Article

Finite element models of augmented vertebral bodies require a
realistic modelling of the cement infiltrated region. Most methods published so
far used idealized cement shapes or oversimplified material models for the
augmented region. In this study, an improved, anatomy-specific, homogenized
finite element method was developed and validated to predict the apparent as well
as the local mechanical behavior of augmented vertebral bodies. METHODS:
Forty-nine human vertebral body sections were prepared by removing the cortical
endplates and scanned with high-resolution peripheral quantitative CT before and
after injection of a standard and a low-modulus bone cement. Forty-one specimens
were tested in compression to measure stiffness, strength and contact pressure
distributions between specimens and loading-plates. From the remaining eight,
fourteen cylindrical specimens were extracted from the augmented region and
tested in compression to obtain material properties. Anatomy-specific finite
element models were generated from the CT data. The models featured
element-specific, density-fabric-based material properties, damage accumulation,
real cement distributions and experimentally determined material properties for
the augmented region. Apparent stiffness and strength as well as contact pressure
distributions at the loading plates were compared between simulations and
experiments. FINDINGS: The finite element models were able to predict apparent
stiffness (R(2)>0.86) and apparent strength (R(2)>0.92) very well. Also, the
numerically obtained pressure distributions were in reasonable quantitative
(R(2)>0.48) and qualitative agreement with the experiments. INTERPRETATION: The
proposed finite element models have proven to be an accurate tool for studying
the apparent as well as the local mechanical behavior of augmented vertebral
bodies.
CI - Copyright (c) 2012 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS