title: Effect of shortening deformity of the clavicle on scapular kinematics: a cadaveric study.
abstract: BACKGROUND
  In some short malunion cases, midshaft clavicular fractures are reported to result in unsatisfactory clinical outcomes. Shortening deformity of the clavicle could change the anatomical alignment of the shoulder girdle and is surmised to affect shoulder kinematics on arm movements. Nevertheless, no report has ever referred to documented changes.
  
  
  OBJECTIVE
  Scapular motion will change with clavicular shortening in cadaveric models.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Twelve cadaveric shoulders were used, and sequential clavicular shortening by 0%, 5%, 10%, 15%, and 20% from the original length was simulated in this study. The scapulothoracic motion during passive arm elevation in 3 planes was monitored using an electromagnetic tracking device. Differences in kinematics of the scapula between the 0% shortening models and the other 4 experimental groups were analyzed.
  
  
  RESULTS
  During arm elevation, posterior tilting and external rotation of the scapula significantly decreased with > or = 10% shortening of the clavicle. Decreased posterior tilting was found with a shorter clavicle and at higher positions of arm elevation in all planes and became obvious during coronal plane elevation. Upward rotation of the scapula did not change with shortening at any elevated arm positions.
  
  
  CONCLUSIONS
  The findings of this study clearly indicated that shortening of the clavicle affects the kinematics in the shoulder girdle.
  
  
  CONCLUSIONS
  The results of this cadaveric study suggest that clavicular shortening of > or = 10% affects scapular kinematics and might produce clinical symptoms.
authors.affiliation: Department of Orthopedic Surgery, School of Medicine, Keio University, Tokyo, Japan. noboru18@nifty.com
authors.forename: Noboru
authors.initials: N
authors.lastname: Matsumura
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Ikegami
authors.forename: Noriaki
authors.initials: N
authors.lastname: Nakamichi
authors.forename: Toshiyasu
authors.initials: T
authors.lastname: Nakamura
authors.forename: Takeo
authors.initials: T
authors.lastname: Nagura
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Imanishi
authors.forename: Sadakazu
authors.initials: S
authors.lastname: Aiso
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D017760:Bone Malalignment / Q000503:physiopathology*; D002102:Cadaver; D002968:Clavicle / Q000293:injuries* / Q000503:physiopathology*; D005260:Female; D050723:Fractures, Bone / Q000503:physiopathology*; D006801:Humans; D008297:Male; D016059:Range of Motion, Articular; D012540:Scapula / Q000503:physiopathology*; D012785:Shoulder Joint / Q000503:physiopathology*