Bone remodeling regulation under unloading conditions: numerical investigations

Area of Science:

• Biomechanics
• Computational Biology
• Bone Physiology

Background:

• Unloading conditions, such as microgravity, significantly impact bone morphology and density.
• Understanding the mechanisms of bone loss is crucial for developing countermeasures.
• Existing models may not fully capture the complex regulatory processes of bone remodeling under unloading.

Purpose of the Study:

• To evaluate if a simple regulatory bone remodeling model can predict the effects of unloading on trabecular bone morphology.
• To compare finite element simulation results with experimental data from a rat tail-suspension model.

Main Methods:

• Rat tail-suspension model to simulate microgravity unloading.
• Histomorphometric analysis of tibial cross-sections to assess bone density and osteocyte distribution.
• Finite element simulations driven by a remodeling law incorporating osteocyte distribution and bone density changes.

Main Results:

• The computational model demonstrated good agreement with experimental data, especially in the initial phase of bone mass loss.
• Simulated bone density variations showed close correlation with experimental findings at days 7 and 13.
• A notable deviation was observed at day 23, but the model remains suitable for simulating unloading effects.

Conclusions:

• A simple regulatory bone remodeling model can effectively predict trabecular bone alterations under unloading conditions.
• The model's ability to incorporate osteocyte distribution aids in mechanoreception simulation.
• This approach provides a valuable tool for studying bone adaptation to unloading and spaceflight environments.