title: A stress MRI of the shoulder for evaluation of ligamentous stabilizers in acute and chronic acromioclavicular joint instabilities.
abstract: OBJECTIVE
  To show the feasibility of a stress magnetic resonance imaging (MRI) as a new method for simultaneous evaluation of the morphology and the functional integrity of the acromioclavicular joint (ACJ) ligamentous stabilizers.
  
  
  METHODS
  MRI of four volunteers, 10 patients with acute, and six with chronic ACJ injuries was performed using a 0.25 T open MRI scanner. A 2D-proton-density and a 3D-gradient-echo sequence at rest and under 6.5 kg shoulder traction were performed. Comparative measurements of the coracoclavicular and the acromioclavicular distance were performed. Additionally, the conoid and trapezoid ligament lengths were measured with multiplanar reconstructions.
  
  
  RESULTS
  MRI at rest correctly identified tears of the coracoclavicular and the acromioclavicular ligaments in eight patients suffering acute ACJ injuries. Stress application helped to distinguish between partial and complete coracoclavicular ligament tears in two cases. Insufficiency of the ACJ ligaments was present in all acute and chronic ACJ injuries. Stress application in chronic ACJ ligaments revealed isolated insufficiency of the conoid ligament in three cases and of the trapezoid ligament in one case. Combined insufficiency was present in two cases.
  
  
  CONCLUSIONS
  Stress MRI facilitates simultaneous acquisition of morphologic and functional information of the ACJ stabilizers. In acute ACJ injuries it helps to distinguish between partial and complete ligament tears. In chronic ACJ injuries it provides functional information of the ligament regrinds.
authors.affiliation: Department of Orthopedic and Trauma Surgery, University Medical Center Freiburg, Germany. kaywan.izadpanah@uniklinik-freiburg.de
authors.forename: Kaywan
authors.initials: K
authors.lastname: Izadpanah
authors.forename: Jan
authors.initials: J
authors.lastname: Winterer
authors.forename: Marco
authors.initials: M
authors.lastname: Vicari
authors.forename: Martin
authors.initials: M
authors.lastname: Jaeger
authors.forename: Dirk
authors.initials: D
authors.lastname: Maier
authors.forename: Leonie
authors.initials: L
authors.lastname: Eisebraun
authors.forename: Jutta
authors.initials: J
authors.lastname: Ute Will
authors.forename: Elmar
authors.initials: E
authors.lastname: Kotter
authors.forename: Mathias
authors.initials: M
authors.lastname: Langer
authors.forename: Norbert P
authors.initials: NP
authors.lastname: Südkamp
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hennig
authors.forename: Mathias
authors.initials: M
authors.lastname: Weigel
mesh_terms: D000173:Acromioclavicular Joint / Q000293:injuries* / Q000473:pathology*; D000208:Acute Disease; D000328:Adult; D002908:Chronic Disease; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000473:pathology*; D008022:Ligaments / Q000293:injuries* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012782:Shoulder; D014143:Traction / Q000379:methods*