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 perforati on of the wall or to substantial bony defects. An experimental study w as undertaken to establish which structures might be affected by these cones. In 20 cadaveric specimens, the acetabula were divided into 4 q uadrants and after the cement was set, the structures within the pelvi s were dissected. In the antero-inferior quadrant the cement impinged on either the obturator nerve or vein, or the external iliac vein. Ant erosuperiorly, these structures and the external iliac artery were imp inged. 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 compl ications through heat necrosis and continuous friction. The posterosup erior quadrant is the safest area to make holes for anchoring the cup.