title: Preoperative agreement on the geometric classification and 2-dimensional measurement of rotator cuff tears based on magnetic resonance arthrography.
abstract: OBJECTIVE
  To determine the intraobserver and interobserver agreement on the geometric classification and 2-dimensional measurements of rotator cuff tears based on magnetic resonance arthrography.
  
  
  METHODS
  We retrospectively reviewed preoperative magnetic resonance arthrograms of 73 consecutive patients who were surgically treated for their full-thickness rotator cuff tears. The images were blinded and evaluated by 2 orthopaedic shoulder surgeons and 2 musculoskeletal radiologists using the geometric classification of rotator cuff tears (type 1, crescent-shaped tear; type 2, longitudinal U- or L-shaped tear; type 3a, massive tear measuring between 20 and 30 mm; and type 3b, massive contracted tear measuring >30 mm) and measuring the sagittal/coronal dimensions of the tear. Review was performed twice with an interval of at least 8 weeks. Agreement was calculated using the linear weighted κ coefficient and the intraclass correlation coefficient (ICC).
  
  
  RESULTS
  The intraobserver agreement was excellent for both the geometric classification and the sagittal/coronal dimension measurement (κ, 0.81 to 0.92; ICC, 0.84 to 0.98). The ICC for the interobserver agreement was excellent for all sagittal and coronal dimension measurements (ICC, 0.95 to 0.97). The interobserver agreement for the geometric classification was good for the orthopaedic surgeons (κ, 0.75 for round 1 and 0.73 for round 2). The interobserver agreement for the radiologists was excellent in observation round 1 (κ, 0.82) and good in observation round 2 (κ, 0.71). The interobserver agreement between orthopaedic surgeons and radiologists was found to be moderate to good (κ, 0.52 to 0.66). The Fleiss κ was 0.66 for round 1 and 0.62 for round 2.
  
  
  CONCLUSIONS
  The geometric classification and the 2-dimensional measurement of rotator cuff tears using magnetic resonance arthrography have good to excellent intraobserver agreement and moderate to good interobserver agreement among experienced observers.
  
  
  METHODS
  Level III, diagnostic study of nonconsecutive patients without consistently applied gold standard.
authors.affiliation: Department of Orthopaedic Surgery, Medical Center Haaglanden, The Hague, The Netherlands. peerzwaal@hotmail.com
authors.forename: Peer
authors.initials: P
authors.lastname: van der Zwaal
authors.forename: Bregje J W
authors.initials: BJ
authors.lastname: Thomassen
authors.forename: Thijs A J
authors.initials: TA
authors.lastname: Urlings
authors.forename: Theodoor P W
authors.initials: TP
authors.lastname: de Rooy
authors.forename: Jan-Willem A
authors.initials: JW
authors.lastname: Swen
authors.forename: Ewoud R A
authors.initials: ER
authors.lastname: van Arkel
mesh_terms: D000368:Aged; D001175:Arthrography; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011300:Preoperative Care; D012189:Retrospective Studies; D017006:Rotator Cuff / Q000601:surgery; D000070636:Rotator Cuff Injuries; D013708:Tendon Injuries / Q000145:classification* / Q000175:diagnosis