X-RAY IMAGING OF ACETABULAR SHELLS: DO RADIOLUCENT LINES ALWAYS CORRELATE TO PHYSICAL GAP?

IntroductionVarious 2D and 3D surfaces are available for cementless fixation of acetabular cups. The goal of these surface modifications is to improve fixation between the metallic cups and surrounding bone. Radiographs have historically been used to evaluate the implant-to-bone fixation around the acetabular cups. In general, a well fixed cup shows no gaps or radiolucency around the cup's outer diameter. In post-operative radiographs, the presence of progressive radiolucent zones of 2mm or more around the implant in the three radiographic zones is indicative of aseptic loosening, as described by DeLee and Charnley [1]. In this cadaveric study, we investigated the X-ray image characteristics of two different types of acetabular shell surfaces (2D and 3D) to evaluate the implant-to-bone interface in the two designs.MethodsSix human cadavers were bilaterally implanted with acetabular cups by an orthopaedic surgeon. 2D surface cups (Trident, Stryker, Mahwah, NJ) and 3D surface cups (Tritanium, Stryker, Mahwa...