Biomedical Engineering Reference
In-Depth Information
Figure 3.1.
Imagesshowingthestructureofbones.(a)Opticalmicrograph
oftransverse crosssectionshowingthemicrostructureofcompactlamellar
bone—humanfemora;(b)SEMimageofaspecimentakenfromthefemoral
head,showingalow-density,open-cell,rodlikestructureofcancellousbone;
(c) SEM image of a specimen from the femoral head, showing a higher-
density, roughly prismatic cell structure of cancellous bone; (d) SEM image
of a specimen from the femoral condoyle, of intermediate density, showing
a stress-oriented, parallel-plate structure of cancellous bone with rods nor-
mal to the plates.
10
,
11
interconnectingsystemsarefilledwithbodyfluids,andtheirvolume
canbeas highas 19%.
12
Thecellularstructure ofcancellousboneis
shown in Figs. 3.1b, 3.1c, and 3.1d.
11
Cancellous bones are made up of an interconnected network of
rods or plates. A network of rods produces low-density, open cells,
whereas one of the plates gives high-density, virtually closed cells.
Inpractice,therelativedensityofcancellousbonesvariesfrom0.05
to0.7,andtechnicallyspeaking,boneswitharelativedensityofless
than 0.7 are classified ascancellous.
11
Human bones are mainly composed of collagen (20 wt. %),
hydroxyapatite mineral (69 wt. %), and water (9 wt. %).
12
Other
organic materials, such as proteins, polysaccharides, and lipids, are
also present in small quantities.
13
The diameter of the collagen
microfibers varies from 100 to 2,000 nm, and these collagen fibers
Search WWH ::
Custom Search