Bone cement penetration of the acetabulum in total hip replacement. An experimental study.

Cones of cement passing through, or below, the acetabulum may be seen after total hip replacement and are due either to iatrogenic perforation of the wall or to substantial bony defects. An experimental study was undertaken to establish which structures might be affected by these cones. In 20 cadaveric specimens, the acetabula were divided into 4 quadrants and, after the cement was set, the structures within the pelvis were dissected. In the antero-inferior quadrant the cement impinged on either the obturator nerve or vein, or the external iliac vein. Anterosuperiorly, these structures and the external iliac artery were impinged. In the posterior quadrants, the obturator muscle and nerve, and vessels, were affected, and inferiorly the external obturator muscle was also involved. The size of the cones depended on the bony depth of the acetabulum. Compared with screws, the cement can cause late complications through heat necrosis and continuous friction. The posterosuperior quadrant is the safest area to make holes for anchoring the cup.