Development, validation, and application of ligamentous cervical spinal segment C6-C7 of a six-year-old child and an adult

Abstract

Background and objectiveThe cervical spine is one of the primary regions that is easily injured in traffic accidents. Although adult cervical spine finite element models have been widely adopted to investigate the cervical injury, few efforts have been made with respect to the development and application of FE models of the pediatric cervical spine, especially that of a six-year-old child. The objective of this study is to develop and validate high quality cervical spinal segment C6-C7 FE models of a six-year-old child and an adult, and to further investigate the differences of C6-C7 between the child and adult under different loading conditions. MethodsThe cervical spinal segment C6-C7 FE models were developed by a structured multiblock method, and were verified under flexion, extension, axial rotation, and lateral bending conditions. The validated models were used to investigate the differences of C6-C7 between the child and adult under different loading conditions. ResultsThe global angular displacement of C6-C7, the ligament elongation ratio, and the maximum effective strain of annulus fibrosus of the child were obviously larger than those of the adult under the same loading conditions. Regarding the loading forms, the flexion angular displacement of C6-C7 of the child was obviously larger than those of the extension and lateral bending, while for the adult cervical segment C6-C7, no obvious differences existed. The elongation ratio of different ligaments was highly dependent on the types of loadings. The maximum effective strain of annulus fibrosus under flexion, extension and lateral bending loads occurred at the compressive region of the front, rear, and one compressive lateral side, in which the annulus fibrosus was more susceptible to injury under the lateral bending condition, compared with those of the flexion and extension conditions. ConclusionsBoth the developed child and adult cervical spinal segment C6-C7 FE models exhibited high biofidelity. The responses (angular displacement, the ligament elongation ratio, and the maximum effective strain of annulus fibrosus) of the child and adult are dependent on the loading types, and the responses of the child were obviously larger than those of the adult under the same loading conditions.