Is the ovine intervertebral disc a small human one? A finite element model study

Area of Science:

• Biomechanics
• Biomedical Engineering
• Comparative Anatomy

Background:

• Sheep are common models for intervertebral disc research.
• Human and ovine discs show similar internal stress responses despite geometric variations.

Purpose of the Study:

• To identify parameters ensuring mechanical comparability between human and ovine intervertebral discs.
• To investigate how geometric and material differences affect disc mechanics.

Main Methods:

• Developed a finite element model of the human L4-L5 lumbar intervertebral disc.
• Validated the human model with in vivo and in vitro data.
• Adapted the model geometry and material properties to ovine disc characteristics.

Main Results:

• Initial adaptation to ovine geometry resulted in higher stiffness and lower nucleus pressure.
• Adjusting annulus and nucleus elasticity improved model-measurement correlation.
• Incorporating species-specific material properties, including glycosaminoglycan content and endplate permeability, achieved good agreement with ovine disc in vitro results.

Conclusions:

• Ovine finite element models require species-specific material properties for accurate simulation.
• Human and ovine intervertebral discs are functionally adapted to produce similar internal stresses.
• This study highlights the importance of material property adaptation for interspecies comparability in disc modeling.