title: Validation of neck axis distance as a radiographic measure for acetabular anteversion.
abstract: Excessive acetabular anteversion is an important treatment consideration in hip preservation surgery. There is currently no reliable quantitative method for determining acetabular anteversion utilizing radiographs alone. The three main purposes of this study were to: (i) define and validate the neck axis distance (NAD) as a new visual and reproducible semi-quantitative radiographic parameter used to measure acetabular anteversion; (ii) determine the degree of correlation between NAD and computed tomography (CT)-measured acetabular anteversion; (iii) establish a sensitive and specific threshold value for NAD to identify excessive acetabular anteversion. This retrospective cohort study included all patients presenting to a single institution over a 14-month period who had undergone a dedicated musculoskeletal CT pelvis along with a standardized anteroposterior (AP) pelvis radiograph. Trained observers measured the NAD on the AP pelvis radiograph and equatorial acetabular anteversion on CT for all hips. Mixed model analysis was used to find prediction equations, and ROC analysis was used to evaluate the diagnostic accuracy of NAD. NAD is a valid semi-quantitative predictor of acetabular anteversion and strongly correlates with CT-measured equatorial acetabular anteversion (P  <  0.0001). A NAD measurement of greater than 14 mm predicts excessive acetabular anteversion with 76% sensitivity and 78% specificity. NAD is an accurate radiographic predictor of acetabular anteversion, which may be readily used as an effective screening tool during the evaluation of patients with hip pain.
authors.affiliation: 1. Division of Musculoskeletal Radiology, Department of Radiology, University of Colorado School of Medicine, University of Colorado Denver, Aurora, Colorado, USA.
authors.forename: Ashley
authors.initials: A
authors.lastname: Nitschke
authors.affiliation: 2. Division of Musculoskeletal Radiology, Department of Radiology and Orthopaedics, University of Colorado School of Medicine, University of Colorado Denver, Aurora, Colorado, USA; 3. Inland Imaging, PS. Spokane, Washington, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Petersen
authors.affiliation: 4. Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado, Aurora, Colorado, USA.
authors.forename: Jeffery R
authors.initials: JR
authors.lastname: Lambert
authors.affiliation: 4. Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado, Aurora, Colorado, USA; 5. Department of Radiology, University of Colorado School of Medicine, University of Colorado Denver, Aurora, Colorado, USA.
authors.forename: Deborah H
authors.initials: DH
authors.lastname: Glueck
authors.affiliation: 2. Division of Musculoskeletal Radiology, Department of Radiology and Orthopaedics, University of Colorado School of Medicine, University of Colorado Denver, Aurora, Colorado, USA.
authors.forename: Mary Kristen
authors.initials: MK
authors.lastname: Jesse
authors.affiliation: 2. Division of Musculoskeletal Radiology, Department of Radiology and Orthopaedics, University of Colorado School of Medicine, University of Colorado Denver, Aurora, Colorado, USA.
authors.forename: Colin
authors.initials: C
authors.lastname: Strickland
authors.affiliation: 6. Division of Sports Medicine and Hip Preservation, Department of Orthopaedics, University of Colorado School of Medicine, University of Colorado Denver, Aurora, Colorado, USA.
authors.forename: Omer
authors.initials: O
authors.lastname: Mei-Dan