Diaphyseal structural properties of equine long bones.

This study evaluates the structural properties of different segments of equine long bones under various conditions such as axial compression, torsion, and four-point bending. The stiffness values for each bone were determined and compared based on the position of the load applied.

Objective and Methodology

• The research aimed to evaluate the single-cycle structural properties of various segments of equine long bones such as the humerus, radius, third metacarpal bone, femur, tibia, and third metatarsal bone under pressures like axial compression, torsion, and four-point bending.
• The load was applied to either the caudal or lateral surface of a diaphyseal segment, and the stiffness values were calculated from load-deformation curves created for each bone and test mode.

Findings

• During compressive tests, the stiffness ranged from 2,690 N/mm for the humerus to 5,670 N/mm for the femur, indicating that different bones have different ranges of stiffness when subjected to compression.
• In torsional tests, stiffness ranged from 558 N.m/rad for the third metacarpal bone to 2,080 N.m/rad for the femur. This suggests that the femur is stiffer in torsion compared to the third metacarpal bone.
• In nondestructive 4-point bending tests, stiffness ranged from 3,540 N.m/rad for the radius to 11,500 N.m/rad for the third metatarsal bone.
• It was found in some bones, like the humerus, radius, and tibia, the stiffness was not significantly impacted by whether the central load was applied to the caudal or lateral surface.
• Contrarily, for the third metacarpal and metatarsal bones, applying the central load to the lateral surface resulted in significantly greater stiffness than if it was applied to the palmar or plantar surface. For the femur, it was significantly stiffer when the central load was applied to the caudal surface instead of the lateral surface.
• The load-deformation curves resulting from four-point bending to failure displayed a bilinear pattern in some instances. This consisted of a linear region at lower bending moments that corresponded to stiffness values from the non-destructive tests and a second linear region at higher bending moments with greater stiffness values.

Conclusion

• The findings of the study contribute to our understanding of the structural properties of equine long bones. Such knowledge could be valuable in understanding bone biomechanics in horses and potentially improving treatments for equine bone injuries.