Biomedical Engineering Reference
In-Depth Information
results of infrared spectroscopy, inelastic neutron scattering, and nuclear magnetic
resonance spectroscopy, cf. [82-86].
1.2.5
Structure of the Bone
The structure of bone is nonhomogeneous. The bone tissue contains two main
types of tissues: dense cortical bone and porous trabecular bone, cf. Figure 1.10.
The tissues have similar biological activity; the difference is in geometry - in the
arrangement of the microstructure. The outer layer of bone tissue is hard and is
called the
compact bone
(known also as
cortical
or
dense bone
). This part of the tissue
gives bones their smooth, white, and solid appearance, and accounts for 80% of
the total bone mass of an adult skeleton. Compact bone tissue is called so because
of its very small gaps and spaces in comparison with the inner trabecular bone.
Trabecular (cancellous or spongy) bone accounts for approximately 15% of the
total bone mass. The vertebrae and pelvic bones contain relatively high amounts of
trabecular tissue and are common sites of osteoporotic fractures, whereas the long
bones (e.g., femoral neck) contain a relatively high amount of cortical bone.
The metaphysis is the wider portion of a long bone adjacent to the epiphyseal
plate, cf. Figure 1.10b. It is this part of the bone that grows during childhood; as
Appears at the
end of the first year;
joins body at
about 18th year
Appears at 13th -14th
year; joins body at
about 18th year
Appears at
4th year;
joins body
at about
18th year
Articular cartilage
4
Ephiphyseal line
Epiphysis
Metaphysis
Spongy bone
Medullary cavity
Nutrient foramen
1
Body
7th
year
Endosteum
Periosteum
Diaphysis
Articular cartilage
Metaphysis
Appears at the
ninth month
of fetal life
Joins body at
20th year
Epiphysis
2
(a)
Lower extremity
(b)
Figure 1.10
Human femur. (a) Development and
(b) anatomical structure. It is noted that the metaphysis is
essential for the growth of long bone. After [63, 74-76].
