Fig. 1

Parameters measurement of virtual screw. ① Axial perspective view of the right acetabular posterior column, the yellow triangle area is the safe zone for screw placement; A: Quadrilateral plate; B: Posterior acetabular wall; C: Acetabular dome. ② Axial perspective view of screw ③ Point O: Exit point; Line segment OF: Distance between exit point and the true pelvic rim; Line segment OE: Distance between exit point and ipsilateral anterior sacroiliac joint line. ④ Posterior view of the right hemipelvis; Point P: Entry point. ⑤ Lateral view of the right hemipelvis; Point P: Entry point; Point L: Most distal point of the ischial tuberosity. ⑥ Bottom view of the right hemipelvis; Point P: Entry point at the ischial tuberosity; The solid yellow lines: Medial and lateral edge of ischial tuberosity; The dotted yellow line: Central line of the ischial tuberosity