PLACEMENT OF SCREWS IN THE UNCEMENTED ACETABULUM - ANATOMIC ANALYSIS OF THE DANGER ZONE

Six cadavers were used to define the projection of the external iliac artery on the inner table of the acetabulum, and to quantitatively det ermine bony dimensions of the danger zone with regard to screw placeme nt. The results showed that the majority of projections of the externa l iliac arteries were located on the superior portion of the posterosu perior quadrant and extended to the mid-superior portion of the antero superior quadrant (danger zone). The inferior portion of the danger zo ne was relatively far from the external iliac artery. The greatest dep ths of bone were found in the inferior portion of the danger zone, and the depths of bone in the middle and superior portion of the danger z one were relatively thinner. This anatomic study showed that the real danger zone was found in the middle and superior portions of the anter osuperior quadrant of the acetabulum. The inferior portion of the ante rosuperior quadrant was relatively safer. This area may be considered if transacetabular screw placement in the anterosuperior quadrant is r equired.