title: Kinematics of the upper cervical spine in rotation: in vivo three-dimensional analysis.
abstract: METHODS
  Kinematics of the upper cervical spine during head rotation were investigated using three-dimensional magnetic resonance imaging (MRI) in healthy volunteers.
  
  
  OBJECTIVE
  To demonstrate in vivo intervertebral coupled motions of the upper cervical spine.
  
  
  BACKGROUND
  Although various in vivo and in vitro studies have identified the normal movement patterns of the upper cervical spine, no previous studies have accurately analyzed in vivo three-dimensional intervertebral motions of the upper cervical spine during head rotation.
  
  
  METHODS
  Fifteen healthy volunteers underwent three-dimensional MRI of the upper cervical spine using a 1.0-T imager in progressive 15 degrees steps during head rotation. Segmented three-dimensional MRIs of each vertebra in the neutral position were superimposed over images taken at other positions, using voxel-based registration. Relative motions between occiput (Oc) and atlas (C1) and between C1 and axis (C2) were measured and described with 6 degrees of freedom by rigid body Euler angles and translations.
  
  
  RESULTS
  Mean (+/- SD) maximum angles of axial rotation in Oc-C1 and C1-C2 were 1.7 +/- 1.5 degrees and 36.2 +/- 4.5 degrees to each side, respectively. Increases in angle of axial rotation in C1-C2 became smaller with increased head rotation, indicating axial rotation in C1-C2 displayed nonlinear motion. Coupled lateral bending with axial rotation was observed in the direction opposition to that of axial rotation in Oc-C1 (mean, 4.1 +/- 1.4 degrees) and C1-C2 (mean, 3.8 +/- 3.0 degrees). Coupled extension with axial rotation occurred at both C0-C1 (mean, 13.3 +/- 4.9 degrees) and C1-C2 (mean, 6.9 +/- 3.0 degrees).
  
  
  CONCLUSIONS
  We developed an innovative in vivo three-dimensional motion analysis system using three-dimensional MRI. In vivo coupled motions of the upper cervical spine investigated using this system supported the results of the previous in vitro study.
authors.affiliation: Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Suita, Japan. ishii-takahiro88@umin.ac.jp
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ishii
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Mukai
authors.forename: Noboru
authors.initials: N
authors.lastname: Hosono
authors.forename: Hironobu
authors.initials: H
authors.lastname: Sakaura
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Nakajima
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Sato
authors.forename: Kazuomi
authors.initials: K
authors.lastname: Sugamoto
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa
mesh_terms: D000328:Adult; D001368:Axis, Cervical Vertebra / Q000033:anatomy & histology / Q000502:physiology; D001696:Biomechanical Phenomena / Q000379:methods / Q000706:statistics & numerical data; D001270:Cervical Atlas / Q000033:anatomy & histology / Q000502:physiology; D002574:Cervical Vertebrae / Q000033:anatomy & histology / Q000502:physiology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D009333:Neck / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D012016:Reference Values; D012399:Rotation; D013131:Spine / Q000033:anatomy & histology / Q000502:physiology*