Initial anisotropy in demineralized bovine cortical bone in compressive cyclic loading-unloading

Area of Science:

• Biomaterials Science
• Orthopedic Biomechanics
• Materials Science

Background:

• Bone is an anisotropic material with complex mechanical properties.
• Understanding demineralized bone's mechanical behavior is crucial for tissue engineering and regenerative medicine.
• Collagen and microstructural architecture significantly influence bone mechanics.

Purpose of the Study:

• To investigate the mechanical properties of demineralized bovine cortical femur bone under cyclic loading.
• To analyze the anisotropic mechanical responses in longitudinal, radial, and transverse directions.
• To correlate mechanical properties with bone microstructure and collagen fiber alignment.

Main Methods:

• Cyclic loading-unloading compression tests were performed on demineralized bovine cortical femur bone.
• Tests were conducted in three anatomical directions: longitudinal, radial, and transverse.
• Mechanical responses were analyzed within the physiological strain range.

Main Results:

• Loading responses were non-linear in the longitudinal direction but nearly linear in radial and transverse directions up to 2% strain.
• Non-linear unloading responses resulted in hysteresis and energy dissipation, varying by direction.
• Anisotropy was observed: radial direction was most energy dissipative, longitudinal direction was stiffest.
• Cyclic loading primarily affected bone stiffness in radial and transverse directions.

Conclusions:

• Demineralized bovine cortical femur bone exhibits significant mechanical anisotropy.
• Collagen fiber alignment and microstructural differences drive these anisotropic properties.
• Findings provide insights into demineralized bone's suitability for biomechanical applications.