Pelvic Incidence (PI)

Last edit by Alaric Steinmetz on

Synonyms: PI

The Pelvic Incidence is a parameter used to help determine the sagittal balance of the spine.

Definition

The Pelvic Incidence is defined as the angle between a perpendicular line from the middle of the top plate of S1 and a line from the femoral head to the middle of the top plate of S1[^1].

Normal Values

In a healthy person, the Pelvic Incidence is about 50° and does not change after the skeletal system has matured[^2].

Figure

Pelvic Incidence
Schematic diagram for calculating the pelvic incidence adapted from Drago A. et al (2018)