The Effect of Fluid-structure Interaction in Finite-element Analysis of Skull Bone on Relieving Cerebral Injury in a Porcine Model

Introduction: Bone tissue is non-homogeneous, porous and anisotropic. Compact bone contains a hierarchical structure of interconnected channels, and cancellous bone is the spongy construction with the biphasic of viscous fluid and elastic solid materials. Fluid flow in and out has also been suggested to play a role in the mechanosensory system of bone.

Objective: To investigate the influence of interstitial fluid on the microstructural skeleton of compact and cancellous skull bone by finite-element simulation with the changing intracranial pressure.

Methods: Scanning Electron Microscopy (SEM) was adopted to determine the microstructural parameters of fresh porcine skull bone, which used to create a microscopic model of skull bone subjected to a fluid-solid interaction analysis.

Results: Simulations were performed with and without Fluid-Structure Interaction (FSI). The strain and stress rate of the skull-bone microstructure increased with the tissue fluid by 38.5% and 21.5%, respectively. Especially for compact skull bones, the microstructure strain and stress rate were greater by 1.42 to 2.49 times and 1.39 to 2.42 times, respectively, when the tissue fluid flow was included.

Conclusion: In conclusion, the deformation of skull bone tissue is enhanced with the increase of interstitial fluid under the same pressure, which would absorb more impact on cerebral injury caused by intracranial hypertension. Conversely, the load-bearing of bone tissue is enhanced with the increase of solid bone skeleton under the same pressure. During the analysis on mechanical properties of skull bone with FSI, the compact and cancellous bones are not regarded as a single phase solid structure and the porous material characteristics must be considered.