title: Sonography of the coracohumeral interval: a potential technique for diagnosing coracoid impingement.
abstract: OBJECTIVE
  Coracoid impingement has been recognized as an etiology for anterior shoulder pain; however, no imaging reference standard exists. We used sonography to compare the coracohumeral interval (CHI) in asymptomatic volunteers with the CHI in patients with coracoid impingement.
  
  
  METHODS
  Bilateral shoulder sonography was performed in 19 asymptomatic volunteers (10 men and 9 women) and in 8 shoulders in 7 patients (6 men and 1 woman) with a clinical diagnosis of coracoid impingement. With the arm adducted across the chest, the interval between the coracoid process and the lesser tuberosity of the humerus was measured using a linear array ultrasound transducer with a peak frequency of 13 MHz.
  
  
  RESULTS
  In the asymptomatic volunteers, the mean +/- SD for the CHI was 12.2 +/- 2.5 mm (range, 7.8-17.5 mm). In the symptomatic shoulders, the mean +/- SD for the CHI was 7.9 +/- 1.4 mm (range, 5.9-9.6 mm). Repeated measures analysis of variance revealed the CHI to be significantly narrower in symptomatic shoulders than in asymptomatic volunteers (P < .0001).
  
  
  CONCLUSIONS
  These data suggest a role for sonography in diagnosing coracoid impingement.
authors.affiliation: Department of Orthopedics, Thomas Jefferson University and Hospitals, Philadelphia, Pennsylvania, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Tracy
authors.forename: Tamara A
authors.initials: TA
authors.lastname: Trella
authors.forename: Levon N
authors.initials: LN
authors.lastname: Nazarian
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Tuohy
authors.forename: Gerald R
authors.initials: GR
authors.lastname: Williams
mesh_terms: D000328:Adult; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019534:Shoulder Impingement Syndrome / Q000000981:diagnostic imaging*; D014463:Ultrasonography / Q000379:methods*; D055815:Young Adult