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

THE EFFECT OF HIGH TIBIAL OSTEOTOMY ON STRESS
DISTRIBUTION IN THE TIBIO-FEMORAL JOINT: A FINITE
ELEMENT STUDY
F. Reisse 1 , H.J. Hillstrom 1,2 , R. Walker 1 , D. Carpanen 1 , C. Imhauser 2 , Z. Dewan 2 ,
M. Koff 2 , J.K. Dowell 3 1 ,2
, R. Mootanah
1. ABSTRACT
Osteoarthritis (OA) is a degenerative disease of the joints and a leading cause of
disability. Lower limb malalignment, which results in increased peak compressive
pressure in the knee joint, is a primary factor for knee OA. High tibial osteotomy (HTO)
is a realignment surgery to restore knee function and minimise excessive loading across
the knee articulating surfaces. However, the link between malalignment and stress in the
knee is not well understood. Therefore, the aim of this study is to develop a threedimensional
(3D) finite element (FE) model to predict the effects of realignment
techniques on the knee joint contact stresses for improved surgical outcomes. High
resolution magnetic resonance imaging scans of a cadaveric knee were acquired to
create 3D models of the knee joint. FE packages were used to determine stress
distributions in the medial and lateral compartments of the knee joint. This FE model
was validated by a parallel in-vitro cadaveric study carried out at the Hospital for
Special Surgery. The peak compressive stress was 60% higher in the malaligned knee
than in the well-aligned knee. Our results highlight the importance of understanding the
effects of HTO on the knee joint contact stresses to delay OA progression.
2. INTRODUCTION
Osteoarthritis (OA) is a debilitating degenerative disease involving all the tissues
within the diarthrodial joint, which often leads to significant pain, loss of joint function
and is the leading cause of physical disability in the elderly. Radiographic studies of
US and European populations show that 14.1% of men and 22.8% of women over 45
years of age show symptoms of knee OA (Valkenburg 1980). The World Health
Organisation reports that OA accounts for 1% of total deaths in 2002 and is projected
to be in the ten leading causes of disability adjusted life years (2.5%) in high-income
countries in 2015 (Mathers, Loncar 2005). The reported total cost of OA on the UK
economy is estimated at 1% of annual gross national product and $185.5 billion
annually in the United States (Mathers, Loncar 2005). There is no known cure for OA
and current therapeutic approaches cannot arrest disease progression.
Lower extremity malalignment and corresponding overloading of specific regions
within the joint have been associated with knee OA and is considered to be at least a
component of disease onset and progression (Sharma et al. 2001, Sharma et al. 2010).
Coventry explained how such a slight malalignment initiates a ‘vicious circle’, in
which the resulting excessive stresses to localised cartilage, subchondral bone and the
surrounding soft tissues produces more laxity and joint deformity, thereby repeating
the cyclic degradation mechanism (Coventry 1965). This dramatic increase in
compressive load corresponds to a fourfold increase in the odds of medial tibiofemoral
OA worsening over 18 months (Sharma et al. 2001). The most common
1
Medical Engineering Research Group, Anglia Ruskin University, Chelmsford, UK
2
Hospital for Special Surgery, New York, USA
3
Mid-Essex Hopital Services NHS Trust, Broomfield Hospital, Essex, UK