Fig. 4From: The largest secure corridor of the infra-acetabular screw—a 3-D axial perspective analysisThe measurement of Angle α and β. The red plane represented the medial surface of quadrilateral plate. The yellow plane was perpendicular to the red plane. A View from the yellow plane, α was the lateral inclination angle between the screw and the red plane. B View from the red plane, β was the posterior inclination angle between the screw and the yellow planeBack to article page