title: In vivo analysis of coracoclavicular ligament kinematics during shoulder abduction.
abstract: BACKGROUND
  Anatomic reconstruction of the coracoclavicular ligaments for the treatment of acromioclavicular joint separations provides superior biomechanical stability compared with other procedures. Clavicular and coracoidal footprints of the conoid ligament (CL) and the trapezoid ligament (TL) are well described. So far, little is known about their kinematics and the changes of the coracoclavicular distance during shoulder abduction.
  
  
  OBJECTIVE
  The coracoclavicular distance along the coracoclavicular ligaments changes significantly with shoulder abduction and weightbearing.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  With use of an open magnetic resonance imaging scanner, the shoulders of 13 healthy volunteers were examined in supine and sitting positions. Three-dimensional magnetic resonance images of the shoulders were obtained in 30° increments of abduction (0°-120°). A manual segmentation of the scapula, the clavicle, and the coracoclavicular ligaments was performed. The insertion points of the coracoclavicular ligaments were identified, and automated measures along the ligamentous course were carried out.
  
  
  RESULTS
  During transfer from the lying to sitting position, the coracoclavicular distance showed significant lengthening of 3 mm along the center of the CL, which significantly increased another 3 mm during shoulder abduction to a total lengthening of 6 mm. In the supine position, the coracoclavicular distance along the TL did not elongate significantly. In the sitting position, the distance along the medial portion of the TL shortened significantly, whereas the distance along the center portion did not elongate significantly during shoulder abduction.
  
  
  CONCLUSIONS
  The distances between the coracoclavicular insertion points depend on both patient and shoulder positioning. To prevent overconstraining of the graft, the CL should be fixated during 90° to 120° of shoulder abduction in a sitting position. Isometric reconstruction of the TL can be achieved if precise fixation of the graft at the centers of the conoidal and clavicular footprints is performed.
authors.affiliation: Department of Orthopaedic and Trauma Surgery, University Hospital Freiburg, Freiburg, Germany. izadpanah@me.com
authors.forename: Kaywan
authors.initials: K
authors.lastname: Izadpanah
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Weitzel
authors.forename: Matthias
authors.initials: M
authors.lastname: Honal
authors.forename: Jan
authors.initials: J
authors.lastname: Winterer
authors.forename: Marco
authors.initials: M
authors.lastname: Vicari
authors.forename: Dirk
authors.initials: D
authors.lastname: Maier
authors.forename: Martin
authors.initials: M
authors.lastname: Jaeger
authors.forename: Elmar
authors.initials: E
authors.lastname: Kotter
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hennig
authors.forename: Matthias
authors.initials: M
authors.lastname: Weigel
authors.forename: Norbert P
authors.initials: NP
authors.lastname: Südkamp
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D002968:Clavicle / Q000033:anatomy & histology / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008023:Ligaments, Articular / Q000033:anatomy & histology / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D056888:Patient Positioning; D012785:Shoulder Joint / Q000033:anatomy & histology / Q000502:physiology*