title: Glenohumeral Joint Kinematics following Clavicular Fracture and Repairs.
abstract: The purpose of this biomechanical study was to determine the effect of shortened clavicle malunion on the center of rotation of the glenohumeral (GH) joint, and the capacity of repair to restore baseline kinematics.
  
  
  
  Six shoulders underwent automated abduction (ABD) and abbreviated throwing motion (ATM) using a 7-DoF automated upper extremity testing system in combination with an infrared motion capture system to measure the center of rotation of the GH joint. ATM was defined as pure lateral abduction and late cocking phase to the end of acceleration. Torsos with intact clavicle underwent testing to establish baseline kinematics. Then, the clavicles were subjected to midshaft fracture followed by kinematics testing. The fractured clavicles underwent repairs first by clavicle length restoration with plate fixation, and then by wiring of fragments with a 2-cm overlap to simulate shortened malunion. Kinematic testing was conducted after each repair technique. Center of rotation of the GH joint was plotted across all axes to outline 3D motion trajectory and area under the curve.
  
  
  
  Throughout ABD, malunion resulted in increased posterior and superior translation compared to baseline. Plate fixation restored posterior and superior translations at lower abduction angles but resulted in excess anterior and inferior translation at overhead angles. Throughout ATM, all conditions were significantly anterior and superior to baseline. Translation with malunion was situated anterior to the fractured and ORIF conditions at lower angles of external rotation. Plate fixation did not restore baseline anteroposterior or superoinferior translation at any angle measured.
  
  
  
  This study illustrates the complex interplay of the clavicle and the GH joint. While abnormal clavicle alignment alters shoulder motion, restoration of clavicle length does not necessarily restore GH kinematics to baseline. Rehabilitation of the injured shoulder must address the osseous injury and the dynamic forces of the shoulder girdle.
authors.affiliation: Center for Advanced Orthopaedic Studies, Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Claudio
authors.initials: C
authors.lastname: Rosso
authors.affiliation: Center for Advanced Orthopaedic Studies, Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Michael
authors.initials: M
authors.lastname: Nasr
authors.affiliation: Center for Advanced Orthopaedic Studies, Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.
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, Massachusetts, United States of America.
authors.forename: Ethan R
authors.initials: ER
authors.lastname: Harlow
authors.affiliation: Center for Advanced Orthopaedic Studies, Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.|Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts, United States of America.
authors.forename: Babak
authors.initials: B
authors.lastname: Haghpanah
authors.affiliation: Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts, United States of America.
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, Massachusetts, United States of America.
authors.forename: Arun J
authors.initials: AJ
authors.lastname: Ramappa
authors.affiliation: Center for Advanced Orthopaedic Studies, Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.|Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Ara
authors.identifier: 0000-0003-3992-3489
authors.initials: A
authors.lastname: Nazarian
authors.affiliation: Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: DeAngelis
mesh_terms: D001696:Biomechanical Phenomena; D002968:Clavicle / Q000293:injuries* / Q000601:surgery; D003198:Computer Simulation; D050723:Fractures, Bone / Q000473:pathology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D016059:Range of Motion, Articular; D020127:Recovery of Function; D012785:Shoulder Joint / Q000503:physiopathology*; D014945:Wound Healing