Affiliations: [a] Department for Orthopaedics, Department for Traumatology, Center for Musculoskeletal Surgery, Charité-University Medicine Berlin, 10117 Berlin, Germany | [b] Visualization & Data Analysis Medical Planning & Computational Medicine Groups, Zuse Institute Berlin, 14195 Berlin, Germany | [c] HELIOS Klinikum Emil von Behring, Oskar-Helene-Heim, Department for Orthopaedics and Traumatology, 14165 Berlin, Germany
Correspondence:
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Corresponding author: Robert Karl Zahn, Department for Orthopaedics, Department for Traumatology, Center for Musculoskeletal Surgery, Charité-University Medicine Berlin, Charitéplatz 1, 10117 Berlin, Germany. Tel.: +49 (0)30 450 515 062; Fax: +49 (0)30 450 515 900; E-mail:Robert.Zahn@charite.de
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.
