title: Acromiohumeral distance in a seated position in persons with impingement syndrome.
abstract: OBJECTIVE
  To compare the acromiohumeral distance (AHD) of both shoulders in subjects with a unilateral shoulder impingement syndrome (SIS) and healthy subjects in a seated position during free shoulder movements of large amplitude.
  
  
  METHODS
  Using a 0.5-Tesla SIGNA-SP/i trade mark open-configuration magnetic resonance imaging (MRI) system, the AHD was measured at several arm positions, in a standardized seated position.
  
  
  RESULTS
  In flexion (rest to 130 degrees ), the mean AHD of SIS varied from 8.3 to 2.8 mm, as compared to from 8.7 to 4.1 mm for asymptomatic contralateral shoulders. In abduction (rest to 110 degrees ), the AHD varied from 8.1 to 3.4 mm and from 8.8 to 4.6 mm for SIS and asymptomatic shoulders, respectively. The smallest AHD (P <.01) was observed at 110 degrees. From 80 degrees of arm elevation, the AHD was significantly smaller in impingement than in asymptomatic shoulders (P <.05). The AHD of asymptomatic shoulders did not differ from that of healthy subjects. In SIS, the AHD at rest was correlated with its reduction at all shoulder positions (r(p) = 0.62-0.88), but was a poor predictor of the smallest AHD observed at 110 degrees (flexion, R(2) = 0.09; abduction, R(2) = 0.08).
  
  
  CONCLUSIONS
  In the critical arm elevation positions for impingement, AHD is discriminative for SIS, compared to asymptomatic shoulders and healthy ones. AHD at rest is a good indicator of the magnitude of its reduction in elevation, but not of the smallest AHD in arm elevation.
authors.affiliation: National Defence of Canada, Courcelette, Quebec, Canada. ljhebert@videotron.ca
authors.forename: Luc J
authors.initials: LJ
authors.lastname: Hébert
authors.forename: Hélène
authors.initials: H
authors.lastname: Moffet
authors.forename: Marie
authors.initials: M
authors.lastname: Dufour
authors.forename: Christian
authors.initials: C
authors.lastname: Moisan
mesh_terms: D000173:Acromioclavicular Joint / Q000503:physiopathology*; D000328:Adult; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011187:Posture; D019534:Shoulder Impingement Syndrome / Q000503:physiopathology*