Acetabular anti-protrusio rings and cages in revision total hip arthroplasty

Uncemented hemispherical porous-coated acetabular components work well for the great majority of acetabular component revisions. Unfortunately, when bone loss is so severe that little contact between a porous-coated socket and native bone can be achieved, high rates of failure of uncemented porous-coated sockets have been reported. When circumstances are encountered in which porous-coated hemispherical sockets are unlikely to succeed, acetabular reinforcement devices have advantages over cemented polyethylene sockets alone. The ability of antiprotrusio rings and cages, now used to augment socket fixation to the pelvis, facilitate extensive pelvic bone grafting, and prevent early socket migration, have led to renewed interest in these devices as useful tools in the orthopedic surgeon's armamentarium to manage some of the most challenging acetabular reconstruction problems. This article discusses the rationale for selected use of acetabular reinforcement devices, the reported results of using acetabular reinforcement rings and cages in revision total hip arthroplasty, and the circumstances in which these devices may be considered for acetabular reconstruction at the present time.