title: What is the Fate of Total Hip Arthroplasty (THA) Acetabular Component Orientation When Evaluated in the Standing Position?
abstract: This retrospective study measured the change of the acetabular component orientation between supine and standing radiographs in 113 THA patients and identified the associated anatomical parameters that may help direct pre-operative planning. The mean change of the acetabular component inclination and version from supine to standing was 4.6° and 5.9° respectively (P<0.0001), with 49 (43%) hips showing inclination change >5° and 69 (53%) hips showing version change >5°. Twelve (43%) of 28 'malpositioned' cups became 'well-positioned' and 26 (31%) of 85 'well-positioned' cups became 'malpositioned' upon standing. Changes in inclination were associated with leg length discrepancy and pelvic obliquity; and changes in version were associated with pelvic tilt and pelvic incidence. Standing position and patient factors should be considered when defining "optimal" acetabular orientation.
authors: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: John V
authors: JV
authors: Tiberi
authors: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Valentin
authors: V
authors: Antoci
authors: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Henrik
authors: H
authors: Malchau
authors: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Harry E
authors: HE
authors: Rubash
authors: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Andrew A
authors: AA
authors: Freiberg
authors: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Young-Min
authors: YM
authors: Kwon
mesh_terms: D000077:Acetabulum / Q000601:surgery*; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001847:Bone Diseases / Q000601:surgery*; D005260:Female; D006615:Hip / Q000033:anatomy & histology* / Q000601:surgery; D006801:Humans; D008297:Male; D010388:Pelvis; D011187:Posture; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D016683:Supine Position
keywords: EOS X-ray imaging Acquisition System; acetabular cup position; safe zone; standing; total hip arthroplasty