title: Influence of pelvic tilt on functional acetabular orientation.
abstract: BACKGROUND
  Pelvic tilt influences acetabular orientation (AO). Anatomical AO can be measured in relation to the anterior pelvic plane (APP), functional AO can be calculated relative to table's plane.
  
  
  OBJECTIVE
  To assess to what extent functional AO is determined by pelvic tilt and if APP and table plane give equal information for correct AO.
  
  
  METHODS
  AO was evaluated by computed tomography (CT) scans of 138 patients. Pelvic tilt, anatomical and functional AO were measured, differences between the two reference planes were calculated.
  
  
  RESULTS
  Anatomical and functional acetabular anteversion (AA) were found to be different in 21% of individuals with an enhanced extent of pelvic tilt. Functional AA was increased compared to anatomical AA at high posterior pelvic tilt (p < 0.001). Enlarged anterior tilting of the pelvis reduced APP-related AA (p < 0.002). Anatomical AA positively correlated with pelvic tilt, particularly in females (p < 0.01, correlation coefficient = 0.698, R2 = 0.523).
  
  
  CONCLUSIONS
  APP and table plane do not provide equal information about AO at enhanced pelvic tilt. Functional orientation of the acetabulum is dependent on pelvic tilt, which itself is influenced by anatomical AA and should therefore be analyzed for precise AO.
authors.affiliation: Department for Orthopaedics, Department for Traumatology, Center for Musculoskeletal Surgery, Charité-University Medicine Berlin, 10117 Berlin, Germany.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Zahn
authors.affiliation: Department for Orthopaedics, Department for Traumatology, Center for Musculoskeletal Surgery, Charité-University Medicine Berlin, 10117 Berlin, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Grotjohann
authors.affiliation: Department for Orthopaedics, Department for Traumatology, Center for Musculoskeletal Surgery, Charité-University Medicine Berlin, 10117 Berlin, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Pumberger
authors.affiliation: Visualization & Data Analysis Medical Planning & Computational Medicine Groups, Zuse Institute Berlin, 14195 Berlin, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Ramm
authors.affiliation: Visualization & Data Analysis Medical Planning & Computational Medicine Groups, Zuse Institute Berlin, 14195 Berlin, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Zachow
authors.affiliation: Department for Orthopaedics, Department for Traumatology, Center for Musculoskeletal Surgery, Charité-University Medicine Berlin, 10117 Berlin, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Putzier
authors.affiliation: Department for Orthopaedics, Department for Traumatology, Center for Musculoskeletal Surgery, Charité-University Medicine Berlin, 10117 Berlin, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Perka
authors.affiliation: HELIOS Klinikum Emil von Behring, Oskar-Helene-Heim, Department for Orthopaedics and Traumatology, 14165 Berlin, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Tohtz
mesh_terms: D000077:Acetabulum / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D000293:Adolescent; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D010384:Pelvic Bones / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Acetabular orientation; functional anatomy; pelvic tilt; sagittal balance