Rhesus monkey intervertebral disk viscoelastic response to shear stress

Area of Science:

• Biomechanics
• Biomaterials science
• Orthopedics

Background:

• The intervertebral disk (IVD) is a complex biological structure exhibiting viscoelastic properties.
• Understanding the shear response of the IVD is crucial for diagnosing and treating spinal disorders.
• Existing models may not fully capture the intricate viscoelastic behavior of the IVD in shear.

Purpose of the Study:

• To develop and validate a novel analytical viscoelastic model for the shear response of the Rhesus monkey intervertebral disk.
• To assess the model's ability to predict experimental creep and stress relaxation behaviors.
• To establish a foundational mechanical model for IVD shear properties.

Main Methods:

• A series chain of four Kelvin units was employed to represent the viscoelasticity of the intervertebral disk.
• Material properties were determined by comparing model predictions with experimental strain creep data.
• Model validity was confirmed by its accuracy in predicting experimental stress relaxation test results.

Main Results:

• The developed viscoelastic model successfully captured the shear response of the Rhesus monkey intervertebral disk.
• The model accurately predicted experimental strain creep behavior, allowing for material property determination.
• The model demonstrated high accuracy in predicting experimental stress relaxation, validating its predictive capabilities.

Conclusions:

• The series Kelvin units approach provides the first analytical mechanical model for predicting intervertebral disk creep and relaxation functions in shear.
• This model offers a valuable tool for further research into spinal biomechanics and the development of treatments for disk degeneration.
• The study highlights the importance of viscoelastic modeling in understanding the mechanical behavior of spinal structures.