title: Coupling behavior of the cervical spine: a systematic review of the literature.
abstract: OBJECTIVE
  The purpose of this study was to investigate evidence of consistency of reported directional coupling patterns among selected studies and to determine its use in manual medical treatment.
  
  
  METHODS
  The study was a systematic literature review of English-only journals using PubMed and CINAHL. The keywords included "cervical vertebrae," "biomechanics," "coupling," and "three-dimensional movement" and required coupling directional assessment of individual spine segments.
  
  
  RESULTS
  Four 2-dimensional and 8 3-dimensional studies met inclusion criteria. This study found 100% agreement in coupling direction (side flexion and rotation to the same side) in lower cervical vertebral segments (C2-3 and lower) and variation in coupling patterns in the upper cervical segments of occiput-C1 (during side flexion initiation) and C1-2. Dissimilarities may be explained by differences in measurement devices, movement initiation, in vivo vs in vitro specimens, and anatomical variations.
  
  
  CONCLUSIONS
  These findings suggest that use of 3-dimensional analyzed cervical coupling patterns for the lower cervical vertebral during apposition and treatment application may show clinical use for manual clinicians. The use of directional coupling based on 2-dimensional cervical coupling patterns or upper cervical spine coupling that addresses C1-2 should be questioned.
authors.affiliation: Division of Physical Therapy, Department of Community and Family Medicine, Duke University, Durham, NC 27710, USA. chad.cook@duke.edu
authors.forename: Chad
authors.initials: C
authors.lastname: Cook
authors.forename: Eric
authors.initials: E
authors.lastname: Hegedus
authors.forename: Christopher
authors.initials: C
authors.lastname: Showalter
authors.forename: Phillip S
authors.initials: PS
authors.lastname: Sizer
mesh_terms: D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D020393:Manipulation, Spinal / Q000379:methods*; D009068:Movement / Q000502:physiology*; D018583:Pliability; D012399:Rotation