Trabecular microfracture precedes cortical shell failure in the rat caudal vertebra under cyclic overloading

Area of Science:

• Biomechanical Engineering
• Orthopedic Research
• Tissue Mechanics

Background:

• Microscopic tissue damage in human cancellous bone is linked to fragility and fractures.
• Animal models are needed to study microdamage and repair in cancellous bone.
• The relationship between applied loads and microdamage in animal models is unclear.

Purpose of the Study:

• To determine the relationship between cyclic compressive overloading and microdamage in isolated rat tail vertebrae.
• To establish if rat tail vertebrae can serve as a model for studying cancellous bone microdamage.

Main Methods:

• Rat caudal vertebrae (C7-C9) were subjected to cyclic compressive loading (0-260 N).
• Loading was controlled using custom software to target secondary and tertiary creep-fatigue phases.
• Microdamage in cancellous bone and cortical shell was analyzed.

Main Results:

• Trabecular microfracture was the predominant form of microdamage in cancellous bone.
• Microfracture prevalence increased with applied cyclic loading.
• Damage occurred primarily in cancellous bone before cortical shell fracture.

Conclusions:

• Cyclic loading of isolated rat tail vertebrae induces trabecular microfracture.
• Rat tail vertebrae show potential as an animal model for studying cancellous bone microdamage generation and repair.