title: Tensile failure properties of the perinatal, neonatal, and pediatric cadaveric cervical spine.
abstract: METHODS
  Biomechanical tensile testing of perinatal, neonatal, and pediatric cadaveric cervical spines to failure.
  
  
  OBJECTIVE
  To assess the tensile failure properties of the cervical spine from birth to adulthood.
  
  
  BACKGROUND
  Pediatric cervical spine biomechanical studies have been few due to the limited availability of pediatric cadavers. Therefore, scaled data based on human adult and juvenile animal studies have been used to augment the limited pediatric cadaver data. Despite these efforts, substantial uncertainty remains in our understanding of pediatric cervical spine biomechanics.
  
  
  METHODS
  A total of 24 cadaveric osteoligamentous head-neck complexes, 20 weeks gestation to 18 years, were sectioned into segments (occiput-C2 [O-C2], C4-C5, and C6-C7) and tested in tension to determine axial stiffness, displacement at failure, and load-to-failure.
  
  
  RESULTS
  Tensile stiffness-to-failure (N/mm) increased by age (O-C2: 23-fold, neonate: 22 ± 7, 18 yr: 504; C4-C5: 7-fold, neonate: 71 ± 14, 18 yr: 509; C6-C7: 7-fold, neonate: 64 ± 17, 18 yr: 456). Load-to-failure (N) increased by age (O-C2: 13-fold, neonate: 228 ± 40, 18 yr: 2888; C4-C5: 9-fold, neonate: 207 ± 63, 18 yr: 1831; C6-C7: 10-fold, neonate: 174 ± 41, 18 yr: 1720). Normalized displacement at failure (mm/mm) decreased by age (O-C2: 6-fold, neonate: 0.34 ± 0.076, 18 yr: 0.059; C4-C5: 3-fold, neonate: 0.092 ± 0.015, 18 yr: 0.035; C6-C7: 2-fold, neonate: 0.088 ± 0.019, 18 yr: 0.037).
  
  
  CONCLUSIONS
  Cervical spine tensile stiffness-to-failure and load-to-failure increased nonlinearly, whereas normalized displacement at failure decreased nonlinearly, from birth to adulthood. Pronounced ligamentous laxity observed at younger ages in the O-C2 segment quantitatively supports the prevalence of spinal cord injury without radiographic abnormality in the pediatric population. This study provides important and previously unavailable data for validating pediatric cervical spine models, for evaluating current scaling techniques and animal surrogate models, and for the development of more biofidelic pediatric crash test dummies.
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, NC 27708-0281, USA. jfl1@duke.edu
authors.forename: Jason F
authors.initials: JF
authors.lastname: Luck
authors.forename: Roger W
authors.initials: RW
authors.lastname: Nightingale
authors.forename: Yin
authors.initials: Y
authors.lastname: Song
authors.forename: Jason R
authors.initials: JR
authors.lastname: Kait
authors.forename: Andre M
authors.initials: AM
authors.lastname: Loyd
authors.forename: Barry S
authors.initials: BS
authors.lastname: Myers
authors.forename: Cameron R Dale
authors.initials: CR
authors.lastname: Bass
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001696:Biomechanical Phenomena / Q000502:physiology*; D002574:Cervical Vertebrae / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005333:Fetus / Q000502:physiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D016059:Range of Motion, Articular / Q000502:physiology; D013718:Tensile Strength / Q000502:physiology*