Hindawi Publishing Corporation
e Scientic World Journal
Volume , Article ID , pages
http://dx.doi.org/.//
Research Article
Theoretical Prediction of Ultrasound Elastography for
Detection of Early Osteoarthritis
Lan Wang,
1,2
Shigao Chen,
3
Kai-Nan An,
4
Hui-Lin Yang,
2
and Zong-Ping Luo
2
1
Orthopaedic Institute, e 1st Aliated Hospital Soochow University, 708 Renmin Road, Suzhou, Jiangsu 215007, China
2
Department of Orthopedics of the 1st Aliated Hospital Soochow University, 708 Renmin Road, Suzhou, Jiangsu 215007, China
3
Basic Ultrasound Research Laboratory, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine,
Rochester, MN 55905, USA
4
Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
Correspondence should be addressed to Lan Wang; anny@gmail.com and Zong-Ping Luo; zongping
luo@yahoo.com
Received August ; Accepted October
Academic Editors: F. Frauscher and J. Zheng
Copyright © Lan Wang et al. is is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Ultrasound elastography could be used as a new noninvasive technique for detecting early osteoarthritis. As the rst critical step,
this study theoretically predicted the excitation power and the measurement errors in detecting cartilage detect. A nite element
model was used to simulate wave propagation of elastography in the cartilage. e wave was produced by a force ,andthewave
speed wascalculated.enormalcartilagemodelwasusedtodenetherelationshipbetweenthewavespeedandelasticmodulus.
Various stiness values were simulated. =10N with a duration of . ms was required for having measurable deformation ( m)
at the distal site. e deformation had a signicant rise when the wave crossed the defect. e relationship between the wave speed
and elastic parameters was found as =1.57×(/(2×(1+)))
1/2
,wherewas the elastic modulus, was Poisson’s ratio, and
was the density. For the simulated defect with an elastic modulus of MPa which was slightly stier than the normal cartilage,
the measurement error was . MPa. e results suggested that, given the simulated conditions, this new technique could be used
to detect the defect in early osteoarthritis.
1. Introduction
e early diagnosis is a critical component in the treat-
ment and prevention of osteoarthritis (OA) [–]. Currently,
research of early OA detection focuses largely on mea-
suring structural changes using techniques of radiography
[], scintigraphy [], dual-energy X-ray absorptiometry [],
arthroscopy [], and magnetic resonance imaging (MRI) [],
or on using biomarkers through biological specicity [, ].
However, studies showed that the incubation period of OA
aer cartilage injuries might be up to – years, and only –
% patients had trauma symptoms and movement disorder,
suggesting that early symptomatic and structural changes
were minimal []. e limited structural changes pose chal-
lenges in the structural-based diagnostic methods. Mean-
while, biomarker techniques also face challenges from uncer-
tainty in locking one or several markers from a considerable
number of inammatory cytokines for the early defect [].
As a noninvasive method of quantifying mechanical
properties of so tissues, elastography has been successfully
used in detecting lesions and pathological changes of various
tissues or organs, including skeletal muscle, cardiac muscle,
liver, prostate, breast, and thyroid [–]. By using either
ultrasound or MRI, elastography detected the propagation of
shear wave passing through the tested areas and calculated
elastic modulus changes in the tested area from the shear
wave propagation speed [–]. Several theoretical models
were proposed for determining and calculating the elastic
modulus changes [–].
In contrast to limited macrostructural changes in early
cartilage degeneration, early component changes are substan-
tial [–]. e normal cartilage consists of more than %
type II collagen, while degeneration causes signicant reduc-
tion of type II collagen and increase of type I collagen.
Mechanically,typeIcollagencanbeuptotimesstierthan