On a Constitutive Material Model to Capture Time Dependent Behaviour of Cortical Bone

Artikel i vetenskaplig tidskrift, 2014

It is commonly known that cortical bone exhibits viscoelastic-viscoplastic behavior which affects
the biomechanical response when an implant is subjected to an external load. In addition, long
term effects such as creep, relaxation and remodeling affect the success of the implant over time.
Constitutive material models are commonly derived from data obtained in in vitro experiments.
However during function, remodeling of bone greatly affects the bone material over time. Hence it
is essential to include long term in vivo effects in a constitutive model of bone. This paper proposes
a constitutive material model for cortical bone incorporating viscoelasticity, viscoplasticity, creep
and remodeling to predict stress-strain at various strain rates as well as the behavior of bone over
time in vivo. The rheological model and its parameters explain the behavior of bone subjected to
longitudinal loading. By a proper set of model parameters, for a specific cortical bone, the present
model can be used for prediction of the behavior of this bone under specific loading conditions. In
addition simulation with the proposed model demonstrates excellent agreement to in vitro and in
vivo experimental results in the literature.