Semi-Automated μCT-Based Modeling of Vertebral Bony Endplate Microporosity and Mechanical Properties: Linking Microstructure to Inferred Mechanical Performance.

Background: The vertebral bony endplate (BEP) plays a role in regulating both mechanical load transfer and nutrient transport to the intervertebral disc, functions strongly influenced by its microstructural porosity. Variations in porosity impact bone strength, elasticity, and solute diffusion, affecting its overall mechanical competence. Methods: A semi-automated modeling workflow was established to quantify pore geometry and connectivity of the BEP and relate them to zone-specific mechanical and transport properties using relationships previously established in the literature. Six to eight BEPs from four bovine subjects were imaged using micro-computed tomography. The central zone and two peripheral zones of each BEP were segmented, and their microstructural properties, including tortuosity, porosity, and pore radii, were quantified using the pipeline to assess BEP heterogeneity. These metrics were then used to infer the BEP's zone-dependent density, Young's modulus, compressive strength, and shear modulus. Results: The BEPs showed spatial, intra-subject, and inter-subject morphological variability, which affected their predicted mechanical and transport properties. These findings highlight the limitations of purely idealized BEP representations in silico simulations and support the incorporation of uncertainty modeling strategies that account for physiologically relevant variations in the BEP. Conclusion: This semi-automated modeling approach represents a tangible step toward more realistic in silico simulations of vertebral endplate function.