness index (CTI) and canal flare index (CFI) on an anteroposterior radiograph (using Osirix software). Do: outer diameter (the shaft's outer diameter at 10 cm below the lesser trochanter), Di: inner diameter (the shaft's inner diameter at 10 cm below the lesser trochanter, measured at the same level as Do), CW: canal width (the canal width measured at 2 cm above Line a), Line a: a line drawn perpendicular to the femoral shaft through the middle point of the lesser trochanter, Line b: a line drawn parallel to the shaft to be used as a reference for drawing Line a, Line c: a 10-cm line drawn perpendicular to Line a, used to identify the shaft's inner and Do measurement levels.