Material and compositional properties of selectively demineralized cortical bone

Area of Science:

• Biomaterials Science
• Orthopedic Research
• Materials Science

Background:

• Cortical bone exhibits a complex hierarchical structure.
• Understanding the mechanical properties of bone at different structural levels is crucial for diagnosing and treating bone diseases.
• Selective demineralization is a key technique for probing bone's composite nature.

Purpose of the Study:

• To investigate the effects of buffered ethylenediamine-tetraacetic acid (EDTA) on the mineral content and mechanical behavior of cortical bone.
• To analyze the hierarchical structural changes induced by EDTA treatment.
• To differentiate the mechanical properties of mineralized and demineralized bone components.

Main Methods:

• Timed immersion of cortical bone samples in buffered EDTA.
• Optical microscopy and histological analysis for structural characterization.
• Three-point flexure testing for mechanical evaluation of intact and demineralized samples.
• Microhardness testing, scanning acoustic microscopy, and wavelength dispersive analysis for site-specific property determination.

Main Results:

• EDTA treatment resulted in a heterogeneous structure with a mineralized core and a demineralized collagenous layer.
• Intact specimens showed reduced brittleness with increased EDTA immersion time.
• Core specimens exhibited decreased elastic flexural properties.
• Mineralization and site-specific properties of cores were unaffected, but mineralized volume fraction decreased due to vascular channel widening.

Conclusions:

• Buffered EDTA treatment effectively creates distinct mineralized and demineralized regions within cortical bone.
• This method allows for the investigation of site-specific mechanical properties and localized heterogeneities.
• The technique facilitates the determination of material and physical properties of both intact and demineralized bone tissues in a single sample.