This is constructed with the patient supine as a rough means of detecting disturbance of the normal anatomy of the femoral head and neck. It is a right-angled triangle, with the following sides:
A. A straight line connecting the greater trochanter of the femur with the anterior superior iliac spine;
B. A vertical line down from the anterior superior iliac spine towards the bed;
C. A horizontal line starting at the greater trochanter, and meeting side B.
The length of C is gauged on each side, and the sides compared. Pathology of the femoral head or neck which displaces the greater trochanter will tend to shorten this side of the triangle.
Last reviewed 01/2018