Modeling fluid flow in bone mechanoadaptation

Abstract

It is well known that bone adapts to load, but the exact mechanical stimuli that trigger bone remodeling are poorly understood. Many in vivo loading studies use strain-matched loading to examine bone cell response, tissue remodeling and mechanoadaptation, and other mechanobiological responses of bone. However, strain-matched loading fails to account for a time-dependent stimulus, such as interstitial fluid flow. Poroelastic finite element modeling of murine uniaxial tibial loading allows that fluid flow to be investigated as a signal for bone remodeling. Using this technique to inform in vivo experimental design is a critical step in isolating the effects of various mechanical stimuli in bone mechanoadaptation. Poroelastic anatomical models of the murine tibia were generated and used to simulate different loading parameters to contribute to in vivo experimental design. It is known that mechanoadaptation occurs for loading profiles with a high strain magnitude and high maximum interstitial fluid velocity, while loads with low strains and low maximum fluid velocities fail to induce adaptation. The poroelastic model informed experimental decisions on pre-load, peak load, loading rate, and frequency to design load profiles for studies that could isolate the roles of strain and maximum fluid velocity on the mechanoadaptive response of bone. In vivo observations can then be compared to finite element analysis results to investigate the correlation between predicted regions of high strain or fluid velocity and locations of bone adaptation. --Author's abstract