High strain rate testing of bovine trabecular bone

Area of Science:

• Biomechanics
• Orthopedic Research
• Spinal Injury Research

Background:

• Spinal vertebral burst fractures can lead to severe spinal cord injuries due to posterior vertebral body failure.
• Assessing the precise damage from burst fractures is challenging due to their unique nature.
• Trabecular bone's dynamic properties are critical in determining fracture outcomes.

Purpose of the Study:

• To investigate the dynamic deformation response of trabecular bone.
• To compare dynamic and quasistatic deformation responses.
• To understand the effects of strain rate on trabecular bone strength and fracture behavior.

Main Methods:

• Utilized a modified split-Hopkinson pressure bar apparatus with quartz-crystal embedding for compliant materials.
• Tested bovine trabecular bone with and without marrow.
• Accounted for orthotropic properties by testing along principal material axes, identified via microcomputed tomography.
• Shaped stress wave pulses for constant strain rate and homogeneous deformation.

Main Results:

• Trabecular bone strength increased by approximately 2-3 times as strain rate rose from 10(-3) s(-1) to 500 s(-1).
• Bone fracture occurred beyond a critical strain threshold.
• Dynamic properties differ significantly from quasistatic responses.

Conclusions:

• Dynamic properties of trabecular bone are vital in spinal vertebral burst fractures.
• Increased strain rates enhance trabecular bone strength.
• This research provides foundational data for understanding and managing burst fracture injuries.