title: Measurement of the acromiohumeral interval on standardized anteroposterior radiographs: a prospective study of observer variability.
abstract: BACKGROUND
  An acromiohumeral interval narrower than 6 mm has been considered pathologic and strongly indicative for rotator cuff tears by numerous authors. This prospective study assessed interobserver and intraobserver variability in the radiographic measurement of the acromiohumeral interval.
  
  
  METHODS
  Five board-certified orthopedic surgeons independently reviewed 58 blinded, standardized anteroposterior shoulder radiographs. The acromiohumeral interval was measured in millimeters. The 5 investigators classified each image a second time in random order.
  
  
  RESULTS
  After the same 58 radiographs had been evaluated by the 5 investigators at both examination time points, no significant differences were noted in the interobserver and intraobserver measurements (P < .05). The respective maximum interobserver and intraobserver differences were 4 and 3 mm (range, 0-4 mm).
  
  
  CONCLUSIONS
  The assessment of the acromiohumeral interval using standardized anteroposterior radiographs is a reliable and reproducible method of measurement.
  
  
  METHODS
  Level 1; Investigating a diagnostic test.
authors: Department of Orthopedics, Medical University Graz, Graz, Austria. gerald.gruber@klinikum-graz.at
authors: Gerald
authors: G
authors: Gruber
authors: Gerwin A
authors: GA
authors: Bernhardt
authors: Heimo
authors: H
authors: Clar
authors: Maximilian
authors: M
authors: Zacherl
authors: Mathias
authors: M
authors: Glehr
authors: Christian
authors: C
authors: Wurnig
mesh_terms: D000174:Acromion / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015331:Cohort Studies; D005260:Female; D006801:Humans; D006811:Humerus / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011336:Probability; D011446:Prospective Studies; D011859:Radiography / Q000592:standards*; D012680:Sensitivity and Specificity; D012785:Shoulder Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D018709:Statistics, Nonparametric