Radiology Case Reports Volume I, Issue 4, 2006 Dissociation of a Bipolar Prosthesis after Right Hip

Abstract

We report the case of an 84-year-old woman with a dissociated bipolar component of her right hip hemiarthroplasty. Dissociation of components is a rare but increasingly recognized consequence of modular componentry. Radiologists should be aware of the distinction between dislocation of a prosthesis and dissociation of its bipolar components, and be able to describe these complications accurately in their interpretations. Case Report We report the case of an 84-year-old woman who fell, resulting in a fracture of her right femoral neck. This fracture was treated with placement of a bipolar hemiarthroplasty. Two weeks later, a routine post-operative radiograph demonstrated an abnormal appearance of her arthroplasty, despite no history of hip pain, leg numbness, or weakness. Initial right hip radiographs demonstrated dissociation of the components of the bipolar hemiarthroplasty, with inferomedial displacement of the acetabular cup component, and with the prosthetic femoral head abutting the roof of the acetabulum (Figure 1). There was no evidence of fracture or loosening of the femoral component of the prosthesis. The patient underwent successful conversion to total hip replacement and had an uneventful postoperative course. Discussion Although interpositional hip arthroplasty was first performed in the 1800's (1), it did not become commonplace, Citation: Grauke LJ, Richardson ML. Dissociation of a bipolar prosthesis after right hip hemiarthroplasty. Radiology Case Reports. [Online] 2006;1:55. Copyright: © Luke J. Grauke. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs 2.5 License, which permits reproduction and distribution, provided the original work is properly cited. Commercial use and derivative works are not permitted. Abbreviations: THA, total hip arthroplasty Luke J. Grauke (Email