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Posterior Acetabular Wall Frx: Danger Zone

     



- Discussion:
    - refers to the portion of the posterior wall and column at the mid acetabulum lying above the ischial spine;
    - screws placed in this one are at risk for joint penentration;
    - anatomic safe zone:
           - entry point 2 cm medial to the lateral acetabular margin and angled medially 45 deg;
                  - this allows 5 mm between screw threads and subchondral bone;
           - entry point 3 cm medial to the lateral acetabular margin and angled medially 15 deg;
                  - this allows 5 mm between screw threads and subchondral bone;
           - angulations were determined from the perpendicular to the posterior column;
           - note that the average total width of the posterior column is 4.8 cm;

                   

    - flouroscopically assisted screw insertion:
           - by showing the "end-on profile" of the lag screws, the surgeon can be relatively assured that the screws lie outside the joint



Danger Zone of the Acetabulum.

Radiological diagnosis of screw penetration of hip joint in acetabular fracture reconstruction.