title: The function of the acromioclavicular and coracoclavicular ligaments in shoulder motion: a whole-cadaver study.
abstract: BACKGROUND
  Scapulothoracic dyskinesis is an important consequence of acromioclavicular joint dislocations. However, no reports have described changes in 3-dimensional motions of the scapula and clavicle with respect to the thorax caused by acromioclavicular joint dislocation.
  
  
  OBJECTIVE
  Sectioning of the acromioclavicular (AC) and coracoclavicular (CC) ligaments affects scapular and clavicular motion in a whole-cadaver model.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  We evaluated shoulder girdle motion (scapula, clavicle, and humerus) relative to the thorax of 14 shoulders from 8 whole cadavers after sequential sectioning of the AC and CC ligaments (trapezoid and conoid ligaments). An electromagnetic tracking device measured 3-dimensional kinematics of the scapula and clavicle during humerothoracic elevation in the coronal and sagittal planes and adduction in the horizontal plane.
  
  
  RESULTS
  Sectioning of the AC ligament increased clavicular retraction during sagittal plane elevation and horizontal plane adduction. Sectioning of the trapezoid ligament decreased scapular external rotation during sagittal plane elevation and horizontal plane adduction. Sectioning of the conoid ligament decreased scapular posterior tilting during sagittal plane elevation and horizontal plane adduction. Acromioclavicular and CC ligament sectioning also delayed clavicular posterior rotation and increased clavicular upward rotation during coronal plane elevation.
  
  
  CONCLUSIONS
  Our study revealed that AC and CC ligament disruption affected in vitro shoulder girdle kinematics in the whole-cadaver model.
  
  
  CONCLUSIONS
  The results of this cadaveric study revealed that AC and CC ligament disruption could cause dyskinesis of the scapula and clavicle. The kinematic changes could be a potential source of pain and dysfunction in the shoulder with AC joint dislocation, and therefore surgical reconstruction may be indicated in certain patients.
authors.affiliation: Department of Orthopedic Surgery, School of Medicine, Keio University, Tokyo, Japan. satoshiohki@gmail.com
authors.forename: Satoshi
authors.initials: S
authors.lastname: Oki
authors.forename: Noboru
authors.initials: N
authors.lastname: Matsumura
authors.forename: Wataru
authors.initials: W
authors.lastname: Iwamoto
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Ikegami
authors.forename: Yoshimori
authors.initials: Y
authors.lastname: Kiriyama
authors.forename: Toshiyasu
authors.initials: T
authors.lastname: Nakamura
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
authors.forename: Takeo
authors.initials: T
authors.lastname: Nagura
mesh_terms: D000173:Acromioclavicular Joint / Q000502:physiology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D002968:Clavicle / Q000502:physiology; D005260:Female; D006801:Humans; D008023:Ligaments, Articular / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009068:Movement; D012540:Scapula / Q000502:physiology; D012782:Shoulder / Q000502:physiology*