Finite element analysis of cervical spinal instability under physiologic loading.

Area of Science:

• Biomechanics
• Spinal Surgery
• Orthopedics

Background:

• Cervical spinal instability lacks a clear definition and established criteria.
• Understanding the biomechanical contributions of spinal components is crucial for injury assessment.
• Limited finite element studies exist on the biomechanical response of the cervical spine to injury.

Purpose of the Study:

• To develop and validate a nonlinear finite element model of the lower cervical spine.
• To investigate the biomechanical response of the cervical spine to injury by simulating damage to stabilizing structures.
• To elucidate the individual roles of ligaments, facet joints, and discs in maintaining cervical spinal stability.

Main Methods:

• Development and validation of a comprehensive, geometric, nonlinear finite element model of the lower cervical spine.
• Simulation of injuries by independently altering spinal components (ligaments, facets, disc nucleus).
• Analysis of biomechanical responses under various loading conditions (compression, shear, moments).

Main Results:

• Ligaments are critical for resisting shear and rotational moments.
• The disc nucleus provides initial stiffness under multiple physiologic loads.
• Facets are important for resisting compression, shear, and torsion at higher loads.

Conclusions:

• The study provides new insights into the biomechanical roles of spinal components in cervical stability.
• Findings highlight the interconnectedness of ligaments, facets, and discs in maintaining spinal integrity.
• Results correlate with experimental data and clinical observations, aiding in understanding cervical injuries.