title: Standing versus supine radiographs in RSA evaluation of femoral head penetration.
abstract: Evaluation of polyethylene acetabular component wear in total hip arthroplasties commonly is performed using serial radiographs of the hip by measuring the change in the location of the center of the femoral head in relation to the acetabular component. Of the different methods currently used for this purpose, radiostereometric analysis (RSA) is considered the most accurate and precise. In all such radiographic studies, it is assumed the femoral head is seated into the deepest portion of the acetabular component during all radiographic examinations. Although most radiographs used for wear measurements are taken with the patient supine, we questioned whether standing radiographs, with substantial joint load, are better suited for these measurements. We evaluated two groups of patients having total hip arthroplasty who had radiostereometric radiographs taken in supine and standing positions. The average femoral head penetration that occurred between the 6-month and 2-year time interval was measured with radiographs taken in the standing or supine position. We found no difference between the average total femoral head penetration when using supine or standing radiographs.
authors.affiliation: Orthopaedic Biomechanics and Biomaterials Laboratory and the Adult Reconstructive Unit of the Department of Orthopaedic Surgery of Massachusetts General Hospital and Harvard Medical School, Boston, 02114, USA. cbragdon@partners.org
authors.forename: Charles R
authors.initials: CR
authors.lastname: Bragdon
authors.forename: Jonas
authors.initials: J
authors.lastname: Thanner
authors.forename: Meridith E
authors.initials: ME
authors.lastname: Greene
authors.forename: Henrik
authors.initials: H
authors.lastname: Malchau
authors.forename: Georgios
authors.initials: G
authors.lastname: Digas
authors.forename: William H
authors.initials: WH
authors.lastname: Harris
authors.forename: Johan
authors.initials: J
authors.lastname: Kärrholm
mesh_terms: D001175:Arthrography / Q000379:methods*; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D005270:Femur Head / Q000000981:diagnostic imaging* / Q000601:surgery; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D006801:Humans; D010780:Photogrammetry; D011187:Posture; D011475:Prosthesis Failure; D013997:Time Factors