The bone diagnostic instrument III: testing mouse femora

Area of Science:

• Biomechanics
• Materials Science
• Orthopedics

Background:

• The bone diagnostic instrument (BDI) is a tool for testing human bone mechanical properties.
• Adapting the BDI for small animal models, like mice, is crucial for studying bone diseases and treatments.
• Previous studies highlight elastic modulus, hardness, and indentation distance increase (IDI) as key mechanical property indicators.

Purpose of the Study:

• To modify the BDI for accurate testing of mouse femora.
• To investigate the effects of short-term running on the mechanical properties of young versus mature mouse femora.
• To assess the impact of aging on mouse femur mechanical properties using the modified BDI.

Main Methods:

• Reduced effective instrument weight and designed new probe assemblies to minimize damage to small mouse bones.
• Developed new testing protocols with smaller testing forces and fabricated a jig for securing mouse femora.
• Measured elastic modulus, hardness, and indentation distance increase (IDI) in young and old mice, comparing exercised and control groups.

Main Results:

• Exercise in young mice significantly lowered IDI, suggesting improved post-yield mechanical competence.
• Aging led to a significant increase in IDI and decreases in elastic modulus and hardness in mouse femora.
• The modified BDI successfully obtained statistically significant results for both exercise and aging effects.

Conclusions:

• The adapted BDI is effective for analyzing mechanical properties of mouse femora.
• Exercise during bone development enhances mechanical competence in young mice.
• Aging significantly alters the mechanical properties of mouse femora, with implications for skeletal health studies.