Biomedical Engineering Reference
In-Depth Information
2
Numerical Simulation of Bone Remodeling Process Considering
Interface Tissue Differentiation in Total Hip Replacements
Eduardo A. Fancello, Darlan Dallacosta, and Carlos R. M. Roesler
2.1
Introduction
An artificial joint is generally used to replace a natural one that does not function
properly because of degenerative diseases such as osteoarthritis, or because the
natural joint has to be replaced, for instance, in the process of removing a bone
tumor. The treatment of such problems aims at restoring the joint function and
relieving pain. In cases where it is not possible to apply conservative methods of
treatment, there arises the need for joint replacement with components that aim
to reestablish the functionality of the original joint. The technique used in the
functional recovery of the hip joint through the replacement of both sides of the
joint is called total hip arthroplasty (THA). This is a standard surgical procedure
employed in orthopedics.
During the surgery, the head of the femur is removed and replaced with a metal
femoral component inserted inside the medullary cavity of the bone (diaphysis -
Figure 2.1). The femoral component has a spherical proximal extremity, which
allows rotation on the surface of the acetabular component. This component, nor-
mally manufactured using polyethylene, covers the acetabular cavity and through a
proper fit with the femoral component allows the execution of the joint movements.
Bone is a live tissue capable of modifying its structure according to the mechanical
requirements imposed on it, which makes it different from any other material. This
adaptive behavior is known as
adaptive bone remodeling
and consists of deposition
and resorption of bone material over time, causing external geometric changes and
internal changes in the bone microstructure [1].
After the insertion of the femoral component, the equilibrium and the load
distribution in the femur are modified, initiating the remodeling and adaptation to
the new distribution of stresses resulting from the placement of the prosthesis. One
clinically reported consequence of this change is the loss of bone mass (resorption)
in the femur, which can lead to a fracture and/or reduce the quantity of bone mass
available for a future surgical revision.
In order to predict this mass exchange, different bone adaptation models have
been proposed in the literature. Pioneering studies postulated the existence of a
