Finite Element Poroelastic Analysis of Vertebral Endplate Changes Effect on Disc Height

INTRODUCTION: The intervertebral disc undergoes extensive age related degenerative changes. The mechanism for disc degeneration is multifactorial and many studies have proposed that decreased nutrition to the disc is a major contributor to the degeneration process. Because the adult disc nucleus is avascular, the only sources of nutrition are diffusion from the blood vessels of the annulus and vertebral endplate and convective flow. During aging, permeability and porosity of the cartilage endplate decrease, reducing the ability for fluid to transport nutrients into the disc. Recent studies have reported endplate permeability spanning three orders of magnitude during the aging process. With this large range of reported permeabilities, it is especially important to understand how endplate permeability affects the convective flow of nutrients in and out of the disc. To accomplish this, theoretical and mathematical models have been utilized in limited capacity. The purpose of this study was to investigate the effect of changing the permeability and porosity of the cartilage endplate to simulate aging using the finite element poroelastic method.