title: In vitro 3D-kinematics of the upper cervical spine: helical axis and simulation for axial rotation and flexion extension.
abstract: OBJECTIVE
  Registration of 3D-anatomical model and kinematics data is reported to be an accurate method to provide 3D-joint simulation. We applied this approach to discrete kinematics analysis of upper cervical spine (UCS) during axial rotation (AR) and flexion extension (FE) to create anatomical models with movement simulation including helical axis.
  
  
  METHODS
  Kinematics and CT imaging data were sampled in ten anatomical specimens. Using technical and anatomical marker digitizing, spatial position of segments was computed for five discrete positions of AR and FE using a 3D-digitizer. Computerized tomography was used to create anatomical models and to assure kinematics and imaging data registration for simulation. Kinematics was processed using orientation vector and helical axis (HA) computation.
  
  
  RESULTS
  Maximal standard error on marker digitizing was 0.47 mm. Range of motion and coupled movement during AR was in agreement with previous in vitro studies. HA location and orientation have shown low variation at the occipitoaxial and atlantoaxial levels for FE and AR, respectively.
  
  
  CONCLUSIONS
  We developed a protocol to create UCS anatomical model simulations including three-dimensional discrete kinematics, using previously validated methods. In this study, simultaneous segmental movement simulation and display of HA variations was shown to be feasible. Although partially confirming previous results, helical axis computation showed variations of motion patterns dependent on movement, level and specimen. Further in vivo investigations are needed to confirm relevance of this method in the clinical field.
authors.affiliation: Laboratory of Anatomy, Biomechanics and Organogenesis, Université Libre de Bruxelles, Route de Lennik 808, CP 619, 1070, Brussels, Belgium. pdugaill@ulb.ac.be
authors.forename: Pierre-Michel
authors.initials: PM
authors.lastname: Dugailly
authors.forename: Stéphane
authors.initials: S
authors.lastname: Sobczak
authors.forename: Victor
authors.initials: V
authors.lastname: Sholukha
authors.forename: Serge
authors.initials: S
authors.lastname: Van Sint Jan
authors.forename: Patrick
authors.initials: P
authors.lastname: Salvia
authors.forename: Véronique
authors.initials: V
authors.lastname: Feipel
authors.forename: Marcel
authors.initials: M
authors.lastname: Rooze
mesh_terms: D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000502:physiology*; D003198:Computer Simulation; D006801:Humans; D021621:Imaging, Three-Dimensional; D008953:Models, Anatomic; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012399:Rotation