Mechanical behavior of human morselized cancellous bone in triaxial compression testing

Area of Science:

• Biomedical Engineering
• Orthopaedic Surgery
• Materials Science

Background:

• Morselized cancellous bone is widely used in orthopaedic surgery.
• Its mechanical properties remain poorly characterized.
• Understanding these properties is crucial for graft optimization.

Purpose of the Study:

• To characterize the mechanical properties of fresh-frozen human morselized cancellous bone.
• To investigate the influence of confining pressure on bone graft behavior.
• To determine the Young's modulus and Poisson's ratio of this graft material.

Main Methods:

• Adapted a triaxial compression test apparatus from soil mechanics.
• Tested fresh-frozen human morselized cancellous bone specimens.
• Applied confining pressures ranging from 0.276 to 0.552 MPa to 30% axial strain.

Main Results:

• Observed bimodal stress-strain behavior: initial stiff linear response followed by a compliant linear response.
• Apparent axial moduli were linear functions of confining pressure.
• Particle size (0.42-3.2 mm) did not significantly affect mechanical properties.
• Determined nominal Young's modulus of 100 MPa and Poisson's ratio of 0.2.

Conclusions:

• Morselized cancellous bone exhibits pressure-dependent mechanical behavior.
• The characterized properties provide essential data for orthopaedic graft applications.
• Established a methodology for testing particulate bone graft materials.