Development and evaluation of a paediatric mid-thoracic spine finite element model

Abstract

The objective of this study is to develop and evaluate a finite element (FE) model of paediatric mid-thoracic spine. The FE model was developed from a 3D scan of a physical model of human vertebrae for 8-9 years old thoracic spine from T4T8. A geometrical reference from a human CAD model was used as a visual reference to develop a vertebral column. Intervertebral discs, bony endplates and cartilaginous endplates were then added to complete the FE model. The spinal ligaments were modelled as non-linear springs and link elements. The adult scale model of 141% from a paediatric model was used to validate the FE model as information of adult spine was available. The range of motions (ROM) of scaled up FE model were within the range of adult spine hence suggested that the FE model can be used as a guidance to compare with paediatric FE model. Two different boundaries conditions were applied to validate the paediatric FE model. The first condition was to observe the ‘geometrical effect’ and the second condition was to observe the ‘material effect’ on the FE model. A pure moment of ±7.5 Nm to represent adult loading was applied for all six DOFs; flexion, extension, lateral bending, and axial rotation to both models under all conditions. The results showed no significant effect for the first condition (geometrical effect) while there is a significant effect for the second condition (material effect) between adult and paediatric FE model. Although, the vertebral body had been simplified, the results showed that it did not significantly affected the ROM, taken into consideration that the FE model developed in this study was with detailed anatomical of a paediatric spine. The range between all 6 DOFs was significantly reduced in this study potentially due to the fact that cortical bone was considered. Hence, suggested that the FE model of paediatric thoracic spine developed in this study can be used for further investigation.