Early Subsidence of the Exeter Femoral Stem within the Cement Mantle in Primary Arthroplasties and in Revisions Using Impacted Allografts and Cement: A Roentgen Stereophotogrammetric Analysis

In five primary hip arthroplasties and in six revisions with impacted, morselized allografts and cement, roentgen stereophotogrammetric analysis (RSA) was planned to be used to measure the subsidence of the polished and double-tapered Exeter femoral stem, relative both to the cement and the femur. Only in two primary arthroplasties and in two revisions could the tantalum markers be adequately imaged for RSA evaluation. The stems in the primary arthroplasties subsided 1.4 to 2.0 mm and all the subsidence occurred within the cement mantle. The two revisions subsided 1.9 to 3.1 mm within the cement mantle, but there was also a slight subsidence of the cement in relation to the femur, 0.5 to 0.4 mm, respectively. No radiographic signs of stem loosening were found in any of the hips. Our findings of subsidence of the Exeter femoral stem within the cement mantle with no radiographic signs of loosening are in accordance with those reported by the Exeter group. The present technique using tantalum markers in the medioproximal aspect of the cement mantle must be considered as difficult.