title: Ultrasonographic measurement of the axillary recess thickness in an asymptomatic shoulder.
abstract: OBJECTIVE
  The purpose of this study was to measure the axillary recess (AR) thickness in an asymptomatic shoulder by using ultrasonography (US) and to analyze the factors affecting it.
  
  
  METHODS
  We recruited 141 patients (52 males; 89 females; age, 57.7±9.9 years) with unilateral shoulder pain and performed US on the unaffected shoulder. Two physiatrists measured the AR thickness of the unaffected shoulder independently. All patients were examined in an upright sitting position with 90° shoulder abduction. The ultrasonographic transducer was placed longitudinally on the mid-axillary line and along the long axis of the humeral shaft. The factors affecting the AR thickness values were analyzed, and intra-class correlation coefficients were used for assessing the reproducibility of each measurement.
  
  
  RESULTS
  The intrarater reliability values for the two physiatrists were 0.98 and 0.96, respectively. The inter-rater reliability of the mean AR thickness measurements was 0.91. The mean AR thickness in all subjects, males, and females was 2.8±0.6 mm, 3.1±0.6 mm, and 2.6±0.5 mm (P<0.01), respectively. No difference between the left and the right sides (males, P=0.086; females, P=0.535) or between the dominant and the non-dominant sides (males, P=0.173; female, P=0.244) was found. The AR thickness correlated positively with the height (r=0.313, P<0.01) and the weight (r=0.319, P<0.01). However, it did not correlate with the body mass index (r=0.152, P=0.077) or the age (r=-0.056, P=0.515).
  
  
  CONCLUSIONS
  US measurements of the AR thickness in asymptomatic shoulders demonstrated excellent intrarater and inter-rater reliabilities. The AR thickness showed anatomical variation with sex, height, and weight.
authors.affiliation: Department of Rehabilitation Medicine, Catholic University of Daegu School of Medicine, Daegu, Korea.
authors.forename: Gi-Young
authors.identifier: 0000-0003-0056-1556
authors.initials: GY
authors.lastname: Park
authors.affiliation: Department of Rehabilitation Medicine, Catholic University of Daegu School of Medicine, Daegu, Korea.
authors.forename: Jin Hoon
authors.identifier: 0000-0001-9725-9921
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Rehabilitation Medicine, Catholic University of Daegu School of Medicine, Daegu, Korea.
authors.forename: Dae Gil
authors.identifier: 0000-0002-8423-8045
authors.initials: DG
authors.lastname: Kwon
keywords: Axilla; Shoulder; Ultrasonography