title: Plain radiographs fail to reflect femoral offset in total hip arthroplasty.
abstract: Successful biomechanical reconstruction is a major goal in total hip arthroplasty (THA). We measured leg length (LL), global (GO) and femoral offset (FO) change on anteroposterior pelvis radiographs and on three-dimensional computed-tomography (3D-CT) with fiducial landmarks after cementless THA on 18 hips of cadaveric specimens. Measurements on radiographs were performed twice by four examiners and showed high interobserver (mean CCC ≥0.79) and intraobserver agreements (mean ICC ≥0.88). Mean differences between radiographic and 3D-CT measurements were 1.0 (SD 2.0) mm for LL, 0.6 (SD 3.6) mm for GO and 1.4 (SD 5.2) mm for FO. 1% of radiographic LL-, 15% of GO- and 35% of FO measurements were outside a tolerance limit of 5mm. Radiographs seem acceptable for measuring LL/GO change but fail to reflect FO change in THA.
authors.affiliation: Department of Orthopedic Surgery, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Weber
authors.affiliation: Department of Orthopedic Surgery, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Woerner
authors.affiliation: Department of Orthopedic Surgery, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Hans-Robert
authors.initials: HR
authors.lastname: Springorum
authors.affiliation: Institute of Medical Statistics and Epidemiology, Munich Technische Universitaet, Munich, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Hapfelmeier
authors.affiliation: Department of Orthopedic Surgery, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Grifka
authors.affiliation: Department of Orthopedic Surgery, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Tobias F
authors.initials: TF
authors.lastname: Renkawitz
mesh_terms: D001175:Arthrography / Q000379:methods / Q000592:standards* / Q000706:statistics & numerical data; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D002102:Cadaver; D005269:Femur / Q000000981:diagnostic imaging* / Q000601:surgery*; D057918:Fiducial Markers; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data; D015588:Observer Variation; D010388:Pelvis / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000592:standards* / Q000706:statistics & numerical data
keywords: accuracy; femoral offset; global offset; leg length; radiography; total hip arthroplasty