CORR Insights^®: Early Subsidence Predicts Failure of a Cemented Femoral Stem With Minor Design Changes

Excerpt

Consistently excellent clinical results and quality-of-life outcomes have been demonstrated with many cemented hip stems in THA during the past 40 years. Long-term series and systematic analyses have supported the use of cemented stems as a legitimate alternative to noncemented stems from a clinical and economic perspective [1, 5, 8]. However, there are ongoing reports [3, 7] of higher than acceptable long-term aseptic loosening rates for some cemented stems, including the specific “shape-closed” stem design that was the subject of this study. Shape-closed stems, such as the Charnley prosthesis, are designed to achieve mechanical stability through geometry and surface characteristics that encourage rigid prosthesis-cement fixation and an evenly distributed cement mantle. These are distinguished from the highly polished, tapered design of the “force-closed” stems (eg, the Exeter stem), that convert millimeter-level stem subsidence into a long-term stabilizing force on the prosthesis and cement mantle. …