Femoro-epiphyseal acetabular roof (FEAR) index

Last revised by Henry Knipe on 30 Nov 2022

The femoro-epiphyseal acetabular roof (FEAR) index is a radiographic measurement to help identify clinical hip microinstability in acetabular dysplasia.


The FEAR index should be used in conjunction with clinical and other radiographic features for the identification of clinically unstable dysplastic hips 3.


To measure the FEAR index, a line is drawn along the lateral and medial points of the center of the femoral head physeal scar, and a second line is drawn between the medial and lateral points of the acetabular sourcil 1.


A positive FEAR index has been purported as between ≥3-5º 2-4.

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