Mechanical and morphological properties of trabecular bone samples obtained from third metacarpal bones of cadavers of horses with a bone fragility syndrome and horses unaffected by that syndrome.

The research investigated the mechanical and morphological properties of trabecular bone samples obtained from horses with and without bone fragility syndrome (BFS), revealing that horses with BFS exhibit differences in bone structure and strength.

Methodology

The team studied cylindrical trabecular bone samples taken from the distal aspects of the third metacarpal bones of cadaveric horses. The sample included 39 horses, with 19 showing signs of BFS and the remaining 20 serving as healthy controls. The techniques applied in this study included:

• Imaging via micro-CT to determine various parameters such as bone volume fraction; apparent and average mineralized bone densities; and trabecular number, thickness, and separation.
• Compression tests to assess the apparent elastic modulus and stresses, strains, and strain energy densities at yield, ultimate, and failure loads.

Findings

The research found notable differences between the bone samples of horses with BFS and the controls:

• BFS bone samples exhibited a 25% lower bone volume fraction and 28% lower apparent density, indicating that they had less bone material relative to the total volume of bone and a reduced mass per unit volume
• There were fewer trabeculae (the rod-like structures in spongy bone tissue), as shown by an 18% lower trabecular number, along with a reduced thickness of these structures and increased separation between them
• BFS bone samples showed a 22% lower apparent modulus, indicating a reduced material stiffness
• They displayed 32-33% lower stresses, suggesting lower resistance to load
• Strains (the deformation responses to stress) and strain energy densities (energy absorbed per unit volume prior to fracture) at yield, ultimate, and failure loads were 10-18% and 41-52% lower respectively in the BFS samples, suggesting compromised bone performance.

Notably, there were no detected differences between groups regarding mean mineral density and trabecular anisotropy (differences in material properties along different directions within the bone).

Conclusion

From these findings, the researchers concluded that horses with BFS experience osteopenia (lower bone density) and compromised trabecular bone function, which aligns with symptoms of bone deformation and pathological fractures common in affected horses. Their results imply that the effects of BFS may be systemic, affecting various bones not immediately presenting clinical symptoms, and leading to alterations in both morphological and mechanical properties of the bones.