Fig. 3

Measurement of proximal femoral anatomical parameters. a Three slice levels along the femoral shaft were taken. The proximal-distal distance between the proximal end of the greater trochanter (GT) and the center of the lesser trochanter (CLT) was defined as 100% proximal femoral height (H). The mid-femoral neck (MFN) level was located 33% distal to GT. The low femoral neck (LFN) level was located 66% distal to GT. The CLT level was taken at the level passing through CLT. The FA-MFN (b) and FA-LFN (c) were defined as the angle between the line (dotted line) bisecting the anterior and posterior cortex of the femur neck and PCA (solid line). The FA-CLT was considered equivalent to femoral canal major-axis torsion: the angle (major-axis angle) formed by the line (dotted line AB) connecting the longest transverse diameter of the canal and the PCA (solid line) (d). The CF-LFN (e) and CF-CLT (f) were defined as the angle between the PCA (solid line) and the line parallel to the CF (dotted line)