title: Kinematics of the cervical spine in lateral bending: in vivo three-dimensional analysis.
abstract: METHODS
  Kinematics of the cervical spine during lateral bending were investigated using a novel system of three-dimensional motion analysis.
  
  
  OBJECTIVE
  To demonstrate in vivo intervertebral coupled motions of the cervical spine during lateral bending of the neck.
  
  
  BACKGROUND
  No previous studies have successfully documented in vivo three-dimensional intervertebral motions of the cervical spine during lateral bending.
  
  
  METHODS
  Twelve healthy volunteers underwent three-dimensional magnetic resonance imaging (MRI) of the cervical spine in 7 positions with 10 degrees increments of lateral bending. Relative motions of the cervical spine were calculated automatically by superimposing a segmented three-dimensional-MRI of the vertebra in the neutral position over images of each position using volume registration.
  
  
  RESULTS
  Mean maximum lateral bending of the cervical spine to one side was 1.6 degrees to 5.7 degrees at each level. Coupled axial rotation opposite to lateral bending was observed in the upper cervical levels (Oc-C1, 0.2 degrees ; C1-C2, 17.1 degrees ), while in the subaxial cervical levels, it was observed in the same direction as lateral bending except for at C7-T1. Coupled flexion-extension motion was small at all vertebral levels (<1.1 degrees).
  
  
  CONCLUSIONS
  We succeeded in identifying in vivo coupled motions of the cervical spine in lateral bending for the first time.
authors.affiliation: Department of Orthopaedic Surgery, Hoshigaoka Koseinenkin Hospital, Osaka, 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: Ryutaro
authors.initials: R
authors.lastname: Fujii
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Nakajima
authors.forename: Shinichi
authors.initials: S
authors.lastname: Tamura
authors.forename: Motoki
authors.initials: M
authors.lastname: Iwasaki
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Kazuomi
authors.initials: K
authors.lastname: Sugamoto
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000295:instrumentation / Q000379:methods; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000502:physiology*; D005260:Female; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods; D008297:Male; D018583:Pliability; D011859:Radiography