Biomedical Engineering Reference
In-Depth Information
(a)
(b)
Knee OA in Men
Knee OA in Women
40
40
30
30
Obese
20
20
Obese
10
10
Non-obese
Non-obese
0
0
20
30
40
50
60
70
80
20
30
40
50
60
70
80
Age
Age
Fig. 1 Age-dependent prevalence estimates of diagnosed symptomatic knee osteoarthritis (OA)
in non-obese and obese a men and b women. Obesity accelerates the development of knee OA
(horizontal arrow) and increases the prevalence of OA (vertical arrow) in both men and women.
Graphs are based on US national health information survey estimates as determined by [
10
]
significantly harms lifestyle factors related to psychological well-being, indepen-
dence, and participation in daily activities. The financial and functional burden of
OA, as assessed by the need for total knee joint replacement surgeries, is expected
to grow between 2005-2030 by nearly 700 % [
13
]. Thus, there is a critical need
for developing effective prevention and treatment strategies. There have been
considerable advances in the development of new methods for detecting OA
pathology, identifying risk factors and susceptible populations, and developing
therapies for managing pain and improving function. However, there are no dis-
ease-modifying OA drugs or treatments available for clinical use.
The goal of this chapter is to discuss the potential biomechanical links between
obesity and OA in the context of aging. Although obesity was once considered a risk
factor for knee OA primarily through increased joint loading and excessive 'wear
and tear', the effect of obesity on joint loading is much more complex. Obesity alters
joint loading frequency, magnitude, and duration both positively and negatively
depending on the anatomical location and time-scale of analysis [
14
-
18
]. This
chapter will review these changes along with recent advances in our understanding
of how obesity and aging up-regulate cellular stressors and impair cellular stress-
defense pathways, focusing on articular cartilage. The role of mechanosensitive
mediators will be discussed in this framework.
2 Obesity and Joint Loading
Obesity significantly alters the pattern of loading in weight-bearing joints, although
the changes do not necessarily result in an increase in the total magnitude of joint
stresses and moments [
16
,
19
,
20
]. Obesity is generally associated with slower
self-selected walking speeds, shorter step lengths, and wider step widths [
18
].
Relatively small reductions in walking speed by obese adults (from 1.4 m/s to
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