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

1. ABSTRACT
MODELING OF ARTICULAR CARTILAGE GROWTH
Krishnagoud Manda 1 and Anders Eriksson 2
Articular resurfacing metal implants have recently been proved as a better alternative to
the traditional biological treatment methods when tested in animal models, treating full
thickness localized articular cartilage defects in the knee joint. From the animal models,
we have observed that the cartilage was seen growing around the implant postoperative.
The long term objective of the present work is to develop an analytical model of the
articular cartilage growth around the metal implant, filling cartilage defects, by
including more realistic knee condyle geometry and dynamic loading situations. A
simplified 2D axisymmetric representation of the human femoral articular cartilage was
developed. The cartilage was modeled as a biphasic fluid saturated porous medium and
a spatially varying load was assumed on to the cartilage surface to represent the realistic
loading situation in the joint. An algorithm was developed for growth of articular
cartilage by considering two individually growing constituents (proteoglycans and
collagens) in the extracellular solid matrix of cartilage. From this model, we want to
investigate the effect of mechanical factors and role of metal implant on the growth of
cartilage around the localized metal implant.
2. INTRODUCTION
Articular cartilage (AC) is a hydrated connective soft tissue that provides low friction,
wear resistant, load-bearing surface in the diarthrodial joints. The degeneration or wear
of the cartilage is a huge problem that affects millions of people every year. Traditional
biological methods to treat the cartilage defects have many limitations. Alternatively,
localized resurfacing metal implants, replacing degenerated portions of the cartilage, are
used to restore the healthy environment by reproducing the articulating surfaces in the
joints, and have been showing good clinical outcomes (Custers et al., 2007, Manda et
al., 2011a, 2011b). It has been shown that the local biomechanical factors directly affect
the cartilage growth at the defect site (Duda et al., 2005, Klisch et al., 2008, Darling et
al., 2003). From preliminary sheep experiments (Episurf Medical AB, Stockholm), we
observed that the cartilage was growing around the implant, where the mechanical
stresses, strains or fluid velocities are high (Manda et al., 2011a, 2011b). We believe
that the healthy mechanical environment may have stimulated the growth of cartilage
around the implant. This is a very complex problem and is of tremendous importance. In
order to investigate this, there is need for developing an analytical articular cartilage
growth model (ACGM) with the metal implant filling degenerated portion of the
cartilage.
1
Doctoral student, KTH Mechanics, Royal Institute of Technology, 10044 Stockholm, Sweden.
Email:krishnagoud@mech.kth.se
2
Professor, KTH Mechanics, Royal Institute of Technology, 10044 Stockholm, Sweden.