PROXIMAL AND DISTAL FEMORAL CENTRALIZERS IN MODERN CEMENTED HIP-ARTHROPLASTY

Third generation cementing techniques using intramedullary restrictors , low porosity cement with pressurization, lavage, and cement-stem bon d enhancement do not prevent implant malalignment and inadequate cemen t mantle thickness, This has led to the development of modular proxima l and distal centralizers to control the alignment of the femoral comp onent and maintain an adequate thickness of the cement, thereby theore tically decreasing the rate of aseptic loosening. A retrospective anal ysis was performed of 100 primary cemented centralized femoral compone nts. At an average followup of 5.7 years (range, 4-8 years), the avera ge Harris Hip Score was 90, There were no cases of aseptic loosening, osteolysis, or impending failure. Ninety-one percent of femoral stems were implanted with satisfactory alignment with an optimal cement thic kness. However, six distal centralizers and one proximal centralizer f ractured at the time of insertion and voids frequently were seen in an d around the distal centralizer. Although centralizers improve prosthe sis alignment and cement mantle thickness, the long term effects of ce ntralizer fracture and distal cement voids need to be observed to dete rmine if centralizers improve previous implant survival.