Fig. 4From: The placement of percutaneous retrograde acetabular posterior column screw based on imaging anatomical study of acetabular posterior column corridorMeasurement of screw angle. ① Point P: Entry point. The blue solid line represented the coronal plane; The red arrow represented the optimum orientation of the screw and the dotted yellow arrows on both sides represented the critical orientations. ② Point P: Entry point. The blue solid line represented the sagittal plane; The red arrow represented the optimum orientation of the screw and the dotted yellow arrows on both sides represented the critical orientationsBack to article page