title: Pediatric and adult three-dimensional cervical spine kinematics: effect of age and sex through overall motion.
abstract: METHODS
  Cross-sectional study.
  
  
  OBJECTIVE
  To determine the effect of age and sex on the three-dimensional kinematics of the cervical spine.
  
  
  BACKGROUND
  Spine kinematics information has important implications for biomechanical model development, anthropomorphic test device development, injury prevention, surgical treatment, and safety equipment design. There is a paucity of data of this type available for children, and it is unknown whether cervical spine kinematics of the pediatric population is different than that of adults. The helical axis of motion (HAM) of the spine provides unique information about the quantity and quality (coupling etc.) of the measured motion.
  
  
  METHODS
  Ninety subjects were recruited and divided into 6 groups based on sex and age (young children aged 4-10 years, older children aged 11-17 years, adults aged 25+ years). Subjects actively moved their head in axial rotation, lateral bending, and flexion/extension. An optoelectronic motion analysis system recorded the position of infrared markers placed on the first thoracic vertebrae (T1) and on tight-fitting headgear worn by the subjects. HAM parameters were calculated for the head motion with respect to T1.
  
  
  RESULTS
  HAM location in axial rotation and flexion/extension was more anterior in young females compared to adult females. Young females had a more anterior HAM location in flexion/extension compared to young males, indicating an effect of sex. For females, the HAM locations of adults were superior to those of children in flexion/extension and lateral bending whereas in males the HAM locations of adults were inferior to those of children. Age-related differences in HAM orientation were also observed in axial rotation and lateral bending. CONCLUSION.: Cervical spine kinematics vary with age and sex. The variation in spine mechanics based on age and sex found in the present study may indicate general trends that would grow stronger in even younger children (age <4 years).
authors.affiliation: Injury Biomechanics Laboratory, Division of Orthopaedic Engineering Research Department of Mechanical Engineering, ICORD University of British Columbia, Vancouver, BC, USA.
authors.forename: Laura L
authors.initials: LL
authors.lastname: Greaves
authors.forename: Carolyn
authors.initials: C
authors.lastname: Van Toen
authors.forename: Angela
authors.initials: A
authors.lastname: Melnyk
authors.forename: Lynn
authors.initials: L
authors.lastname: Koenig
authors.forename: Qingan
authors.initials: Q
authors.lastname: Zhu
authors.forename: Stephen
authors.initials: S
authors.lastname: Tredwell
authors.forename: Kishore
authors.initials: K
authors.lastname: Mulpuri
authors.forename: Peter A
authors.initials: PA
authors.lastname: Cripton
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018583:Pliability; D016059:Range of Motion, Articular; D012399:Rotation; D012737:Sex Factors