Normative 3D acetabular orientation measurements by the low-dose EOS imaging system in 102 asymptomatic subjects in standing position: analyses by side, gender, pelvic incidence and reproducibility

• Published in: Orthopaedics & traumatology, surgery & research surgery & research, 2017-04, Vol.103 (2), p.209-215
• Main Authors: Thelen, Thomas, Thelen, Philippe, Demezon, Hugues, Aunoble, Stephane, Le Huec, Jean-Charles
• Format: Article
• Language: English
• Subjects: 3D orientation; Acetabulum - anatomy & histology; Acetabulum - diagnostic imaging; Adult; Asymptomatic subjects; EOS; Female; Humans; Imaging, Three-Dimensional - methods; Male; Native acetabulum; Organ Size; Orthopedics; Pelvis; Posture; Prospective Studies; Reproducibility of Results; Sex Factors; Surgery; Tomography, X-Ray Computed - methods; Young Adult
• ISSN: 1877-0568; 1877-0568
• DOI: 10.1016/j.otsr.2016.11.010

Abstract Background Three-dimensional (3D) acetabular orientation is a fundamental topic in orthopedic surgery. Computed tomography (CT) allows 3D measurement of native acetabular orientation, but with a substantial radiation dose. The EOS imaging system was developed to perform this kind of evaluation, but has not been validated in this indication with specific attention to the acetabulum. We therefore performed a prospective study using EOS to assess: 1) the reproducibility of the 3D acetabulum orientation measures; 2) normative asymptomatic acetabular morphology in standing position, according to side and gender; and 3) the relationship between acetabular anteversion and pelvic incidence. Hypothesis The low-dose EOS imaging system is a reproducible method for measuring 3D acetabular orientation in standing position. Patients and Methods In a previous prospective study of spine sagittal balance, 165 asymptomatic volunteers were examined on whole-body EOS biplanar X-ray; 102 had appropriate images for pelvic and acetabular analysis, with an equal sex-ratio (53 female, 49 male). These EOS images were reviewed using sterEOS 3D software, allowing automatic measurement of acetabular parameters (anteversion and inclination) and pelvic parameters (pelvic incidence, pelvic tilt and sacral slope) in an anatomical (anterior pelvic plane: APP) and a functional reference plane (patient vertical plane: PVP). Results Both intra- and inter-observer analysis showed good agreement (ICC>0.90); Bland-Altman plot distributions were good. Acetabular anatomical anteversion and inclination relative to APP (AAAPP and AIAPP, respectively) were significantly greater in women than in men, with no effect of side (right AAA: women 21.3°± 3.4° vs. men 16.1° ± 3.3° (p