Biomedical Engineering Reference
In-Depth Information
Table 5.2
Elastic properties, permeability and porosity of joint tissues (adapted, with permission,
from [
74
])
Poisson's
ratio
Permeability (m
4
/N
Elastic modulus (MPa)
s) Porosity (%)
∙
2.7
0.64
10
15
[
79
]
Hyaline
articular
cartilage
0.07-1.23 [
75
]
0.15-0.26
[
78
]
65-85% [
157
,
158
]
0.994
0.28 [
76
]
102 [
77
]
320 [
64
]
a
15,000-22,000
[
20
,
80
,
81
]
b
Articular
calcified
cartilage
1,150 [
82
]
a
Subchondral
bone
50-90% [
84
]
1,147 [
77
]
78-92% [
85
]
820-1,370 [
83
]
18,000 [
20
]
b
Cancellous
bone
4,590 [
82
]
4-12.8 [
86
]
19,800 [
6
]
<
5[
87
]
3.7
10
13
[
91
]
Cortical
bone
5,440 [
82
]
0.28 [
90
]
3.8
3.1
(Proximal);
9.3
5.7 (mid-
diaphysis);
51.3
7.7
(distal) [
92
]
11,800 [
88
]
20,000 [
89
]
b
0.2
10
15
[
93
]
Nucleus
pulposis
Aggregate compressive:
0.3 [
93
]
0.47 [
94
]
0.75 [
95
]
Tensile: 0.04 [
94
]
0.2
10
15
[
93
]
Annulus
fibrosis
Aggregate compressive:
0.56 [
93
]
1[
97
]
0.70 [
95
]
Tensile: 20 [
96
]
a
Data are collected from bulk beam bending experiments
b
Data are collected from nanoindentation of plastic-embedded sections
Bone remodeling on the underside of the ZCC securely anchors the hyaline
cartilage and ZCC to the underlying SCB via puzzle-like interlocks (Fig.
5.2
;
arrows) [
20
,
108
]. Remodeling, or resorption of the underside of ZCC by
osteoclasts and subsequent infilling of the newly vacant regions with bone by
osteoblasts, creates a tortuous, interdigitated interface (Fig.
5.2
). While this process
may lead to thinning of the hyaline cartilage, healthy joint tissues are observed to
maintain a consistent ZCC thickness [
110
]. This thickness is noted across species to
occupy ~6-8% of the total cartilage height [
104
,
111
,
112
] and may diminish with
aging and disease (e.g., osteoarthritis). However, evidence is lacking to demonstrate
that the process of ZCC thinning is normal in healthy, mature cartilage.
5.2.2.3 Subchondral Bone
The layer of relatively uniform, dense SCB plays a critical role in redistributing the
diverse stresses from the overlying soft cartilage or IVD and into the subchondral
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