title: Influence of disruption of the acromioclavicular and coracoclavicular ligaments on glenohumeral motion: a kinematic evaluation.
abstract: Changes to the integrity of the acromioclavicular (AC) joint impact scapulothoracic and clavicular kinematics. AC ligaments provide anterior-posterior stability, while the coracoclavicular (CC) ligaments provide superior-inferior stability and a restraint to scapular internal rotation. The purpose of this cadaveric study was to describe the effect of sequential AC and CC sectioning on glenohumeral (GH) kinematics during abduction (ABD) of the arm. We hypothesized that complete AC ligament insult would result in altered GH translation in the anterior-posterior plane during abduction, while subsequent sectioning of both CC ligaments would result in an increasing inferior shift in GH translation.
  
  
  
  Six cadaveric shoulders were studied to evaluate the impact of sequential sectioning of AC and CC ligaments on GH kinematics throughout an abduction motion in the coronal plane. Following an examination of the baseline, uninjured kinematics, the AC ligaments were then sectioned sequentially: (1) Anterior, (2) Inferior, (3) Posterior, and (4) Superior. Continued sectioning of CC ligamentous structures followed: the (5) trapezoid and then the (6) conoid ligaments. For each group, the GH translation and the area under the curve (AUC) were measured during abduction using an intact cadaveric shoulder. Total translation was calculated for each condition between ABD 30° and ABD 150° using the distance formula, and a univariate analysis was used to compare total translation for each axis during the different conditions.
  
  
  
  GH kinematics were not altered following sequential resection of the AC ligaments. Disruption of the trapezoid resulted in significant anterior and lateral displacement of the center of GH rotation. Sectioning the conoid ligament further increased the inferior shift in GH displacement.
  
  
  
  A combined injury of the AC and CC ligaments significantly alters GH kinematics during abduction. Type III AC separations, result in a significant change in the shoulder's motion and may warrant surgical reconstruction to restore normal function.
authors.affiliation: Center for Advanced Orthopaedic Studies, Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Kempland C
authors.initials: KC
authors.lastname: Walley
authors.affiliation: Center for Advanced Orthopaedic Studies, Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.|Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, USA.
authors.forename: Babak
authors.initials: B
authors.lastname: Haghpanah
authors.affiliation: Center for Advanced Orthopaedic Studies, Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hingsammer
authors.affiliation: Center for Advanced Orthopaedic Studies, Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Ethan R
authors.initials: ER
authors.lastname: Harlow
authors.affiliation: Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, USA.
authors.forename: Ashkan
authors.initials: A
authors.lastname: Vaziri
authors.affiliation: Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: DeAngelis
authors.affiliation: Center for Advanced Orthopaedic Studies, Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.|Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Ara
authors.initials: A
authors.lastname: Nazarian
authors.affiliation: Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. aramappa@bidmc.harvard.edu.|Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Stoneman 10, Boston, MA, 02215, USA. aramappa@bidmc.harvard.edu.
authors.forename: Arun J
authors.initials: AJ
authors.lastname: Ramappa
mesh_terms: D000173:Acromioclavicular Joint / Q000293:injuries* / Q000503:physiopathology; D001696:Biomechanical Phenomena; D006801:Humans; D008023:Ligaments, Articular / Q000293:injuries*; D008297:Male; D008875:Middle Aged; D012785:Shoulder Joint / Q000503:physiopathology*
keywords: Acromio-clavicular ligaments; Coraco-clavicular ligaments; Glenohumeral joint; Kinematics; Ligament resection; Type II AC injury; Type III AC injury