Cervical intervertebral disc injury during simulated frontal impact

Area of Science:

• Biomechanics
• Spinal Injury Research
• Trauma Mechanics

Background:

• Cervical disc injuries from frontal impacts are clinically observed but poorly understood biomechanically.
• Existing research lacks detailed data on the mechanisms of disc injury during frontal collisions.

Purpose of the Study:

• To quantify peak dynamic disc annular tissue strain and disc shear strain during simulated frontal impacts.
• To compare these strains with physiological loading and previously reported rear-impact data.
• To identify specific cervical levels at risk during frontal impact simulations.

Main Methods:

• Simulated frontal impact on a whole human cervical spine model with muscle force replication.
• Testing at horizontal accelerations of 4 g, 6 g, 8 g, and 10 g at the T1 vertebra.
• Comparison of measured strains against established physiological limits and rear-impact data.

Main Results:

• Peak disc shear and annular tissue strain exceeded physiological limits at C2-C3 starting at 4 g and 6 g, respectively.
• These strains propagated throughout the cervical spine at 10 g (excluding C4-C5).
• C5-C6 showed high injury risk in both frontal and rear impacts; frontal impacts also risked subfailure injuries at superior levels like C2-C3.

Conclusions:

• Frontal impacts induce significant cervical intervertebral disc strain, exceeding physiological limits at relatively low accelerations.
• The C5-C6 level is particularly vulnerable, with superior levels also at risk during frontal impacts.
• These subfailure injuries may underlie chronic head and neck pain reported by patients post-impact.