TABLE II.

Definitions of Spinopelvic Parameters

Parameter	Definition
Lumbar lordosis (LL)26	Lumbar lordosis was calculated as the Cobb angle between a line drawn along the superior end plate of L1 and another line drawn along the superior end plate of S1
Sacral slope (SS)21	Sacral slope was calculated as the angle between a line drawn along the superior end plate of S1 and the horizontal axis
Pelvic incidence (PI)21	Pelvic incidence was calculated as the angle between the line from the center of the femoral heads to the middle of the superior end plate of S1, and the line perpendicular to the superior end plate of S1 from its midpoint
Pelvic tilt (PT)21	Pelvic tilt was calculated as the angle formed between the line from the center of the femoral head to the middle of the superior end plate of S1 and the vertical axis
Pelvic-femoral angle (PFA)27	The pelvic-femoral angle was calculated as the angle between the line from the center of the femoral heads to the middle of the superior end plate of S1 and the femoral axis