Comparison between bone density and bone strength in glucocorticoid-treated aged ewes

Area of Science:

• Veterinary medicine
• Orthopedics
• Bone biology

Background:

• Glucocorticoids can induce bone fragility.
• Assessing bone fragility is crucial in short-term studies.
• Dual-energy X-ray absorptiometry (DXA) is a common bone densitometry technique.

Purpose of the Study:

• To evaluate DXA as an indicator of bone fragility in glucocorticoid-treated ewes.
• To correlate DXA measurements with biomechanical parameters in ewe bones.

Main Methods:

• Ex-vivo DXA measurements on HOLOGIC QDR-1000+ device.
• Three-point bending tests on femurs.
• Compression tests on cancellous bone cylinders from lumbar vertebrae (L4-L6).
• Study included 27 aged ewes (16 treated with methylprednisolone, 11 controls).

Main Results:

• Significant correlations found between femoral bone mineral density and bending stiffness (r=0.65) and ultimate bending strength (r=0.64).
• No significant correlations between vertebral bone mineral density and biomechanical parameters.
• Vertebral DXA results were influenced by large posterior arches composed of cortical bone.

Conclusions:

• DXA provides a reliable assessment of bone strength in ewe femurs.
• DXA results for ewe vertebrae require careful interpretation due to anatomical variations.
• Findings are relevant for understanding bone fragility in ovine models and potential limitations in DXA application in this species.