Radio-translucent 3-axis mechanical testing rig for the spine in micro-CT.

Area of Science:

• Biomedical Engineering
• Orthopedic Research
• Materials Science

Background:

• Studying bone microstructure under mechanical load is crucial for understanding spinal health and disease.
• Existing methods lack the capability to assess whole vertebrae microstructure during mechanical testing.

Purpose of the Study:

• To design and develop a 3-axis radio-translucent mechanical testing rig for spinal research.
• To integrate this rig with micro-CT scanning for simultaneous mechanical loading and imaging of vertebrae.

Main Methods:

• Development of a 3-axis radio-translucent mechanical testing rig.
• Integration with a Shimadzu micro-CT scanner.
• Mechanical testing of goat and porcine vertebrae under compression, flexion-extension, and lateral bending.
• Noncontact digital markers method for deformation analysis.
• Comparison with industrial-grade compression testing machines.
• Micro-CT scanning of vertebrae before and after loading to failure.

Main Results:

• The rig successfully applied pure moment loading in multiple deformation modes.
• Deformation ranges were comparable to previously documented results.
• Stepwise compression loading closely approximated continuous loading.
• High-resolution (32.80 µm isotropic) micro-CT images of loaded porcine vertebrae were obtained.
• Trabecular microarchitecture of a whole vertebra under compression failure (12.1% strain) was visualized for the first time.

Conclusions:

• The developed 3-axis testing rig is feasible for spinal research and testing.
• This apparatus enables unprecedented in-situ study of whole vertebrae microstructure under mechanical loading.
• The rig facilitates detailed analysis of bone mechanics and failure mechanisms in vertebrae.