Cortical and trabecular bone adaptation to incremental load magnitudes using the mouse tibial axial compression...

Area of Science:

• Orthopedics and Sports Medicine
• Biomechanical Engineering
• Cellular and Molecular Biology

Background:

• The mouse tibial axial compression model allows simultaneous study of cortical and trabecular bone adaptation.
• This model often results in woven cortical bone and inconsistent trabecular bone adaptation.
• Optimizing loading parameters is crucial for studying bone adaptation.

Purpose of the Study:

• To investigate bone adaptation to varying load magnitudes using the mouse tibial axial compression model.
• To identify a specific load that induces simultaneous lamellar cortical and trabecular bone adaptation.
• To refine the mouse tibial axial compression model for future research.

Main Methods:

• Adult female C57BL/6 mice were subjected to axial tibial loading at 5N, 7N, or 9N for 4 weeks.
• In vivo peripheral quantitative computed tomography (pQCT) assessed longitudinal cortical bone changes.
• Ex vivo micro-CT and histomorphometry evaluated cortical and trabecular bone adaptation.

Main Results:

• A dose-dependent response was observed in cortical bone, with higher loads increasing lamellar bone adaptation.
• The 9N load group showed a 42% increase in estimated mechanical properties (polar moment of inertia) at the midshaft.
• Trabecular bone adaptation was only significant at 9N, with a 31% increase in bone volume fraction.
• A 9N load induced simultaneous lamellar cortical and trabecular bone adaptation.

Conclusions:

• A 9N load successfully induced simultaneous lamellar cortical and trabecular bone adaptation in the mouse tibia.
• This optimized loading parameter (9N) enhances the utility of the mouse tibial axial compression model.
• The findings provide a foundation for future studies on simultaneous bone adaptation within a single loaded element.