A diffusion-weighted imaging informed continuum model of the rabbit triceps surae complex.

Area of Science:

• Biomechanics
• Computational Biology
• Animal Models

Background:

• NZ white rabbits are valuable research models due to their physiology and genetic sequencing.
• Limited computational models exist for rabbit muscle, particularly the triceps surae complex.
• The triceps surae complex shares biomechanical similarities with human muscles, making it translatable for research.

Purpose of the Study:

• To develop a geometrical model of the rabbit triceps surae.
• To incorporate diffusion-weighted imaging (DWI)-based fiber architecture into the model.
• To estimate rabbit-specific passive material properties and validate the model's predictive capabilities.

Main Methods:

• Constructed a geometrical model of the rabbit triceps surae using DWI-based fiber data.
• Estimated passive material properties from MRI-inferred muscle deformation and custom-rig force measurements.
• Validated muscle shape prediction against experimental data from a second rabbit.

Main Results:

• Rabbit triceps surae steady-state force post-rigor is comparable to post-mortem for small deformations.
• Force increases with deformation, providing a method to assess passive muscle behavior.
• DWI fiber orientation significantly impacts computational muscle shape and mechanics during simulated contraction.

Conclusions:

• The developed model provides crucial insights into rabbit triceps surae mechanics.
• Estimated material properties can inform continuum rabbit muscle models for pathology and treatment investigations.
• Findings have potential translatability to human musculotendon research and clinical applications.