title: Comparison of Intraoperative Fluoroscopic Dunn View With Magnetic Resonance Imaging to Determine Femoral Version.
abstract: OBJECTIVE
  To compare femoral version measured with a fluoroscopic Dunn view taken at the time of hip arthroscopy with values derived from axial magnetic resonance imaging (MRI) scans.
  
  
  METHODS
  Of 159 hip arthroscopies performed from January 2014 through March 2015, 50 patients had magnetic resonance imaging (MRI) scans with a protocol that incorporates femoral version analysis. Dunn views are performed as a routine part of the preoperative fluoroscopic examination at the time of arthroscopy. Femoral version was measured from the fluoroscopic views and compared with values calculated from axial MRI images. The measurements were compared with a paired t test for difference in means, the intraclass correlation coefficient (ICC) for reliability, and the limits of agreement method of Bland and Altman.
  
  
  RESULTS
  There was a very small but statistically significant difference between the measurement on fluoroscopic Dunn view and the value on axial MRI (mean difference, 1.4°, P = .03). The ICC was 0.809 (P < .0001), indicating substantial agreement. By the Bland and Altman method, the 95% limits of agreement for fluoroscopic versus MRI measurement were -7.6 to 10.4, with no significant difference in variance by Pitman test (P = .526).
  
  
  CONCLUSIONS
  With careful attention to technique, the fluoroscopically simulated Dunn view can be used to measure femoral version with acceptable accuracy and obviates the need for repeat 3-dimensional imaging for patients who already have an MRI scan without version analysis.
  
  
  METHODS
  Level II, testing of previously developed diagnostic criteria with a gold standard.
authors.affiliation: Center for Hip Preservation, Virginia Mason Medical Center, Seattle, Washington, U.S.A.. Electronic address: Carabeth.lee@virginiamason.org.
authors.forename: Cara Beth
authors.initials: CB
authors.lastname: Lee
authors.affiliation: Orthopedics Department, Southern California Permanente Medical Group, Anaheim, California, U.S.A.
authors.forename: Hillard T
authors.initials: HT
authors.lastname: Spencer
mesh_terms: D000293:Adolescent; D000328:Adult; D001182:Arthroscopy; D060750:Bone Anteversion / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery; D057925:Femoracetabular Impingement / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery; D005270:Femur Head / Q000000981:diagnostic imaging*; D005471:Fluoroscopy; D006801:Humans; D021621:Imaging, Three-Dimensional; D007432:Intraoperative Period; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D055815:Young Adult