title: Three-dimensional clavicular motion during arm elevation: reliability and descriptive data.
abstract: METHODS
  Cross-sectional.
  
  
  OBJECTIVE
  To determine the reliability of a surface sensor measurement of clavicular motion during arm elevation and to describe 3-dimensional clavicular motion in an asymptomatic population.
  
  
  BACKGROUND
  Abnormal scapular motion on the thorax has been implicated in shoulder pathology. Without the ability to measure clavicular motion, it is not possible to identify if abnormal scapular motions derive from the sternoclavicular or acromioclavicular joints.
  
  
  METHODS
  Thirty-nine subjects participated in the investigation, including an asymptomatic group (n = 30) and a group with a history or current symptoms of shoulder pathology (n = 9). Clavicular angles relative to the thorax were tracked with surface electromagnetic sensors on the thorax, clavicle, and humerus as subjects completed humeral flexion, scapular plane abduction, and abduction. Within-day reliability was assessed using intraclass correlation coefficients and SEM. Descriptive statistics quantified sternoclavicular joint motions for the various arm movements.
  
  
  RESULTS
  Reliable measurements were obtained, with intraclass correlation coefficients ranging from 0.93 to 0.99, and SEMs from 0.9 degrees to 1.8 degrees. Between-day reliability SEM values were generally 2 degrees to 4 degrees. During elevation of the arm, the clavicle with respect to the thorax generally undergoes elevation (11 degrees-15 degrees maximum), retraction (15 degrees-29 degrees maximum), and posterior long-axis rotation (15 degrees-31 degrees maximum), with variability between subjects and planes of motion regarding the magnitude of motion.
  
  
  CONCLUSIONS
  Rehabilitation approaches attempting to improve shoulder motion should benefit from improved knowledge of 3-dimensional contributions of the clavicle to normal and abnormal scapular kinematics.
authors.affiliation: Program in Physical Therapy, Department of Physical Medicine and Rehabilitation, The University of Minnesota, Minneapolis, MN 55455, USA. ludew001@umn.edu
authors.forename: Paula M
authors.initials: PM
authors.lastname: Ludewig
authors.forename: Stacy A
authors.initials: SA
authors.lastname: Behrens
authors.forename: Susan M
authors.initials: SM
authors.lastname: Meyer
authors.forename: Shawn M
authors.initials: SM
authors.lastname: Spoden
authors.forename: Laura A
authors.initials: LA
authors.lastname: Wilson
mesh_terms: D000293:Adolescent; D000328:Adult; D001132:Arm / Q000502:physiology*; D001696:Biomechanical Phenomena / Q000295:instrumentation*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006811:Humerus / Q000502:physiology; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D009068:Movement; D016059:Range of Motion, Articular; D012540:Scapula / Q000502:physiology; D012782:Shoulder / Q000502:physiology*; D012785:Shoulder Joint / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation