title: Defining the lateral edge of the femoroacetabular articulation: correlation analysis between radiographs and computed tomography.
abstract: OBJECTIVE
  The purpose of this study was to analyze the variation in measuring the lateral center edge angle of Wiberg (LCEA) using the lateral edge of the sourcil (LCEA-S) compared to the lateral edge of the acetabulum (LCEA-E), and to correlate these measurements with three-dimensional computed tomography (3D-CT)-based analysis of the femoroacetabular articulation.
  
  
  METHODS
  A retrospective analysis was performed on 24 patients (45 hips) treated for hip dysplasia at a single institution. All patients were required to have an anteroposterior (AP) pelvis radiograph and pelvic CT. LCEA-S and LCEA-E measurements were calculated from radiographs. Axial CT images were processed to standardize pelvic orientation and calculate the LCEA at three points (posterior, central, anterior) along the acetabular edge. Correlation analysis was used to evaluate radiographic and CT measures.
  
  
  RESULTS
  Eight males and 16 females with an average age of 14.6 years were included. The LCEA-S (16.5° ± 2.0°) was found to be significantly less than the LCEA-E (26.0° ± 2.0°) (p < 0.001). The LCEA-S had the greatest correlation with the central measurement on the 3D-CT (r s = 0.893; p < 0.001). The LCEA-E had the greatest correlation with the anterior measurement on the 3D-CT (r = 0.834; p < 0.001).
  
  
  CONCLUSIONS
  The LCEA can change significantly depending on the bony landmark used to define the lateral edge of the femoroacetabular articulation. The edge of the sourcil most closely correlates with the central weight-bearing portion of the articular surface on the 3D-CT and should be used to define the LCEA when treating patients with hip dysplasia.
  
  
  METHODS
  Level III, retrospective comparison study.
authors.affiliation: Department of Orthopedics, University of California, San Diego, San Diego, CA, USA.
authors.forename: Ashish
authors.initials: A
authors.lastname: Mittal
authors.affiliation: Department of Orthopedics, Rady Children's Hospital, San Diego, 3030 Children's Way, Suite 410, San Diego, CA, 92123, USA.
authors.forename: James D
authors.initials: JD
authors.lastname: Bomar
authors.affiliation: Department of Orthopedics, Rady Children's Hospital, San Diego, 3030 Children's Way, Suite 410, San Diego, CA, 92123, USA.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Jeffords
authors.affiliation: National Cheng Kung University Hospital, Tainan City, Taiwan.
authors.forename: Ming-Tung
authors.initials: MT
authors.lastname: Huang
authors.affiliation: Department of Orthopedics, University of California, San Diego, San Diego, CA, USA.|Department of Orthopedics, Rady Children's Hospital, San Diego, 3030 Children's Way, Suite 410, San Diego, CA, 92123, USA.
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Wenger
authors.affiliation: Department of Orthopedics, University of California, San Diego, San Diego, CA, USA. vupasani@rchsd.org.|Department of Orthopedics, Rady Children's Hospital, San Diego, 3030 Children's Way, Suite 410, San Diego, CA, 92123, USA. vupasani@rchsd.org.
authors.forename: Vidyadhar V
authors.initials: VV
authors.lastname: Upasani
keywords: Hip dysplasia; LCEA; Lateral center edge angle; Sourcil