title: Measurement of lateral acetabular coverage: a comparison between CT and plain radiography.
abstract: We prospectively evaluated the degree of absolute agreement between measurements of lateral center-edge angle (LCEA) on plain radiography (XR) and computed tomography (CT) in a consecutive cohort of 205 patients (410 hips) undergoing hip arthroscopy. Preoperative measurements of the LCEA were performed bilaterally utilizing standardized anteroposterior radiographs and coronal reformatted CT scans. Demographic variables including age, gender, height, weight, BMI and clinical diagnosis were recorded for all patients. Overall, measured values of the LCEA were 2.1° larger on CT compared with XR (32.9° versus 30.8°, P < 0.001). Subgroup analysis revealed the highest mean difference in hips with acetabular dysplasia and concomitant cam-type femoroacetabular impingement (FAI) [mean difference (CT-XR) 5.5°, 95% confidence interval (CI) 3.7°-7.3°, P = 0.011], followed by hips with isolated acetabular dysplasia (mean difference [CT-XR] 4.9°, 95% CI 2.7°-7.0°, P < 0.001). In contrast, 119 (29.0%) of the hips demonstrated larger measurements of the LCEA on 25 XR relative to CT. Of these hips, 20 (16.8%) had pincer-FAI and 25 had cam-FAI (21.0%), representing a significantly higher proportion compared with all other clinical subgroups (P = 0.045 and 0.036, respectively). Our study demonstrates measured values of the LCEA are consistently inflated on CT relative to XR for a wide variety of hip pathologies, highlighting the need for standardization and validation of CT-based measurements to improve the quality of clinical decision making.
  
  
  METHODS
  Diagnostic Level II.
authors.affiliation: 1. Department of Orthopaedic Surgery, University of Colorado School of Medicine, Aurora, CO, USA.
authors.forename: Vivek
authors.initials: V
authors.lastname: Chadayammuri
authors.affiliation: 2. Department of Orthopaedic Surgery, Division of Sports Medicine and Hip Preservation.
authors.forename: Tigran
authors.initials: T
authors.lastname: Garabekyan
authors.affiliation: 3. Department of Radiology, Division of Musculoskeletal Radiology, University of Colorado School of Medicine, Aurora, CO, USA.
authors.forename: Mary-Kristen
authors.initials: MK
authors.lastname: Jesse
authors.affiliation: 2. Department of Orthopaedic Surgery, Division of Sports Medicine and Hip Preservation.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Pascual-Garrido
authors.affiliation: 3. Department of Radiology, Division of Musculoskeletal Radiology, University of Colorado School of Medicine, Aurora, CO, USA.
authors.forename: Colin
authors.initials: C
authors.lastname: Strickland
authors.affiliation: 1. Department of Orthopaedic Surgery, University of Colorado School of Medicine, Aurora, CO, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Milligan
authors.affiliation: 2. Department of Orthopaedic Surgery, Division of Sports Medicine and Hip Preservation.
authors.forename: Omer
authors.initials: O
authors.lastname: Mei-Dan