Biomedical Engineering Reference
In-Depth Information
9
Experiment
s
9.1 Introduction
In the previous chapters, theoretical and numerical models for bone
remodeling were described. Experimental approaches are also important
in bone performance analysis. In this chapter some recent developments in
experiments with bone materials are reported.
Many experimental studies have been carried out over the past decades
on the mechanical behavior of bone tissues under various external loadings
[1-4]. These studies have focused on sample preparation, effects of micro-
structure on bone properties, and piezoelectric properties of bone materials.
Yin et al. [5] indicated that the ability to remove soft tissue from skeletons
effectively without compromising surface morphology or bone integrity is
paramount. Their experiments showed that there was no significant differ-
ence among the microstructures in terms of porosity and microhardness
values of bones when they were cleaned in water, trypsin, and detergent
macerations. In general, the commonly used methods for cleaning bones can
be categorized as manual cleaning, enzymatic maceration, cooking, water
maceration, and insect consumption [6]. Enzymatic maceration is consid-
ered the most convenient method, employing digestive enzymes such as
trypsin, prepsin, or papain [7,8]. To enhance cleaning capability, cheap and
easily available laundry detergents are also introduced at room temperature
or elevated temperatures [6]. Studies have shown that cleaning using pow-
dered detergent allowed the largest segments of DNA to be amplified. It may
have less degradative effect on bone DNA than boiling bone and bleaching
processes [9,10].
Regarding the biomechanical testing of bone tissue, work to date has
mainly focused on macroscopic fracture based on structural characteriza-
tion [11] and micromechanical behaviors [3]. Studies [12,13] have quantita-
tively addressed fracture behaviors associated with the microstructure of
bone tissues. Relationships between fatigue or cyclic loading and microcrack
formation have been reported [11,14]. On the other hand, indentation tests
represent a promising direction in characterizing the quality of bone repair
as a function of location [11,15-17]. These tests have been used to measure
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