Figure 1.

Illustration showing the pelvic parameters included in this analysis, that is, sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI). PI is a morphological parameter, whereas SS and PT are positional parameters. PI represents the algebraic sum of SS and PT, (PI = SS + PT). SFD is the horizontal distance between the vertical bi-coxo-femoral axis and the vertical line passing through the posterior corner of the sacrum. The horizontal distance between C7 plumb line and the posterior corner of the sacrum (SC7D) was also measured. These two values were then used to calculate SC7D/SFD ratio, which correspond to the ratio of SC7D to SFD.