ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

1. ABSTRACT
Simulation of the bone remodeling process of the scapula
C. Quental 1 , J. Folgado 2 , P. Fernandes 3 and J. Monteiro 4
Finite element bone remodeling simulations have been applied to several parts of the
human skeleton. Nevertheless, the shoulder joint is one of the less studied parts,
compared to hip and knee, and little work focus on the bone remodeling process of the
scapula. The aim of this work is to fit the bone remodeling model used to a threedimensional
model of an intact scapula as a first step towards the study of the
complications of the shoulder arthroplasty. The bone remodeling model is based on a
global optimization criterion that takes into account both the structural stiffness and the
metabolic cost of bone maintenance. The boundary conditions include full muscle and
joint loads taken from a multibody system of the upper limb based on the same subject
whose scapula is here analyzed. The bone remodeling simulations are evaluated by
quantitative and qualitative comparisons between the predicted and the specimen’s bone
density distribution. The results show that the bone remodeling used is able to
successfully replicate the actual bone density of the scapula.
2. INTRODUCTION
The shoulder arthroplasty has become an efficient treatment for primary and secondary
degenerative conditions of the shoulder joint [1]. However, as with other joint
replacements, it is associated with a multitude of complications that compromise the
long-term success of the procedure. Even though the cause of failure is multifactorial,
the loss of bone resulting from the bone adaptation to the implant is often highlighted as
an important mechanism [2, 3].
Based on the Wolff’s law, which states that bone is able to adapt its structure to better
support the applied loads, several mathematical models have been presented to study
and simulate this process. In general, these models assume bone to be a linear elastic
material whose density is a function of a local mechanical stimulus.
Despite some finite element models of the scapula having been developed, these have
mainly focused in the changes in stress following the shoulder arthroplasty. Even
though Sharma et al. [4] address the bone remodeling process, only two-dimensional
analyses of the scapula are performed. The current work focuses on the bone
remodeling process of an intact scapula as a first step towards the development of a
subject-specific bone remodeling simulation after a shoulder arthroplasty. Clearly,
before understanding the changes in bone after the implant is inserted, it is of major
importance to comprehend its behavior in healthy conditions. The bone remodeling
1
MEng, IDMEC, IST, Technical University of Lisbon, Av. Rovisco Pais 1, Lisbon, Portugal
2
Professor, IDMEC, IST, Technical University of Lisbon, Av. Rovisco Pais 1, Lisbon, Portugal
3
Professor, IDMEC, IST, Technical University of Lisbon, Av. Rovisco Pais 1, Lisbon, Portugal
4
Professor, Faculty of Medicine, University of Lisbon, Av. Prof. Egas Moniz – Hospital de Santa Maria,
Lisbon, Portugal