Trabecular deformations during screw pull-out: a micro-CT study of lapine bone

Area of Science:

• Biomedical Engineering
• Orthopedic Surgery
• Materials Science

Background:

• Mechanical fixation of endosseous implants in trabecular bone is complex due to its porous nature.
• Improving fracture fixation in osteoporotic bone necessitates understanding implant-bone interaction under load.

Purpose of the Study:

• To investigate the mechanical interaction between screw implants and trabecular bone.
• To analyze strain distribution and failure patterns during implant pull-out.

Main Methods:

• Screw implants were inserted into rabbit femur trabecular bone.
• In-situ pull-out tests were conducted within a computed tomography scanner.
• Digital volume correlation (DVC) was used to analyze 3D deformation and strain fields.

Main Results:

• Highest shear strains were observed between the screw's inner and outer thread diameters.
• Compressive strains were detected at greater distances from the screw, with smaller tensile strains.
• Identified strain concentrations and trabecular failure locations.

Conclusions:

• Experimental data on strain distribution and failure patterns can inform the design of novel screw implants.
• Findings can be utilized to validate and refine numerical simulations of implant fixation.