Mitigating both neck and head injuries in the pediatric population relies heavily
on improving our understanding of the underlying biomechanics of the pediatric
cervical spine. The tensile response for individual motion segments and the
whole cervical spine (WCS) has been reported, but there is no data
characterizing the intersegmental kinematics of pediatric WCS under axial
loading conditions. The structural response of motion segments and WCS provide
valuable data for the design and validation of biofidelic physical and
computational models for the pediatric population. However, the use of motion
segment data to construct WCS response or the use of WCS axial response to
accurately characterize intersegmental response may present limitations to
accurately modeling the pediatric cervical spine response. In this secondary
analysis of the work of Luck et al. (2008, 2013), the fixed-fixed, low
load, quasi-static tensile response of the WCS and individual motion segments
(O-C2, C4-C5, and C6-C7) of a six-year-old postmortem human surrogate (PMHS) was
investigated to quantify and compare the intersegmental kinematics under both
conditions. In the whole spine, O-C2, C3-C4, C6-C7, and C7-T1 exhibited a
tensile response, C2-C3 and C5-C6 exhibited a compressive response, and C4-C5
did not exhibit an appreciable response in the axial loading direction.
Furthermore, when compared to the tensile behavior of the individual motion
segment load-controlled tests, C6-C7 exhibited reduced axial displacement and an
increased stiffness at higher loads (≥13.5 N), suggesting the recruitment of
more superficial ligamentous layers that span multiple vertebrae in the whole
spine. Regarding vertical displacement and rotation, O-C2 exhibited the largest
amount of rotation of 5.57 degrees in flexion and all segments exhibited some
amount of anterior–posterior (AP) displacement. The intersegmental kinematics
provide biomechanical response data that may support both physical and
computational surrogate design and validation as well as data for comparison to
isolated FSU testing conditions.
